FXUS66 KLOX 160441
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
840 PM PST TUE DEC 15 2009

.SYNOPSIS...
PARTLY CLOUDY SKIES AND SEASONAL TEMPERATURES ARE EXPECTED ON 
WEDNESDAY...ALTHOUGH A WEAK DISTURBANCE MAY BRING A FEW SHOWERS TO 
NORTHERN SAN LUIS OBISPO COUNTY WEDNESDAY AFTERNOON AND EARLY 
EVENING. FOR THE REST OF THE WORK WEEK...WEAK TO MODERATE OFFSHORE 
FLOW WILL PREVAIL...WITH CLEAR SKIES AND TEMPERATURES JUST ABOVE 
SEASONAL NORMALS. ONSHORE FLOW IS EXPECTED TO REDEVELOP OVER THE 
WEEKEND...WITH INCREASING CLOUDS AND COOLER TEMPERATURES.

&&

.SHORT TERM (TONIGHT-FRI)...PLENTY OF HI LEVEL MOISTURE ASSOCIATED 
WITH A WEAK UPPER LEVEL DISTURBANCE WAS MOVING INTO SRN CA THIS 
EVENING. IT LOOKS LIKE MORE HI CLOUDS WILL MOVE INTO THE REGION 
OVERNIGHT BUT THEY SHOULD THIN OUT SOME AT TIMES. PATCHY DENSE FOG 
MAY DEVELOP IN THE SLO COUNTY INTERIOR VALLEYS LATE TONIGHT AS WELL. 
GENERALLY WEAK OFFSHORE FLOW WILL PREVAIL OVERNIGHT...WITH LOCAL 
GUSTY CANYON WINDS POSSIBLE BELOW AND THRU THE FAVORED PASSES AND 
CANYONS.

A FLAT UPPER RIDGE IS EXPECTED OVER SRN CA ON WEDNESDAY...ALTHO A 
WEAK FRONT MAY APPROACH NORTHERN SLO COUNTY BY AFTERNOON WITH SOME 
CLOUDS AND A SLIGHT CHANCE OF A SHOWER. IT LOOKS LIKE THE CHANCES OF 
ANY SHOWERS IN THIS AREA WILL BE AT MOST 15 PERCENT...SO CONFIDENCE 
IN ANY SHOWER ACTIVITY IS FAIRLY LOW. OTHERWISE THERE SHOULD SOME 
MORE HI CLOUDS OVER THE DISTRICT THRU THE DAY. UPPER RIDGING SHOULD 
THEN GRADUALLY BUILD ALONG AND OFF THE SRN CA COAST THU THRU FRI. 
MORE OFFSHORE FLOW IS EXPECTED OVER THE REGION...WITH GUSTY NE 
CANYON WINDS POSSIBLE MAINLY NIGHT AND MORNING HOURS ESPECIALLY OVER 
PORTIONS OF VTU/L.A. COUNTIES...AND OVER EASTERN PORTIONS OF SBA/SLO 
COUNTIES. WINDS MAY EVEN APPROACH ADVISORY LEVELS AT TIMES...BUT AT 
THIS TIME IT APPEARS SUPPORT FOR WIDESPREAD ADVISORY LEVEL WINDS IS 
MINIMAL. EXCEPT FOR LOW CLOUDS AND FOG MOVING INTO THE SLO/SBA 
COUNTY INTERIOR VALLEYS FROM THE SRN SAN JOAQUIN VALLEY NIGHT AND 
MORNING HOURS...IT LOOKS LIKE MOSTLY CLEAR SKIES WILL PREVAIL OVER 
THE DISTRICT THU THRU FRI. TEMPS ACROSS THE REGION ARE EXPECTED TO 
BE NEAR OR SLIGHTLY ABOVE SEASONAL NORMS ON WED...THEN SEVERAL 
DEGREES ABOVE NORMAL FOR MANY AREAS THU AND FRI...WITH SOME HIGHS IN 
THE WARMEST VALLEYS OF L.A./VTU COUNTIES APPROACHING 80 DEGREES ON 
FRI AFTERNOON.   

...FROM PREVIOUS DISCUSSION...

.LONG TERM (SAT-TUE)...SATURDAY LOOKS VERY SIMILAR TO FRIDAY, THOUGH 
MAYBE A DEGREE OR TWO COOLER AT LOWER ELEVATIONS AS OFFSHORE FLOW 
WEAKENS A TAD. SUNDAY NOW SHOULD BE VERY SIMILAR TO SATURDAY AS 
MODELS NOW SHOW VERY LITTLE CHANGE IN THE RIDGE ALOFT OR WITH 
OFFSHORE FLOW. BY MONDAY MODELS DO SHOW THE RIDGE WEAKENING WITH 
GRADIENTS TURNING ONSHORE. THIS WILL INITIATE A COOLING TREND WHICH 
IS EXPECTED TO CONTINUE TUESDAY AS THE RIDGE IS REPLACED BY A TROF 
APPROACHING FROM THE NORTH. THE 12Z ECMWF ACTUALLY BRINGS IN SOME 
LIGHT PRECIP WITH THIS TROF ON TUESDAY BUT RUN TO RUN CONSISTENCY 
WITH THE ECMWF HAS BEEN POOR AND THE GFS KEEPS THE STORM TRACK WELL 
TO THE NORTH. SO FOR NOW THE FORECAST REMAINS DRY THROUGH TUESDAY, 
BUT COOLER WITH AN INCREASE IN CLOUDS.

&&

.AVIATION...15/2330Z...HIGH CONFIDENCE IN VFR CATS EVERYWHERE 
THROUGH 06Z. MODERATE CONFIDENCE IN VLIFR CATS AT KPRB ARRIVING 
07-10Z TONIGHT. 30 PERCENT CHANGE OF BRIEF MVFR BR AT KLGB AFTER 
12Z. WINDS WILL REMAIN LIGHTER THAN SEASONAL...BUT SHOULD STRENGTHEN 
SLIGHTLY ON WED. 

KLAX...HIGH CONFIDENCE TAF.

KBUR...HIGH CONFIDENCE TAF.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...SIRARD/WOFFORD
AVIATION...KITTELL
SYNOPSIS...MEIER

WWW.WEATHER.GOV/LOSANGELES