FXUS66 KLOX 240444
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
845 PM PST WED DEC 23 2009

.SYNOPSIS... 
A HIGH PRESSURE AREA WILL MOVE INTO THE REGION CLEARING THE SKIES 
AND WARMING THE TEMPERATURES FOR THURSDAY INTO CHRISTMAS. A LOW 
PRESSURE AREA...WITH A SERIES OF WEAK STORMS MOVING THROUGH WILL 
BRING A SLIM CHANCE OF RAIN WITH A COOLING TREND FOR LATE SATURDAY 
THROUGH MONDAY. A DRY NORTHERLY FLOW WILL START UP MONDAY NIGHT.  

&&

.SHORT TERM (TONIGHT-SAT)...CLEAR SKIES COVERED THE FORECAST AREA 
THIS EVENING...AND EXCEPT FOR A FEW HI CLOUDS POSSIBLY MOVING IN 
LATER TONIGHT...SKIES WILL REMAIN GENERALLY CLEAR IN ALL AREAS. 
OFFSHORE GRADIENTS HAVE HELPED TO KEEP LOCAL GUSTY NE CANYON WINDS 
OVER PORTIONS OF THE VTU/L.A. COUNTY MTNS WHICH SHOULD CONTINUE 
OVERNIGHT. WITH A COOL...DRY AIRMASS OVER THE DISTRICT...IT LOOKS 
LIKE TEMPS WILL FALL RATHER QUICKLY OVERNIGHT WHERE WINDS ARE LIGHT. 
AREAS OF FROST IS POSSIBLE LATE TONIGHT IN THE VENTURA COUNTY 
INTERIOR VALLEYS AND ALONG THE SBA S COAST...WHERE A FROST ADVISORY 
IS IN EFFECT. SOME FROST WILL ALSO BE POSSIBLE IN MOST OTHER VALLEYS 
AS WELL. 

AN UPPER LEVEL RIDGE OFF THE CA COAST WILL GRADUALLY BUILD E AND 
INTO CA THRU LATE THU THEN LINGER OVER THE REGION THRU CHRISTMAS 
DAY. THE UPPER RIDGE WILL WEAKEN AND MOVE E FRI NIGHT AND SAT AS AN 
UPPER LEVEL TROF OVER THE E PAC PUSHES INTO THE CA COAST BY LATE 
SAT. DRY WEATHER CAN BE EXPECTED OVER THE FORECAST AREA THROUGH FRI 
NIGHT. WEAK OFFSHORE FLOW NIGHT AND MORNING HOURS CAN BE EXPECTED 
OVER INTERIOR VTU/L.A. COUNTIES THRU FRI MORNING. OTHERWISE WINDS 
ARE EXPECTED TO BE RATHER WEAK THRU SAT MORNING...THEN BECOME MORE 
ONSHORE BY SAT AFTERNOON. A WEAKENING COLD FRONT ASSOCIATED WITH THE 
UPPER TROF WILL MOVE INTO SLO/SBA COUNTIES ON SAT...BRINGING MOSTLY 
CLOUDY SKIES AND A SLIGHT CHANCE OF SHOWERS MAINLY TO PORTIONS OF 
SLO COUNTY SAT AFTERNOON... AND PARTLY CLOUDY SKIES ACROSS THE REST 
OF THE DISTRICT. HI TEMPS ACROSS THE DISTRICT ARE EXPECTED TO BE 
MILDER AND CLOSER TO NORMAL FOR MOST AREAS FOR THU AND FRI...THEN 
TURN COOLER AND SLIGHTLY BELOW NORMAL FOR SAT.

...FROM PREVIOUS DISCUSSION...

.LONG TERM (SUN-WED)...GFS AND ECMWF IN SOMEWHAT BETTER AGREEMENT FOR
BRINGING RAIN INTO THE REGION FOR SUNDAY...SO HAVE BUMPED UP POPS TO 
AROUND 30 PERCENT IN MOST AREAS. WHILE THIS WILL BE OUR BEST CHANCE 
OF WIDESPREAD RAINFALL DURING PERIOD...AMOUNTS ARE EXPECTED TO BE 
FAIRLY LIGHT. EXTENDED MODELS SHOWING MORE OF A NORTHWEST FLOW 
PATTERN FROM SUNDAY NIGHT THROUGH WEDNESDAY...BUT STILL CONSIDERABLE 
VARIANCE IN PRECIPITATION OUTPUT BETWEEN THE GFS AND ECMWF 
SOLUTIONS. AT EITHER RATE...ANY PRECIPITATION THAT FALLS DURING THIS 
PERIOD IS EXPECTED TO BE LIGHT. 

&&

.AVIATION...23/2325Z...HI CONFIDENCE IN CURRENT TAF PACKAGE. LOCAL 
LLWS CONDITIONS AT TIMES WILL BE POSSIBLE THRU EARLY THIS EVENING IN 
AND AROUND KVNY.

KLAX AND KBUR...HI CONFIDENCE IN CURRENT TAFS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
FROST ADVISORY (SEE LAXNPWLOX).

&&

$$

PUBLIC...SIRARD/GOMBERG
AVIATION...SIRARD
SYNOPSIS...SETO

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