FXUS66 KLOX 212123
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
125 PM PST MON DEC 21 2009
.SYNOPSIS...
LOW PRESSURE WILL BRING A CHANCE OF SHOWERS AND A COOLING TREND TO
THE REGION INTO TUESDAY. BLUSTERY WINDS ARE FORECASTED TONIGHT INTO
WEDNESDAY IN THE FAVORED LOCALES. THE REST OF CHRISTMAS WEEK LOOK
FOR MOSTLY CLEAR SKIES AND A WARMING TREND. A STORM SYSTEM MAY
APPROACH EARLY NEXT WEEK WITH A CHANCE OF RAIN AND A COOLING TREND.
&&
.SHORT TERM (TODAY-THU)...A COLD UPPER LOW IS CENTERED JUST OFF THE
BC COAST THIS AFTERNOON WITH A WEAK COLD FRONT STRETCHING SOUTH
ALONG THE THE CALIFORNIA COAST. VBG RADAR IS PICKING UP ON SOME
ECHOES OVER THE NWRN SLO COUNTY COAST THAT MAY BE REACHING THE
GROUND AS SPRINKLES OR VERY LIGHT SHOWERS. GOES PWAT ESTIMATES ARE
AROUND 1 INCH JUST WEST OF THE CENTRAL COAST COAST AND I EXPECT THE
FRONT TO TAP INTO SOME OF THIS HIGHER MOISTURE LATER THIS AFTERNOON
AND EVENING. STILL NOT EXPECTING MUCH RAIN AT ALL FROM THIS SYSTEM
BUT PERHAPS JUST ENOUGH TO WET THE GROUND UP THERE.
AS USUAL THE FRONT WILL WEAKEN FURTHER ROUNDING PT CONCEPTION, BUT
THEN SOME ENHANCEMENT MAY OCCUR ACROSS LA COUNTY LATER TONIGHT AS
THE ONSHORE PUSH CREATES SOME ADDITIONAL LIFT AND SQUEEZES WHAT'S
LEFT OUT OF IT, ESPECIALLY THE ERN LA COUNTY FOOTHILLS AND SAN
GABRIEL VALLEY. THE OTHER AREA THAT WILL LIKELY SEE PRECIP FROM THIS
SYSTEM IS THE GRAPEVINE AREA, ESPECIALLY AS WINDS SHIFT TO THE
NORTHWEST LATER TONIGHT AND EARLY TUESDAY AND LOW LVL MOISTURE IN
THE CENTRAL VALLEY IS LIFTED UP THE NORTH FACING SLOPES. IF THE NAM
IS CORRECT WE'LL SEE SNOW LEVELS DROPPING RAPIDLY TONIGHT AND
FALLING TO AS LOW AS 2500 FEET TUESDAY MORNING. WILL NEED TO KEEP A
CLOSE WATCH ON THIS TO SEE IF ENOUGH PRECIP DEVELOPS TO WARRANT A
WINTER STORM WARNING FOR THE GRAPEVINE AREA AS THERE IS THE
POTENTIAL FOR ACCUMULATING SNOW AT PASS LEVEL.
MAIN IMPACT OF THIS SYSTEM WILL BE WINDS AND COLDER TEMPERATURES AND
THESE HAVE BEEN PRETTY WELL ADVERTISED. HIGH WIND WATCHES WERE
POSTED LAST NIGHT FOR TUESDAY THROUGH WEDNESDAY MORNING ACROSS THE
MOUNTAINS AND SOME OF THE VALLEYS. MADE SOME ADJUSTMENT TO THE
STARTING TIME OF THE WATCH AS IT LOOKS LIKE WINDS SHOULD BE STARTING
UP A LITTLE EARLIER NOW. HOWEVER, NOT REAL CONFIDENT WE'LL GET
WARNING LEVEL WINDS IN THE LA VALLEYS OR EVEN SBA COUNTY SOUTH COAST
BUT THE MOUNTAINS LOOK SOLID AND I EXPECT WE'LL SEE OUR USUAL
FAVORITE LOCATIONS LIKE WHITAKER PEAK WILL COME IN WITH GUSTS UP TO
OR EVEN EXCEEDING 70 MPH.
TUESDAY NIGHT INTO WEDNESDAY WINDS WILL BE SHIFTING TO THE
NORTHEAST, SHUTTING OFF OR DECREASING IN SOME AREAS BUT STARTING UP
IN OTHERS. VERY COLD TEMPERATURES EXPECTED TUESDAY NIGHT IN WIND
SHELTERED LOCATIONS AND FROST ADVISORIES MAY BE NEEDED FOR PORTIONS
OF VENTURA AND LA COUNTIES.
AN UPPER RIDGE WILL BE BUILDING OVER THE AREA WED AND THU FOR A
SLIGHT WARMING TREND. WEAK TO MODERATE OFFSHORE FLOW WILL HELP WARM
TEMPS AT LOWER ELEVATIONS BUT IT WILL TAKE A COUPLE DAYS TO FULLY
RECOVER FROM THE COLD AIR THAT THIS CURRENT TROF WILL LEAVE BEHIND.
AS A RESULT, HIGHS PROBABLY WON'T BOUNCE BACK TO NORMAL UNTIL THU AT
THE EARLIEST. WINDS PROBABLY NOT STRONG ENOUGH FOR ADVISORIES BUT
THE USUAL FAVORED SANTA ANA WIND LOCATIONS WILL LIKELY SEE GUSTS
INTO THE 40S.
.LONG TERM (FRI-MON)...NICE WEATHER TO CONTINUE RIGHT ON THROUGH
CHRISTMAS DAY AND INTO SAT WITH DAYTIME HIGHS HOVERING NEAR TO
SLIGHTLY ABOVE NORMALS. MODELS IN DECENT AGREEMENT SUNDAY AND MONDAY
SHOWING AN UPPER LOW UNDERCUTTING THE RIDGE ACROSS THE ERN PACIFIC,
BUT BIG DIFFERENCES EXIST WITH THE TRACK OF THE LOW. THE GFS IS
ACTUALLY THE WETTER MODEL BY FAR WITH A VERY SIGNIFICANT SYSTEM
MOVING ONSHORE AS EARLY AS SUNDAY. THE ECMWF AND CANADIAN MODELS
TAKE THE LOW SOUTH INTO NRN MEXICO AND ACTUALLY MISS SO CAL
COMPLETELY. SO WE'LL HAVE TO SEE HOW THIS PLAYS OUT OVER THE NEXT
SEVERAL DAYS. FOR NOW I'VE KEPT IN A GENERIC SLIGHT CHANCE OF
SHOWERS FOR SUN AND MON SINCE AT THIS TIME ANY OF THOSE MODEL
SOLUTIONS ARE EQUALLY PLAUSIBLE SCENERIOS.
&&
.AVIATION...21/1755Z
HIGH CONFIDENCE IN VFR EVERYWHERE THROUGH 00Z. LIGHT SHOWERS WILL
DEVELOP OVER KPRB KSBP AND KSMX BETWEEN 22Z AND 04Z. 15-30 PERCENT
CHANCE OF -SHRA ELSEWHERE. MVFR CIGS/VIS COULD FORM LATER TONIGHT
WITH THE ADDED MOISTURE...BUT CONFIDENCE IS LOW. KPRB COULD SEE LIFR
CONDITIONS AFTER 10Z...BUT DEPENDS ON WHEN NORTHERLY WINDS INCREASE.
IF THEY ARE DELAYED...FG LIKELY. WIDESPREAD AND STRONG W-NW WINDS ON
TUE...WITH LLWS CONCERNS.
KLAX...HIGH CONFIDENCE THROUGH 00Z. 15 PERCENT CHANCE OF -SHRA
BETWEEN 05Z AND 12Z...BUT MOST LIKELY NOTHING. IFR COULD BRIEFLY
DROP TO MVFR CIGS/VIS BETWEEN 08Z AND 14Z. STRONG WEST WINDS
EXPECTED TUE...PEAKING WITH GUSTS INTO 30KT RANGE BETWEEN 22Z AND
04Z TUE/WED.
KBUR...HIGH CONFIDENCE THROUGH 00Z. 20 PERCENT CHANCE OF -SHRA
BETWEEN 05Z AND 14Z...BUT MOST LIKELY NOTHING. IFR COULD BRIEFLY
DROP TO MVFR CIGS/VIS BETWEEN 08Z AND 14Z. STRONG NW WINDS
EXPECTED TUE...WITH POSSIBLE LLWS CONCERNS.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
GALE WATCH (SEE LAXMWWLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).
&&
$$
PUBLIC...WOFFORD
AVIATION...KITTELL
SYNOPSIS...SETO
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