Area Forecast Discussion
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FXUS66 KLOX 100347
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
847 PM PDT TUE APR 9 2013
.SYNOPSIS...
WEAK TO MODERATE SANTA ANA WINDS WILL AFFECT SOUTHWEST CALIFORNIA
THROUGH WEDNESDAY. TEMPERATURES WILL RISE TO WELL ABOVE NORMAL ON
WEDNESDAY UNDER THE OFFSHORE FLOW...AND WILL REMAIN ABOVE NORMAL
THROUGH LATE IN THE WEEK. A SHIFT TO ONSHORE FLOW COULD BRING
CLOUDS AND FOG TO COASTAL AREAS AS EARLY AS FRIDAY...AND INTO
EARLY NEXT WEEK WITH A COOLING TREND.
&&
.UPDATE...
OFFSHORE SURFACE PRESSURE GRADIENTS CONTINUE TO DEVELOP ACROSS THE
AREA THIS EVENING AS COLD AIR REENFORCEMENT ARRIVES OVER THE
MOJAVE DESERT ALTER TONIGHT. NAM-WRF SOLUTIONS ARE INCREASING THE
STRENGTH OF THE SANTA ANA WINDS...AND ADVISORIES HAVE BEEN
EXPANDED ACROSS LOS ANGELES COUNTY. LOCALLY GUSTY WINDS WILL
ALSO DEVELOP ACROSS THE EASTERN VENTURA COUNTY LATER TONIGHT AND
INTO WEDNESDAY.
WITH THE COLDER AND DRIER AIR MASS ESTABLISHING ACROSS THE
AREA OVERNIGHT...LOW TEMPERATURES WERE TWEAKED DOWN ACROSS THE
INTERIOR. PATCHY FROST MAY DEVELOP ACROSS PORTION OF THE ANTELOPE
VALLEY AND SAN LUIS OBISPO COUNTY VALLEYS.
&&
.PREV DISCUSSION...
SHORT TERM...GRADIENTS SHOWING STRONG OFFSHORE TENDENCIES TODAY,
WHICH IS TO BE EXPECTED AS WE TRANSITION FROM A STRONG NORTHWEST
WIND EVENT INTO A LIGHT TO MODERATE SANTA ANA TONIGHT AND
WEDNESDAY. STILL SOME LINGERING GUSTY WINDS TODAY BUT MUCH WEAKER
THAN MONDAY. THE SANTA ANA EVENT WEDNESDAY IS WEAK BY COMPARISON
AND WILL IMPACT FAR FEWER PEOPLE WITH THE STRONGEST WINDS CONFINED
TO THE LA MOUNTAINS. MODEL SOLUTIONS SUPPORT DECENT ADVISORY LEVEL
WINDS IN THOSE AREAS AFTER MIDNIGHT TONIGHT THROUGH EARLY
WEDNESDAY AFTERNOON. SOME PERCENTAGE OF THOSE WINDS WILL FILTER
DOWN INTO THE VALLEYS AND POSSIBLY EVEN PORTIONS OF THE LA/VENTURA
COAST AS WELL, BUT OUTSIDE OF SOME TYPICALLY STRONGER AND VERY
ISOLATED SPOTS (WILEY RIDGE I`M LOOKING AT YOU) MOST AREAS SHOULD
BE IN THE 15-25 MPH RANGE.
HIGHS WEDNESDAY PROBABLY THE BIGGER TOPIC OF CONVERSATION FOR MOST
AREAS WITH TEMPERATURES EXPECTED TO SOAR WELL INTO THE 80S FOR THE
LA/VENTURA VALLEYS AND HIGH 70S TO LOWER 80S FOR PORTIONS OF THE
COAST. OUTSIDE OF THOSE AREAS HIGHS STILL EXPECTED TO BE 5-10
DEGREES ABOVE NORMAL ON AVERAGE. NOT EXPECTING ANY RECORDS WEDNESDAY
AS MOST RECORDS ARE IN THE 90S.
SANTA ANA WINDS EXPECTED TO WEAKEN DURING THE AFTERNOON AS GRADIENTS
QUICKLY TURN BACK ONSHORE AHEAD OF A WEAK TROF DROPPING SOUTHEAST
THROUGH CALIFORNIA ON THURSDAY. THIS WILL BRING A BRIEF RETURN OF
BREEZY NORTH/NORTHWEST WINDS THURSDAY AFTERNOON AND EVENING, THOUGH
CONSIDERABLY WEAKER THAN WHAT THE AREA EXPERIENCED MONDAY. NOT
EXPECTING ANY ADVISORIES AT THIS TIME, THOUGH NORTHERLY WINDS
BLOWING THROUGH THE SANTA YNEZ RANGE COULD GUST INTO TO NEAR 40 MPH
AT TIMES THERE. TEMPERATURES MOST AREAS EXPECTED TO BE A FEW DEGREES
COOLER WITH THE ONSHORE FLOW THURSDAY, THOUGH THE NORTHERLY WINDS IN
SRN SBA COUNTY COULD RESULT IN LOCAL WARMING THERE.
AGAIN THE TRANSITION FROM N/NW WINDS TO NORTHEAST THURSDAY NIGHT
INTO FRIDAY WITH A WEAKER SANTA ANA WIND EVENT EXPECTED FRIDAY
MORNING. THE 12Z/18Z NAM AND TO A LESSER EXTENT THE GFS SHOWS 950
TEMPS CLIMBING TO THE LOW TO MID 20S(C) WHICH, IN COMBINATION WITH
THE OFFSHORE GRADIENTS, SHOULD WARM TEMPS BACK UP INTO THE 80S AND
MAYBE EVEN CLOSE TO 90 IN THE WARMEST LA/VENTURA VALLEY AREAS.
LONG TERM...THE ONSHORE/OFFSHORE GAME FLIPS BACK TO ONSHORE FOR
A•
THE WEEKEND, BRINGING COOLER TEMPS FOR COAST AND VALLEYS AND A
RETURN OF THE MARINE LYR BY SATURDAY. IN FACT, ONSHORE GRADIENTS
REALLY TIGHTEN UP SUNDAY AFTERNOON INTO SUNDAY NIGHT AND WILL VERY
LIKELY SEE ADVISORY LEVEL WESTERLY WINDS RETURNING TO THE ANTELOPE
VALLEY AND POSSIBLY GUSTY WINDS FOR THE I5 CORRIDOR AS WELL.
ANOTHER INSIDE SLIDER SYSTEM FOR NEXT MONDAY WILL BRING INCREASING
NORTH/NORTHWEST WINDS AGAIN TO THE FAVORED AREAS (I5 CORRIDOR,
ANTELOPE VALLEY, SANTA YNEZ RANGE, CENTRAL COAST) AND COULD ALSO
SPIN UP A DEEP ENOUGH MARINE LYR FOR SOME LOCAL DRIZZLE MONDAY
MORNING, ESPECIALLY EASTERN LA COUNTY. WE THEN TRANSITION TO
OFFSHORE FLOW NEXT TUESDAY.
&&
.AVIATION...10/0009Z.
VFR CONDITIONS ARE EXPECTED AT ALL TERMINALS. THERE IS SLIGHT CHANCE
OF VLIFR TO LIFR AT CENTRAL COAST TERMINALS BETWEEN 04Z AND 10Z.
PERIODS OF MODERATE TO STRONG LOW-LEVEL WIND SHEAR AND TURBULENCE
ARE EXPECTED AT LOS ANGELES AND VENTURA COUNTY TERMINALS BETWEEN 04Z
AND 16Z.
KLAX...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. PERIODS OF
MODERATE TO STRONG LOW-LEVEL WIND SHEAR AND TURBULENCE ARE EXPECTED
BETWEEN 04Z AND 16Z. THERE IS A 30 PERCENT CHANCE OF NORTHEAST TO
EAST WINDS BEING GREATER THAN 7 KNOTS BETWEEN 08Z AND 14Z.
KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. PERIODS OF
MODERATE TO STRONG LOW-LEVEL WIND SHEAR AND TURBULENCE ARE EXPECTED
BETWEEN 04Z AND 16Z.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
GALE WATCH (SEE LAXMWWLOX).
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
&&
PUBLIC...HALL/MW
AVIATION...HALL
SYNOPSIS...SMITH/HALL
WWW.WEATHER.GOV/LOSANGELES
Webmaster
US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
Los Angeles/Oxnard Weather Forecast Office
520 North Elevar Street
Oxnard, CA 93030
Tel: (805) 988-6610