RECENT WEATHER SYNOPSIS
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01/02/02 Soggy flow from the SW continues, but hopefully is due to dry out starting tommorow. Since 12/26/01 when the current storm sequence began, Pacifica has received 4.55" of rain. We have now had measurable precip 19 out of the last 21 days. Temps have remained mild, with SNL hovering between 6,500 and 8,000'. Pacifica YTD is now 21.43" or 205% of normal and is nearing our historical yearly average of 23". For the northern 2/3 of the state, a broadbrushed 120-175% PON is quite typical, but again well over 200% in favored hilly areas. Fortunately only nuisance flooding and mudslides in the North Bay from this last gully-washer, however main-stem rivers such as the Napa and Russian rivers did rise alarmingly close to flood stage. Many parts of the North Bay have been soaked with well over 20" in orographically favored areas over the last few weeks. The recent generic pattern has featured a dominant, and stationary GOA low that keeps spinning in moisture plumes and impulses underneath that plow into a weak, but equally stagnant SW-NE oriented western ridge. The lows start out disorganized then seem to deepen off the coast as they hit the ridge before weakening again and getting deflected back up north as the tails work inland. As a result, not a lot of moisture is making it's way over the Sierra or down the coast as each impulse rapidly looses steam as it dies in the drier continental air. SoCal continues relatively dry, with the cutoff point between normal and below normal rains about Pt. Concepcion. We are hopeful for our customary mid-Winter dry spell to finally take hold as storms start getting shunted "up and over" the West Coast ridge...during which time most precip will be light with tails weakly dragging accross the northern reaches of the state.
12/20/01 1800hrs Thursday eve. : The local Emergency Alert System is going off on ABC Channell 7. Last time I heard that was after the Loma Prieta Earthquake in '89. I thought we were under attack or something...it was a Severe Thunderstorm Alert for the south Santa Clara-Morgan hill area. 3/4"size hail, ferocious straight line winds (don't know exact strength, yet) and a Tornado bearing cell had just pummeled the coast in a swath between Santa Cruz and Watsonville and was heading inland. The Tornado was probably a "landspout", but it did snap a bunch telephone poles and blew off a barn roof....but the severe t'storm stuff was for real. After the first T'storm + tornado blew on through to the east, another major cell blossomed again in almost the same place off the coast and clobbered the coast once again. This time Davenport was pounded with huge hail and lightning. The cell rolled over the hills then intensified even further and caused all kinds of grief for the S. Silicon Valley area again, resulting in a second Emergency Alert, for exactly the same area. At first I thought the warning system was flakey, but the dialogue clearly mentioned a second cell forming. The radar pic showed the second cell anchored over the San Jose area, with many similarities to a meso-cyclone. Redish areas on the radar were areas of hail. Rainfall in normally dry Morgan Hill, received 3.43" of rain....2.6" falling from the two cells alone. Most rain I could find was from a reporting station in the hills above Los Gatos (west of San Jose) with 5.12". Most Santa Cruz stations received a good 2-2.75". The Sierra picked up another 2' snow above 8,000', and brief accumulations as low as 2,000'. Snow level for the most part hung around 3-4K' for all of California. Mt. Hamilton Rd. (elev. 4,200')east of S.J. is currently closed due to snow. More locally, rain totalled a modest 1.26", but still was the clear winner in the rain dept. Even normally wet Kentfield only got 1.1". Most other places around the Bay were less than an inch. Venado in Mendocino County topped out at 1.93".
12/15/01 A chilly 39F this morning ( 20's over the hill in the
North and East Bay) after a quick moving, yet potent GOA blasted the area
yesterday morning with 1-2" in favored areas and winds up to 50 mph. This
was a classic GOA low, with the core low screaming down the coast and main
trough axis virtually 90 degrees relative to the low's track. Wx plots
showed a near perfect coincidence of peak wind, wind shift from South to
North, peak rain and barometric minimum. All in all, the storm brought 44
mph gusts and 0.98" rain here in Pacifica, despite only lasting less than
6 hrs. Remote stations in the Sierra received over 3' of snow, but 18-24"
were much more common. Accumulations down to 3,000' were noted. I-5 in NorCal
was once again closed due to near-blizzard conditions. The storm rapidly
dried out as it pushed into SoCal, but once again high winds hit Kern County
and over the higher ridges. After a few minor tails drag through the State
next week, it looks like the quasi-permanent EPac High will begin it's yearly
push into and over the Western US, bringing a prolonged period of stagnant
conditions with fog, chilly air and crummy viabilities. Most storminess will
be pushed "up and over", so I expect the East will start to see Winter in
Earnest, as suggested by Joe Bastardi's recent commentary (thanks Gary).
In "normal" years, our Winter is in two parts, with a 3-6week dry period
sandwiched in between. So far, I have been pleased with the "normalcy" of
our season so far, so I would guess our main rains may take a break after
the first of the year for at least a few weeks.
On another note, quite a swarm of activity north of the Bay Area near the Ukiah area, with a 4.0 magnitude quake hitting the area yesterday. Elevated activity in the area has been going on for weeks now. Directly south of the Ukiah area is The Geysers near Calistoga, a notoriously active region. However, activity has increased many fold recently, including a 3.6 jolt..quite large for a geo-thermal event. Since all this activity is buried within the swarm, it's difficult to determine foreshock/aftershock categories for the activity. Another observation is that much of the activity is quite shallow, some at 0.0 Km depth. I estimate that should the entire fault rupture, from the Geysers to Ukiah, a 6.0 - 7.0 magnitude quake could occur. Given the recent elevated activity in the area over the last 2-3 years (Napa, Yountville, Burney Falls, Redding all with strong shocks), and the distance away from the stress relief of Loma Prieta in '89, this part of California is showing definite signs of stress accumulation. If Loma Prieta was any indication, these moderate quakes may continue on/off for many years before a major rupture takes place....or it may happen tommorow. Such is life in Earthquake Country.
12/03/01 Northerly winds have evolved after our last low slipped down south as upper level energy has kicked out to the NE, while a weak surface vortex moved south over central portions of Calif. The track saw the low go inland around the Ca/Ore border accompanied by a huge shower field to it's west. Tornado watches were briefly raised on 12/2 (after the previous post) from a severe T'storm east of Red Bluff/Chico. Heavy showers, though predicted, never really materialized here in Pacifica as the shower field disintegrated rapidly once the low made landfall. However, all day in Silicon Valley, locally intense squalls developed seemingly out of nowhere in time frames less than 1 hr before dumping heavy rain then dissipating. Very unusual. Some breathtaking scenery all around as multi-colored skies with a great variety of clouds dominated the sky. Sunrise with deep red skies silhouette three huge Cb's over the far south Bay was particularly spectacular. Behind this low, north to northwest winds aloft will continue, allowing some minor impulses to brush the northern areas with some showers in 24 and again in 72 hrs, but most energy should stay well to the north, allowing us to dry out for a while. Some other notes on recent events:
From 12/01 to 12/03: Peak rain noted so far: 11.5" in Boulder Creek (coast
range south of San Francisco) and 10.4" in Ross (Marin County just north
Minimum rain same period: 0.86" in Livermore.
Peak winds: est 100+mph on the highest ridges at Squaw Valley
Total rain in Pacifica during 11 days from Nov 21st to Dec. 2nd: = 9.32"
Total rain at SFO (<5 miles east of Pacifica on the other side of The Hill) = 4.4"
# days with winds > 30 mph (same period) = 5
# days with wind > 50 mph = 4
# days with wind > 60 mph = 1
# days with measurable precip = 9
# days with rain > 1" = 5
# days with rain > 2" = 2
Lowest bar. press = 29.41" on the 24th.
12/02/01 End of Major GOA Sequence
Twin GOA lows battered the West Coast and produced 5.3" of rain in last 24hrs here in Pacifica. We received 2.6" in the 8 hrs alone from Storm #2 early this morning , with the parent low still well off the coast. Going back to the start of this pattern 10 days ago on the 21st, rain since then has been 9.12". Power was on/off all night. Flooding danger briefly introduced into the North Bay...the Russian River rose 13' in 18 hrs yesterday. Local street flooding is occurring throughout the Bay Area, and small creeks have risen dramatically in a very short time period. Will be checking on river levels later on. Storm #1, despite it's core being way up by the Canadian border, brought winds to 49mph and 2.39" of steady rain between 0000 and 2100 on 12/01. The large low slowed as it hit the coast, and the long tail first stalled (a-la hosed), then slowly dragged down the coast. No real cold frontal passage with this event, as the more warm front-like peak rains came almost 3 hrs after barometric low and peak wind speeds. . The winds seemed to have finally mixed out the cold air that's been trapped up north, hence snow levels have briefly risen back up to the 4-5K' levels. Storm # 2, dragging very chilly air behind it and feeding on the sub-tropical tap generated by Storm #1, swung underneath #1 and slammed into the coast around the Cal/Ore border. Rain and wind pummeled the entire coast with gale/storm force winds and torrential rains ahead of this potent low all night. Frontal passage is not expected here for hours yet...and IR imagery indicates it could be a whopper. In two distinctly different rain bands, rainrates were sustaining around 0.9"/hr. Rainrates>0.6" fell for the last 4 hrs. Rainfall is now squally, and should remain so until main frontal passage. Peak winds of 53mph hit a few hours ago, and are still gusting in the mid-40mph range out of the South. My gut feeling is the Sierra may pick up anywhere up to 8' (feet) of snow over the higher ridges as each storm's wind flow has produced perfect orographic enhancement conditions + unusually low snow levels for such wet storms. Snow level with Storm #2 may once again drop to <2,000' up north on it's backside. I understand near sea level SNL for the Seattle area is possible. As of 0600 hrs, 12/02/01 unbelievable range in precip values. Boulder Creek last 24 hrs. 9.41": San Jose 0.39" Davenport 0.89 : Hayward 4.7": Oakland 0.61 : Ross 6.3" : Santa Rosa <1" : San Pedro Creek (near my old digs next to the ocean, where we flooded in 1982) crested just 3' below flood stage. Some local street flooding, shopping center parking area, and front lawn flooding in lower Linda Mar. Ridgetops in the Sierra clocked 105+ mph winds. Up to 6' snow possible in higher elevations, 2-4' common below 7,000'.Pacifica
Summary to date: Note "Normal" is based on my records to 1984.
Nov. total 6.3" (181 PON)
Dec. rain to date (2 days) 5.39" (or 139 PON for the entire month)
RYTD - 12.39" (228 PON)
Normal to date 5.4"
11/29/01 Storm #1 of an upcoming now 4 storm sequence dropped 1.9" rain to Pacifica in a 7 hr period. Most rain came during in one 3 hr stretch with rainrates between 0.3"/hr to 0.5"/hr. Peak rain was 0.22" from 2100-2130. Minor property damage from high winds that hit 80+ on exposed ridges. In Pacifica, peak wind gust was 59mph and once again accompanied the barometric frontal passage. Depending on many factors, peak storm winds as well as rainfall often does not occur in conjunction with lowest barometric pressure....which has been the case for the last 2-3 yrs. The pattern we are in now is a classic GOA sequence of storms of relatively similar strength and character hitting the coast every 48-60hrs. Other details on Storm#1: I-5 just north of Redding to the Oregon border (150 miles) was shut down almost 12 hrs due to blizzard conditions above 2,000''. Mt Shasta City, elev. 3,500' was socked with 20" in 18 hrs. Cazadero (far North Bay Area) rain for 24hrs was 5"+. Santa Lucia's just south of Santa Cruz had 2.6". Storm#2+3 now expected over the weekend into early next week before a 1 day lull followed by a colder storm on Wed.
11/28/01 The entire West Coast is bracing for another 1-2 punch from two more intense Pacific lows, once again powering down the coast from the GOA. Significant snow accumulations may occur as low as 1,500-2,000' in the far NW corner of the state, with SNL as low as 3,500' locally. Winds are anticipated to gust near 50mph later today and tonight, accompanied by occasionally heavy rain. I expect another "classic" GOA frontal passage with this one, perhaps even more spectacular than the last one 5 days ago. Heavier precip and wind is possible for storm #2, due to hit around the middle of the weekend. Both lows are deep, with significant windfields extending almost 1,000 miles away from the core low. Both storms have the potential to do local damage for the next week or so, due the strength of the subtropical feed fueling storm # 1.
11/25/01 The second of two cold core lows over the last 4 days is now exiting California, after bringing 60mph wind to Pacifica and many places inland, and rainfall between 0.59" (Oakland) to over 4" in orographically favored areas of the S.Cent Sierra. In Pacifica, we received only 0.89". Lightning, thunder, heavy rain and pea-hail accompanied by peak winds clearly defined the brief frontal passage at around 0700 on the 24th, with many showers of instability behind the front. This storm could have been a lot worse had it not been moving almost 40mph as it zipped to the SW. Rain in earnest only lasted 6 hrs here. The worst of it were the power failures (3) which neccesitated powering the house on our portable generator for almost 5 hours total. Some locally moderate wind damage was noted in the form of roof damage and downed trees/limbs across the state. These last two storms carried more wind than events over the last few years, hence the extra damage to overgrown trees, etc. We have yet to even approach soil saturation, so small stream flood flooding has not been a problem. A quick check of snow depths in the Cent Sierra shows 50%-85% of normal..example: a paltry 6" at Caples Lake, elev. 7,800' before this last event, now up to 15". Average to date is around 20" by now.
11/23/01 Our last storm 2 days ago brought widely varying rainfall to the state as orographic lifting played a huge role in wringing out moisture from the moist SW flow. A strong low core north of Washington brought gusty winds and huge surf to the coast but only 0.26" rain in Pacifica. Mountain areas to our north had much more, led by Mt St. Helena with 3.4" and the west slopes of the Sierra with over 5" in many spots (Blue Canyon had 4.55"). Rain rates dropped dramatically to the south as the Santa Lucias only received a little over 1". Winds however really pounded the Kern County area (South Central Sierra) with top speeds of 114mph reported in remote locations, and 80's-90's widespread. The Mojave desert area also clocked widespread winds in the 80+ range. In it's wake, the exiting system left a weak ridge over the west coast with plenty of dirt riding up and over, giving us mostly cloudy, cool weather today (Fri.) On the west side of the weak EPac high, a baroclinic low has formed and is tapping both cold N.Pacific air from a large general low in the northwest Pacific and warmer air north of 25N (no tropical feed at this time, fortunately). This is setting the stage for a possibly major rain event within 24 hr. should the entire system remain progressive and continue pushing east. The main caveat is all ingredients need to stay intact to maintain the storm's dynamics. Should the EPac high or the NPac low stall (which often happens this time of year), the moisture supply will likely outrun the baroclinic low and our storm will rapidly become nothing more than a nuisance.
11/18/01 SPECIAL LEONIDS REPORT
A great show, best I've ever seen by far. We (our family of 3) observed the event from Sonora, in the Sierra foothills, elev 2,000', under crystal clear skies overhead and hazy horizons. After starting our observing period in earnest around 0915, by 0030 (all times in GMT) we had seen 100's of meteors with activity still on the order of 2-4/min, and showing little signs of slowing down. We observed Zhr of 300-500 between 1000 and 1130 , with the most intense peak between 1010 and 1030, during which we counted 83 in a single ten minute period - equivalent to almost 500/hr. I believe there were three "peaks": the smallest around 0945, the main event around 1010-1030 and the last around 1120 which had a high percentage of the brightest meteors visible in Orion (a trend which continued after the peak, just less numerous). On several occasions, multiple meteors were visible nearly continuously for extended times as long as 5 seconds. Shortly after 1015, we estimated in one minute a max count of 19 (even with three sets of eyes, counting at times was impossible), which occurred quite suddenly after a brief lull. Within our general observation time period of 0930 and 0030, the most active swarms lasted 10-15 minutes each, with sporadic flurries at other times interspersed within the background activity of 3-5 meteors/min. The background activity occasionally fell to the 1-3 meteors/min range (mostly faint, short lived meteors) but these brief lulls were short in duration and about as numerous as the flurries. While all the meteors had Leo generally as the radiant point, (we saw zero non-leonids meteors), they seemed most numerous in three distinct areas of the sky away from Leo: slightly east of and including Orion; north of Ursa Major (big dipper); and the vicinity of Gemini. It was our observation that activity seemed to peak in one area or another, but rarely simultaneously. The largest meteors (although bright ones were periodically seen throughout our observing period) seemed most frequent after the peaks of swarms. Three fireballs were seen at 1030, 1100 and 1120, while generally smaller, faster meteors were seen during the swarms. Many, many meteors with residual tails of colored smoke were seen, mostly reds and blues, with a few blue/greenish. Two of the three fireballs exploded/flared at the end, which actually created shadows on the ground, producing long-lived ion trails that lasted over 1 minute (both blue-green) The other fireball low over the northern horizon, was visible for well over a second leaving a red/yellow trail but no ionized afterglow. Very few other yellow trails noted. Preliminary data from SpaceWeather.com had the peak at 800+/hr in the continental US, and 1200/hr in Hawaii. Unconfirmed reports from a high elevation observatory in the Southwest (Arizona?) had peak rates as high as 2,220/hr, however many were reportedly very faint and were likely invisible to observers closer to sea level. Local news sources said NASA estimates over Cent Calif ranged to 1,200/hr. . Was lucky to get almost 4 dozen meteors on video-tape, with a couple particularly brilliant. 1 such meteor was captured flying right through Orion, and may be of good enough quality for a still. I found that by setting my video-cam to the Super Nightshot mode (which is the infra-red only setting), a couple of meteors not seen optically showed up via their heat trails. Very cool.
11/10/01 Major Early Fall Rain Event
After a nice 2 week lull in-between storms (last one Oct 30), starting the night of 11/11 and ending 2 days later (11/13, 1100), Pacifica was slammed with 3.4" from a double barreled system that also dumped huge rains in the surrounding coast range and the "North Counties". NWS cited numerous 4"+ totals. The pattern set up first with a weakening, convective low that moved NE over the Cent Coast on 11/11, bringing warm light rains to most places, but more substantial rains in orographically favored areas (such as my house sometimes is!). While many places were measuring rain in 1's or 2's tenths, we received 1.35" here, with isolated higher totals elsewhere. After saturating the atmosphere, a second, more potent low moved down the coast, and working with the combined moisture of leftovers from Storm#1 and a mild tropical feed, flared to big-time proportions right off the coast. After stalling, and strengthening a bit, the parent low shifted N while the trough continued pushing head-on into the Cent Coast. Frontal passage occurred here on 11/13 between 0715 and 0730, when 0.47" fell. For the hour between 0700 and 0800, 0.8" fell. Not bad. Fortunately, we only had modest wind, topping out at 37mph. Interesting note, the strongest sustained winds, by far, occurred after the rain subsided and on a strongly rising barometer, except the wind direction never changed from dead South. The trough axis ran right up the coast like run in a nylon stocking (yup, my wife has educated me). Since there doesn't appear to be any strong signals one way or the other, for my early Winter forecast I must rely on the observation that the prime Winter storm tracks have been generally advertised during the late Summer/early Fall of these last few years of La Nada. Coupled with my totally unscientific "senses" I believe these early storms may be signaling an early Winter pattern of a split flow in the jet, with moderately long periods of dry interrupted by significant rain events whenever the two jets merge off the coast...a-la a Pineapple Connection. Snowfall in the Sierra, so critical to our Summer water/electricity supply, can be above normal should the snow level remain below 6K'. While these rains were certainly significant, and badly needed, our rain-to-date totals for the year are only near to slightly below normal. Some mountain and inland locations are still much below normal, while others, mostly nearest the coast, are closer to100% after the last event.
10/30/01 2001-2002 Rainy season begins!
After a most benign October and minimal "Indian Summer", a deep plume of tropical moisture streaming northeastward for the past several days interacted with a deep GOA trough advancing from the West and brought 0.6" rain to Pacifica, 1/2 inch to San Francisco, 3/4"+ to the North Bay and almost 1 1/2" to the Santa Lucia mountains to our south. The system was slow in organizing, and models handled it generally well. Given the deep moisture available, it was actually a bit surprising we didn't get more rain than we did. Fortunately, the low didn't deepen quite as much as expected as cold air didn't advect quickly enough. The main low is currently lifting to the NE, dragging a non-descript front along the coast. In it's wake, a zonal flow is starting to develop, and two more quick moving short waves may bring more unsettled weather to the area in 24 and 48 hrs respectively, this time from a more W NW direction. This pattern is quite unusual in that typically our early rains are the result of lows sweeping inland to the north dragging tails that progressively sag deeper to the south as the rainy season matures. The departing system's moisture plume strongly resembled a "Pineapple Connection", the likes of which we haven't seen for the last few years, and even when it does occur, generally happens much later into the rainy season. In October 1999, a very strong low developed off the coast which brought huge surf and early rain to Pacifica, but remained off the coast before sliding south, thus setting the pattern for the next two + years. We are hoping that this storm will help define a more west-east generic storm track for the first part of our rainy season, and if it pans out, a wet and blustery early Winter may be on tap.
10/01/01 Heat wave simmers down! An unexpectedly strong offshore gradient developed Saturday night (12mb SFO-WMC) which brought record temps briefly to the area yesterday. By 0700 in the morning, temps aloft at 3,800' (Mt Diablo) had climbed to 78F with 30+ mph easterly winds. Daily record highs of 93 in S.F. and 90.6 here in Pacifica were noted, as well as record temps in San Jose and elsewhere. It amazing how fast temps can fluctuate hereabouts this time of year. For example in Pacifica , after a steady climb, temps peaked at 91 @ 3 p.m. By 4:40p.m. under slackening winds, temp was down to 75F and by 6:30 down to 69.8. I was in Livermore, in the far South-East Bay, and easterly (offshore) winds were gusting to nearly 30mph, temps in the low 90's and humidity in the teens. To be honest, without the winds it was very comfortable with warmth/low humidity conditions. This morning (0700) the fog is back, streaming into/under the Golden Gate. Here at my house though, brilliant sunshine, calm winds and a pleasant 60F. It wouldn't surprise if parts of The City hit 80+ while other parts closer to the ocean/bay have trouble hitting 60. This morning's fog is only a couple hundred feet thick, but it is cold and thick with well-defined boundaries. The Bridge's towers are basking in sunshine while the deck is invisible. Just another of those classic "only in SF" pictures. Beautiful.
09/30/01 Indian Summer (misnomer) arrived in San Francisco yesterday,
as well as our Golden Crown sparrows which arrived exactly on schedule on
Friday the 28th. Offshore winds have developed in back of our latest trough
which pushed through to our north on Fri/Sat. While no record busting temps
are anticipated, at least we'll get a few 70+ days out of it. Some interesting
Offshore SST's have developed a temperature "wall" about 25 miles offshore. According to a local outdoor writer, as well as my own fishing information, near-shore temps continue to hang at 53F (as of 09/27) which is 6-8 degrees cooler than typical this time of year.These temps continue out to 25 miles offshore, where an abrupt change in SST occurs, with 62-64F noted. The dividing line between warm and cold water is extremely sharp, only 25 yards wide in some places, with major upwelling taking place on the cool side. On the cold side of the line, huge schools of krill have accumulated, and as a result the largest groups of whales seen in memory are gorging on the feed. However, the water temp is so cold anchovy and sardines have been pushed north, and Oregon commercial fisherman actually out-fished their California cousins. California Kings have been caught in record numbers in Oregon, while Oregon Silvers (coho), which feed on krill, have been caught down here. In the warm water, tropical fish are showing with dorado and baracuda and huge numbers of albacore tuna being caught
09/25/01 -Major Solar Flare
Last night's lightning show brought our final rain total to 0.21", bringing our total rain to date (since July 1) to .35". NWS reported an estimated 1,600 lightning strikes in Cent. California from three distinct T'storm "lines" that developed then moved through the area late yesterday afternoon through 2100 last night. Other unconfirmed reports had over 4,000 hits over all of northern California, which puts this storm relatively on par with the record Sept. '99 event. However, I was out chasing the lightning, as I was in '99, and last night's event was much tamer than the '99 event. I won't quibble the numbers, but I can't agree that the lightning was equal to '99. Interesting though, that two major summer events such as last night's and '99 produced the most lightning in local weather records within 2 years of each other (different mechanisms, though). Last night's event was notable in another regard....I watched the entire day's cloud development, and I never saw a Thunderhead! In fact, not even a cumulus cloud. As sometimes happens, upper level moisture can produce extreme turbulence within a fairly narrow zone in the atmosphere. Hence, clouds seen from the ground take on a rather benign alto stratus look, with cells on top of the stratus. And such was the case last night. I monitored clouds tops via the internet, and never saw a top > 25,000', with cloud base generally around 8,000'. From my vantage point on the west side of The Bay, I could see over 30 miles in any direction...and lightning was occurring randomly over the entire area. Note that in '99, the summer storms preceded a drier than normal winter overall. Will have to wait and see if history repeats.
BTW, autumn has definitely set in, as colors are starting show everywhere. We had a sudden, brilliant Spring, and flora appears bent on repeating with Fall colors. Amazing what a little La Nada does for resetting Nature's clock(s).
09/24/01-Major T'storm Outbreak in Bay Area!
After toying with the coast for the last several days, a Pacific (not tropical) upper low finally pushed to the coast with at least two major squall bands in front of the parent low, and a possible third on the way. So far, almost 0.2" of rain during the last Tstorm, with thunder and lightning lasting a couple of hours. As I write this note, another flash after an hour lull just lit up the back hill. The squall bands became very well defined late this afternoon along a good stretch of the entire Cent Coast, with heavy rain embedded. Moderate storms have erupted from off the coast all the way to the Sierra. Tropical showers/Tstorms in Sept. are certainly not unheard of, in fact they are most prone in mid Sept thru early Oct. However, they almost always come from tropical surges usually from dying hurricanes. This low drifted up from the SW, picking up cold air support as it pushed north. The upper low is being pushed by yet another digging trough coming down from the GOA, which may bring more light rain late this weekend or early next week. This is our typical "Summer" period, and Sept. frequently has the highest mean temp of the year (59-61 typical). This year, Summer still has not arrived...and if the 30 day progs are close, we may not see our classic late summer/early fall sunshine with no fog at all. I suspect folks inland should pay attention to this system, considering the punch it already has working with not-as-juicy Pacific air.
08/22/01 Howdy all, been a while since my last post, but as is typical this time of year, there's been little to report event-wise. However, from a more broadbrush perspective, the summer has been unusually cool here on the coast, with some sporadic higher than normal temps in the valley areas. Our weather continues to be periodically influenced by North Pacific upper lows that pivot underneath the parent quasi-permanent Gulf of Alaska low. As these lows wing eastward, they push cool moist air onto the coast ahead of them, and while even high clouds are often missing, enough energy at the surface can cause drizzle heavy enough to be classified as light rain. For instance, July 18th brought .12" of rain/drizzle. The pattern is much more typical of late Spring or Fall when dying fronts brush the coast. All summer long our Sea Surface Temps (SST's) have remained a steady 54-57F, however there has been a hint of a more westerly/northwesterly component to the swell than usual. The exception to this pattern brought a sudden, major shift in sea and swell direction (12' seas) from the south-southwest during the third week of July that lasted almost a week. This event was triggered by a freakish low at the surface moving north from off Pt. Concepcion. Most southern moisture packages come in the form of upper level dying/dead hurricanes/tropical storms this time of year, not surface lows. As for the flora/fauna/environment scene, you all know about the fires...but read into this the lack of summer rains over the mountains and darn near critical dryness over the last 2yrs in the Northwest. Local tree growth, shrubbery/etc however has remained green and strong so far , mainly due from normal rains for the year here locally. With rainyear 2000-2001 (July1-June30) now over, San Francisco precip totals fell within a narrow normal zone with much below average rains to the north and much above average rains in the southland. But isn't that typical of strong El Nino patterns you ask? Indeed it is. Until recently however, the last two year's Central Pacific SST's have been consistently near to slightly below normal (La Nina evolving into La Nada into the current El micro-Nino). Very Curious.
Now for the real reason for this post (it's about time). It's getting chilly! Santa Rosa had a low of 45F 2 nights ago. In Pacifica, I've logged 2 other sub-50F low readings as well in the last 2 weeks. What's interesting is that these temps are well BELOW SST temps. Usually with summer onshore flow our nighttime temps are within 1-2degrees of the local SST, It takes an unusual set of circumstances (plunging upper level lows) to drive cold air this far south. Freezing levels near 11,000 has been forecasted up north in Washington and snow is possible over the higher mountains farther south.
BTW, a final note of interest. Striped Bass season lasted only 5 weeks this year and was squashed big time by the aforementioned southern shift in the surf direction in mid July. However, for those five weeks preceding, it was Glorious fishing for the shore casters. I got lucky twice with one major run yielding 12 fish (all released) between 14-22lbs, and a 29 pounder in another run (I kept that one). All told the total was 23 fish for the season and son Joel had 6. This compares to 3 for me last year and 0 for Joel. I bore you with this trivia only to illustrate how different fish feeding patterns can be affected by changes beyond our capabilities to identify them, let alone measure those changes. By most rights, this year's oceanic environment was a carbon copy of last year, but obviously someone forgot to tell the Striped Bass.
06/08/01 Warm temps the last few days, but hardly any records. Our Summer fog pattern appears ready to finally settle in after fits and spurts over the last month or so. With SST's still 54-56F, I expect a cool, foggy Summer, similar to last year's. However, remember that even though temps overall were below normal coastside, intermittent hot spells occurred, some producing record temps...just like this year (see below). Salmon fishing, after a good start mostly south of Half Moon Bay and very good in Monterey, has tapered off to almost nil everywhere along the Cent Coast. The commercial fleet has apparently located fish 30-50 miles offshore and down very deep. If these are the same schools from down south , then their migration pattern may be reverting to one typical of many years ago when fish moved offshore to our north before turning around and coming south again closer to shore. Have also noted an unusual revision in Dr. Gray's Hurricane Forecast, which now calls for an above average Atlantic season after predicting a very modest season at best only a few months ago. Prime reason seems to be a scaled back prediction of warming Pacific waters, hence the predicted mild El Nino may not appear as intensely, if at all, in the near term. If this pattern does pan out, then a continued La Nada pattern may be in the offing, possibly signaling a continued below-normal rainfall pattern in No/Cent Calif.
05/31/01 RECORD HEAT IN SF ON 30th A month of extremes to say the least. Beginning with the unheard of frost on the 2nd, things got roaring hot by the 30th, setting all kinds of records including an unbelievable 101F in San Francisco, and 92 (briefly) here. In Spring Valley, the "official" RAWS site about 3 miles from here as the crow flies, temp hit 96. By comparison, San Francisco's alltime high is 104 and 96 here in Pacifica, so here in May we neared hottest-ever conditions. Note the record highs mentioned above occurred last year on June 14, so the La Nada weather pattern seems anything but "nothing". Can't help but think that the intense Solar activity in April as mentioned a while back set the stage for such unusual extremes. May is often an unpredictable month, some years no rain at all, and others (such as 97-98) when 4" can fall, sometimes in convective patterns. This year, we received only .03" in drizzle, and we were hard pressed to see any clouds at all (excluding the fog, that is). Grasses, trees and virtually all forms of flora are lush this Spring. Fire officials have already raised the Red Flag alerting residences of an extremely high fire danger for the upcoming fire season. Just cross your fingers we have a cool, foggy Summer to keep things in check
5/02/01 MAY FROST!!! Early this morning, frost on the roofs at the bottom of the hill I live on. Temp up here 42F. Absolutely, positively unheard of for this time of year. Strong westerly winds early yesterday shifted northerly and died down overnight, resulting in dead still air which allowed cold air to sink into sheltered valleys.... yet 56 mph howled in the east bay hills that same hour! Boy, can things change in a hurry! As of 2100 hrs, winds are now gusting from the ENE at over 30mph here, and over 60mph in the higher hills. Temp is a robust 69F and showing no signs of cooling off as a low gathers strength over the Four Corners region before kicking east.
4/10/01 SNOWING IN BAY AREA!!! Second week in April (8th), and it was SNOWING at 1,720 on Hiway 9 (around 10 miles East of Santa Cruz Bob's place). It was 30 in Napa and 31 in Santa Rosa. These freezing temps at sea level are extremely rare this late in the season, and agri-business is in a tizzy over potential damage. Typically, we have seen our last frost for the year by early March, assuming we get any at all. Total rain from this moisture starved system was .89"., and we are continuing to have intermittent light rains. Also noted a severe storm east of Los Angeles that caused a 100 car pileup and regrettably one death. Solar activity remains very active (but subsiding) however a moderate, long duration C class flare appears to have been in Position "A" early on the 9th with a major space storm expected sometime between the 11th and 12th...so northern lights are a distinct possibility. This last two week period has been a great laboratory for measuring the direct weather effects of solar storms, as these recent solar wind blasts came on very suddenly after a prolonged downtrend in activity. For those in the know, an excellent signal to noise ratio.
4/05/01 If you read this note before 4/06, check out this web site ( http://dxlc.com/solar/ ) for info on the incoming shockwave from the largest flare in over 25 yrs (est.), an X-22 mag. flare + CME (some key satellite instruments apparently saturate around X-18 strength, so the X-22 magnitude is subjective). The flare occurred April 2. Another X-class flare occurred today. 1/1/2 weeks ago, another major flare sequence occurred, and has been mentioned in a couple of places as a weather (tropospheric) trigger for many of the current unusual atmospheric dynamics. In Pacifica, for example, a very unusual frost was everywhere this morning from what weems like the umpteenth time since last August a blast of cold, northern air plunging straight down the coast and it's associated "cutoff low".. Air aloft (850mb) was within 2C of the temps in February when record snows hit No + So Cal. Despite predictions of convection and possible snow down to 1,500-2,000', the air was so dry only a few isolated Cu evolved over the hills. Unless we get a real late rain event (unlikely), this rainyear will be slightly below normal in Pacifca (cent Ca.), with much below in the North to above normal in the South.
4/01/01 After near record temps on 3/31, the pattern is finally showing signs of another N-S shot of cold air. At this time, storms appear to want to track too far West to bring us much rain, however cold air plunging down the coast may bring some damaging cold.
3/07/01 Continuing this La Nada yearlong pattern of long spell rain events interspersed between equally long periods of dry, another six straight days of rain have just ended, with flooding rains to our south and high winds here. While only 1.03" fell in Pacifica for the entire 6 day event, many places in SoCal, especially near Santa Barbara/Ventura counties received up to 15" rain the mountains and 6-8" in the lowlands. As mentioned in my post 10 days ago, a complex pattern of a first low pummeling the coast moving up from the SW then retrograding off NoRcal coast while a second, colder storm moved N-S west of the first low and eventually picking up the now weakened first low and flung the entire mess onto the coast mostly from Cape Mendocino south to northern Mexico. As the first low brushed by the Cent Coast at a respectable pressure of 992mb, the main event was the wind, which topped 80mph on Mt. Diablo and up to 60 at Pigeon Point. Peak wind here in Pacifica was 52mph, and almost 36hrs of sustained heavy wind plagued the area as the first low drifted up the coast before weakening. After one more shot of rain expected on the 9th, all progs show us finally developing a decent enough ridge to the north dry us out for the next 10 days (hopefully).
2/26/01 After nine straight days of rain (17th-25th), skies and lawns are finally trying to dry out. A seemingly endless parade of four upper level lows and numerous secondary /eddylows belted the coast and brought intermittent rains, and occasional convection, but no sustained, heavy rains..at least to Pacifica. We totalled a respectable 4.42" for the entire period, and of the nine rain-days, the largest daily rain came on the 19th when exactly 1" fell. in 4 bursts. Elsewhere, though, especially in SoCal and the mountains south of Monterey, received heavy rains and ground is now near/past saturation. Snow once again was reported in the Bay Area hills on the23rd and 24th, however this time snow was confined to elevations >1.5- 2K' north of the central Bay Area, and rose quickly to 3,500' near Mt. Hamilton. Even though temps were generally still below normal, this rainy period featured a track with a much more west-east component and juicier air along with it. An interesting note to rainfall patterns up and down the coast, as SoCal is now above normal rains, but PON drops as you go northward. SF seems about the "average" line, with most areas northward into Canada below to much below normal to date. Eureka, is currently 65% of normal, while here in Pacifica, our 18.6" rain to date is near normal (19-20") and approaching the low end of our normal annual rain total (yearly norm 23"-30"). As for storm pattern, all storms moved across the Pacific along a near zonal flow until slowing and basically were either cutoff or shunted away from the coast as energy split both north and south, with the cold cores generally moving inland south of Pt. Conception after meandering along the coast. Only once did some tropical moisture get entrained -on the 19th, but the bulk of the precip hit SoCal. After a couple days of clearing, it looks like another round of rain is in our future, as this time a low to our southwest looks like it will move up the coast before going into retrograde off NoRcal coast as a second, colder, low drops N-S down the coast and anchors off SoCal, absorbing the first low in the process. A potent warm from is starting to appear on satellite now from the first low, with convection along the leading edge and along the trailing cold front associated with the core low itself-an interesting start considering the storm is 32'Lat. and still 1,000 miles away. Will wait to see if this complicated pattern verifies.
2/17/01 Pineapple? I 'm smelling raisins..as in winds coming
from the SE. As of early this a.m., a "new" cold upper low @ 45N (first visible
to me yesterday morning) on the northern quadrant of weakening parent low
which is now around 32N, appears to be shifting north and west off the B.C.
coast, robbing the parent low of upper air support...hence the "stretching
out" and weakening of the front which is easily seen on Satellite. The parent
low, now quite weak barometrically, is sitting west of Pt. Conception (should
be spelled Concepcion), and is pushing moisture north , but since we are
on the "dry" or wrap-around side, yesterday's prediction of heavy rain seems
too optimistic. This first storm seems to be undergoing a classic "martyr"
pattern...a la the sacrificial lamb that moistens up the atmosphere ahead
of the holy army to follow (Sun nite/Mon then again on Thurs.). I don't really
see a "Pineapple connection" developing----as yet. The jet(s) are still too
far split, and the southern one in particular seems to be sagging south ahead
of today's storm instead of pulling north. Storm #2 on Sun. nite does show
some nice digging, but persistent doldrums air south of around 25N seems
to be retarding the juicing up of the upper air flow..hence minimal tropical
enhancement. What seems to be missing is a strong suppressed EPAC high flinging
moisture up and over the west/northern flank to serve as fuel for storms
to the North (dirty ridges).. Note that, except for a tantalizing hint of
a 1,000 mile long west-east flow north of Hawaii (good direction, but still
somewhat moisture starved), most of the cloud streams across the entire Pacific
(refer to NRL Stitched Pacific IR ) are showing an "outward" bowing, evidence
that weather is being produced by advancing cold air. Dirty ridges and the
like, show an "inward" bowing to the cloud/moisture stream, which indicates
advancing warm air packages. When a persistent dirty ridge fuels a
quasi-stationary GOA low, a deep trough can develop over time along the flanks.
I think today's storm (#1) looks like the energy in the North wants to go
into retrograde and set up the GOA low half of the connection, however the
moist subtropical ridge seems weak/missing. However, once the GOA low is
set up later today, storm #2, should pivot underneath and slam into the West
coast by Monday, briefly dragging some subtropical air up ahead of it before
a decent cold front passage. Good rain early next week is my bet, and some
orographically enhanced precip likely in the North Bay and the Santa Lucia's.
Rain on Tues/Wed. if any, will be a good indicator of the strength of the
hose, if any, should it get turned on. The Thurs. storm (#3) looks great
on satellite NE of Japan, and has excellent cold and warm air inflows..however
it too may push north before sliding south and is likely to loose some tropical
support as it advances. Time will tell.
An interesting observation, I was glancing at rainfall PON for the entire West coast, and the farther north you go up to B.C. the less rain PON there has been. While I would say this Winter has been anything BUT El Nino-like down here, the rainfall distribution is disturbingly El Nino-ish. Alaska has had one of the warmest/driest Winters on record, also another El Nino-like feature....yet SST's have shown very little anomolous warmth, and the tropics have been extremely quiet, especially the ITCZ. I have often wondered if basic airflow changes precede SST changes, or vice-versa. When the El Nino of 1997-98 died, La Nina-like cold air brought the big chill in December '98. SST's were still warm but fading when the rain pattern shift occured. This year, SST's are hinting of a return to El Nino conditions, but very minor changes in temps have been noted so far, but rainfall totals (not pattern) suggest otherwise. Very, very curious. So much for the progs of a "normal" Winter..ha, ha.
02/15/01 The second upper level low mentioned in the previous posting has just now started to kick east after sliding/meadering down the coast all the way past the Mexican border. Wrap-around moisture had continued in the Bay Area, keeping skies partly cloudy, but no more rain after the 12th here, although showers did develop over the valleys and points south on the 13th. Heavy wind, rain and snow pummelled the southland, even heavier than up here a few days earlier. 5' of snow had been reported on Mt. Blady, with widespread snow down to 3,500'. Flash flood watches were posted for the entire southern Cal coast, and some minor landslides were reported, but no major damage to speak of. %" of rain was reported in many locations, including downtown LA. It finally appears the High pressure that nosed north is going to be undercut by a couple of developing Pacific lows, both of which will be able to tap juicier air than their cold air cousins. Right now, the first and probably stronger event will be here in 72 hrs or so. Even after the 3"+ rain in SF during the last week, rain PON is still only around 75%..another testimony of just how dry our early season was.
02/12/01 MAJOR BAY AREA SNOW EVENT!
After another 12 days of dry, twin lows plummeted down the coast and brought intermittant heavy rain, thunderstorms and widespread snow down to surface levels east and north of the Bay Area between the 9th and 12th. 2.81" of rain fell here in Pacifica, with many ice pellet showers and lightning on the 10th and 11th. Both upper level lows came straight down the coast after swinging up and over a narrow ridge extending well into the arctic. The modified-arctic-air-fueled lows spawned intense convective activity at times, with T'storms, occassionally reaching moderate in intensity (especially on the night of the 10th). Convective activity was noted in both the forerunning cold fronts and in squalls behind the fronts and near the vortex cores. Both upper lows intensified as they moved south into moister air, and significantly exceeded model expectations. Over 5" liquid equivalent fell in favored mountainous areas, mostly in the Santa Lucias. 3-4" was widespread in other areas, although some lowland areas, less favorable oragraphically, only recieved 1.75-2". Overall, the general snow level was 2K' for the weaker Friday event and 1K'-1.5K' for the stringer Sun/Mon. event, however snow fell in many areas at much lower elevations. Mount Hamilton, in the SE of the Bay Area, elev. 4.2K' received 30" of snow, with unofficial reports of 6' drifts. It is unknown if this is the largest single snow accumulation, but recent memory suggests it is. HiWay 17, elev 1.7K' in the Santa Cruz Mountains was closed on the morning of the 12th with 8" of snow. Many trees in the area were felled in part or whole from the weight of the snow. The entire coast mountain ridge line along freeway 280 down the Peninsula was solid white along the ridge line, often extending halfway down the mountain slopes. While I have seen/experienced a number of lower snow level events, this was by far the heaviest snow I've seen locally since the early 60's. Temps dropped to 38F in Pacifica early on the 12th, as the cold core of the second low made it's closest approach to the area but no snow was noted here. Montara Mountain, elev. 2K' in southern Pacifica received a good dusting, which lasted all day.
02/02/01 A flat ridge extending well into Wash/B.C. and weak dynamics will extend for the foreseeble future our current dry spell now up to 5 days and counting. Current model runs are abit wishy-washy 5-6days out, but broad-brushing all possible scenarios indicate no serious rain for as long as 10-14 days. YTD in Pacifica stands at 10.79", about 3.5" below average. Recent Sierra surveys now show only 30- 70pon water content in most areas. Due to colder than normal temps during precip periods, the snow is drier than other years, hence lower water content...but the silver lining is it is not melting, either. Most forecasters mention last year when Dec.early Jan. dry spells warned of serious rain shortfalls only to be salvaged by mega-rains in late Jan-Feb. timeframe. With a similar early Winter pattern this year, it would therefore take another gully-washer month-6wks to bail us out again. And this was the time last year when rains were pummelling the area. This year, no pummellings as yet...and none on the horizon. Climatologically speaking, Feb. is our last "best" chance for prolonged, serious make-up rains. Once early March kicks in, storms start to become individualized and airmasses increasingly progressive, so the 8-12 rain periods we are counting on become less and less likely quickly with time.
1/27/01 A fabled frost last night as virtually everything was coated in ice this a.m. Not a cloud in the sky as light northerly winds develop. Another period of dry weather appears on tap, as the potent low of the last two days that brought heavy rain, wind and snow/hail to many areas zommed down the coast and weakened before nudging inland to the four corners region. As offshore winds develop we expect warming temps for at least a few days. We just can't seem to get a prolonged rainy period going, or a zonal flow with tropical moisture entrained. Even though current Pacifica Jan. rain is now a near normal 5.0", overall we are still only 60% of normal for the season. Despite most storms being cold and low snow levels have prevailed, the Sierra is also still behind normal with 50-75% of normal common throughout the mountains. It will be interesting to note if the dry spell gets broken by another shot of cold from the GOA, just like it has numerous times since October. Since November, the three main blasts have all been progressively colder. And since now is the time of year (climatologically) when it is most likely to snow, who knows?
1/26/01 Scattered showers from towering Cu brought a visually spectacular finish to a wild 48 hrs. as water spouts spotted by NOAA P3 recon on 1/25, were imbedded in a very cold frontal trough that brought severe lightning, and snow/hail down to 1,000' in many areas. Temp in Pacifica plunged to 39F briefly during frontal passage around 1430, bringing heavy and accumulating hail that lasted for hours afterward. The intense front line actually caused severe severe T'storm warnings for the immediate Cent Coast region, and reds were popping on the radar along the frontal zone as it passed Santa Cruz/Monterey. Snow was reported at Clear Lake, outside Santa Rosa, on the Sonol grade and in Scotts Valley. Once again, as during the strom of 1/11, local wind gusts topped out at 51mph, and rainfall rates approaching 2"/hr fell briefly during frontal passage.A total of 2.3" has fallen since the start of this current event of two lows starting on the 23rd. Since November, all of our rain has fallen during three distinct periods of 4-7 days of consecutive rain intersperced by very dry periods. Due the mild December and January, many plum and cherry trees have already blossomed, so the hail may make for a lousy fruit season for these early bloomers. Surf has been impressive a well with 20'+ almost regularly at the pier. Earlier storms have carved out huge troughs and bars along the immediate coast, and during low tide, the rip currents from water flowing off the bars are causing counter-flow waves as high as 4'...and when they collide with incoming surf creates monster clashes that shoots entire waves 30-40' in the air. Cold but clear, dry air is quickly returning, and heavy frost should occur.
1/23/01 After 12 straight days of dry benign weather with cool nights and moderate aft highs, a series of cold GOA lows began making their way down the coast. A modest 0.40" fell, but the cold air has brought snow levels down to the top of the local Bay Area peaks. A cold troguh is expected through tommrow, then a more potent system in with 72 hrs. Lots of cold air and shower activity for us in the near future.
1/11/01 Live from Bullseye-land,
It's down to scattered light precip now after a wild 48 hrs, as a deep Pacific low (which had been tracked and modeled beautifully for the previous 5 days) finally drifts to our south along the coast then inland. I must say, for all the ballyhoo about the MRF, it was right on as far as this major disturbance was concerned. Timing, strength and QPF estimates all held up well against the data. The main, upper level low (now cutoff) separated from the surface low which is currently pushing slowly west-east into Nev/Utah. Major league surf pounded Pacifica beaches yesterday and especially late this morning, with estimated 35' surf (42' swells at the Point Arena offshore buoy) which rode ashore on astronimical high tides (close to 7')..plus the seas..and acentuated high tides from water piling up along the coast from the onshore winds..put them all together...voila.. Considerable damage and beach errosion locally and down Monterey way, according to news tid-bits. I personally went down to the pier at 3pm (4 hours after the high tide), and it was rough, but relatively speaking only a "4" on Craig's big surf scale (1-5). There were more news crews than anybody there. 2.26" has fallen in the last 48 hrs here, and not a lot more likely. Frontal passage at 12 noon yesterday dumped .29" in 15 minutes (1.2"/hr rainrate) with wind gusts to 51. Not bad. Stations in the southern coast range and Santa Lucia's have officially logged over 4.5" in the last 24hrs alone and heavy rain will continue to fall for the next few hours at least. I would guess the highest rain totals for the entire 2 storm punch will be close 9-10" in remote mountain areas, and 1.5-4" widespread in the lowlands. Of note, Los Gatos, in the southern peninsula, received 4.53 as of 4pm today for the last 24 hrs. Another curious note, we had condiderable convective activity from numerous imbedded cells both from the first surface low and the upper level cutoff behind it. In fact, T'storms occurred on the leading edge of the first warm front..a very unusual event. Whatever lightning we get in Winter is usually associated with trough/frontal passages or in the cold Cb cells following a cold front.
1/08/01 Starting on 7th, the first of a pair of deep Pacific lows has finally plowed through the ridge, bringing the first decent rain in 2 1/2 months. 0.62" fell in Pacifica, and low level rains were up to 1" in wetter spots. Wind gusted to 42mph briefly in the cold front. On the 8th, warmer air advecting ahead of the next low brought light rain. The next low looks potent, and the warnings are already starting to be posted.
1/03/01 After nearly a month of enduring a blocking ridge and the occassional associated 60's-70's along the coast , the ridge is finally starting to break down and onshore flows resume. The first in what hopefully will be a series of Pacific lows should be here in 4-5 days or so. The Nov./Dec. time period in many locales were the driest on record. Only 1.52" fell in Pacifica, far below the normal 7.05".
12/04/00 After a zonal flow mildly developed then dissipated 3-5 days ago, foggy/hazy air has settled in lower elevations, with warmer, much clearer air above 2,000'. Moderate offshore gradients has kept the north Bay in below normal temps and the beach quite pleasant. This dry pattern is disturbing as storms continue to fail to penetrate the blocking ridge both offshore and over the western plateau region, and can be a precursor to a prolonged dry period. A possible incursion of very cold arctic air is possible with a week, and if past history is any indicator (1990 and 1998), December freezes are generally followed by prolonged dry periods (in 1990 it lasted all Winter and Spring, but in 1998, rains resumed in earnest by late January, 1999).
11/31/00 SPECIAL FALL SYNOPTIC REVIEW:
Note: Due to technical difficulties, this page has been offline for almost three months. This posting is a generalized review of that time period.
In a now-distant post earlier this fall, I noted Pacifica had been experiencing
a continuing, and progressively colder pattern of bringing cutoff lows down
the coast on a near N-S axis..a pattern that may still produce further
events later on this Winter. As of this posting, the generic pattern has
been temporarily modified by offshore winds at the surface and warm
air aloft with widespread tule fog inland and pleasant beach
conditions. The actual beginning of this pattern using 20-20 hindsight
appears to have started way back in late August. Since then, cold air has
intermittantly been funneled south and has now resulted by far the
coldest Nov. in my records. September and October were cool and
anomolously wet as upper lows continued to dive down the coast producing
occassionally wild weather, with local downpours, but minimal "typical" eastern
Pacific storms to speak of. The entire fall, many Pacific lows either
kicked "up and over" or dove down the coast then cutoff near the SoCal coast
unable to penetrate the cool continental air mass. However, there were
exceptions. Starting on Aug 30th, a multi day event featuring both sub-tropical
and cold, northern air produced 0.16" in Pacifica, and much heavier
amounts to our south and southeast - including flash floods in SE Calif..
Initially warm, near-equatorial air moved north over Calif. in a flow
resembling a Pineapple connection around the eastern flank of twin cut-off
lows that eventually dug offshore down to near 15N . The main rain
resulted from an accompanying GOA type frontal passage as the northern
low raced inland to our north... very rare so early in the year. In
S.F. and elsewhere, record rains for the date got wrung out of the juicy
air on 09/01. The accompanying and post-frontal chilly air resulted
in widespread record lo/highs, 6,500 SL in no. Sierra, 7" of snow
on Donner Summit, and a post frontal trough on 09/02 which triggered scattered
Cu and iso shwrs, even some convection inland (none locally). Other notable
after effects of this event included the locals hills getting splashed with
a touch of green by early September, but a return to dry conditions put the
early bloom on hold again. The near all-summer long western wildfires in
Idaho/Montana/Washington were finally controlled as Pacific moisture/cold
air finally worked inland. A second, less potent event occurred
between the 15th and 17th, which was related to the persistent deep
trough and associated cut-off low at it's tip flinging low level up
from the sub-tropics. A few afternoon convective showers were noted on the
aft. of the 16th (a decent short shot in Milpitas around noon), but no lightning
to speak of. As the upper low drifted offshore, Diablo winds at the
surface brought widespread record temps, and peaked at 90.3 on the 18th...by
far the highest temp in my records for Sept. ( old record was 87F set last
year). Overall, the 90.3 was the fourth 90+ reading in Pacifica in my records.
Despite the two extreme heat waves in early June and late September , the summer was overall quite cool and had many similar characteristics as last year - a tie to La Nina???.....most reads on La Nina say she is virtually gone and near normal SST's are now the norm....but there was no mistaking September as both warm and summerish and yet cool, very fall like at times..typical of the wild swings attributable to a La Nina pattern. For October, we had an unusually high eight days of rain >.01", + two other .01" days of actual rainfall (as compared to coastal drizzle which oftentimes accumulates generally a hundredth or two, but can occassionally get to .10" with higher dew points). By any measure, an unusually cool and frequently wet month. Jly-Jun rainfall to date climbed to over 4", about 50% greater than normal. While it is uncommon to have had such significant rain by October , we have had wet Octobers before. In most cases, October rains are associated with cut-off lows that get parked (lost) next to the West Coast, and as such become capable of flinging moist tropical up the coast..and such was the case this year. By November, the N-S flow returned with a vengance, bringing very cold air , early frosts and frequent but light prcip. Pacifica's mean temp for Nov. was 51.9F. By comparison, in 1997, I only recorded three days with lo temps below 50F for the entire month. A "typical" Nov. mean is 54-56F. A small difference perhaps temp wise, but the mitigating influence of the ocean on local temps is strong..so any time mean temps fall below SST's (56-58F locally), an anomolous pattern is at work. My lo for the month was 40F on the 13th, with heavy ice on cars/lawns due in part to extremely still air and remnants of frigid northern air pulled down by a near continuous series of upper lows diving N-S down the coast. Lows at night were in the mid/lo 40's from 6th - 18th. The heavy frosts peaked with four straight days of ice/frost from the 10th through the 15th. Golden Gate Park in San Francisco reported a low of 31 degrees on the 12th. The same morning, we had to delay teeing off for my regular Sun. golf (dawn patrol) due to "frost" on the greens. The 18th fairway was so heavily frosted it looked like a snowfall. The golf course is adjacent to the coastline, and moist sea air must have infiltrated about 300 yards inland, then froze on the grass. The 15th fairway alongside was 100 yards closer to the ocean, and virtually frost free. A most beautiful and unusual sight anytime of the year to be sure.... But to have it happen in the beginning of November?. So guess what? The xact same conditions on the following Sat (11/18)!!!! If anything, the frost was heavier..and the temp back in the canyon on the 6th hole at 8:15 was 34F. Usually, our rainy season is just starting by now as lows start pelting the NW and tails/troughs drag down the coast..with maverick lows dipping farther south. Some storms can pack a whallop. Thanksgiving in 1980 brought 78mph wind to Pacifica (I remember..lost a good portion of my roof)..and as a youngster, I can remember many blustery, early season storms this time of year...but never the bone chilling cold like we've experienced on/off for the entire late-summer - fall period. Snow was falling as low as 2,000' locally in mid-November, and unofficial reports had flurries falling in parts of San Francisco (elev. 1,100'). Despite the wild, crazy weather that often accompanies upper lows in the near vicinity, by month's end only .80" of rain fell despite 6 days of rain and 6 other with trace amounts. The coldness and dryness of the continental airmass over us at the surface, coupled with a strong inversion layer under an increasing SW flow aloft, also resulted in widespread tule fog developing in the inland valleys. Not an unfamiliar pattern associated with such a large dry airmass diving down to the equator ....storms to the north starve for moisture.
9/03/00 Record cold/rain at the end of August! A usually quiet month, early August certainly lived up to it's typical, and boring, pattern of F&LCNM (Fog and low clouds nights and mornings) ...until the last 3 days, when an very unusual combination of sub tropical moisture swinging around a vigorous cutoff low off the SoCent Calif. coast merged with a deep, cool trough digging south from GOA. Officially, Pacifica received only .09" for the month, however many records were set on the 30th through Sept.1 for both daily precip and daily lo/highs throughout Cent and No. Calif. Both Santa Rosa and San Jose, at the northern and southern extremities of the Bay Area had record lo/highs, 62 and 64 respectively...a full 20 degrees below normal. Some scattered convection was noted in southern Monterey County on the 30th, and also in the Cent Valley on Sept. 1. As the northern trough rapidly dug south off the coast, snow level in the northern Sierra dropped to 6,500' on 9/01, prompting a special advisory from the NWS. Snow levels in the Cent Sierra near Tahoe was 7,000'...chains were briefly required at Donner Summit (I-80) elev 7,800', and an estimated 5" briefly accumulated. It was unusual but not unheard of for snow this time of year...I personally encountered 7 inches of snow at Caples Lake (elev. 7,820') in the Cent Sierra in late August of 1968, with snow reported down to 6,500'. Record lows near the coast were set by a combination of an unusually deep and cold trough digging from the north, and our below average Sea Surface Temps, which consistently were below 60F north of Point Concepcion and only 53-55F locally. Due to the almost constant onshore flows, the largest anomalies were nearest the coast (as expected), as much as 4 degrees below normal for this time of year. Despite the overall cold water data, the ocean remains offcolor from plankton (red tide) growth. My explanation is: ....while the overall SST is below normal, there has been a persistent trend for a "relatively" shallow warmer layer (54F on the top and 53 below), but sufficiently thick to cap upwelling. Hence water clarity dramatically improves, and allows deeper light penetration into the sea. Increased light (coupled with before-mentioned solar activity) means extra plankton growth...hence the red tide explosion. UNFORTUNATELY, the red tide has also clobbered our local striper fishing, which was virtually none-existent all month. A last note, between the 12th and 17th, mild offshore winds cooled SST's and increased radiational cooling enough to give us the earliest sub-50F low of the season-(49.5F). In general, we do not get such temps until late Sept to early Oct.... and according to my records, by far the earliest in my data.
8/03/00 Mother Nature continues her tantrums this month, with 8 days of precip, mostly in the form of drizzle from heavy, low fogs and 1 bonafide rain event which deposited .15" locally on the 5th. A total of .27" fell for the month, while not a lot, it was still the wettest July for my record base dating to 1984. After the blistering record heat of June, winds have persisted under strong onshore pressure gradients. The mean temp of 58.7 was also the coolest in memory. Only 6 days reached the 70 degree mark, 3 of them on the last three days of the month after two weeks of solid fog and drizzle. Our warm temps came after a switch in the near constant W-E wind flow aloft early in the month, to the SSE . Around the 26th winds at 30k' were actually due East. The cause was a large high centered over the four corners going retrograde and quickly moving westward. Heavy T'storms were noted in the Sierra and western Nevada as tropical moisture was flung north around the high's western edge. Only high clouds were noted here, although dew points rose considerably. Sea surface temps nudged upward to 57-58F locally, and up to 62F about 35 miles offshore. Major red tide explosions have virtually halted the local fishing scene, which is very unusual considering the SST's were below the generally accepted 60+ temps required to foster heavy plankton growth. Some salmon are being caught near the bait schools, and after a 1 day flurry on the 18th, only 3 Striped Bass have been reportedly caught since then along the beaches. Around the 20th, a huge red tide invaded Half Moon Bay, trapping bait fish by the tens of millions near shore, and eventually suffocated them as oxygen went to nil. The major, (in size) kill resulted in anchovy, sardine, smelt, mackerel and hearing all washed ashore and piled up in places up to an estimated 1 1/2 feet deep. The combination of fish, in addition to the quantity, was an interesting note. The stench was unbelievable....with the odor clearly noticeable all the way to Pacifica when the winds shifted the right way (south). Locally, huge schools of anchovy and sardine started crashing the beaches with many locales noting bait washing up on shore.
7/15/00 Light , big drop rain in Pacifica, as tropical moisture is being flung up the coast by a subtropical ULL off Baja, and is overrunning a thick, fog/stratus layer almost 3'K thick, enhancing the basic yuck of the last 2 weeks. The onshore pressure gradient between San Francisco and Sacramento is a very healthy 3.4mb this morning. After the record heat in June, temps have significantly cooled to much below normal over most the state and the West in general. Rain for the month (most occurring in the form of heavy drizzle and light rain early in the month) now at .16", the highest July rain total I've recorded in 16 years. As a result of the strong SSW onshore winds pushing warmer water northward, SST's have now warmed to near 58 and red tide (plankton) is choking the water. Most fishing has ceased immediately near the beach, although some Salmon are still being caught offshore...many in the 30-40lb category. Fishing in the Bay remains very good. Offshore fish have been reportedly gorging on krill and anchovy. Bait is crashing local beaches, but no fish. White Sea Bass reportedly were caught in Linda Mar last week, just before the onset of the red tide. There is an unusual feeling of Deja Vu, as the basic pattern seems a near repeat of last year at this time...and makes me wonder if La Nina is indeed on the way out as being advertised.
6/15/00 NEW San Francisco Heat Record!!! Hi temp in San Francisco set the alltime high for any date with 105F. San Jose and a reported 20 other stations all recorded alltime highs, ranging from 109 in San Jose to 114 in Fairfield. Higher temps were unofficially reported, with 117 mentioned in the Clear Lake area. In Pacifica, the high reached 96 degrees, 5 degrees above my previous max in 1995. Because data for Pacifica is fragmentary past 20 years ago, it is difficult to assess if this was an alltime record or not. As of today, temps along the cost are cooling quickly, and San Francisco is around 30 degrees cooler than this time yesterday. Inland temps are still hot, and a few more daily records are likely to be set before overall cooling takes affect over the next few days. 6/14/00 Record Heat Wave!!! Last night at 2045 hrs, temps were a comfortable 61.6F. When I got up this morning at 0545, it was 81! By 0900 it was already 90F. Or, a 30 degree rise in temp overnight into early this morning! Amazing. Needless to say, this should be one of the hottest days we've experienced since moving to Pacifica nearly 30 years ago. Temp right near the water is still a wonderful 64F, but go up no more than 200' in elevation (above the inversion) and temp skyrockets. Amazing to be able to drive literally a couple of blocks and go from 90+ temps down to the mid 60's in the span of less than a minute. Elsewhere in the Bay Area, yesterday's temps were a scorching 110 in Santa Rosa, and even hotter in other locations. But that was yesterday. Today is supposed to be even hotter. Since our high temp during the day yesterday topped out at only 79F, that was 2 degrees cooler than our starting temp for today at 0400. It's possible even San Francisco (city) will eclipse the 100 degree mark today. Brush and wildfires are breaking out in numerous places, with the largest near Lake Berryessa. Smoke from this fire reached Pacifica early this a.m. as the developing offshore winds started bringing the smoke (and heat) from inland areas.
6/08/00 An unusually vigorous trough moved through last night/this morning with 1/3 inch of rain here in Pacifica, but generally only a tenth or so elsewhere. The mountains however, have received 1/2" to 3/4", with almost 6" snow at the upper elevations of the Sierra. Snow level for this system was around 7,000', and briefly lower with cold air advection. The basic pattern is a mini-version of that seen all Winter, as a cool trough digs N-S off the coast then cuts off near the coast and drifts inland. In this case, the low cutoff right over the Bay Area. Typically, this pattern lasts 7-10 days, so another trough might be expected in a few days, followed by a return to offshore winds and hot temps before we settle back down into typical fog in the morning summer stuff.
6/03/00 Typical Spring weather has returned, with fog in the morning and late at night, and pleasant temps during the afternoon. Light to moderate onshore winds prevented any serious heating, but abundant sunshine prevailed anyway in the afternoon. Nighttime low temps have dropped as low as 46 under clear skies, and around 52 when foggy..a sure sign that SST's around 52-53F remain locally., where they have been the last couple of months or so. The first organized tropical storm of the EPac season developed last week, a little early, but mostly on schedule. Tropical trades continue to push convection out over open water, and no land has been affected. Have noted however, that Hawaii is significantly behind normal rains, especially on the leeward side of the islands. I'm sure the quasi-permanent cutoff lows we've been monitoring for the last month or so just north and east of the islands is partially responsible.
5/24/00 Well, seemed like no sooner that I thought how boring (and hot!) the weather had become out here, one of the strangest twists in the local enviorn I've seen in years took place.....it rained....it was hot..and it was cold...and it was VERY windy..all at the same time. From the 18th to the 24th, we had been experiencing near record heat in some inland locations, and a toasty upper 70's the last few days in Pacifica as well. But starting Monday, a small upper level eddy low started deepening right off the SoCal coast, and by yesterday evening, virga with light sprinkles began falling over a wide area. We knew something was very odd when aloft high and mid-level stratus and StCu started thickening and pouring in from the East, while at the surface, a strong onshore pressure gradient brought strong SSW winds, fog and sub-60 temps along the immediate coast and into the Bay in the lower 2,000' of the atmosphere. A good friend of mine biking in the local hills encountered winds estimated at 50mph+ on the south facing ridges! While the rain was no more than a spattering, the mere uncertainty of it all was very amusing. As for the near future, a bonafide trough is now slogging down the coast, and some showers are possible over SoCal as the pesky ULL starts to drift inland. Don't know what effect this will have inland..usually when lows start digging east this far south the SW, southern Rockies, Texas and the Plains can get clobbered. It just seems that there isn't a lot of energy yet with this system..but will require a close eye on it for the next few days.
5/14/00 As for the recent weather, numerous T'storms and heavy squalls fell throughout the region for the last 48 hrs but none here in Pacifica. 0.56" did fall, which is a large amount for May (average monthly rain is only 0.65"). The stacked low(s) are now marching rapidly east and should be affecting the inland areas of the country starting today, but really getting going by Wednesday. The lows seem to be losing strength, but some re-strengthening may occur as more juicy air from the Gulf tries to move into the system. These lows have the potential for severe weather, so everyone west of the Mississippi should be monitoring the progress of these systems closely, although the track seems to want to shift the lows to the north.
5/12/00 Thin high clouds covers the entire west coast in advance of another cold trough and parent low expected over the weekend. Currently, a deep, cold trough is digging rapidly south off the west coast at about 135 west. Progs have rain on/off for over 48hrs starting Sat. Nite...however I think this is a bit too aggressive, so will settle on Mother's Day afternoon before things get interesting. As noted before, serious rains in May are always unusual, and worth noting. How far this trough digs off the coast is likely to be a harbinger of things to come farther inland, and whether the Southwest and points farther east will be hit with severe weather. The air associated with this trough is very chilly for this time of year, and snow levels to 5,000' have been mentioned...even lower in the north. Since this will be another upper low, and likely to cutoff, high variability in the forecast and actual weather experienced is likely. BTW, the new ENSO update is out, and contrary to a media story earlier this week, the La Nina is not rapidly evolving in another El Nino. While some changes in SST's off S. America and the far western Pacific have been noted, the underlying strength of the warming is low...hence a gradual return to "normal" SST's for the foreseeable future is the most likely scenario.
5/10/00 The jet has shifted north and skies have cleared, although some cool air advecting around a new, plunging GOA low brought early morning temps to 45 in Pacifica, and local light frosts in sheltered areas up north. As this upper low drops down the coast over the next 4-5 days, it should cutoff then swing inland, perhaps directly over Cent. California. With lifted index forecast to be -2 to -4, and a deep pool of cold air to work with, thunderstorms over the area in a few days are expected. Should the progs verify, a chance for severe storms in the Cent Valley exists.
5/08/00 A very unusual rain event for May, as another sag in a strong westerly jet carried abundant low level moisture directly due east before flinging it over the coast. Numerous stalled eddy lows (six total in the Northern hemisphere of the Pacific) north and south of the jet, helped pump moisture and energy surges into the stream, and set up another zonal flow or pipeline that at one time stretched clear across the Pacific (Fig.1). 0.82" of rain fell in Pacifica, with higher amounts in orographically favored areas and in isolated pockets where showers amplified rainrates. Because the main flow was almost directly west to east, temps have been steady and cool.
4/17/00 An unusually significant rain event in April for this part of the world, as 1.89" has fallen in last 24 hrs, almost all in a 14hr period ending at 6am. Forecasts have been calling for heavy showers and T'storms this aft, but the sun is shining bright and winds are brisk from the SSW. And no more rain. Some mountain areas to the north and south had up to 3", and locally even more I understand in SoCal coastal areas this morning/aft. They should be on the lookout for flash floods and slides in fire ravaged areas. A deep, cold cutoff low has dug deep into the tropics and brought moist, juicy air up all along the West Coast, while the core remains SW and offshore of San Francisco. My take is the low is drifting too far south to give us much more action up here, but L.A. is in the bullseye. This is the first serious rain since March 9, a very long run of dryness considering March is typically a rainy month, and April less so, but still capable of decent rain totals. Some more troughiness is expected later in the week and maybe again late in the weekend. At the very least, the general pattern sure has changed for the time being. Expect severe weather outbreaks inland as this thing chugs into the continental US via SoCent California - into Arizona
3/25/00 Continued dry, with occasional periods of warmer than normal temps and offshore breezes in the aftermath of several dry fronts that move through every 3-4 days. However, temps are still cool immediately post frontal, with lows in the hi 30's low 40's in outlying areas. Last appreciable rain was 3/09, and it's possible that will be it for the year. The offshore winds briefly hit 50+ in the East Bay hills on 3/22, and temps nudged 80 in many areas once the winds decreased. Currently, an impressive low tracking to the coast may bring some showers in 72-48 hrs, but we are not holding our breath. With cool SST's still offshore (52F), and an imposing continental ridge, fronts lose much of their punch as they approach the coast, and this one should do the same. Flora is in full bloom, and allergies are widely reported as the worst in many years. Grasses and trees have heavy foliage for this time of year, however fruit trees are still slow in waking up. The cherry trees, while blooming on schedule in late Feb.-Mar., didn't seem to have the same volume of blooms, nor did they bloom suddenly..more gradually in nature.
3/19/00 Continued dry, with some very nice temps in the mix. In Pacifica, temps were in the mid-60's on the 17/18th. A definite shift in the jet stream to the north appears to have ended our primary rainy season, with only occasional spritzles possible for the remainder of the rainy season.
3/12/00 A generally dry period, and the rainy season appears about over. Last low on 3/09, went almost directly down the coast, unable to penetrate the western US ridge until going inland near LA. Locally, .29" fell and snow fell on the local hills down to 3K', and lasted for almost two days at the highest levels (Mt. Hamilton.
3/05/00 February turned out as one of the rainiest on record in terms of total rain, and many records for # days with rains were set around the area.( see the Archives for details) After the mid-month hosing, the general storm track started to quickly evolve into a more Spring like pattern, with cutoff lows starting to track much more N-S, bringing heavy rain at last to SoCal and then inland, producing unusually early season severe weather in the southern plains through the Gulf Coast. As these lows moved past the coast, some of the heaviest winds of the season were noted, with winds peaking at 56mph on the 26th. Here's an interesting sidelight - while many places along the coast and especially inland experienced briefly severe weather in the form of hail, T' Storms and very heavy downpours, (numerous funnel sightings near Fresno on the 28th) Pacifica , near the heart of the Pineapple Express, seemed to escape the brunt of these events. Pea hail fell only once on the 28th, and no T'storms or heavy frontal passages occurred all month - mostly wind and steady rains during the Pineapple hosing early in the month, and lighter steady rain intermixed with moderate rains/winds later on. While the pattern remains dynamic and somewhat progressive, the cutoff lows are starting to adopt more leisurely tracks and are starting to stall near the coast, as is typical for this time of year. What is missing is potent pockets of very cold core storms which often brings the most severe weather of the year. So far, only 2 storm cores were cold enough to drop snowlevels to the highest Bay Area peaks, and none of the events have resulted in snow sticking around longer than 24hrs.
2/15/00 3.16" of rain has occurred in 36 hrs between 2/13 and 2/14, with 2.24" falling on the 13th. A total of 6.24" has fallen in the last 3+ days - all from another tropical connection, similar to the one in the last week of January. Local flooding has occurred, and many rivers are at/near flood stage, but so far no major flooding events have occurred. Over 14" rain fell in the Santa Lucia's, which seemed to be ground zero for the hosing. Napa/Sonoma areas rivers are high, but the Russian River crested just below flood stage at Guerneville. Elsewhere, some small landslides have been noted, but again, no major events to mention.
2/12/00 1.80" yesterday from the latest and strongest in a trane of storms that continue to march across Cent. Calif. mostly from Westerly directions. Nearly 4" precip in last 10 days, with near constant rain on/off for the last 4 days (6 out of the last 10). Rains are being produced by a series of progressive lows riding inland on 100kt-150kt jet streams which bring moisture surges from the SW. A deep tropical connection is currently developing with the next storm, and heavy rains on top of already saturated soils may spell trouble in the next few days. Last night's trough brought winds to 51mph, strongest of the year so far. Rain totals in Santa Lucia Mountains which are most orographically favored in the SW flows, are nearing 12" over the last week. It's possible another 6-10" may fall during the next 5-7 days. Note: L.A. area, including San Diego now receiving first significant rains of the year.
2/02/00 After the hosing of last week, skies are gradually drying out. Scattered ground fog and local drizzle in area. The jet is in split flow, with Cent Calif in the middle. Some decent activity offshore, but only chance for light precip for the next few days. Temps hitting 63 last two days - stiff Diablo winds early morning till noon 2/02.
1/25/00 Huge rains batter Central Coast!
Some times you feel like a fruit, (pineapple, of course) and sometimes you don't! A classic pattern of a very deep trough off the coast coupled with a juicy flow around a suppressed EPac high NE of Hawaii ( best intensification of the southern jet all Winter-over 150knots) has created a deep, steady onshore flow of moisture. Due to the VERY dry conditions of the last two months or so, flooding has been minimal. By 1200 1/24, many areas nearly doubled their entire rainfall total to date. Over 5.25" of rain fell in Pacifica since Sat. evening (1/22), with lessor amounts inland, except in the hills and south coast down Santa Cruz way, where around 12" fell in localized areas of the Santa Lucia mountains. According to my local records (which weren't as accurate in the old days), our 5.25" was the highest 2 day total since the catastrophic floods of Jan. 4, 1982 (8.5" in 26 hrs in Pacifica, up to 14" in the watershed areas). Even the El Nino of '97-98 couldn't top this. Rainfall at Soquel, near the coast just south of Santa Cruz measured 7.5"-8". The air is extremely wet in the lower levels, and steady, moderate rains are expected to continue sagging to the south before the trough finally pushes inland. An urban and small stream flood advisory is in effect for the entire area. Fortunately, not a lot of wind with this event...the low wasn't particularly deep but huge in size..hence it's presence was felt from the Gulf of Alaska to past Hawaii, where it sucked up all those Pineapples! Upper air dynamics are actually relatively moderate, however orographically enhanced rainfall is the rule with SW pineapple connections that stall in one spot, and this event was no exception. The main rain band was only around 150 miles wide, with the most intense rains within a 50 mile wide "core" zone. As the zone crept up and down the coast, the Pineapple express managed to affect most of the Cent/South Central coast, with lighter amounts north of Pt. Reyes and south of Santa Barbara. The rains around Monterey and the South Bay were a major boost to the area's fast-dwindling water supply, as key reservoirs were drying up and water rationing was being planned. Reports from the Sierras are sketchy at present, but over 10' in the higher elevations should be common as the snow level hovered around 6,500'to 7,500' for the vent.
As for the recent huge East Coast snowstorm, so much for the NWS's new supercomputer, eh? I heard via the media that some areas in South Carolina and in a swath up through New Jersey that were expecting 2-3" received almost 2 FEET (20")!! I wonder if the new computer has a software glitch similar to what caused the recent Mars Explorer probe to burn up attempting to enter orbit around Mars? Maybe the new NWS computer is programmed in cm instead of inches - (re: kilometers or miles) oh well, ..what's the difference. So much for predicting Ma Nature..may she forever reign supreme over us meddling humans.
01/15/00 A cold core low and associated trough appears to finally be moving toward the West Coast after hovering and deepening offshore for the last few days. Subtropical moisture is being pulled up ahead of the storm, and has a vague Pineapple connection look to it. Heavy, steady rains have fallen over the last few days over northern California, with 9" reported in Humboldt County (near Cape Mendocino). There is even a decent chance that the trough will sag all the way to SoCal by tommorow. LA and San Diego, as you know, have had virtually no rain since last April...both areas have less than 1" to date. Another good shot of rain, with an even deeper subtropical connection is expected by Tuesday, before drying out a bit and two weaker systems enter the area.later next week. With "generally" onshore flow conditions evolving over the last 2 weeks or so, this appears to be a major weather pattern shift, and one that we haven't seen around here in a couple of years. It will be interesting to note if this is a harbinger event signaling a major overall climate shift..perhaps the beginning (takes a long time for ocean water to change temperature) of the demise of La Nina and a return to more normal weather by Spring and Summer?
01/03/00 Continued dry and mild, although the winds are gradually adopting a more onshore flow (as speculated on last week).. Heavy stratus and even some drizzle on New Years' Eve as the onshore flow peaked under the influence of a weak upper level low that spun in over SoCal, bringing them the first significant rain in over two months. San Diego received over .50" in many locals. Wx today (1/03) was warm under clear skies, but a dirty ridge and maybe some trough energy due in later tommorow?
12/28/99 Changes in the works? A very unusual pattern with temps in the 70's widespread, with 7 going on 8 days of 70+ readings in Monterey, a new record for the time of year according to the NWS. In fact, they are checking to see if this may be a record for ANY time of year, Summer and Fall included. With a seemingly endless string of days with dry, warm, offshore winds, many of the hills and landscape is adopting a brown color, much more typical of Summer. Locally, December appears to be on track as the warmest and one of the driest on record. (only 0.72" so far). The local media showed a stat where December has had 22 out of 27 days with above normal temps. The record low rain in Pacifica was in 1989, when only .02" fell. Normal would be 3.84". The last significant rain fell way back on the 9th. Currently, an upper level low is moving offshore West of SFO, and has been following a retrograde path (WNW) for the last few days. Because the low was Continental in origin, little moisture is available for precip, and only a few high clouds near the Vortex center is visible....however, models are confused as to what to do about this thing..with some bringing it back onshore later this week with the possibility of tapping into some tropical moisture currently off SoCal. Dynamics appear good, but moisture (or lack of) is the big question. To be honest, I can only remember 1 other time when an upper low moved in retrograde from the East this time of year. ('85, I think). There have been other notable upper lows that have swept down from the NNE, which often produce our most unusual (freak) events...i.e. cold/snow. As for now, temps remain very pleasant (in the mid 60's in Pacifica), and as the low moves farther offshore, winds will start to swing around and become onshore, bringing more "normal" temps to the area. Also, there is a strong hint that the overall pattern is about to change around the first of the year. It is unclear, however, how much moisture will get entrained in the developing trough.
12/10/99 Continued cool with regular visits from GOA troughs dominates our pattern. 5 quite ordinary storms have moved through in the last two weeks, however none gave us more than .73" of rain. November wound up with 4.12", which is actually a bit above normal..however compared to the rest of Cent and Southern California this was an anomaly. Most areas continue below normal rains (mostly 40 - 70% of normal), and SoCal is experiencing a second year in a row with much below normal rains (<0.5" YTD or 20% of normal). Due to weak upper air dynamics, moisture is confined to lower levels of the atmosphere hence a significant delta in rain between the immediate coast and points just a few miles farther inland. Rain to date in Pacifica stands at 6.51", however SFO has only 2.63". Long range models indicate a continued below average rain pattern, and some possibly very cold air toward the end of the month.
11/20/99 Another (third in a week) trough moved through on 11/19, bringing our seasonal total to 4.72". By comparison, SF Airport has only 1.64". So far, this is a repeat of last year, when we received over 7" more rain than the Airport despite being only 5 miles or so apart linearly. The main difference of course is that I am located in the hills just to the West of the Airport, and because these La Nina storms seem to have abundant low level moisture, orographically favored areas have significantly enhanced rains. High pressure now appears to be building over the EPac, but farther out to sea, and some impulses are expected to ride "up and over", dragging tails through the Bay Area, but no real rains. If the models are correct, a prolonged dry period may be shaping up as the High intensifies over the West during the coming week.
11/10/99 A powerful trough moved through on 11/07, bringing very heavy rain for a brief time that flooded local streets and causing widespread power outages. During the frontal passage, visibility was reduced to virtually nil on the hiway, (I was caught in it). A total 1.29" fell here, and winds gusted to 43mph. This pattern was a repeat of the earlier sequence of an unusually vigorous trough deepening just off the coast then slamming the immediate coast, with lighter precip the farther inland you go. Not a lot of cold air, as the flow aloft is predominantly from the SW, and overall winds appear zonal in nature. We continue to have the storm door open, however the next impulse is expected to stay north of San Francisco, with shots at rain every 48 hrs for the foreseeable future.
10/29/99 I am pronouncing the opening of the '99-'00 rainy season in Pacifica (last year I opened the season almost 3 weeks early on Oct. 4---this year is more typical of the "traditional" opening of late October to early November). While the timing of the "start" of our rainy season is a subjective one, there is a distinct difference in our local climate that accompanies the shifting of the jet stream southward. and the first Gulf of Alaska storm sweeping down the coast. The winds associated with these early storms typically produce the first significant seas/surf of the year...and this year is no exception - 35' waves hit the northwest coast (over 50' on outside waters) , and local seas/swells reached an est. 30' in Pacifica. There is a special "scent" to the ocean when storm driven waves are present. Sometimes we get big swells in dead of Summer, but it doesn't "smell" the same. This year's first storm was unusually large and potent for this time of year, and is currently moving inland near the Canadian border after battering the Northwest. A significant total of 1.21" of precip fell and winds gusted to 40 mph - with over 2" in the typically wetter northern counties. After threatening and lowering skies all day yesterday (the fog bank on Mt. Montara/Pedro Point ridgeline grew to over 2k' thick on a perfect West to East axis), rain finally began around 2030, and from 2300 last night to 0030 (10/28), the rain rate was >. 33"/hr. Trough passage occurred around 0030 this morning, with moderate frontal characteristics (dramatic rain and wind drop-off, but no major wind shift or heavy post frontal squalls).
9/10/99 For most Bay Area Natives, 9/08 - 09 was the most spectacular lightning show ever seen in the Bay Area (yes, I did get some great video's both here on the coast and from the SF Peninsula)...and at times rivaled some gems witnessed in Colorado and elsewhere. At it's peak, the NWS reported 217 lightning strikes during a 15 minute period last night along the squall line stretching from just south of San Jose to off the Marin Coast. At that time, 6 different cells were active within my eyesight along I-280 along the SF Peninsula. Lightning was hitting the ground along the Peninsula's bayfront near Belmont with aircraft trying to land at SFO between me and the lightning. I videoed 1 bolt which I thought hit a plane, but no such reports (fortunately). Tremendous cloud-to-cloud mosaics with dozens of filaments stretching sometimes 10's of miles and lasting multiple seconds. Hail was reported in many locations, with a brief outburst in Pacifica around 4pm. A total of 0.15" of precip in briefly moderate showers fell here, and over 0.75" fell in the hills south of here. Because of the traning effect of the storms (axis almost perfectly S-N with zero W-E advection ) Pacifica had on/off lightning/rain for 15 hours...with lightning visible constantly all night in my area. The peak came at 0400of 10/09 when lightning repeatedly struck the hilltop/ridge directly to my south (about 1/4 mile as the crow flies - about an average par 5 in golf), with thunder arriving less than a second after the flash. With the echoing along the hills, it was clearly the loudest thunder I have ever heard. This event came as a total surprise to virtually everyone in weather watching/forecasting. Other than some high clouds associated with what appeared to be another in a long sequence of cool air upper lows hitting the coast from the SW and positioned off Point Concepcion, there was little sign of the low's presence. Radar/visible loop analysis (hindsight), indicated that starting around noon of 9/08, moisture flowing up from the tropics (Hurricane Greg remnants) got caught in the upper low's circulation and in 2-3 hours rapidly developed a very impressive T'storm line on the NE flank of the low in a line stretching from south of Monterey to just north of San Francisco. Due to the low's slow easterly movement (none), the showers/T'storms started traning right up the coast, mostly along the western Coast Range mountains. Close to 1" fell in localized regions of the southern Coast Range This event has been reported in the media (CNN Live @ 0200 on 10/09 showing great lightening over The City) as the best/worst T'storm in over 25 years around here. I saw the one in 1984. This had it whipped hands down.
8/13/99 Fog and low clouds in abundance with frequent (and heavy) morning drizzle and zero ceilings. The last upper low tracked NE as promised, bringing a rare and damaging tornado to Salt Lake City. Heavy convection in the Sierra's. Lake Tahoe only in the 60's and T'storms on the 9th and 10th. A temporary ridge is expected to break back down and allow another trough to drop down, but not nearly as strong as the ULL of early this week.
8/08/99 Back online after a short hiatus. Current August weather pattern features an extremely rare series of cutoff lows dropping down the coast from the north, with widespread drizzle and light showers reported over much of the state - with 0.16" here in Pacifica on 8/05-06. Some convection noted, mostly inland, especially in NorCal and the southern deserts. The lows (three total) drop down the coast inside a deep trough just off the coast, then cutoff and slide back to the NE. As a result, more tropical-like conditions are along the immediate coast, with dewpoints in the high 50's, to low 60's. Inland, where stratus is less but higher level clouds prevail, temps are only in the 70' to low 80's, with many valley stations reporting record low/highs for the date(s). Livermore, usually at least in the mid 80's this time of year, peaked out at 65F on 8/05. With such cool inland temps, the typical pressure gradient has slackened greatly and our onshore winds are quite a bit calmer than normal. Near zero' surf has been noted on several days during the last 2 weeks - sometimes the ocean is so calm as to pick up reflections of navigation lights from offshore shipping vessels. Other than the current series of upper lows off the coast, our coastal weather seems unusually sensitive to subtle changes in wind flow patterns along the coast. With the hot spell of early in July, winds either blew from the NNE, or were light/absent -indicating a slackening and even slightly offshore pressure gradient between the coast and inland (Sacramento Valley, etc.) During the second week, wind direction gradually shifted to more typical WSW. But instead of remaining there, troughiness to our north caused winds to shift to SSW. A prime effect of these SSW winds is to move relatively warmer southern latitude water northward, and dew points as well as SST's have spiked upwards by almost 8F in the last 3 weeks - in stark contrast to the 46-48F a mere 2 1/2 months ago. SST is now up to 58-60F in the immediate area. Nearshore SST at Santa Cruz was unofficially (but reliably) reported at 62, and 60F water was off Fort Bragg, where a large Tuna (albacore) school has been spotted only minutes from the coast. The warmer water is quite shallow, but it is sufficiently warm to cap ocean waters and prevent turnover/upwelling. Because the warmer water is juicier air, fog is enhanced, to the point of widespread drizzle along the coast and unseasonably cool temps at times in the valleys. These oscillations in hot/cool conditions is hardly a rarity along the coast, however the rate and magnitude of the changes appears highly unusual. A great example was during the first week of July, when temps in the northern Sac. Valley (Red Bluff) set temp records of 118F. Temps closer to home (Gilroy) got to 113. However, by the second week, hi temps in Stockton were in the low to mid 70's and 80's in red Bluff...a good 20-25 degrees below normal for this time of year. Despite the local warming Pacific coast waters, long range ENSO models now show a continuation of La Nina conditions is expected through the Spring of '99-'00. With global atmospheric heat further dissipating after the El Nino of '97-'98, this years La Nina influenced winter may be drier than last...possibly very much drier.
7/12/99 Alternately hot then cold with fog conditions prevail. When skies clear at night, lows are still dropping to the high 40's, with a 47 logged on 7/09...very chilly for July. Still hot inland, and some record temps for the date noted...most notably 114 in Redding on 7/11. We are expecting continued hot temps inland, and after some more warm skies along the beach today, a slight cooling trend should begin along the coast. However, tropical moisture is finally entering the picture, which may help keep temps down a bit. For days, progs have been showing increasing S-N gradients aloft, with the flow locally from the easterly directions...however they have been weaker than expected, and the moisture/cloudiness had been very slow to arrive. Last week, unexpectedly heavy monsoonal rains hit the southern Nevada desert, with Las Vegas picking up almost a year's worth of rain in two days (avg rains a little over 4"). Rain also occurred in other SW areas and in the California deserts. SST remains stable at 52 degrees, and Striped Bass and Salmon are finally showing in numbers along the coast to go along with massive schools of anchovy. Dirty water and rough shorebreak limits fishing access, but when the surf calms down, as on 7/10, Stripers were caught from San Francisco to Pacifica in scattered pockets. This fishing season is a good month behind schedule, but the cool SST's may bring an above average season for the remainder of the summer.
6/29/99 Generally warm weather intermixed with periods of morning fog. Stratus thickness continues to fluctuate as troughs are still moving through, which alternately deepens the marine layer until trough passage, then thins it back out again. Offshore winds in the aftermath of these weak troughs are shooting temps up, especially away from the immediate coast. On several occasions, temp gradients have hit 15 between hear at the beach, a scant 3 miles away, Temps have hit the century mark inland, with the East Bay starting to show near record temps for the date. SST now stable at around 52 degrees, about 4-6 degrees cooler than normal.
6/22/99 Until today, foggy, and most mornings with drizzle has dominated the pattern for the last few weeks. Weak troughs continue to brush by, with the most notable effects being incursions of cooler air, and the associated drizzle, followed by chilly northwest winds. The NW wind in turn, keeps SST's down as upwelling is amplified. However, the good news is that upwelling is starting to be countered by winds for the last two weeks shifting gradually to the SW, which pushing slightly warmer water surface water northward, thereby slackening the temperature gradient of ocean waters and reducing upwelling. As temps heat up in the Central Valley, cold sea air is drawn inland along the Central California Coast from the SW and NW focusing on the the Golden Gate area. The winds patterns, when viewed graphically, clearly shows a "funnel" shape with the business end flowing right through the Golden Gate. Where the wind blows, 50's prevail. If you are sheltered from the wind, 70's are the rule. Such is the case today, as offshore winds have developed in the wake of moderate surface low/trough which passed through yesterday afternoon. After a positively miserable day with drizzle and cold winds most of the day, fog abruptly cleared at 1800, which is usually the foggiest and breeziest time of the day...a clear indication that the "funnel" effect was being temporarily minimized by large air mass movements. Even though offshore winds have developed and temps are finally at to significantly above normal in most of the areas, the fog bank is still only 1 mile off the Pacifica coast, with fog crossing the coastline around Daly City. Within the fog and along the wind shear zone on it's edges, temps are in the middle 50's..while at my house, approximately 3 linear miles inland, the current temp is 77F, with a high of 80 earlier. Easily, the warmest day of the year so far. Ahhhh, Summer in "The City".
6/09/99 Cool and breezy conditions prevail. An upper low that moved through on the 06/02 brought drizzle and light rain to the area (0.11" here), and SNOW down to 4K' in the Sierra and down to 5K' in SoCal. The hills above San Diego actually reported up to 3" at 5.5K'. SST off the coast has now risen to the 50F mark. Local fisherman are reporting that the thermocline has virtually disappeared, as water temps are quite uniform down to depths over 300'. This means the likelihood of any abrupt change in SST is about nil...so we can expect with a high degree of confidence a cool, blustery summer here on the coast and breezy, dry conditions in the interior regions. However, should the heat low in the Central Valley get overly developed as can sometimes happen when high pressure gradients develop between the ocean and the valley, some tropical moisture inflows will be possible later in the summer, producing some of our rare summer T'storm weather.
6/01/99 Cool temps have returned after a pleasant 30th and 31st, with ample sunshine and afternoon sea breezes. For the month, May turned out to be the coldest in over 30 years, and was 4.2 degrees below normal. Dry troughs continue to push through, whose main effect is to amplify the stratus off the coast and usher in more chilly air from the GOA. Bear, Mountain Lion and Coyote problems all were reported in the last 10 days. SST climbed to a bit over 50 after prolonged south winds on the 22nd and 23rd pushed a little warmer water in the south northward. Upwelling, due to the more typical WNW winds has also held SST down. Salmon fishing as well as other sport fish continues very spotty, and many days boats can't get on the water to locate schools. Surf continues basically rough and very choppy, especially when massive fog banks are hanging just offshore and heavy winds occur along the edge of the fog bank. Only on rare days when winds calm has the ocean been flat enough to fish.
5/18/99 Continued cool and blustery. Surf has quieted down to 2-4' shore breaks..the lowest it's been all year to date. Low temps still in the low 40's when skies clear, and highs are only barely reaching the 60's on occasion, mostly in the 50's. No rain, and none expected, except for drizzle with the typical late season dry fronts...with the latest currently moving through the area. Expect clearing tonite (and some fog) and slightly chillier temps than the last two nights.
5/09/99 Two dry fronts through the area. Extensive fog and some drizzle too, in the pre-frontal pressure waves. SST reports show as low as 46 degrees off Marin County coast, and 48-50F between Pacifica and Half Moon Bay. The cold SST's are now being cited as a prime cause for the very cold Spring temps. Not a novel idea, as this page has frequently mentioned the SST's as being well below normal for months.
5/02/99 A moderately strong cold front for this time of year is currently moving through the area. It has retained strength longer than expected, as only sprinkles in the north bay were expected. This is the first measurable precip since 4/11. Temps have not been near the highs in the middle of the month, as a cool trough invaded the area on the 26th and brought blustery winds and cold air, but no precip although the mountains weren't so lucky, as the low dropped south inland and brought some occasionally moderate snow down to lake level. Brief road closures over the major HiWay occurred . Unusually cold air air followed, and on the morning of the 27th, some very light roof frost was noted in secluded valleys a few blocks away, although our official air temp never got below 42F here. With the blustery winds came above normal surf to the area, with chop close to 15' and swell of almost 10'. The 25' seas really put the Salmon fleet on ice. SST remains about 50F, which is still 4-6 degrees below normal for this T.O.Y...so significant upwelling is still occurring. Apple and other fruit trees are finally starting to come into bloom..a good 3-4 weeks late. I saw some maple trees in the canyons of the Peninsula actually having leaves turning color after our cold snap on the 26th-27th. How strange seeing dead leaves on the sidewalk and other trees nearby just coming into bloom.
4/24/99 Spring has sprung! After the last cold snap and precip event on 4/11-4/13, a formidable pressure ridge coupled with dry fronts rippling through has kept us dry and even warm at times. On 4/15, HI temp hit 79F and over 75F for three days. Some major onshore winds on the 21st and 22nd brought some local damage, with gusts in the 40+ range throughout the area as low pressure moved in over SE Calif.. Cool temps returned to the mountains, as snow from the cutoff low moving back to the NE from off SoCal, and brought temporary road closures to the mountains ...but as mentioned above, just winds here. Local SST remains below average as the combination of upwelling and heavy winds has kept temps to around 50F. Foggy times are still dropping air temps to the upper forties and low fifties, and given our proximity to the ocean, these temps (on average and under otherwise quiescent periods) rarely deviate +/- 1-2F from actual SST. While this is certainly a pleasant Spring pattern, things may change back to cold and breezy next week, as the ridge collapses and a strong trough moves in off the coast. As often happens this time of year, highs building in after dry lows can bring strong offshore winds and much above average temps. However, these spells are typically short-lived (indicating a progressive pattern) as compared to the autumn, when warm temp patterns can linger for weeks.
4/11/99 April rains now up to 2.26" (1.36" is the monthly average) as 1.21" rain fell in the last 24 hours from the latest cold core low moving down the coast from the Gulf of Alaska. All precip has been in the form of light to moderate rain, with light winds and no convective activity (at least locally). Hopefully (more like wishful thinking), this is the swan song for our very chilly spring weather pattern . This low has remained just offshore, so temps have been milder, in the upper 40's - low 50's. The previous vortmax, through here on 4/08, brought 0.9" of precip, thunderstorms and snow down to 1,500' locally. Mt. Montara, (elev 1,950') got a quick dusting of snow in the middle of the day, and some major pea-hail fell in squalls in the lowlands. Lawns, cars etc .were encased in the little white pellets Thurs. nite from the heaviest such squall I've seen in years, and with temps at 39F (at 7:30 in the evening, no less), it lasted for a couple of hours. Such cold temps in April in the Bay Area is unusual, to say the least.... heck 39 degrees ANYTIME near the beach is unusual. Snow near sea level was noted in heavier squalls to our north. On 4/06, winds up to 46 mph were clocked from the WNW, and the ocean was a writhing froth of fury, and looked like the heart of El Nino storms last year. Even some erosion was noted, but fortunately the heavy seas condition lasted only about 48 hrs (instead of the weeks -on -end during El Nino). An interesting note with this low was that while air temp at sea level was a very chilly 43F at Half Moon Bay in the middle of the day, the snow level remained about 3,500' ( local wind mixing and a slight southwesterly flow aloft kept temps aloft a bit warmer than usual). These lows are potent, and as they progress inland, once moisture becomes available, can produce some devastating weather, such as yesterday's Tornado outbreak in the upper midwest which resulted from our low that pummeled the area on 4/06. Progs are now calling for a decent ridge to build over the west and the storm door to close for a while, and we may actually experience some normal to even a bit ABOVE normal temps for the first time in quite a while.
4/04/99 A wild one yesterday in the Bay Area, as a very deep low moved down the gut of California, producing unusually high winds along the coast and some severe weather inland. While we did not receive a single drop of rain in Pacifica, winds reached 48MPH from the NW, 51 at SFO. As the low stalled over the Central Sierra during the day, a Thunderstorm line formed on the EASTERN flank of the low over the coast range and produced rain/hail just to our east. The storm became so strong, that at 1540, the NWS issued a severe thunderstorm warning for northern Santa Clara Valley as a cell exploded over the Milpitas area. Coupled with converging winds from different directions, some rotation was noted and tornado watches were considered but never issued. By today, skies have cleared completely, and the winds have died down to a mild, spring-like breeze of around 10mph. Another deep low is seen on satellite at this time off Vancouver, and models are now forecasting this low to drop more along the coast on Mon/Tues, which should increase precip, but winds will be lower. It too seems to have a good cold air package with it, and we may get some more wild weather along the coast. The severity will depend on the exact track of the low and where it crosses the coast.
3/31/99 Another cold one, with temps in the low 40's in the mornings and struggling to hit mid 50's in the afternoons. A recent check of long term temp records reveals that March in San Francisco was the 8th coldest on record, and San Jose was the 6th coldest. Here in Pacifica, it is the coldest since I've started my weather monitoring (49.9F mean temp).. This last little blast brought about .18" of rain, a bit disappointing as this had the look of some classic March wildness to it, but it fizzled big time as it plowed down the coast. Once again, moisture (or lack of it) was the problem. Looks like Spring continues to knock on the door, as near to actually slightly above normal temps may arrive later this week into the weekend. This last low is part of an unusually deep trough, and it's possible Colorado may actually get something out of it if Gulf moisture can get drawn up north. With warm temps in Chicago and Minnesota, it seems probable that increasing dew points will follow. Most flora is in decent Spring bloom, but hardly the explosion we typically see. Some trees have been in bud for well over a month, while others (like birches and others) are just now starting to leaf out. The apple tree in my back yard has no signs of budding yet (not a big surprise, as it didn't fully drop all it's leaves until the end of December...another backlash from El Nino???). Seems like Ma Nature is still a bit confused out here after the wild fluctuations in "normal" weather patterns the last couple of years.
3/27/99 1.09" fell on the 24th /25th from an all night event, as the most recent in a long series of upper level lows exits the area (a classic March pattern, except the lows continue sliding down the coast instead of moving inland across Calif.). A deep cutoff low, originally forecast to move swiftly through, instead stalled offshore of Vancouver then weakened , as a secondary wave/weather maker for our area developed on the tail then slid down the coast into Central Baja. The sucker low brought steady, light/briefly moderate rain all along the coast and into SoCal (for a change) as it crept south, with only light precip inland. A ridge and near-zonal flow is now setting up, which should choke off the rains for awhile and MAYBE give us the first decent spring-like weekend in at least a couple of months (my golf game has really suffered). Rain total for the year in Pacifica stands at 24", which is just about normal for the entire year and about 115% of NTD ( I'm actually a little surprised...as we have not had a single "major" storm all rainyear, however the frequency of troughs and minor rain events , especially since mid-January, has made up for it). With still around a month left to our rainy season, we normally should add a bit to this total in the form of scattered showers and frontal tails dragging weakly across the area....will have to wait and see. Temps are finally creeping back to normal for this date, but the effects of the prolonged cool temps (actually all winter) are unclear. On one hand, we may drag winter out a bit longer than normal with on again/off again rains well into April, ..or the almost continuous lack of a rich moisture feed may cause these weak troughs/fronts to dry out altogether as they run into the E Pacific High that develops around this time of year.
3/23/99 Today marked five consecutive days of measurable precip as the fifth in a series of cutoff lows over the last few weeks moved through the area early a.m. bringing 1/3" precip to Pacifica. The trend continues for these cold core lows dropping down along the West coast, but due to lack of available moisture, only light to moderate precip has resulted. ..and because the lows are cutoff, surface troughing has been minimized and winds /precip have been generally light. The exception has been in orographically favored areas such as the Santa Cruz mountains, where up to 1.5" has fallen at times. The track has been to swing the lows inland over Central and Southern Calif . then east and weakening. Significantly lower precip than normal in the Central Rockies continues, and the Southwest in general. Rain in Pacifica for March now totals 2.6"...about 65% of normal, and continues the winter-long trend of frequent but generally light rains south of San Francisco. Snowfall in the Sierras, especially north of Mammoth Lakes, continues well above normal, but below average south of there. Because these lows are bringing in cold air, snow levels remain quite low, and average around 3,500 to 4,500'. Some convection was noted on the 19th and 20th from a vortmax that moved inland over the Monterey area, and a brief T'storm developed over the coastal hills, but dissipated during the day. The last in the current series of lows is now forecast to enter the area tonite, and may be the strongest of the series, with colder air and better upper air support anticipated..but because it is moving quite quickly, rainfall amounts will be reduced. After that, a zonal flow will likely develop and we should go dry for a while, and possibly bring the first dry weekend to the Bay Area in over two months.
3/15/99 Skies are cloudy and temps cool at 45F, as 0.80" rain from the latest upper level low that SLOWLY meandered down the coast on the 13th and 14th. SoCal looks like it may get some decent rain and convective activity today. The rain here was much heavier along the immediate coast, as the "trough" stalled, then lost much energy and moisture as it moved inland into a blocking ridge. For a good portion of yesterday, SFO, about 6 miles inland, was receiving no rain while it was raining steadily here in Pacifica. Most inland areas received around 0.20" or less, and many areas got nothing. The coastal hills received around 1", and snow again fell to around the 3K' level. Also, as speculated on last week, this current low off our coast has cut off, which explains the slow movement. This is the one I felt will bring much needed snow to the central part of the Rockies...and I still am holding out hope. This storm appears to have more support than the last one, and may swing a tad more to the NE once it moves inland. The trough associated with it seems to be assuming a negative tilt, which is increasing convection (and possible T'Storms). As I mentioned earlier, these slow moving storms sometimes can draw up lots of Gulf moisture, so severe weather in the Southwest and Texas is possible (but without a strong jet, tornadoes are less likely). Don't expect anything for at least 48-72 hrs . from another cold low scheduled to seep down the coast from the GOA. Models on timing and intensity are not in agreement at this time...and unless the jet changes, another glancing blow to the coast is probable.
3/09/99 Classic March weather, as a cold, blustery trough came through, dropping 1.2" rain in Pacifica, with generally lighter amounts elsewhere. VERY heavy rain, (0.55") fell during frontal passage last evening during a 25 minute period, complete with ice pellets and bonafide small hail. A decent thunderstorm also hit around midnight, with 3 good thunderclaps and brief, heavy ice pellet precip. Due to perfect orographics in Pacifica, we received significantly heavier rain than other nearby locations. The cold air brought snow in decent amounts (up to 6" around Mt. Hamilton and Skyline) down to around 2K', with snow sticking at the 3K' level. The main low is currently stalled off the Wash/Canadian border, but the next in the series of lows should kick it east later today/tonite. With this type of pattern, (not seen in recent years), it would not be unusual to have a low cutoff near the West Coast in a week or so, bringing intermittent, slow moving troughs through our area for a prolonged period. Sea Surface temps offshore are now running about 50F, which is about 4-6F below typical, and about 1 degree cooler than last week. Significant upwelling is continuing offshore, and much above normal baitfish continues to be reported in most locations, as well as inside the Bay itself, and as a result,excellent sport Salmon fishing is expected for the opener this weekend. The overall Wx pattern is complex, as the jet stream is quite amplified at this time, in marked contrast to the relatively flat, zonal pattern that has characterized this winter so far. A record low for the date occurred in downtown Oakland on the morning of the 8th (42F), reflecting the very chilly air. Continued unsettled weather is expected for at least the next week or so, and continued cold temps are likely as the jet continues to dive down the coast from the GOA.
3/01/99 The latest in a series of three dying troughs through here early on 3/01, bringing mostly drizzle , fog and light rain most of the day on 2/28. Only .08" recorded here. Warm air advecting ahead of the trough raised dewpoints to 58F, which is the highest in months. With clearing skies today, temps to the mid 60's (and 70's elsewhere) is possible. This air mass is clearly warmer and more humid than what we have been experiencing since early December. In years past, a warm, spring-like spell like this would occur between mid Dec. to mid Jan.- a sort of mid-winter break that separated our "early season" rain pattern from the "late season" pattern. This year, while the dry spell occurred right on schedule, it was much colder and lasted much longer than normal creating one of the driest periods during that time frame on record. If the current blip of warmer temps is indeed reflecting a generic shift in the pattern, we might expect below normal rain for the remainer of the late season rain period, as lows are guided farther to the north and drying occurs along the southern troughs. On the other hand, if this is just a delayed "break" in the overall Winter pattern as would normally occur much earlier in the season, a turbulent Spring might be on hand, as cold core lows will be drawn down the coast by the EPacific High retreating out to sea. With the basic Winter pattern continually putting us right on the edge of serious rains (near average rains here and above normal rains to the north), I am leaning toward a drier than normal but cool Spring. It will take a few weeks to analyze whether our rains here are nearly over or will continue well into April/May like last year. With still almost three months to go in the rainy season, Eureka has now received 100% of their annual rain total (37") and San Francisco with 18",is also nearing annual norms (20.5") with 120% of normal to date. However, just to the south at San Francisco Airport (SFO) which typically receives almost the same rain as The City , only 80% (11.7") of normal to date has fallen and 65% of annual totals. SoCal continues less than 40% of normal to date in most areas (L.A. has received barely 4" as compared to a normal of almost 11"). The Santa Cruz area is an anomaly, as zonal flows have hovered twice over the area this Winter..and near normal rain totals have resulted in a narrow band-maybe 50-75 miles north to south. Sierra snowpack water content in the Cent Sierra (near Tahoe) was just measured at 166% of normal (over 300" of snow currently at top of Kirkwood), but the southern Sierra is only 60% or less. The northern mountains, and especially in the far NW, continue way above normal, with exceptionally hazardous conditions in Washington and the Northern Oregon Cascades.
2/22/99 Thunder associated with a cold trough and an embedded upper low hit early morning of 2/21. A juicy plume of moisture had hovered over the coast most of the day on 2/20, but lack of upper air support for most of the time contributed to the low rain totals (mostly below 1" in the Bay Area-0.74" here). Basic Zonal flow pattern continues, with ridging nudging north then mid-Pacific lows riding on 140-160kt jets beating it back down south. Some of these lows are bringing unusually cold air down behind them, but either lack of moisture or weak dynamics has prevented the big Gullywashers that sometimes occur in these patterns. Most of the heavy rains that have fallen have been due to orographic enhancement. Some stronger storms possible in a few days, although things should dry out now for a few days under the influence of a weak, dirty ridge. Rainfall now near to above normal north of San Francisco It looks doubtful any appreciable change in the pattern will occur this rainyear, and the Southland looks like it has a nasty fire season on the horizon.
2/08/99 Heavy rain through area on 2/5 - 7 as 2 cold lows embedded in a long fetch of mid-Pacific moisture pummeled the coast. North Bay Counties were harder hit, with some danger of flooding on the Napa and Russian Rivers, but rivers receded quickly once the rains quit. A classic cold front/T-Storm line hit early on 2/06, with lightning and thunder. Heavy T'storm activity in the South Bay and in Monterey area. Up to 5" rain in Santa Cruz area, though much less over the hill in San Jose. Sierra received up to 7' in the highest elevations with 4' common at around 7K'. Snow level down to 2K' on back side of last impulse. With all the snow in the Sierra's, only flurries occurred in Reno, with no snow sticking. Snow pack in the mountains now generally near normal in water content, with comparable snow packs to last year at this time..Skies clearing rapidly, and intermittent weak fronts scheduled through over the foreseeable future.
2/01/99 Rain has tapered off for the near term, as we have just
finished a stretch of 12 days out of the last 16 with measurable precip.
bringing monthly rains to near normal. Significant rain on 1/29-30 brought
1.4" to Pacifica in a 6 hour period, and was punctuated by brief, intense
rain in two major bursts. Some local flooding and standing water resulted,
but no major damage or problems to speak of. Temps remain on the cool side,
and frost and light freezes have been occurring most every night when rain
and winds calm down. Fog in inland areas has also been a persistent problem
when winds calm. Snow in the local hills down to 2K' have occurred, with
snow to 1K' on the 24th when a very cold trough pushed through. The low skirted
the coast and moved inland over S. Central Calif. and brought up to 6" of
snow to the BAKERSFIELD AREA..the first such
event in over a quarter century.
1/16/99 Light rain and drizzle from a zonal flow-like warm front has ended over four weeks of dryness, with the only precip in that time frame in the form of snow flurries on Dec. 20th (see next entry). This is one of the longest dry spells during our typically rainiest months in memory. Offshore winds started to subside about a week ago, as the dominating high(s) over the upper plateau and the East Pacific finally moderate and weaken. The blocking ridge over the E Pacific is being slowly pushed south, and a zonal pattern is starting to develop across the Pacific then continuing over the continental U.S. As a result, temps should start to moderate some over a wide portion of the U.S., and rain in the form of shortwaves spaced 36-48 hrs apart should hit the Pacific coast with some regularity for the next 10 days or so, at least. Currently, rainfall PON's are as low as 20-30% in So Cal, rising to above average in the NW corner of the state. Overall mean temps inland had been averaging over 5 degrees below normal, with regular freezing temps in outlying as well as urban areas, but quite mild and windy from the NE on the coast. Temps are now expected to moderate as cloud cover and warm, moist Pacific air finally invades the region. As this pattern matures, the jet is expected to adopt a more meridonal flow, bringing colder rains and temps back to the region.
12/24/98 SPECIAL SNOW REPORT!! A rapidly advancing arctic airmass from the NNE brought record cold and snow showers to Pacifica on 12/20. The cold air mass affected most of the country including the West Coast. This was preceded by an extended period of record warm temperatures in Pacifica which twice hit 77F in the preceding week. The Snow was produced by an embedded low in a rapidly advecting cold airmass diving down the heart of the state which produced a sort of "bowshock" effect along the arctic frontal zone. The front stalled briefly over Monterey, and embedded thunderstorms along this front created up to 6" of snow locally in the hills and flurries to sea level in Monterey County and lesser amounts here. Briefly moderate snow was reported at Rockaway Beach in Pacifica. 5 separate snow squalls hit my house from between 0630 and 1100 hrs, with one at 0930 producing thundersnow and briefly near zero visibility. Air temp at 37F prevented snow from sticking, but nearby Montara mountain was completely encased in white on two occasions. Squalls also produced moderate pea hail on three occasions. Totals liquid precip was only .06", as dew points quickly fell into the 20's after the initial frontal passage. Near record cold has followed the snow event, with high temps in the upper thirties to mid forties throughout the area. Lows in the mid-teens were widely reported. Agriculture has been hard hit by the widespread freeze, with low temps at Bakersfield in the mid to upper teens. This cold air will eventually be replaced by a more progressive, almost zonal flow pattern which will develop to our north, then slowly sag south.
12/02/98 A deep, cold GOA low hit the coast on the 29-30, bringing high winds, huge surf and 1-2" rain locally and up to 3" in the coastal hills and Sonoma County. Rain total in Pacifca was 1.18" for the event, with a nice frontal passage dropping about .5" in an hour. Expect more cold impulses with dropping snow levels to the higher Bay Area hills in 4-5 days, but after that, the cold dry air will enhance the EPac high, and we should go dry for a while. This event brought November rains to generally near normal, with above average rains along the Cal/Ore border. Wound up with 15 days of rain and 4.6" for the month (above both historical and recent norms, but well below the 7.93 of last year's El Nino).
11/25/98 P/C here in Pacifica and mild. Southerly winds and impressive storms to our north but no real rain to speak of for at least 72hrs. 11 days of rain but only 2.48" here for the month. Every month of this climatological year ( July-June) has been below average, and most stations in the central/southern part of the state are now only 30-60% of normal for this date. SoCal is actually worse, as they have not had any real rain in weeks. I believe their winter rains are only about 25% of normal. The storm track is still 90 degrees to the coast, centered between British Columbia and the Ore/Wash border, and fronts are continually dying on the south end. Northern Calif near the border has received heavy rains, but totals drop fast as you move down the coast. As I have mentioned before, what rain we get in La Nina years often occurs early in the season, so this current trend of below average rains is worrisome. Almost no hope now of regular rains...if we do get rain it will most likely result from a drop in the jet and tropical moisture getting pumped in..a la Zonal flow. It will surprise me if we get more than 5 real rain events (although a 5-10 day deluge during any single event is not out of the question). One interesting note: Huge surf pounded the coast on Tuesday, with up to 30' waves at Mavericks, about 10 miles south of here. Storms in the NW are producing winds to near hurricane force over the water and downslope winds inland and over the summits even stronger. Winds to 118mph noted in the Northern Sierra on Tues/Wed. As of now, I see little fundamental change in this pattern for the foreseeable future. Hope I'm wrong, but a drought seems to be shaping up for the Central part of the west
11/15/98 Much of the early optimism about a "near normal" winter may have been wishful dreaming at that. Last weeks storms fizzled as high pressure off the coast has dried thing out with upper air support diminishing with rising heights. Weak fronts and dry tails continue to move through, but very little rain this week. with only .30". The Pacific NW is getting clobbered as tropical moisture is being channelled into the area by high pressure ridge offshore deflecting storms and moisture right into Ore/Wash, but precip tapering off fast the farther south you go. Looks like a mini-zonal flow pattern setting up over the Mainland..with moisture cutoff to the south and clipper lows screaming eastward. Temps remain coolish, and the first frost seen over on the peninsula on the 9th (a mild 44 here). Rain prospects appear weak for at least the foreseeable future, save for a chance of showers around Tuesday. Already, juicy Pacific storms are having a tough time penetrating the ridge, and the ridge should continue to strengthen as the winter progresses. A weak trough may bring light rain in 36-48 hrs, but then an even stronger ridge builds in behind. It will take one heck of a storm to break through now, or the high to retreat and allow some GOA energy to slide down the coast.
11/8/98 - Moderate rains (.85" here) are hitting Calif. at this time as a series of potent GOA lows swoop down the coast bringing high winds, rain here and snow to the Sierra's. This is a very winter-like pattern, with storms (and old typhoons) starting to line up out over the ocean and rapidly marching eastward then diving down the coast then inland. We expect another potent storm in 72-96 hrs. Cold air in back of the current system may bring showers of instability and an outside chance of T'Storms (especially in the valleys).
10/24/98, Special La Nina
My thanks to Steve for getting me off my duff and getting this written. The fall season appears early as on 10/22, we went to NE Calif. mountains fly-fishing for some trophy trout at Eagle Lake (my son, Joel, was the big winner with a 6.5 pounder). A chilly 34F in rain and 30mph winds when we left the lake(5,500'), encountering moderate snow over the hill getting into Susanville, as well our trip over the Sierra's to Redding. The sights were spectacular, as peak fall colors were punctuated by a whipped cream-like dusting of snow. Golden fields with glistening edges, contrasted sharply with darker underparts of mammoth Pine and Spruce trees. Similar treats going through Lassen Park, and the lower Trinity Alps along HiWay 299. As for Pacifica, I am wondering if the event (La Nina) will be as strong as forecasted. Current data continues to show below normal SST's in the Central Pacific, but no real change in the last few months. Giant Chilean squid continue to be caught in record numbers immediately off the coast of San Francisco which probably further highlights the magnitude of the last cycle of ENSO, which drove these creatures north. These "suckers" can be up to 6 FEET in length and weigh 40+Lbs. Talk about a Calamari feed! Obviously, something in our local environment is favorable to them. We had a rather tranquil summer/early fall, although early, fall-like light rains were occurring in September. Only had one summer infusion of tropical moisture, which resulted in a few isolated T'storms in early August. What a change from last May, (the last gasp for El Nino, and also the start of rapid SST fluctuation) which was one of the wildest months on record with four separate tornado days in Central Calif. and 300-500% above average rain for the month.
The cold front through here on 10/23 was a classic Pacific trough with a deep cold core moving steadily W to E, and actually intensifying unexpectedly on it's southern flank (.75-1.25" over most of the Bay Area). This set the trend for lows extending to slightly lower latitudes for this T.O.Y.. sometimes, this trend can give substantial early rains, but by Jan/Feb, cold air from the Upper Plateau starts spilling westward (Santa Ana's) and bridges with the EPacific High...thereby shunting storms "up and over", and we go dry. The main hinge is available moisture from offshore. Our SST's have remained steady in the 53-57 region, which is near normal for this time of year. Sometimes, SST's are a little warmer as the strong NW winds along the coast have subsided.In 1997 (El Nino), temps were well into the 60's at this time. As for SoCal, look for some howling Santa Ana's in the Jan-Feb timeframe. I think some strong winds will also develop as shorterm high's build in in back of these fall storms. With these early rains, I think the fire season's end has come...and it looks like it was the second much below normal fire season in a row.
My Winter hope is that GOA lows will continue be strong enough to maintain strength as they plow into increasingly drier air over N. America and provide at least near normal annual rains. As the La Nina develops, the E Pacific high will intensify, but hopefully stay far enough west to limit bridging and allow cold storms to march down the coast. So, in a nutshell, looks like a below to near-normal rain year, with no prolonged drought periods, either. A major exception may arise should the high "tip over" and a zonal flow pattern develop, which can create catastrophic floods within the narrow band of intense rainfall along the zonal boundary. I expect some cold events out here also, as lows being pumped down the coast from the north can bring unusually low snow levels. I think So.Cal will have a stronger than normal Santa Ana year, within periods of extreme warmth and dryness during mid-winter - although a heavy rain period is not out of the question should a zonal pattern develop.
10/04/98: I have proclaimed the Rainyear of 98-99
has begun in earnest, with 4 straight days of rain (mostly light drizzle,
with occasional stronger showers) throughout the region from 9/27 - 10/2.
Most upper air support was provided by a pesky upper level low-then-trough
which managed to get trapped over Cent. California. It produced widespread
light showers coastside, and showers w/heavy T'Storms in the mountains, and
the season's first decent snows down to 7,500'. Another in the current series
of troughs moved through the region on 10/02, leaving brisk winds and cool
temps in it's wake. Only light drizzle here, with heavier amounts along the
Cal/Ore border. By 10/4, light winds and warming temps under crystal
blue skies have returned, but no major heat as would be typical this time
of year. Extended models differ, as one keeps the pattern progressive with
another cooldown 72-96 hrs from now, while the EUR/UK models show the current
So far, this has been an unusually cool and cloudy Indian Summer, with fog and stratus tops up to 3K' piling over the hills from strong onshore pushes of cool marine air. Normally, stratus layers thin out this time of year, with our particularly beautiful pattern of fog hugging the ground in thin, dense layers calmly infiltrating the immediate Bay.
On the Nature front, very light leaf drop noted so far,despite the early rains and cool temps. Many fruit trees and other flora did not fair particularly well this summer, as temps and sun hours were below normal.
Sea Surface temps locally are 53-54F, a couple of degrees below norm this time of year, and a far, far cry from the 67-71F this time just a year ago . Giant squid (4' long) are being caught very near the surface off the Marin coast and points north . Attempts to keep these rare creatures alive in tanks have largely failed so far. Up to 20 have been reported caught in a single day by party boats. It was a good Bass year, with many runs in the early and middle of summer, with most heavy action over by mid-August, although some bass are still getting caught over a wide area. Most fish have migrated back into The Bay, and have been caught in high numbers (hopefully signalling a return of this prized sport fish).