FXUS66 KHNX 251708
 AFDHNX
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
 908 AM PST WED NOV 25 2009
 
 
 .SYNOPSIS...THANKSGIVING DAY IN THE CENTRAL CALIFORNIA INTERIOR 
 WILL BE DRY AS A HIGH PRESSURE RIDGE REMAINS OVER THE WESTERN
 U.S. PATCHY MORNING FOG WILL CONTINUE TO BE A CONCERN FOR THE 
 SAN JOAQUIN VALLEY. A LOW PRESSURE TROUGH WILL MOVE ACROSS THE 
 THE AREA ON FRIDAY BRINGING INCREASING CLOUDS.
 
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 .DISCUSSION...A LITTLE PATCHY FOG ACROSS THE VALLEY THIS MORNING
 IS BURNING OFF WITH IMPROVING VISIBILITIES. SATELLITE WATER VAPOR
 IMAGERY SHOWS A WEAK SHORT WAVE MOVING SOUTH OVER CENTRAL CA WHICH
 MAY HAVE HELPED LIMIT THE FOG DEVELOPMENT. SUNNY SKIES WILL PREVAIL
 THROUGH THE DAY WITH TEMPERATURES WARMING TO AT OR SLIGHTLY ABOVE
 YESTERDAY`S HIGHS. LITTLE CHANGE IS IN STORE THROUGH THANKSGIVING
 DAY AS WE REMAIN UNDER THE WARM SIDE OF AN UPPER RIDGE. A QUICK
 UPDATE TO THE GRIDS AND ZONES HAS BEEN ISSUED THIS MORNING TO ADD
 PATCHY FOG IN FOR THE VALLEY AGAIN TONIGHT. FORECAST MODELS ARE
 NOW TRENDING TOWARD A SLOWER AND FARTHER SOUTH TRACK WITH THE END
 OF THE WEEK TROUGH. WILL EVALUATE NEW MODEL SUITE THIS MORNING FOR 
 POSSIBLE ADDITION OF POPS TO THE FRIDAY AFTN-SATURDAY PERIOD WITH
 THE AFTERNOON FORECAST PACKAGE.
 
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 .AVIATION...
 LOCAL MVFR VISIBILITIES UNTIL 18Z WEDNESDAY IN THE SAN JOAQUIN 
 VALLEY. MVFR VISIBILITIES WILL RECUR AFTER 06Z THURSDAY AND PERSIST 
 UNTIL 18Z THURSDAY WITH LOCAL IFR DUE TO FOG. VFR CONDITIONS CAN BE 
 EXPECTED ELSEWHERE ACROSS THE CENTRAL CALIFORNIA INTERIOR THROUGH 
 18Z THURSDAY.
 
 &&
 
 .AIR QUALITY ISSUES...
 ON WEDNESDAY NOVEMBER 25 2009... UNHEALTHY FOR SENSITIVE GROUPS IN
 FRESNO AND KERN COUNTIES.  FIREPLACE/WOOD STOVE BURNING IS
 PROHIBITED IN FRESNO... KERN... KINGS... MADERA AND MERCED
 COUNTIES.
 FURTHER INFORMATION IS AVAILABLE AT VALLEYAIR.ORG
 
 &&
 
 .FROM PREV DISCUSSION... /ISSUED 545 AM PST WED NOV 25 2009/ 
 
 
 THE UPPER-LEVEL RIDGE IS IN PLACE OVER CALIFORNIA THIS MORNING...AND
 THE IMMEDIATE FORECAST CONCERN IS PATCHY VALLEY FOG DEVELOPMENT...
 NAMELY WHERE...WHEN AND HOW EXTENSIVE. VISIBILITIES SO FAR THIS
 MORNING HAVE NOT FALLEN AS FAST AS ON TUESDAY MORNING...SUGGESTING
 THAT FOG MAY FORM LATER IN THE MORNING...TOWARD DAYBREAK.
 
 THE NEXT CONCERN IS THE UPPER-LEVEL TROUGH FORECASTED TO MOVE THROUGH
 CALIFORNIA FRIDAY. THE NEW 00Z RUNS HAVE SLOWED THE TIMING OF THE
 TROUGH...TRENDING MORE TOWARD FRIDAY AFTERNOON AND NIGHT. THE
 NAM-12...GFS AND ECMWF CONTINUE TO BE MOSTLY DRY AT THE MID LEVELS
 /850-700-MB/ WITH THE TROUGH SO DO NOT EXPECT ANY PRECIPITATION.
 HOWEVER...THE TROUGH IS PART OF A BROAD EAST-PACIFIC SYSTEM THAT
 IS TAPPING INTO A FETCH OF UPPER-LEVEL MOISTURE EXTENDING ACROSS
 THE PACIFIC TO TYPHOON NIDA. THIS INDICATES THAT THERE COULD BE
 ABUNDANT HIGH CLOUDS WITH THE TROUGH AS IT MOVES THROUGH.
 
 THE MODELS CONTINUE TO FORECAST A SURGE OF COLD AIR WITH THE 
 TROUGH...WITH 850-MB TEMPERATURES DROPPING 4-6 C FROM 00Z FRIDAY TO 
 00Z SATURDAY. SURFACE TEMPERATURES FRIDAY WILL BE 5-8 DEGREES COOLER 
 THAN THURSDAY...AND A FEW MORE DEGREES COOLER SATURDAY.
 
 AN UPPER-LEVEL EAST-PACIFIC RIDGE BEGINS BUILDING INTO CALIFORNIA 
 SUNDAY AND WILL BE OVER THE REGION THROUGH THE FIRST HALF OF NEXT 
 WEEK. THIS WILL ALLOW TEMPERATURES TO WARM TO A FEW DEGREES ABOVE 
 NORMAL WITH CONTINUED DRY WEATHER.
 
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 .HNX WATCHES/WARNINGS/ADVISORIES...
 NONE.
 &&
 
 
 
 PUBLIC...DCH/SANGER
 AVN/FW...MENDENHALL
 
 WEATHER.GOV/HANFORD