155
FXUS66 KHNX 121010
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
310 AM PDT MON MAY 12 2008
DISCUSSION
HIGH TEMPERATURES SUNDAY WARMED A FEW DEGREES OVER
SATURDAY IN MOST AREAS...REACHING THE MID 80S TO LOWER 90S IN THE
CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY. COALINGA WAS THE WARM SPOT
IN THE CENTRAL/SOUTH VALLEY WITH A HIGH OF 91...ONLY 1 DEGREE LOWER
THAN THE HOT SPOT IN THE ENTIRE HANFORD WARNING/FORECAST AREA...CHINA
LAKE N.A.W.S. WITH A HIGH OF 92 DEGREES.
THE WARM WEATHER...AROUND 5-8 DEGREES ABOVE NORMAL...WILL GIVE WAY TO
COOLER TEMPERATURES THE NEXT COUPLE OF DAYS AS AN UPPER-LEVEL TROUGH
BRINGS A COLD AIRMASS AND LOCALLY WINDY CONDITIONS TO THE REGION.
SATELLITE LOOPS SHOW THE TROUGH MOVING INTO THE PACIFIC NORTHWEST
AND NORTHERN CALIFORNIA THIS MORNING. THE MARINE LAYER HAS DEEPENED
TO ALMOST 3000 FEET AT FORT ORD IN RESPONSE TO THE APPROACHING
TROUGH...AND MARINE AIR PUSHING THROUGH THE SACRAMENTO DELTA ALREADY
HAS RESULTED IN AS MUCH AS 6 DEGREES COOLING IN PARTS OF THE SAN
JOAQUIN VALLEY FROM 24 HOURS EARLIER. MOS GUIDANCE HAS HIGH
TEMPERATURES TODAY DOWN 8-10 DEGREES FROM SUNDAY...AND THE FORECAST
REFLECTS THIS.
LOCALLY GUSTY WINDS HAVE DEVELOPED IN THE KERN COUNTY DESERTS AHEAD
OF THE TROUGH...BUT HAVE MOSTLY REMAINED BELOW ADVISORY CRITERIA.
ONE CONCERN IS THAT IT HAS BEEN HARD TO GET WIDESPREAD ADVISORY-LEVEL
WINDS FROM THE LAST FEW TROUGHS DESPITE STRONG SURFACE-PRESSURE
GRADIENTS. THE NAM DOES FORECAST A FEW GRADIENTS TO TIGHTEN LATER
TODAY...AND GENERALLY HAS TIGHTER GRADIENTS OVER THE KERN COUNTY
DESERTS THAN THE GFS. /THE GFS HAD UNDERFORECAST 06Z SURFACE-PRESSURE
GRADIENTS IN MOST AREAS./ THE NAM MET GUIDANCE FOR EDWARDS AFB DID
A GOOD JOB SUNDAY EVENING WITH SUSTAINED WIND SPEEDS AND FORECASTS A
MAXIMUM SUSTAINED WIND AT 25 KTS AT 00Z TUESDAY. AT THIS TIME...WINDS
ARE LIKELY TO REMAIN JUST BELOW ADVISORY THRESHOLDS FOR SUSTAINED
WIND SPEEDS...AND THE PROBLEM THEN BECOMES HOW WIDESPREAD THE
STRONGEST GUSTS WILL BECOME.
THE NAM HAS NORTHWEST 15-20 KT 850-MB WINDS OVER THE KERN MOUNTAINS
THIS AFTERNOON AND EVENING...WITH WEST 30-KT WINDS OVER THE EASTERN
KERN DESERTS. THE HIGHER RESOLUTION NAM-12 WINDS ARE ABOUT 10 KTS
STRONGER. BOTH THE NAM AND THE NAM-12 HAVE UPPER-LEVEL SUPPORT WITH
700-MB WINDS ALIGNED WITH THE 850-MB WINDS. THE WINDS TURN ABRUPTLY
NORTHEAST AFTER 09Z TUESDAY AS THE TROUGH DEEPENS AND DIGS INTO
SOUTHERN CALIFORNIA...THEN SUBSIDE AFTER 12Z.
EXPECT THE NORMALLY WINDIEST LOCATIONS...INDIAN WELLS CANYON AND
JAWBONE CANYON AND BELOW THE PASSES...TO REACH ADVISORY CRITERIA FOR
GUSTS /45 MPH/...BUT WIDESPREAD GUSTS GENERALLY WILL BE IN THE 35-45
MPH RANGE. WILL KEEP THE WORDING FOR LOCALLY STRONG GUSTS IN THE
CURRENT FORECAST.
ALSO...A FEW GUSTS TO 25-30 MPH DEVELOPED SUNDAY EVENING ON THE WEST
SIDE OF THE SAN JOAQUIN VALLEY...AND COULD REDEVELOP AS MARINE AIR
SPILLS THROUGH THE PACHECO PASS LATER TODAY.
THE MODELS ARE IN GOOD AGREEMENT WITH THE TROUGH AXIS MOVING THROUGH
THE HANFORD WARNING/FORECAST AREA BY 18Z MONDAY. BUT THEN THE TROUGH
DEEPENS AS THE UPPER-LEVEL LOW DROPS FROM IDAHO SOUTH TO ARIZONA BY
18Z TUESDAY.
AS THE TROUGH DEEPENS OVER THE WESTERN STATES...AN UPPER-LEVEL RIDGE
WILL AMPLIFY IN RESPONSE. THIS RIDGE WILL BUILD INTO CALIFORNIA
WEDNESDAY...BRINGING MUCH WARMER TEMPERATURES. BY 00Z SATURDAY...A
5940-5950-METER 500-MB RIDGE CENTER WILL BE NEAR EUREKA...AND 500-MB
HEIGHTS OVER MOST OF WASHINGTON...OREGON...NEVADA AND CALIFORNIA WILL
BE IN EXCESS OF 5880 METERS. 1000-500-MB THICKNESSES OVER THE
CENTRAL CALIFORNIA INTERIOR ARE FORECAST TO INCREASE TO OVER 5760
METERS BY 00Z SATURDAY...WITH THICKNESSES OF 5820+ METERS OVER
NORTHERN CALIFORNIA. 850-MB TEMPERATURES ARE FORECAST TO WARM TO
24-26 C OVER THE HANFORD WARNING/FORECAST AREA BY 00Z SATURDAY...
VALUES THAT HISTORICALLY HAVE RESULTED IN CENTRAL/SOUTH VALLEY HIGHS
AROUND 100. THIS IS NOT THAT UNCOMMON. HISTORICALLY...THE 50-YEAR
AVERAGE DATE FOR THE FIRST 100-DEGREE DAY IS MAY 27TH AT
BAKERSFIELD...AND JUNE 6TH AT FRESNO...WITH THE EARLIEST DATE OF
APRIL 23RD FOR BOTH CITIES /IN 1910/. ALTHOUGH RECORD TEMPERATURES
ARE NOT FORECAST...THEY WILL BE APPROACHED BOTH FRIDAY AND SATURDAY
/SEE BELOW/...AND THE WARMEST VALLEY AND DESERT LOCATIONS COULD
BREAK 100 BOTH DAYS...AND THE FOOTHILLS ALSO WILL BE WELL INTO THE
90S. THEREFORE...HAVE ISSUED A SPECIAL WEATHER STATEMENT /SEE
SFOSPSHNX OR WWUS86 KHNX/ FOR HEAT-RELATED SAFETY TIPS.
THE RIDGE WILL BEGIN TO WEAKEN SUNDAY AS AN UPPER-LEVEL TROUGH MOVES
INTO THE PACIFIC NORTHWEST...BUT 500-MB HEIGHTS OVER CALIFORNIA ARE
FORECAST TO REMAIN ABOVE 5820 METERS FOR CONTINUED WELL-ABOVE NORMAL
TEMPERATURES.
THURSDAY FRIDAY SATURDAY
BAKERSFIELD
FORECAST HIGH 97 99 99
RECORD HIGH 103 IN 1927 105 IN 1970 103 IN 1970
FORECAST LOW 65 66 68
RECORD HIGH MIN 71 IN 1972 70 IN 1973 71 IN 2006
FRESNO
FORECAST HIGH 96 98 99
RECORD HIGH 102 IN 1927 103 IN 1970 100 IN 1973
FORECAST LOW 65 66 65
RECORD HIGH MIN 70 IN 2006 68 IN 1905 70 IN 2006
AVIATION
A COOL FRONT MOVING THROUGH THE AREA WILL BRING
NORTHWEST WINDS OF 10-20 KTS AFTER 21Z IN THE VALLEY...WITH GUSTS TO
45 KTS OVER RIDGE TOPS OF MOUNTAIN AREAS AND THROUGH PASSES INTO THE
KERN COUNTY DESERTS UNTIL 06Z TUESDAY. OTHERWISE VFR CONDITIONS ARE
EXPECTED THROUGH 12Z TUESDAY.
AIR QUALITY ISSUES
NONE.
HNX WATCHES/WARNINGS/ADVISORIES
NONE.
PUBLIC...SANGER
AVN/FW...MENDENHALL
WEATHER.GOV/HANFORD
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