FXUS66 KLOX 231336
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
337 AM PST WED DEC 23 2009
.SYNOPSIS...
DRY AND SEASONABLY COOL WEATHER WILL PERSIST THROUGH CHRISTMAS.
A SERIES OF MOSTLY WEAK STORM SYSTEMS MOVING THROUGH THE EASTERN
PACIFIC WILL BRING A SLIGHT CHANCE OF RAIN TO THE REGION LATE
SATURDAY OR SATURDAY NIGHT THROUGH MONDAY...THEN DRY WEATHER IS
EXPECTED AGAIN THROUGH WEDNESDAY.
&&
.SHORT TERM (TODAY-FRI)...EXCEPT FOR A FEW LINGERING CLOUDS IN THE
MTNS OF L.A. AND VTU COUNTIES THIS MORNING...SKIES WERE CLEAR ACROSS
THE REGION. WINDS HAVE DROPPED OFF QUITE A BIT IN MOST AREAS...BUT
THERE WAS STILL ENOUGH WIND IN THE MTNS OF L.A. AND VTU COUNTIES TO
KEEP A WIND ADVISORY IN PLACE THROUGH MID MORNING. HOWEVER...EVEN
THESE WINDS SHOULD BEGIN TO RELAX AS THE UPPER LOW PULLS EWD AND THE
WINDS ALOFT DROP OFF. THE COMBINATION OF A COLD AIR MASS AND VERY
DRY CONDITIONS HAS LED TO RATHER COLD READINGS THIS MORNING IN
PLACES WHERE THE WINDS HAVE DROPPED OFF. WITH CONTD DECREASING OF
THE WIND THROUGH SUNRISE...EXPECT TEMPS TO DROP TO FREEZING OR
SLIGHTLY BELOW ACROSS THE COOLER LOCATIONS IN THE WIND SHELTERED
PORTIONS OF THE SAN FERNANDO VLY...THE VTU COUNTY VALLEYS...THE
SANTA MONICA RANGE AND THE SANTA BARBARA COUNTY S CST. THERE WILL
LIKELY BE LOCAL FROST ACROSS CSTL SXNS OF VTU COUNTY...AND PORTIONS
OF THE SAN GABRIEL VALLEY AS WELL. IT WILL BE A RATHER CHILLY DAY
ACROSS THE REGION TODAY...ALTHOUGH MAX TEMPS WILL PROBABLY BE UP A
FEW DEGREES FROM THOSE ON TUE...AND THERE WILL BE CONSIDERABLY LESS
IN THE WAY OF WIND.
WITH CLEAR SKIES...VERY DRY CONDITIONS AND LIGHTER WINDS...IT WILL BE
COLD AGAIN TONIGHT...POSSIBLY EVEN COLDER THAN THIS MORNING IN SOME
AREAS. FROST ADVISORIES MAY BE NEEDED FOR THE VALLEYS OF L.A. AND
VTU COUNTIES...THE SANTA MONICA RANGE...AND THE SOUTH COAST OF SBA
COUNTY. AN UPPER RIDGE IN THE ERN PACIFIC WILL SHIFT SLOWLY INTO THE
W CST TONIGHT AND THU. RISING HEIGHTS/THICKNESSES...AND WARMING AT
850 AND 950 MB SHOULD LEAD TO SEVERAL DEGREES OF WARMING IN MOST
AREAS ON THU...WITH TEMPS NOT TOO FAR FROM SEASONAL LEVELS. THIS
RIDGE WILL HOLD ACROSS THE W CST THROUGH CHRISTMAS...KEEPING SKIES
MOSTLY CLEAR. LOW TEMPS LIKELY WILL NOT BE QUITE AS COLD THU NIGHT.
SOME ADDITIONAL SLIGHT WARMING IS POSSIBLE ON CHRISTMAS...BUT
NOTHING TOO SIGNIFICANT.
.LONG TERM (SAT-TUE)...THE RIDGE ACROSS THE REGION WILL BE KNOCKED
DOWN AND PUSHED EWD SAT AS AN UPPER TROUGH MOVES TOWARD THE W CST.
HOWEVER...THIS SYSTEM IS FCST TO WEAKEN QUICKLY AS IT PUSHES INTO
THE RIDGE...SO ITS IMPACTS ON SRN CA LOOK MINOR AT BEST...CAUSING AN
INCREASE IN CLOUDS AND SOME COOLING. FOR NOW...WILL LEAVE THE SLIGHT
CHANCE OF RAIN ACROSS SLO COUNTY BY SAT AFTERNOON...BUT THAT COULD
EVEN BE A STRETCH. THE ECMWF SHOWS THE SYSTEM HOLDING TOGETHER TO
BRING A CHANCE OF RAIN TO THE ENTIRE AREA SAT NIGHT...WHILE THE GFS
SHOWS NO RAIN AT ALL.
BEYOND THAT...THERE IS A FAIR AMOUNT OF UNCERTAINTY IN THE FORECAST
AS THE MODELS ARE IN DISAGREEMENT WITH EACH OTHER AND FROM THEIR
PREVIOUS RUNS. HOWEVER...BOTH THE GFS AND THE ECMWF SHOW THE SAME
GENERAL IDEA...WITH ANOTHER TROUGH DROPPING SEWD MOVING THRU THE ERN
PAC MOVING TO THE SW OF THE FCST AREA SUN THROUGH EARLY MONDAY. AT
THIS POINT...IT APPEARS THAT THE BULK OF THE ENERGY AND MOISTURE
WILL REMAIN TO THE S AND W OF THE REGION...BUT SLIGHT CHANCE POPS
CERTAINLY LOOK WARRANTED SUN THRU MON. IT LOOKS LIKE NLY FLOW ALOFT
WILL BRING DRIER CONDS MON NIGHT AND TUE.
&&
.AVIATION...23/1140Z.
WINDS ARE EXPECTED TO CALM DOWN BY 18Z ACROSS THE MOUNTAINS. EXPECT
VFR CONDS THROUGH TONIGHT.
KLAX...HIGH CONFIDENCE IN TAF WITH CAVU CONDS THROUGH TONIGHT.. SOME
GUSTY CROSS WINDS EXPECTED UNTIL 13-14Z THIS MORNING.
KBUR...HIGH CONFIDENCE IN TAF WITH CAVU CONDS THROUGH TONIGHT.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
FROST ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
&&
$$
PUBLIC...BRUNO
AVIATION...KAPLAN
SYNOPSIS...DB
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