AREA FORECAST DISCUSSION

 
 FXUS66 KHNX 251345 AAA
 AFDHNX
 
 AREA FORECAST DISCUSSION...UPDATED
 NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
 545 AM PST WED NOV 25 2009
 
 .UPDATE...
 PATCHY FOG HAS BEGUN FORMING IN THE CENTRAL AND SOUTHERN SAN JOAQUIN 
 VALLEY. VISIBILITIES AT THE CASTLE AND HANFORD AIRPORTS HAVE FALLEN 
 TO A QUARTER MILE OR LESS...AND THE VISIBILITIES AT THE MERCED AND 
 VISALIA AIRPORTS HAS FALLEN TO A QUARTER MILE AT TIMES AS FOG 
 PATCHES MOVE INTO AND OUT OF THE AIRPORTS. IN GENERAL...VISIBILITIES 
 ACROSS THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY AT 1330Z /0530 
 PST/ WERE HIGHER THAN AT 1330Z TUESDAY...BUT SOME DEGRADATION IS 
 LIKELY TOWARD SUNRISE. HAVE ISSUED A SPECIAL WEATHER STATEMENT 
 /SFOSPSHNX OR WWUS86 KHNX/ ON THE FOG.
 
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 .SYNOPSIS...WITH HIGH PRESSURE DOMINATING FOR THE NEXT FEW DAYS, 
 SKIES WILL BE MOSTLY CLEAR WITH PATCHY LATE NIGHT AND EARLY MORNING 
 FOG. 
 
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 .DISCUSSION...
 TUESDAY MORNING/S PATCHY FOG BEGAN BURNING OFF BY 17Z /0900 PST/. AS 
 A RESULT...CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY HIGH TEMPERATURES 
 WARMED SEVERAL DEGREES OVER MONDAY/S HIGHS. TUESDAY/S VALLEY HIGHS 
 RANGED FROM 63 /AT MERCED MUNICIPAL AIRPORT/ TO 69 /AT BAKERSFIELD 
 AND COALINGA/. A TRIO OF STATIONS TIED FOR THE WARM SPOT FOR THE 
 HANFORD WARNING/FORECAST AREA. BAKERSFIELD...COALINGA AND THE RIVER 
 KERN RAWS ALL REPORTED HIGHS OF 69 DEGREES.
 
 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.
 
 ANOTHER CONCERN THIS MORNING IS LOW TEMPERATURES. A FEW STATIONS ON 
 THE WEST SIDE OF THE SAN JOAQUIN VALLEY FELL INTO THE 28-32 DEGREE 
 RANGE TUESDAY MORNING...AND WITH CLEAR SKIES AND LIGHT WINDS...COULD 
 SEE SIMILAR LOWS THIS MORNING. HAVE ADDED PATCHY FROST TO THE WEST 
 SIDE ZONES FOR THIS MORNING.
 
 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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 .AVIATION...
 MVFR VISIBILITIES WILL PREVAIL IN THE SAN JOAQUIN VALLEY THROUGH
 MIDDAY TODAY WITH LOCAL IFR/LIFR IN FOG UNTIL 17Z. MVFR VISIBILITIES
 WILL RECUR IN THE SAN JOAQUIN VALLEY AFTER 06Z THURSDAY WITH LOCAL
 IFR DUE TO FOG.  VFR CONDITIONS CAN BE EXPECTED ELSEWHERE ACROSS THE
 CENTRAL CALIFORNIA INTERIOR THROUGH 12Z THURSDAY.
 
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 .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
 
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 .HNX WATCHES/WARNINGS/ADVISORIES...
 NONE.
 
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 $$
 
 PUBLIC...SANGER
 AVN/FW...DURFEE
 
 WEATHER.GOV/HANFORD