FXUS66 KHNX 240531
AFDHNX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
931 PM PST WED DEC 23 2009

.SYNOPSIS...
ALTHOUGH HIGH PRESSURE WILL PREVAIL THROUGH THE REST OF THIS 
WEEK...COLD AIR IS IN PLACE WITH WIDESPREAD FREEZING TEMPERATURES 
EXPECTED TONIGHT IN THE SAN JOAQUIN VALLEY. A SERIES OF LOW PRESSURE 
SYSTEMS COULD BRING UNSETTLED CONDITIONS SUNDAY THROUGH THE MIDDLE 
OF NEXT WEEK.

&&

.DISCUSSION...
AS OF 929 PM PST...CLEAR...COLD...AND CALM ACROSS THE FORECAST AREA
TONIGHT AS FREEZE WARNING FOR THE VALLEY LOOK ON TRACK. LIGHT
WINDS AND CLEAR SKIES WILL SET THE STAGE FOR AN EXCELLENT
RADIATIONAL COOLING SITUATION. 24 HOUR TRENDS ARE AROUND 5 TO 10
DEGREES COOLER THAN THIS TIME YESTERDAY. NO CHANGES TO CURRENT
FORECAST.

.PREV DISCUSSION... /ISSUED 213 PM PST WED DEC 23 2009/ 

DISCUSSION...A RIDGE OF HIGH PRESSURE BUILDING OVER CALIFORNIA
WILL BRING CLEAR SKIES OVER CENTRAL CALIFORNIA TONIGHT AND
THURSDAY WITH SURFACE HIGH PRESSURE OVER NEVADA KEEPING A LIGHT
OFFSHORE FLOW OVER THE REGION. WINDS IN THE SAN JOAQUIN VALLEY
WILL BE VERY LIGHT TODAY AND WITH THE CLEAR SKIES AND A COLD
AIR MASS IN PLACE...TEMPERATURES WILL DROP BELOW FREEZING ACROSS
MUCH OF THE VALLEY. AREAS THAT WERE 28-30 DEGREES THIS MORNING
WILL LIKELY SEE 25-28 DEGREES EARLY THURSDAY MORNING. PLEASE SEE
THE FREEZE WARNING PRODUCT FOR THE DETAILS. THE KERN COUNTY
MOUNTAINS AND DESERTS WILL ALSO BE VERY COLD THURSDAY MORNING WITH
TEENS IN THE MOUNTAIN VALLEYS.

THE RIDGE OF HIGH PRESSURE IS PROGGED TO STAY IN PLACE THROUGH
CHRISTMAS DAY BEFORE IT SHIFTS EAST. THIS WILL BRING DRY WEATHER
ACROSS CENTRAL CALIFORNIA WITH AT MOST SOME PATCHY MORNING FOG IN
THE SAN JOAQUIN VALLEY EACH MORNING. TEMPERATURES WILL SLOWLY 
MODERATE THURSDAY AND FRIDAY.

A TROUGH OF LOW PRESSURE IS PROJECTED BY BOTH THE GFS AND ECMWF
MODELS TO MOVE TO THE CALIFORNIA COAST SATURDAY AND BEGIN
AFFECTING THE CWFA SATURDAY NIGHT. ALTHOUGH THE 12Z GFS HAS COME
INTO BETTER AGREEMENT WITH THE ECMWF...THERE ARE STILL
UNCERTAINTIES IN THE TIMING AND AMOUNT OF PRECIPITATION WITH THIS
EVENT. BOTH MODELS ARE INDICATING THE POTENTIAL FOR A VERY WET
PERIOD SATURDAY NIGHT AND SUNDAY SO HAVE INCREASED POPS FOR THAT
TIME FRAME. THIS SYSTEM WILL CONTINUE TO MOVE THROUGH THE REGION
MONDAY...FOLLOWED BY ANOTHER SYSTEM MOVING IN BY WEDNESDAY.
AGAIN...SIGNIFICANT DIFFERENCES BETWEEN MODELS SO IT IS DIFFICULT
TO PREDICT WHEN THE BREAKS WILL OCCUR BETWEEN SYSTEMS. HAVE
CONTINUED WITH AT LEAST SLIGHT CHANCE POPS EACH PERIOD MONDAY
THROUGH WEDNESDAY.

&&

.AVIATION...
IN THE SAN JOAQUIN VALLEY...VFR EXCEPT AREAS OF MVFR AND LOCAL IFR 
VISIBILITIES IN HAZE AND MIST BETWEEN 08Z THURSDAY AND 19Z THURSDAY. 
REMAINDER OF THE CENTRAL CA INTERIOR...VFR THROUGH 06Z FRIDAY.

&&

.AIR QUALITY ISSUES...
NONE.

&&

.HNX WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING UNTIL 8 AM PST THURSDAY FOR CAZ089>092.

&&

$$

PUBLIC...JDB
AVN/FW...DS
SYNOPSIS...BSO

WEATHER.GOV/HANFORD