Cool . . .Windy . . . Gradual Warming Begins Wednesday

16 Day Forecast, Monday, May 4th, thru Tuesday, May, 20th, 2014 from Atmospherics Group International

 

 

Lower pressures inland will provide an increasing onshore flow into CENCAL thru Tuesday evening.  Low elevation showers and high mtn snows are expected during the next 36hrs, with clearing on Wednesday.  The current system will be recognized by wind rather than precip for the lowlands with blowing dust a possible issue to tangle with for the next 2 days.   Please drive carefully in the blowing dust, since there is ample areas of fallowed ground this year.  The impressive stack of lenticular clouds east of the Sierra Crest today is indicative of the high winds aloft.  With cold air moving into the region Tuesday, would not be surprised to see snow levels briefly drop below 6,000ft in the Sierra, with Tioga Pass likely to close again due to the snow/wind.  An additional 6 inches of snowfall for Mammoth Mt could help prolong their ski season a bit longer.  Longer range shows a gradual warmup which places SJV temps at the hot spots into the 90°’s for next weekend.  This Heat Wave could extend all the way to the end of the 16 Day period ending on Tuesday, May 20th…or beyond.  Expecting many SJV Ag Stations to reach 100°+ on May 13th, 14th and 15th.  No significant CA rainfall is in sight.  The EPAC Tropical Season could get off to an early start on Wed, May 7thwith the possible formation of “Amanda”.  Although the recent charts have diminished its intensity and duration, it will be very interesting to see if it does become strong enough to become a named storm.  The Australian climate scientists have become the first to announce their prediction of the upcoming ENSO event to be a “strong” event.  This would be great news for CA if it does verify.  In the meantime…it is not a good sign to see that the only record set for CA is at Death Valley.  This continues the trend from 2012 and 2013, when Death Valley was named many times with new records.   Details to this and more below;

 

ENSO-El Nino Update;  Australian climate scientists identify rises in Pacific basin temps as having similar characteristics with a developing “STRONG” El Nino event. This is the first credible entity to make such a bold statement.  If the developing ENSO does indeed evolve into a strong El Nino, that could have profound impacts upon CA.  Just remember that if it does not become a strong event there is no correlation or signal for CA wx…no link!  Media should remember to explain that disclaimer.  Weak and Moderate El Nino’s have a 50% chance of wet and a 50% chance of dry results for CA.  Story link below;

http://news.yahoo.com/ocean-data-points-strong-el-nino-climate-scientist-065829620.html

 

 

Winter Wx Advisory for the Sierra above 8,000ft with snow accumulations of up to 3 inches Monday and an additional 3 inches on Tuesday for a storm total of up to 6 inches.  Snow should begin this afternoon and continue overnight, then taper off Tuesday morning before increasing again later Tuesday afternoon and then diminishing during Tuesday evening.  High Winds of up to 60mph are possible near the Crest region.

 

 

FORECAST SUMMARIES

 

Days 1-7;                                                                                                                

 

Mon, May 5h                High Pressure ridging at 140W forces a PACNW trough containing a -28°C cold core centered near Portland, OR to continue to dig southward into NORCAL with 552dm heights reaching across the NORCAL down to near Crescent City, as the -24°Cisotherm heads southward to near Cape Mendocino to Mt Shasta and Alturas by this afternoon.  Vort energy spreads southward thru NORCAL producing shower activity into the Sierra down to near the Kings and Kaweah River basins with snowfall at the higher elevations later today.  Convective Parameters pop up over NORCAL with garden variety Thunderstorms possible over the northern SAC Valley, producing a threat of hail, however the dry 0.5 inch PWAT’s over NORCAL should limit the extent of Thunderstorm development.  Overnight the -24°C cold core drops further southward into NORCAL to near Tahoe while the formation of a closed circulation 552dm Low Pressure center evolves, accompanied with snowlevels lowering to near 7,000-7,500ft with moderate vort energy keeping showers going over portions of NORCAL and into the Sierra.  Winds pick up throughout the SJV tonight reaching up to 30-35mph along the wind favored areas of the Westside, causing Blowing Dustand Hazardous Driving Conditions.

                                    MAX                                                     MIN                                                     PRECIP

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                                    Storm Prediction Center (SPC) is placing a general Thunderstorm Risk area over portions of NORCAL for Monday;

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Tue, May 6th                Another Blustery Day!  The northern portion of the trough shifts into the Great Basin with the backside north flow pattern advecting cool/dry air southward into NORCAL, while the southern portion of the trough sags southward into the Tehachapi Mts and reaches into the upper Mojave Desert region of SOCAL by afternoon.  With clearing skies and northerly breezes over NOR/CENCAL, producing cool temps and partly cloudy skies for the lowlands and cloudy skies and light showers continuing into the Sierra with snowlevels dropping to near 6,000ft.  Temps at some SJV Ag Stations may not reach 70°!  PWAT’s associated with this event are very low, therefore precip accumulations in the Sierra will be light, with high POP’s but low QPF’s expected.  What this storm lacks in moisture is made up for with wind, with gusts of up to 25mph expected along the wind favored Westside with moreBlowing Dust possible.  Light showers may also drift near the Southern Sierra foothill region close to the lower reservoir elevations, especially into Tulare Co with sprinkles or light showers possible near Orosi, Ivanhoe, Visalia or Porterville.  Overnight as the trough begins to kick eastward into the Great Basin, the backside of the trough and it’s northerly flow pattern bring cooler/drier air into CA with clearing and diminishing showers in the Southern Sierra.

                                    MAX                                                     MIN                                                     PRECIP                                                        

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Wed, May 7th               The trough shifts into the Great Basin providing NOR/CENCAL with lighter NW breezes.  As gradual clearing occurs over the Southern Sierra the high winds over the Crest region diminish.  SJV temps regain about +5° of warming from the below average temps of Tuesday.  The onshore westerly flow pattern over the PACNW brings another slug of moisture inland overnight with another shot of shower activity possible into the far NORCAL border region with OR and cloudiness as far south as Monterey.   Noteworthy; the 700mb charts show a low level subtropical disturbance developing SW of Acapulco, Mexico which could be an early detection of possible development of an EPAC Tropical Disturbance.

                                    MAX                                                     MIN                                                     Chart showing possible Tropical System

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Thu, May 8th                As High Pressure slowly rebuilds over CA and with clear skies, temps respond in kind with inland temps warming back into the lower 80°’s with light breezes expected.  An onshore ‘overrunning’ westerly moist flow pattern over the PACNW brings additional rainfall into WA/OR and portions of NORCAL with upsloping cloudiness for the Sierra, but no precip expected, except into the Lassen and Feather River basins.  Overnight additional clouds move into the northern 1/3 of CA on the dirty NW flow pattern with light precip amts from near Santa Rosa to near the Yuba River basin.  The EPAC Tropical Disturbance is shown to move onshore into southern Mexico, which is a new forecast trajectory as compared to 2 days ago.  If the storm does indeed move inland, then it would be the end of the storm’s lifecycle.

                                    MAX                                                     MIN                                                     PRECIP

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Fri, May 9th                 High Pressure rebuilds slowly into CA from the SW with weakening winds aloft.  Temps continue to slowly increase by +1° to +2°, which is a much slower pace than was anticipated 2 days ago.   Light showers may fall into portions of NORCAL as the weak onshore flow continues to the north, into the PACNW.

                                    MAX                                                     MIN                                                     PRECIP

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Sat, May 10th               While a strong 588dm High Pressure circulation forms west of Pt Conception, as the same time a 552dm Low Pressure storm center approaches BC, Canada containing a -28°C cold core.  While precip is limited to the PACNW, some high cloudiness filters into NORCAL on a light NW flow pattern.  The High Pressure over CA produces warming temps with +5° to +6°.

                                    MAX                                                     MIN                                                

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Sun, May 11th              High Pressure with 576dm heights build over CA, with stronger 582dm heights nearing the CA coastline.  The weak disturbance west of the Olympics continues to spread mod rains into WA/OR, with clouds extending southward into NORCAL from Cape Mendocino to Tahoe northward with clear skies for the remainder of CA. Temps remain near persistence. 

MAX                                                     MIN                                                

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Days 8-16, Long Range into Fantasyland OutlookDay 8 begins;

 

Mon, May 12h shows High Pressure continues to intensify offshore west of the coast, with the 582dm heights nearing Pt Conception and light winds aloft producing additional warming with temps in the SJV reaching into the 90°’s and the hot spots reaching into the upper 90°’s.  

 

Tue, May 13th shows High Pressure dominate over the West Coast producing the season’s first widespread100° temps into the SJV.  No rainfall is seen within the 7 most western States due to the High Pressure.

 

Wed, May 14th shows High Pressure continues to intensify over CEN/SOCAL with the warm 582dm heights running from near Monterey to Kings Cyn, producing temps well above average and into the 100°’s for many of the SJV Stations.

 

Thu, May 15th shows a slight retraction of the 582dm heights to the south, with the 582dm heights running from near SLO to near Kings Cyn, producing another day of temps well above average and into the 100°’sfor many of the SJV Stations.  No precip is noted for the West Coast due to the dominant High Pressure, although a Low Pressure center is approaching the PACNW, which begins to move onshore into the Olympics with showers overnight.  

 

Fri, May 16th shows the Olympic Low Pressure opens up into a trough configuration with rainshowers extending southward into WA/OR down to Eugene, OR, with cloudiness extending south to the CA border region.  With slight pressure falls over CA, temps remain close to persistence, with perhaps -3° cooling with most SJV Ag Stations reaching into the upper 90°’s.

                     

Sat, May 17th shows the 582dm heights drop southward into SOCAL as 576dm heights cover CENCAL, producing slight cooling by a few degrees with most SJV Ag Stations reaching into the low to mid 90°’s, …above average.

 

Sun, May 18th shows a persistence pattern over the EPAC/West Coast with little change noted and with above temps continuing over most of CA.

 

Mon, May 19th shows the formation of a large GOA Low Pressure storm which begins to dig SE’ward toward the PACNW, while High Pressure ridging is still dominant over the EPAC/West Coast with little change noted …and with above average temps continuing.

 

Tue, May 20th shows High Pressure shifting eastward into the Great Basin as the large GOA Low Pressure finally reaches into the PACNW with rainshowers spreading into the WA coastline and the cold front aligned north to south, parallel to the WA/OR coastline and then extending SW offshore west of NORCAL.   The pressure drops over NORCAL producing cooling, while temps over CEN/SOCAL continue to be much warmer than average, with high’s into the 90°’s for most of the SJV.

 

 

Special Notation; with High Pressure the dominant feature over the West Coast and CA during week #2, very warm temps are expected for a prolonged period of time with the end not clearly in sight.  The Day 16 scenario is very uncertain, therefore the HEAT WAVE could continue beyond the Fantasyland 16 Day Outlook.

 

 

 

NEW  CA  RECORDS …HEAT!

 

Station                         New Record                Old Record__

Death Valley                  83°       Ties                  83° set in 1918              A 96 year old record!

 

                       

 

 

PRECIPITATION FORECAST

 

Day 1 – 5 QPF:

At 12Z (9am) Monday thru the period day Friday night (Saturday @5am);

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7 Day QPF Chart; shows up to 0.5 inch for the Southern Sierra and portions of NORCAL with diminishing amts surrounding those areas.  Most of the interior lowlands remain dry.   SOCAL coastal areas receive up to 0.2 inch.  The Great Valley is depicted as mostly dry south of Red Bluff.

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16-Day QPF estimates (from the 0Z GFS model) for;

Days 1-7; shows up to 0.5 inch for the Southern Sierra and portions of NORCAL with diminishing amts surrounding those areas.  Most of the interior lowlands remain dry.   SOCAL coastal areas receive up to 0.2 inch.  The Great Valley is depicted as mostly dry south of Red Bluff.

 

Days 8-16; shows dry conditions for most of CA, and only a few light showers possible into the far northern counties near the OR border.

 

GFS 384hr, 16Day QPF Chart shows only light amts of precip offered for CA during the Week #1 period, with up to 0.25 inch reaching into the Southern Sierra and up to 1+inch into the Feather River basin. Most of the Great Valley receives >0.1 inch although Thunderstorms into the SAC Valley today could drop more.  

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EVAPOTRANSPIRATION

 

Weekly Evapotranspiration rates for the local 7 Counties shows up to 1.55 inch near Merced, up to 1.70 inch in western Fresno and Kings Co and up to 2.15 inch near Ridgecrest during the next 7 Days.  The Sierra Crest evaporation loss ranges from 0.92 inch in the upper Tuolumne River basin up to 1.66 inch near Isabella.

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SATELLITE

 

Water Vapor 4KM Image of the West Coast Monday, May 5th, 2014, shows an active cold trough bearing down upon CA and the PACNW region.  The weak and dry cold front is passing thru CENCAL, with the advection of cold air entering into NORCAL, with the dry slot passing east of Cape Mendocino.  

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Visible Satellite Image of the CA Monday, May 5th, 2014, shows considerable cloudiness over portions of NOR/CENCAL, with coastal stratus along the SOCAL coastal region.  An impressive brightly lit stack of lenticular clouds has formed to the east of the Southern Sierra.  The SW flow aloft is evident with the orientation of the cloud streaks.

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If you have any questions please call or text at any time of day or night. 

Comments and suggestions always welcome.

 

Atmospherics Group International

Dan Gudgel              Steve Johnson

559-696-9697                 559-433-7316

BenitoLink Staff