Winter Storm in California, December 17, 2008

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
145 PM PST WED DEC 17 2008

.SHORT TERM (TODAY-SAT)...HEAVY SNOW EVENT FOR THE ANTELOPE VALLEY
AND LA/VTU MTNS PANNED OUT WELL WITH OVER A FOOT OF SNOW REPORTED IN
SOME AREAS AND STILL FALLING HEAVILY. THE SAME NORTHEAST FLOW THAT
REALLY HELPED ENHANCE THE PRECIPITATION THERE HAD THE OPPOSITE
EFFECT ON THE COASTAL SIDE OF THE MOUNTAINS WHERE PRECIPITATION HAS
BEEN LIGHT AND IN SOME CASES NON-EXISTENT. HOWEVER, OFFSHORE FLOW IS
STARTING TO WEAKEN NOW AND LOW LVLS ARE STARTING TO MOISTEN UP SOUTH
OF SBA RESULTING IN MORE WIDESPREAD RAINFALL, THOUGH STILL LIGHT
THIS AFTERNOON. MODELS HAVE BEEN CONSISTENT SHOWING AN INCREASE IN
LOW AND MID LEVEL LIFTING ACROSS LA COUNTY THIS EVENING AS THE UPPER
LOW APPROACHES AND OFFSHORE FLOW WEAKENS. SATELLITE IMAGERY SEEMS TO
CONFIRM THIS IDEA AND FOR THIS REASON WEVE LEFT UP THE FLASH FLOOD
WATCH FOR THE LA COUNTY BURN AREAS AS THE POTENTIAL FOR HEAVY RAIN
STILL EXISTS. IN FACT, LOWER ELEVATIONS OF LA COUNTY COULD SEE AN
INCH TO AN INCH AND A HALF OF RAIN THIS EVENING, WITH AMOUNTS
DROPPING OFF RAPIDLY TO THE WEST.

THE UPPER LOW WILL FINALLY MOVE ONSHORE THIS EVENING AND WE EXPECT
RAIN AND SNOW TO TAPER OFF OVERNIGHT. HAVE EXTENDED THE WINTER STORM
WARNING FOR THE MTNS AND AV UNTIL MIDNIGHT WITH PERHAPS ANOTHER FOOT
OF SNOW POSSIBLE OVER THE HIGHER TERRAIN.

AREAS THAT SEE GOOD CLEARING TONIGHT SHOULD SEE A FAIR AMOUNT OF
FROST THU MORNING, ESPECIALLY THE CENTRAL COAST AND INTERIOR VALLEYS
OF LA/VTU COUNTIES. HAVE ISSUED A FREEZE WARNING FOR THE SANTA YNEZ
VALLEY FOR AT LEAST TWO HOURS OF 28 OR LOWER AND FROST ADVISORIES
FOR THE COASTAL ZONES OF SLO/SBA COUNTIES AND THE VALLEYS OF LA/VTU
COUNTIES FOR AT LEAST 2 HOURS OF 32 OR LOWER.

ASIDE FROM THE MUCH COOLER THAN NORMAL TEMPERATURES, PRETTY BENIGN
WEATHER EXPECTED ACROSS THE AREA THU-SAT. A COUPLE OF WEAK SYSTEMS
WILL BRING A SMALL CHANCE OF LIGHT PRECIPITATION TO AREAS NORTH OF
PT CONCEPTION AND POSSIBLY THE MOUNTAINS THU AND FRI. DAYTIMES HIGHS
WILL REMAIN MOSTLY IN THE 50S AT LOWER ELEVATIONS WITH LOWS IN THE
30S TO LOWER 40S.

.LONG TERM (SUN-WED)...SUNDAY IS EXPECTED TO BE THE NICEST AND
WARMEST DAY WITH HIGHS INTO THE MID 60S AT LOWER ELEVATIONS. BOTH
THE GFS AND ECMWF SHOW A COLD FRONT MOVING THROUGH THE AREA LATE
SUNDAY AND MONDAY SO CONFIDENCE IS HIGHER THAT WELL SEE SOME
PRECIP. THE FRONT ITSELF HAS SOME DECENT LIFT WITH IT BUT ITS FAST
MOVING AND AMOUNTS SHOULD BE UNDER AN INCH IN MOST AREAS. SKIES WILL
LIKELY START TO CLEAR OUT DURING THE DAY MONDAY WITH DRY CONDITIONS
EXPECTED TUESDAY. CONFIDENCE SOMEWHAT LOWER BEYOND TUESDAY AS MODELS
HAVE BEEN GOING BACK AND FORTH WITH REGARD TO THE TIMING OF THE NEXT
SYSTEM DUE SOMETIME AROUND CHRISTMAS. LATEST RUNS OF THE GFS AND
ECMWF SEEM TO SUGGEST A SLIGHT DELAY IN THE ARRIVAL OF THE STORM AS
A WEAK UPPER RIDGE DEVELOPS TUE AND WED AND THE FRONT STALLS ACROSS
THE BAY AREA. FOR NOW WILL GO WITH A SLIGHT CHANCE OF RAIN ON
CHRISTMAS EVE AND IT LOOKS LIKE AN EVEN BETTER CHANCE FOR RAIN AND
HIGHER ELEVATION SNOW ON CHRISTMAS DAY.

&&

.AVIATION...16/1930Z.
SCATTERED SHOWERS ALONG WITH A SLIGHT CHANCE OF THUUNDERSTORMS WILL
CONTINUE THROUGH TONIGHT AND WEDNESDAY WITH VARIABLE CEILINGS AND
VISIBILITIES. AREAS NORTH OF POINT CONCEPTION WILL BE FAVORED FOR
SHOWER ACTIVITY THROUGH THIS AFTERNOON. AREAS SOUTH OF POINT
CONCEPTION WILL BE FAVORED FOR SHOWER ACTIVITY BY TONIGHT AND
WEDNESDAY.

KLAX AND KBUR...FAIR CONFIDENCE IN SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS THIS AFTERNOON THROUGH WEDNESDAY. SKIES WILL BE PARTLY
CLOUDY WITH MOSTLY MVFR CONDITIONS. THERE IS A 30 PERCENT CHANCE
THAT THE SHOWERS WILL ONLY BE IN THE VICINITY RATHER THAN DIRECTLY
AFFECTING THE AIRFIELDS...ALLOWING FOR A GREATER AMOUNT OF TIME WITH
VFR CONDITIONS THAN FORECAST.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING (SEE LAXWSWLOX).
FREEZE WARNING (SEE LAXNPWLOX).
FLASH FLOOD WATCH FOR THE LA COUNTY BURN AREAS (SEE LAXFFALOX).
WIND ADVISORY (SEE LAXNPWLOX).
WINTER WEATHER ADVISORY (SEE LAXWSWLOX).
FROST ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).

&&

PUBLIC...WOFFORD
AVIATION...30

WWW.WEATHER.GOV/LOSANGELES

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
928 AM PST WED DEC 17 2008

CAZ034>041-044>046-051>054-059-087-088-547-548-181400-
SAN LUIS OBISPO COUNTY CENTRAL COAST-
SANTA BARBARA COUNTY CENTRAL COAST-SANTA YNEZ VALLEY-
SAN LUIS OBISPO COUNTY INTERIOR VALLEYS-CUYAMA VALLEY-
SANTA BARBARA COUNTY SOUTH COAST-VENTURA COUNTY COAST-
LOS ANGELES COUNTY COAST INCLUDING DOWNTOWN LOS ANGELES-
VENTURA COUNTY INTERIOR VALLEYS-VENTURA COUNTY COASTAL VALLEYS-
SANTA MONICA MOUNTAINS RECREATIONAL AREA-
SAN LUIS OBISPO COUNTY MOUNTAINS-
SANTA BARBARA COUNTY MOUNTAINS-VENTURA COUNTY MOUNTAINS-
LOS ANGELES COUNTY MOUNTAINS EXCLUDING THE SANTA MONICA RANGE-
ANTELOPE VALLEY-CATALINA ISLAND-SANTA CLARITA VALLEY-
LOS ANGELES COUNTY SAN FERNANDO VALLEY-
LOS ANGELES COUNTY SAN GABRIEL VALLEY-
928 AM PST WED DEC 17 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWESTERN CALIFORNIA.

.DAY ONE... TODAY

THERE WILL BE NUMEROUS SHOWERS TODAY...WITH THE HEAVIEST
PRECIPITATION ACROSS LOS ANGELES COUNTY. THERE IS A SLIGHT CHANCE OF
THUNDERSTORMS...SOME OF WHICH MAY PRODUCE SMALL HAIL AND HEAVY
DOWNPOURS. THERE COULD BE ISOLATED WATERSPOUTS IN THE COASTAL
WATERS. SIGNIFICANT SNOW ACCUMULATIONS ARE EXPECTED ACROSS THE LOS
ANGELES COUNTY MOUNTAINS AND THE ANTELOPE VALLEY...WITH MODERATE
ACCUMULATIONS ACROSS THE VENTURA COUNTY MOUNTAINS. COLD AND WINDY
CONDITIONS WILL BE EXPERIENCED IN THE MOUNTAINS AND ANTELOPE
VALLEY...WITH LOCALLY GUSTY WINDS IN THE VALLEYS OF LOS ANGELES AND
VENTURA COUNTIES. THERE IS THE POTENTIAL FOR DEBRIS FLOWS IN THE
RECENT BURN AREAS OF LOS ANGELES COUNTY. AREAS OF FREEZING
TEMPERATURES ARE EXPECTED IN THE SANTA YNEZ VALLEY LATE TONIGHT.
THERE WILL BE LOCAL FROST LATE TONIGHT IN COASTAL SECTIONS OF SAN
LUIS OBISPO AND SANTA BARBARA COUNTIES AND IN THE INTERIOR VALLEYS
OF VENTURA AND LOS ANGELES COUNTIES.

* WINTER STORM WARNING.......SEE WWUS46 KLOX - WSWLOX FOR DETAILS *

* FLOOD WATCH................SEE WGUS66 KLOX - FFALOX FOR DETAILS *

* WIND ADVISORY..............SEE WWUS76 KLOX - NPWLOX FOR DETAILS *

* WINTER WEATHER ADVISORY....SEE WWUS46 KLOX - WSWLOX FOR DETAILS *

* MARINE WEATHER STATEMENT...SEE FZUS76 KLOX - MWSLOX FOR DETAILS *

.DAYS TWO THROUGH SEVEN... THURSDAY THROUGH TUESDAY

AREAS OF FREEZING TEMPERATURES ARE EXPECTED IN THE SANTA YNEZ VALLEY
THROUGH MID MORNING THURSDAY...WITH LOCAL FROST IN COASTAL SECTIONS
OF SAN LUIS OBISPO AND SANTA BARBARA COUNTIES AND IN THE INTERIOR
VALLEYS OF VENTURA AND LOS ANGELES COUNTIES.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

BOLDT