SFOAFDHNX (05/14/13 0251)
FXUS66 KHNX 140955
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
255 AM PDT TUE MAY 14 2013
.SYNOPSIS...
A WEAK DISTURBANCE WILL MOVE INTO CENTRAL CALIFORNIA TODAY...
BRINGING A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TO THE
SOUTHERN SIERRA NEVADA. TEMPERATURES WILL REMAIN ABOVE NORMAL
THROUGH WEDNESDAY...THEN LOW PRESSURE ALOFT WILL COOL TEMPERATURES
TO NEAR NORMAL THURSDAY THROUGH SATURDAY.
&&
.DISCUSSION...
THE UPPER-LEVEL RIDGE THAT BROUGHT RECORD-SETTING HEAT TO THE
CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY THE PAST FEW DAYS /SEE THE
RECORD REPORT...SFORERHNX OR SXUS76 KHNX/...HAS SHIFTED INLAND AS
AN UPPER-LEVEL SHORT-WAVE MOVED INTO THE PACIFIC NORTHWEST. THE
SHORT-WAVE DEEPENED THE MARINE LAYER AT FORT ORD TO AROUND 1650 FEET
/AS OF 0834Z /0134 PDT/ THIS MORNING...AND GUSTS OF 25-30 MPH FROM
THE SAN LUIS RESERVOIR TO SUNFLOWER VALLEY INDICATE THAT SOME MARINE
AIR ALREADY IS SPILLING THROUGH THE PASSES AND CANYONS OF THE
TEMBLORS AND DIABLO RANGE.
THE GOES WATER-VAPOR LOOP SHOWS A WEAK LOW JUST WEST OF THE MONTEREY
COUNTY COAST. THIS LOW IS FORECAST TO TRAVERSE THE HANFORD WARNING/
FORECAST AREA BETWEEN 18-24Z /1100-1700 PDT/ TODAY...AND WILL BRING
A SLIGHT CHANCE OF THUNDERSTORMS TO THE SOUTHERN SIERRA NEVADA WITH
CHANCE POPS OVER THE HIGHER ELEVATIONS. THE SPC CONVECTIVE OUTLOOK
FOR TODAY INDICATES A GENERAL RISK OF THUNDERSTORMS FOR THE SOUTHERN
SIERRA NEVADA NORTH OF MOUNT WHITNEY...AND THIS LOOKS ON TRACK.
TEMPERATURES WILL REMAIN ABOVE NORMAL TODAY AND WEDNESDAY DESPITE
THE INFLUX OF COOLER MARINE AIR INTO THE CENTRAL AND SOUTHERN SAN
JOAQUIN VALLEY. HOWEVER...A MAJOR CHANGE WILL OCCUR THURSDAY AS A
STRONGER UPPER-LEVEL TROUGH MOVES INTO THE PACIFIC NORTHWEST AND
DIGS INTO CALIFORNIA. 500-MB HEIGHTS OVER THE CENTRAL CALIFORNIA
INTERIOR ARE FORECAST TO FALL BELOW 5760 METERS THURSDAY AND TO 5700
METERS...OR LOWER...FRIDAY AS THE TROUGH AXIS MOVES OVER THE REGION.
850-MB TEMPERATURES OVER FRESNO...WHICH WERE AROUND 23 C MONDAY...
ARE FORECAST TO FALL TO 7.5-8.0 C BY 18Z FRIDAY WITH THE PASSAGE OF
THE TROUGH AXIS. TEMPERATURES IN THE CENTRAL AND SOUTHERN SAN
JOAQUIN VALLEY ARE FORECAST TO DROP TO NEAR NORMAL THURSDAY...AND TO
A FEW DEGREES BELOW NORMAL FRIDAY BEFORE WARMING BACK TO NEAR NORMAL
SATURDAY.
AT THIS TIME...THE TROUGH APPEARS TO HAVE LIMITED MID-LEVEL MOISTURE
THIS FAR SOUTH AS IT MOVES THROUGH CALIFORNIA...BUT A SHIFT IN THE
TRAJECTORY COULD BRING MORE MOISTURE TO THE AREA. HAVE INCREASED
POPS OVER THE SOUTHERN SIERRA NEVADA THURSDAY NIGHT THROUGH FRIDAY
NIGHT...BUT KEPT BELOW 15 PERCENT FOR NOW.
THE MEDIUM-RANGE MODELS BRING ANOTHER TROUGH THROUGH THE PACIFIC
NORTHWEST EARLY NEXT WEEK AND DROP IT INTO THE GREAT BASIN. THIS
TROUGH IS FORECAST TO KEEP AN EAST-PACIFIC UPPER-LEVEL RIDGE
OFFSHORE FOR THE END OF THE EXTENDED FORECAST PERIOD...BUT THERE ARE
SIGNIFICANT DIFFERENCES BETWEEN THE GFS AND ECMWF AND FORECAST
CONFIDENCE IS LOW BEYOND SATURDAY.
&&
.AVIATION...
AREAS OF MVFR AND LOCAL IFR CONDITIONS IN THUNDERSTORMS OVER THE
SOUTHERN SIERRA NEVADA 18Z TUE - 06Z WED. OTHERWISE...VFR ACROSS
THE CENTRAL CA INTERIOR.
&&
.AIR QUALITY ISSUES...
NONE.
&&
.CERTAINTY...
THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS HIGH.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS MEDIUM.
THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED
BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL
INFORMATION AND/OR TO PROVIDE FEEDBACK.
&&
.CLIMATE...
RECORDS
SITE DATE HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR
KFAT 05-14 102:1972 64:1957 66:1996 43:1955
KFAT 05-15 102:1927 60:1953 70:2006 42:1955
KFAT 05-16 103:1970 63:2011 71:2008 40:1894
KBFL 05-14 102:1979 64:1949 72:1976 40:1918
KBFL 05-15 103:1927 60:1953 71:1972 36:1918
KBFL 05-16 105:1970 63:1962 71:2008 39:1918
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
PUBLIC...SANGER
AVN/FW...DCH
SYNOPSIS...SANGER
WEATHER.GOV/HANFORD
