000
FXUS66 KLOX 060001 CCA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
401 PM PST MON JAN 5 2009

...UPDATED AVIATION SECTION...

.SHORT TERM (TODAY-THU)...DYING COLD FRONT DRAGGING THROUGH THE
CENTRAL COAST THIS AFTERNOON. A FEW LIGHT SHOWERS BEING REPORTED BUT
LITTLE IF ANY MEASURABLE RAIN SHOWING UP IN THE GAUGES. MAIN IMPACT
FROM THIS SYSTEM WILL BE TO BRING ABOUT AN INCREASE IN NORTH TO
NORTHWEST FLOW ACROSS THE AREA TONIGHT INTO TUESDAY, WITH ADVISORY
LEVEL WINDS EXPECTED IN THE MOUNTAINS AND SRN SBA COUNTY. MAY EVEN
GET SOME GUSTY WINDS INTO THE NORTHERN VALLEYS OF LA/VTU COUNTIES
LATER TONIGHT BUT WILL NOT INCLUDE THEM IN THE ADVISORY FOR NOW.
WINDS SHOULD START TO TAPER OFF TUESDAY MORNING BUT ENOUGH OF A
GRADIENT SHOULD LINGER THROUGH TUESDAY TO PRODUCE SOME NORTHERLY
WINDS THROUGH THE DAY AND INTO TUESDAY NIGHT AS WELL. IN LA COUNTY
THE STRONGEST WINDS AS USUAL WILL BE THROUGH THE INTERSTATE 5
CORRIDOR.

BEHIND THE FRONT SKIES SHOULD CLEAR OUT UNDER THE NORTHERLY FLOW.
EXCEPTIONS TO THIS INCLUDE THE GRAPEVINE AREA WHERE UPSLOPE
PRECIPITATION AND CLOUDS ARE POSSIBLE THROUGH TUESDAY MORNING, AND
ERN LA COUNTY WHERE LOW CLOUDS MAY LINGER. THERE IS SOME CONCERN FOR
A POSSIBLE EDDY CIRCULATION DEVELOPING OVERNIGHT, BUT AT THIS TIME
IT IS FELT THAT THE NORTHWEST FLOW WILL BE STRONG ENOUGH TO PUSH IT
FAR ENOUGH SOUTH AS TO NOT HAVE MUCH IMPACT LOCALLY. THUS, SKIES
SHOULD BE MOSTLY SUNNY ACROSS MOST OF THE AREA TUESDAY. HIGHS WILL
BE SIMILAR TO TODAY.

HIGH PRESSURE WILL BUILD INTO THE AREA TUESDAY NIGHT AND WEDNESDAY,
RESULTING IN SEVERAL DEGREES OF WARMING WED AFTERNOON.

ON THU, MODELS ARE NOW SHOWING A VERY WEAK COLD FRONT APPROACHING
FROM THE NORTHWEST. THIS WILL CAUSE GRADIENTS TO TURN ONSHORE,
FORCING AN EARLIER SEA BREEZE TO DEVELOP AND DAYTIME HIGHS TO FALL A
FEW DEGREES MOST AREAS. MAY SEE A SLIGHT INCREASE IN CLOUD COVERAGE
NORTH OF PT CONCEPTION BY AFTERNOON BUT NO PRECIP IS EXPECTED.

.LONG TERM (FRI-MON)...THE LAST COUPLE GFS RUNS THREW A LITTLE
WRENCH INTO OUR PLANS FOR A BIG WARMUP LATE IN THE WEEK, INSTEAD
CUTTING OFF AN UPPER LOW FROM THE TROF MOVING INTO THE MIDWEST AND
BRINGING IN A LOT OF COLD AIR WITH IT. THIS SOLUTION WAS THE ONLY
ONE OF THE ENSEMBLE MEMBERS THAT DID THIS, AND THE ECMWF IS ALSO NOT
IN AGREEMENT WITH THIS. HOWEVER, THE EC DID SHOW THE TROF HANGING
BACK WEST FARTHER THAN EARLIER RUNS AND FOR NOW HAVE STRUCK A
COMPROMISE BY LOWERING TEMPS A FEW DEGREES ON FRI AS THE TROF MOVES
THROUGH. HOWEVER, THE CURRENT FORECAST MAINTAINS A WARM AND WINDY
FORECAST SAT-MON, THE LATTER DAY OR TWO OF WHICH ARE STILL INDICATED
BY EVEN THE NEWER GFS RUNS. IT`S JUST THE FRI/SAT TIMEFRAME THAT IS
IN QUESTION AT THIS POINT. IT STILL APPEARS A DECENT SANTA ANA WIND
EVENT WILL DEVELOP, BUT THE STRENGTH AND TIMING, AS WELL AS THE
ASSOCIATED WARM UP IS STILL UNCERTAIN. ALL MODELS STILL POINT TO
UNSEASONABLY WARM TEMPS ACROSS THE AREA BY NEXT MONDAY, WITH
WIDESPREAD 80+ READINGS POSSIBLE AT LOWER ELEVATIONS.

&&

.AVIATION...06/0000Z.
VFR CONDITIONS WILL LIKELY PERSIST AT ALL TERMINALS THROUGHOUT THE
PERIOD...WITH A 40 PERCENT CHANCE OF MVFR CONDITIONS DEVELOPING AT
TERMINALS NORTH OF POINT CONCEPTION AND OVER LOS ANGELES COUNTY
TERMINALS. LOW-WIND SHEAR AND TURBULENCE ISSUES WILL DEVELOP OVER
KSBA...KBUR...AND KVNY THROUGH 12Z.

KLAX...VFR CONDITIONS ARE EXPECTED TO PERSIST THROUGHOUT THE PERIOD.
THERE IS A 30 PERCENT CHANCE THAT 6000 FOOT CEILINGS COULD DEVELOP
BETWEEN 01Z AND 05Z. AFTER 05Z...THERE IS A 40 PERCENT CHANCE THAT
IFR TO MVFR CONDITIONS COULD DEVELOP AND PERSIST INTO 18Z TUESDAY.

KBUR...VFR CONDITIONS ARE EXPECTED TO CONTINUE WITH A 30 PERCENT
CHANCE THAT A 6000 FOOT CEILING MAY DEVELOP BETWEEN 01Z AND 05Z.
BETWEEN 06Z AND 11Z...WEAK TO MODERATE TURBULENCE WILL DEVELOP WITH
LOW-LEVEL WIND SHEAR ISSUES.


&&

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

&&

$$

PUBLIC...WOFFORD/MEIER
AVIATION...HALL

WWW.WEATHER.GOV/LOSANGELES