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.
&&
.SYNOPSIS...WITH HIGH PRESSURE DOMINATING FOR THE NEXT FEW DAYS,
SKIES WILL BE MOSTLY CLEAR WITH PATCHY LATE NIGHT AND EARLY MORNING
FOG.
&&
.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.
&&
.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.
&&
.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
&&
.HNX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...SANGER
AVN/FW...DURFEE
WEATHER.GOV/HANFORD
