Must See! Attached; High Resolution Visible Satellite Image showing a parched CENCAL region including the Southern Sierra. Each river basin is labeled and both FAT and BFL are positioned for reference. Note the rusty-brown scar from the “Rim Fire Burn Area” in the Tuolumne River basin at the top of the pic. Also note the brown/dry Coast Range and Sierra foothills…and the lack of snow coverage in the Sierra high country. It’s hard to discern the difference between the lighter shaded granite with that of snow, but this image really shows the lack of snowpack, both Shuteye and Kaiser are bare.
Wx Headline; Critical Temps possible at only the coldest Stations at night if skies clear, with Record-Setting max temps at the hottest Stations during the afternoons continuing . Unbelievably dry conditions continue to prevail during the next 16 Day period according to several days worth of consistent GFS forecast charts, unfortunately…ending Feb 6th with no precip for most of CA. If those charts verify, not only does January close with Historic Record-Setting dryness for the month and for the season, but February begins on a dry note as well. There is some uncertainty regarding a potential storm system reaching into the northern portions of NORCAL on, Tue Jan 28 as the system weakens rapidly, it does not make it into CENCAL. Unfortunately this is the only storm on the charts for CA thru Thu, Feb 8th according to the 12Z GFS. The GFS has also occasionally trended in placing a vigorous wet storm system near the coastline during the first week of Feb… but is now consistently showing January to end extremely dry. As the GFS has been trending dry again, this spells more trouble in a dire situation for the CA water supply. If the GFS verifies as currently indicated in 10 days ending January 31st it will produce a Record-Setting dry month, smack in the middle of the rainy season. Additional comments below in Special Notations;
View of the GFS 300mb flow pattern observing the Arctic region, NA and the North PAC; showing the Jet Stream splitting at 140W, with High Pressure ridging over CA steering the Jet Stream to the north, into Alaska, then diving SE into the central CONUS down to Florida.
Why is the pattern stuck? Here’s the possible answer; observe the Canadian Hudson Bay Low Pressure trough which is connected to the Russian Kara Sea Low Pressure trough, and neither are moving. So therefore the West Coast Ridge is stuck. The Global Image below shows the view from the North Pole, with the Arctic Vortex circulating around the North Pole, with strong winds around both sides of the Hudson Bay Low trough, which locks it into position. Until the Hudson Bay Low diminishes or progresses, then the West Coast ridge stays where it is. No wonder the NE New England States and Central Canada have had such a harsh winter!
Observations; Satellite Imagery shows high cloudiness spreading northward thru CEN/SOCAL which may cap-off the afternoon temps early. Not sure if they are thick enough to impact out-going radiational cooling for tonight, which will offer a problematic forecast for tonight’s minimums as they did last night in the South Valley. Winds over the region show mixed and variable winds over the SJV with strong SE winds over the Tehachapi’ up to 36mph. Dewpoints in the Kern River basin are extremely low with 3° at Wofford Heights and 1° at Walker Pass. This dry air extends northward thru the Tule, Kaweah and portions of the Kings River basins with Shadequarter reporting a dewpoint of 5°, Pinehurst -8° and Fence Mdw -2°. The extended period of extremely low PWAT’s/Dewpoints over the Sierra are taking an toll on the forests as well as the streamflows.
24hr Precip Summary highlights to 9am Sunday; none
Tue, Jan 21st The RRR High Pressure ridge weakens slightly as a minor shortwave approaches the PACNW. Further west a larger storm intensifies to a 510dm height, with the High Pressure ridge built northward up into Alaska. Skies over CA are partly cloudy from a disorganized area of moisture moving northward. Conditions for CENCAL remain mild and dry with continued frosty morning at the cold spots depending upon the amt of cloud coverage and record-setting heat during the afternoons.
Wed, Jan 22nd The RRR 576dm High Pressure ridge builds northward along the West Coast NA. The previously mentioned small disturbance that was moving into the PACNW, dives rapidly southward into eastern NV and western UT, producing a N-NE flow pattern over CA. Skies over CENCAL remain fair, with frosty mornings in the colder spots and record setting heat during the afternoon.
Thu, Jan 23rd The RRR High Pressure ridge circulation center shifts northward to a position along the BC, Canada coastline, with a trough pattern from the Aleutians digging SE toward Hawaii. The NV/UT disturbance retrogrades westward along the base of the ridge circulation, which could produce some clouds, but lack any moisture. If this vort had some moisture with it then convective activity could be possible as a remote possibility but highly unlikely. CA has mild/dry conditions continuing.
Fri, Jan 24th An impressive Atmospheric River (AR) stretches from the Maritime Continent to a stationary Low Pressure storm center that is locked into position along the western periphery the West Coast High Pressure, therefore the moisture stream takes a 90° left turn and heads north into southern Alaska. The West Coast High Pressure cell is nosing onshore into western WA/OR and SW BC, Canada with a E flow pattern for CA producing more persistent wx, dry/mild conditions with occasional high clouds.
Sat, Jan 25th The previously mention AR is wrapping around the Low Pressure on the western periphery of the ridge, so the moisture ends up mainly affecting the Aleutians. With strong high pressure over CA, persistence remains with warm/mild conditions.
Sun, Jan 26th While the High Pressure ridge remains dominant over the West Coast, the stationary mid PAC storm system continues to gain size, intensity and moisture. CA remains persistent with warm/mild conditions.
Mon, Jan 27th The 576dm High Pressure ridge shifts slightly east onshore over the West Coast, with the monstrous storm system further to the west feeding heavy AR warm rains into southern Alaska and BC, Canada. CA develops a N flow pattern with more persistent conditions…mild/dry.
Days 8-16, Long Range into Fantasyland Outlook; Day 8 begins;
Tue, Jan 28th shows the High Pressure ridge intensifies to 582dm heights over NOR/CENCAL with an offshore flow pattern suggested which should warm temps over CA significantly, with fair/mild conditions.
Wed, Jan 29th shows the 582dm High Pressure onshore over a large portion of CA with fair skies and mild/warm conditions continuing.
Thu, Jan 30th shows the High Pressure ridge weakens slightly to 576dm heights, while a storm system rides over the top of the ridge toward the PACNW. Conditions for CA remain persistent with warm/dry conditions.
Fri, Jan 31st shows further weakening of the High Pressure ridge as it shifts east into the Great Basin which allows a trough to dig southward offshore west of the PACNW. CA remains persistent with warm/dry conditions.
Sat, Feb 1st shows the High Pressure ridge rebuilding near 140W tilted NW up into western Alaska with a downwind flank of frigid ARCTIC air dropping southward toward the PACNW. Under a SW flow pattern CA remains fair, warm and dry.
Sun, Feb 2nd shows the High Pressure ridge at 140W directs the downwind ARCTIC blast to move toward the PACNW, while CA remains fair, mild and dry.
Mon, Feb 3rd shows High Pressure along the West Coast providing CA with fair, mild and dry conditions, while the cold air digs into the Rockies.
Tue, Feb 4th shows High Pressure over the West Coast with a NW flow pattern over CA, as fair, mild and dry conditions continue.
Wed, Feb 5th shows strong 582dm High Pressure over western portions of CA with a NW flow pattern over CA and fair, warm and dry conditions.
Thu, Feb 6th shows strong High Pressure blocking all storm activity far to the north with CA remaining fair, warm and dry.
Persistence at hand for the near term at least, with the addition of occasional mid and high layered cloudiness at times, the RRR High Pressure ridge continues to produce dry conditions, record-setting max temps, light winds, poor air quality, clear to partly cloudy hazy skies and frosty mornings in the coldest regions. The highly amplified pattern continues like a broken record with forecast charts trends suggesting the ridge axis is reinforced, which would imply additional days of warmth, with a dry offshore flow pattern continuing. If records are set again Wednesday it will mark the 10th consecutive day of RECORD-SETTING temps for CA.
Tuolumne Mdws had a temp yesterday of 52°. That Station has had the equivalent of almost 3 feet of snow accumulation this season, but only 4 inches remains with 1 inch of water equivalent. The snowpack in the Sierra is diminishing daily due to warm temps causing runoff and evaporation in addition to the super dry air with dewpoints into the single digits increasing the evapotranspiration rates. The lower elevation’s snowpack is gone, the mid elevations are diminishing, and the high Crest is sublimating back into the atmosphere with the nightly NE super dry 0.1 to 0.2 inch PWAT air from the Great Basin.
River Streamflows continue to drop into record territory for this time of year by big leaps, here are some examples;
River Current Flow (cfs) Old Record____
Scott 82 57 set in 1977 A decrease of 30% from the prior record drought
Eel/Scotia 187 382 set in 1977 A decrease of 52% from the prior record drought
Mattole 51 72 set in 1977 A decrease of 51% from the prior record drought
Russian/Healdsburg 36 61 set in 1977 A decrease of 49% from the prior record drought
Russian/Guerneville 63 90 set in 1977 A decrease of 30% from the prior record drought
Merced River thru Yosemite NP hydrograph showing the river is down to a trickle with daily fluctuations due to snow melt.
The incredibly stubborn and resilient large scale flow pattern over NOAM and nearby waters remains unchanged as an established PAC track lifts up to Alaska on the western periphery of the RRR High Pressure ridge centered over far western NOAM. This scenario offers above normal predictability and confidence given the similar model runs by the GFS over the past several days which keeps CA dry thru the period reaching into the first week of Feb…at least. This pattern is reinforced for much of the upcoming medium range forecast period this weekend and into next week allowing a series of harder to diagnose impulses aloft to drop over the top of the ridge into an amplified central NOAM trough which is giving the eastern portion of the CONUS a repeated beating with one ARCTIC blast after another. This is also what occurred during the 1976-77 CA Drought. Given the amplitude and stability of the RRR High Pressure ridge, which is tied also in large part to the blocky pattern emerging downstream over the Hudson Bay, eastern Canada and eastern CONUS, dry conditions for CA are likely to continue at least 12, and probably thru Day 16.
NEW RECORD TEMPS
Station New Record Old Record__
South Lake Tahoe 58° 55° set in 1994
Merced 68° 58° set in 2000
Madera 69° 67° set in 2009
Hanford 70° 68° set in 2000
Modesto 69° (Ties) 69° set in 2009
SAC Exe 69° 68° set in 2009
Red Bluff 75° 72° set in 2009
Kentfield 68° 67° set in 1945
SF Dwntwn 69° (Ties) 69° set in 2009
OAK Dwntwn 72° 71° set in 1976
Mt View 71° 70° set in 2009
Burbank 84° 82° set in 2009 This was also the 8th consecutive day with 80°+, which ties the record set in 2009
Sandberg 65° (Ties) 65° set in 1994, 1975 and 1971
Paso Robles 78° 77° set in 2009
Elsinore 85° 81° set in 2009
Minimum Temps this morning at the Paramount Citrus Stations ranged from the coolest minimum of a 28° at Orosi, rising to the warmest minimum of 39° at Loma. Increasing amts of cloud coverage kept South Valley stations warmer than expected.
Maximum Temps yesterday afternoon at the Paramount Citrus Stations ranged from the coolest maximum of 69° at Root Creek and rising to the warmest maximum of 75° at Ducor.
Day 1 – 5 QPF:
At 12Z (9am) Tuesday thru the period Saturday night (Sunday @4am) shows; Tue, Wed, Thu, Fri, Sat DRY.
5DAY ACCUMULATION CHART:
Days 6 & 7 QPF thru next Sun/Mon shows CA completely DRY, except for the far north coast with >0.1 inch.
16-Day QPF estimates (from the 12Z GFS) for;
Days 1-8 shows DRY conditions for CA, except for a few light showers in the NW coastal region.
Days 9-16 shows DRY conditions for CA, except for some light rainfall into the NW coastal region as depicted on the chart below↓
Comparison of both Tuesday’s 384hr GFS QPF charts, morning and evening are nearly identical which is amazing in one respect, but very concerning in another respect.
Tuesday’s 12Z 9am Tue morning GFS 384hr, 16Day QPF Chart, showing continued DRY conditions for most of CA thru Thursday, Feb 6th, with some light amts of precip in the far NW coastal region, with up to 0.25 inch for Crescent City.
Tuesday’s 12Z 9pm Tue evening GFS 384hr, 16Day QPF Chart, which appears nearly identical to the morning run 12 hrs earlier, with continued DRY conditions for almost all of CA, with a slight chance of some light precip in the far NW coastal region with >0.1 inch
Feather River Basin 10-Day QPF showing only 0.2 inch has fallen since Jan 12. The suggested snow level at 12,000ft on Tues, Jan 28th to Sat, Feb 1st indicates another heatwave lasting thru at least Sat, Feb 1.
Water Vapor 4KM Image of the West Coast at 8am Tuesday, January 21, 2013, shows a weak disturbance SW of San Diego circulating some subtropical mid and high layer cloudiness into SOCAL, which is spreading into CENCAL. The outline of the High Pressure ridge is observed up into the PACNW
Enhanced Satellite Image of the CA at 8am Tuesday, January 21, 2013, shows some high and mid layer cloudiness spreading over SOCAL northward into CENCAL.
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Comments and suggestions always welcome.
Atmospherics Group International
Dan Gudgel Steve Johnson