Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 180004 AAB
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
505 PM PDT WED SEP 17 2014

...AVIATION DISCUSSION UPDATED...

.SYNOPSIS...

THE LOW WILL DEEPEN THE MARINE LAYER AND COOL TEMPERATURES TO BELOW
NORMAL BY FRIDAY. GUSTY SUNDOWNER WINDS WILL OCCUR TONIGHT IN THE
SANTA BARBARA AREA. A WARMING TREND WILL BEGIN SATURDAY AS HIGH
PRESSURE BUILDS.

&&

.SHORT TERM (TODAY-SAT)...TEMPS TODAY TRENDING COOLER BY 4-8 DEGREES
ON AVERAGE AS GRADIENTS TREND ONSHORE AHEAD OF AN APPROACHING TROF.
CONVECTION GETTING A SLOWER START TODAY BUT WE ARE STARTING TO SEE
SOME DEVELOPMENT ACROSS ERN LA COUNTY. DECIDED TO KEEP THE FLASH
FLOOD WATCH GOING GIVEN THAT WE ARE SEEING SOME DEVELOPMENT BUT
STILL THINK THAT MOST OF THE CONCERN WILL BE TO OUR EAST WITH THE
BETTER MOISTURE AND INSTABILITY.

ANOTHER HOT SUNDOWNER FOR SRN SBA COUNTY THIS AFTERNOON AND EVENING.
ALREADY GETTING SOME GUSTY WINDS DEVELOPING NEAR GAVIOTA WITH TEMPS
CLIMBING INTO THE 90S. EXPECT THIS TO CONTINUE THROUGH THE EVENING
WHERE A WIND ADVISORY IS IN EFFECT.

COOLING TREND TO CONTINUE THROUGH FRIDAY AS THE TROF MOVES ONSHORE
AND EVENTUALLY EVOLVES INTO A CUTOFF LOW OVER SRN CA FRIDAY INTO
SATURDAY. A WEAK FRONT WILL MOVE THROUGH THU AND CAUSE THE MARINE
LYR TO DEEPEN QUITE A BIT. N OF PT CONCEPTION IT SHOULD DEEPEN UP
OVER 2000 FT WITH CLOUDS SPILLING WELL INTO INTERIOR SLO COUNTY. IT
DOESN`T LOOK LIKE THE FRONT WILL HOLD TOGETHER WELL ENOUGH TO BRING
ACTUAL RAIN, BUT THE DEEPENING MARINE LYR COULD SPIT OUT SOME
DRIZZLE UP NORTH EARLY THU. FURTHER SOUTH WE`RE EXPECTING LOW CLOUDS
TO START FORMING OVER THE BIGHT TONIGHT AND PUSH ONSHORE LATE AND
INTO THE LOWER VALLEY AREAS THU MORNING. THE BIG ONSHORE PUSH WILL
BRING CONSIDERABLE COOLING TO ALL AREAS BUT ESPECIALLY THE VALLEYS
WHERE HIGHS WILL DROP FROM THE LOW 100S TODAY TO THE MID 80S THU IN
MANY AREAS.

FURTHER COOLING AND MARINE LYR DEEPENING (ESPECIALLY S OF PT
CONCEPTION) FRIDAY AS THE TROF EVOLVES INTO A CUTOFF LOW. THE
POTENTIAL FOR DRIZZLE WILL SHIFT TO LA/VENTURA COUNTIES FRI AS THE
MARINE LYR LIKELY SHOOTS UP OVER 2500` AND GETS CLOSE TO THE LOWER
COASTAL SLOPES. WILL PROBABLY GET SOME AFTERNOON CLOUD BUILDUPS OVER
THE MTNS AS WE GET SOME COOLING ALOFT WITH THE UPPER LOW BUT IT
DOESN`T LOOK UNSTABLE ENOUGH FOR TSTORMS. MOST AREA HIGHS EXPECTED
TO TUMBLE BELOW SEASONAL NORMS FRI FOR THE FIRST TIME IN 2 WEEKS.
HIGHS AND OVERNIGHT LOWS WOULD CERTAINLY BE EVEN COOLER IF IT
WEREN`T FOR SST`S THAT ARE CURRENTLY RUNNING ABOUT 4-7 DEGREES ABOVE
NORMAL. THE WARMER SST`S WILL LIKELY RESULT IN A WEAKER LOW LEVEL
INVERSION AND EVEN MORE UNPREDICTABLE MARINE LYR BEHAVIOR THAN
USUAL, BUT CERTAINLY EARLIER CLEARING THAN WOULD TYPICALLY BE
EXPECTED WITH SUCH A DEEP MARINE LYR.

THE CUTOFF LOW STARTS TO FILL SAT AS THE LONG WAVE RIDGE AMPLIFIES
ALONG THE WEST COAST SO MOST AREAS SHOULD SEE A FEW DEGREES
OF WARMING SATURDAY WITH A SLIGHTLY LOWER MARINE LYR DEPTH.

.LONG TERM (SUN-WED)...MODELS AGREE ON THE CUTOFF LOW LIFTING
NORTHEAST SUNDAY FOR ADDITIONAL WARMING AND MARINE LYR SHRINKAGE.
THE WARMING TREND TO CONTINUE THROUGH TUESDAY WITH HIGHS CLIMBING
BACK TO NORMAL LEVELS AS EARLY AS MONDAY AND POSSIBLY SLIGHTLY ABOVE
TUESDAY. FOR THE LATTER HALF OF NEXT WEEK THE MODELS HAVE SHIFTED
BIG TIME AWAY FROM THE HUGE 600+DM HIGH OVER NRN CA TO A RATHER DEEP
TROF ACROSS THE PAC NW. EVEN THE 5 WAVE PATTERN HAS SHIFTED TO A
TROF ALONG THE WEST COAST FOR LATE NEXT WEEK. CONFIDENCE STILL NOT
PARTICULARLY HIGH GIVEN THE EXTREMES IN BOTH SOLUTIONS, BUT GIVEN
THAT THE 12Z ECMWF AND GFS ARE BOTH IN REMARKABLE AGREEMENT ON THIS
CHANGE I`M INCLINED TO GO ALONG WITH IT. WITH THIS IN MIND MOST
AREAS SHOULD SEE A COOLING TREND BEGINNING WEDNESDAY AND CONTINUING
THROUGH THE END OF NEXT WEEK. IT`S A FAR CRY FROM WHAT LOOKED LIKE
AN EVEN HOTTER HEAT WAVE THAN WHAT WE JUST EXPERIENCED AND I WOULD
NOT BE TERRIBLY SURPRISED TO SEE THE MODELS FLIP BACK TO THAT
SOLUTION.

&&

.AVIATION...17/2355Z...GENERALLY MODERATE CONFIDENCE IN THE 00Z TAFS
DUE TO UNCERTAINTIES WITH TIMING OF LOW CLOUDS TONIGHT AND THU FOR
ALL THE COAST AND ADJACENT VLY AIRFIELDS. HOWEVER...THERE IS
GENERALLY HI CONFIDENCE THAT LOW CLOUDS AND LIFR/IFR/MVFR CONDITIONS
WILL AFFECT MOST OF THESE AIRFIELDS DURING THE TAF PERIOD. THE ONSET
OF LOW CLOUDS WILL RANGE FROM 03Z THIS EVENING AT KSMX TO 17Z THU AT
KSBA...ALTHO THE LOWEST CONFIDENCE FOR LOW CLOUDS WILL BE AT KSBA.
ALSO...THE TIMING OF THE ONSET OF THE LOW CLOUDS MAY BE OFF
PLUS/MINUS 1-2 HOURS ESPECIALLY S OF POINT CONCEPTION. THERE IS ALSO
UNCERTAINTY TO THE TIMING OF THE LOW CLOUDS SCATTERING OUT THU
AFTERNOON FOR MOST AIRFIELDS WHICH MAY BE OFF PLUS/MINUS AN HOUR OR
TWO...BUT SHOULD LINGER THRU MUCH THE THU AFTERNOON AT KOXR...KLAX
AND KLGB. LOW LEVEL WIND SHEAR IS POSSIBLE AT TIMES TONIGHT AT KSBA
DUE TO GUSTY N CANYON WINDS IN THE VICINITY. FOR KPMD AND KWJF...HI
CONFIDENCE IN VFR CONDITIONS THRU THU...WITH GUSTY SW WINDS EARLY
THIS EVENING AND AGAIN BY THU AFTERNOON.

KLAX...MODERATE CONFIDENCE OVERALL IN THE 00Z TAF DUE TO
UNCERTAINTIES WITH TIMING OF LOW CLOUDS LATE TONIGHT AND THU. THE
LOW CLOUDS WITH MVFR CIGS SHOULD DEVELOP AROUND 10Z THEN LINGER THRU
22Z BEFORE MOVING BACK INTO THE AIRFIELD BY 03Z THU EVENING. THE
TIMING OF THE ONSET AND DISSIPATION OF THE LOW CLOUDS MAY BE OFF
PLUS/MINUS 1-2 HOURS. OTHERWISE...VFR CONDITIONS CAN BE EXPECTED
THIS EVENING THRU LATE TONIGHT AND AGAIN LATE THU AFTERNOON AND
EARLY EVENING. THERE IS A 20 PERCENT CHANCE THE LOW CLOUDS MAY NOT
SCATTER OUT AT ALL ON THU.

KBUR...MODERATE CONFIDENCE OVERALL IN THE 00Z TAF DUE TO
UNCERTAINTIES WITH TIMING OF LOW CLOUDS LATE TONIGHT AND THU. THE
LOW CLOUDS WITH MVFR CIGS SHOULD DEVELOP AROUND 12Z THEN LINGER THRU
22Z. THE TIMING OF THE ONSET AND DISSIPATION OF THE LOW CLOUDS MAY
BE OFF PLUS/MINUS 1-2 HOURS. OTHERWISE...VFR CONDITIONS CAN BE
EXPECTED THIS EVENING THRU LATE TONIGHT AND AGAIN LATE THU AFTERNOON.

&&

.MARINE...17/215 PM
HIGH CONFIDENCE IN CURRENT MARINE FORECAST. ADVISORY LEVEL WINDS
ACROSS MUCH OF THE OUTER WATERS THROUGH LATE IN THE WEEK.  THE
STRONGEST WINDS WILL BE NEAR POINT CONCEPTION DURING THE MID
AFTERNOON TO EARLY EVENING PERIOD.

THE WESTERN HALF OF THE SANTA BARBARA CHANNEL WILL HAVE LOCAL
NORTHWEST WIND GUSTS TO 25 TO 35 KT DURING THE NEXT FEW LATE
AFTERNOONS AND EVENINGS RELATED TO SUNDOWNER WINDS OFF THE SANTA
BARBARA COUNTY SOUTH COAST.  MAY NEED AN ADVISORY AGAIN THIS
AFTERNOON AND EVENING IF IT DEVELOPS BEYOND A LOCAL EVENT.

&&

.BEACHES...17/215 PM
THE LONG PERIOD SOUTHERN HEMISPHERE SWELL HAS BEEN DIMINISHING.  IT
WILL CONTINUE TO BRING ELEVATED SURF ALONG SOUTH AND SOUTHWEST
FACING BEACHES AND A SIGNIFICANT AMOUNT OF RIP CURRENT ACTIVITY
THROUGH AT LEAST THURSDAY THOUGH THESE EFFECTS WILL DIMINISH OVER
TIME.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
BEACH HAZARDS STATEMENT (SEE LAXCFWLOX)
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&
$$

PUBLIC...MW
AVIATION...SIRARD
MARINE/BEACHES...KJ
SYNOPSIS...MW

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