Area Forecast Discussion
Issued by NWS Los Angeles, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KLOX 180407
AFDLOX

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

.SYNOPSIS...
OTHER THAN SOME GUSTY SUNDOWNER WINDS ACROSS SOUTHERN SANTA BARBARA
COUNTY...QUIET WEATHER IS ANTICIPATED TONIGHT. LOW PRESSURE WILL
DEVELOP THURSDAY AND FRIDAY ALONG THE WEST COAST...BRINGING COOLER
TEMPERATURES AND INCREASING COASTAL LOW CLOUDS. FOR THE WEEKEND AND
INTO EARLY NEXT WEEK...HIGH PRESSURE WILL GRADUALLY BUILD AND RESULT
IN A GRADUAL WARMING TREND.

&&

.SHORT TERM (TONIGHT-SAT)...THERE WERE SOME GUSTY W WINDS ALONG THE
IMMEDIATE COAST OF VTU/L.A. COUNTIES THIS EVENING...WITH GUSTY SW
WINDS IN PARTS OF THE ANTELOPE VLY. GUSTY N CANYON WINDS DEVELOPED
IN THE SANTA YNEZ RANGE AND S SBA COAST...WITH A WIND ADVISORY IN
EFFECT FOR THE SBA S COAST THRU MIDNIGHT. OTHERWISE...MOSTLY CLEAR
SKIES COVERED THE FORECAST AREA THIS EVENING. A WEAKENING COLD FRONT
WAS APPROACHING THE CENTRAL COAST THIS EVENING. LOW CLOUDS
ASSOCIATED WITH THE DYING FRONT ARE EXPECTED TO MOVE INTO SLO/SBA
COUNTIES OVERNIGHT ALONG WITH PATCHY DRIZZLE. LOW CLOUDS SHOULD ALSO
DEVELOP S OF POINT CONCEPTION LATER TONIGHT AND AFFECT THE L.A.
COUNTY COAST BEFORE MOVING UP THE COAST AND INLAND VERY LATE TONIGHT
INTO THU MORNING. ELSEWHERE...MOSTLY CLEAR SKIES WILL PREVAIL THRU
THE NIGHT.

A RATHER SHARP UPPER LEVEL TROF OVER THE E PAC WILL MOVE INTO NRN
AND CENTRAL CA ON THU. AN UPPER LEVEL LOW IS FORECAST TO DEVELOP OFF
THE CENTRAL CA COAST THU NIGHT THEN DRIFT TO A POSITION NEAR OR JUST
SW OF POINT CONCEPTION ON FRI. THE UPPER LOW SHOULD DRIFT NE AND
INLAND SOME OVER SWRN CA ON SAT. IT APPEARS THE MAIN AFFECT OF THE
UPPER LOW WILL BE TO DEEPEN THE MARINE LAYER WITH PLENTY OF LOW
CLOUDS FOR THE COAST AND VLYS NIGHT AND MORNING HOURS...AND POSSIBLY
EVEN INTO THE AFTERNOON. PATCHY DRIZZLE CAN ALSO BE EXPECTED OVER
THE COAST AND VLYS THU NIGHT AND FRI MORNING...ALTHO THERE MAY ALSO
BE PATCHY DRIZZLE IN SOME AREAS FRI NIGHT INTO SAT MORNING. A FEW
AFTERNOON CU BUILDUPS CANNOT BE RULED OUT OVER THE MTNS BY SAT...BUT
AT THIS TIME IT APPEARS THE CHANCES OF ANY THUNDERSTORMS ARE LESS
THAN 10 PERCENT AS THERE WILL NOT BE A WHOLE LOT OF MOISTURE WITH
THE UPPER LOW AND INSTABILITY SHOULD BE MARGINAL AT BEST FOR THE
MOST PART. A LARGE IMPACT OF THE UPPER LOW WILL BE MUCH COOLER
TEMPERATURES IN ALL AREAS...AS HIGHS FALL TO NEAR NORMAL TO SLIGHTLY
BELOW NORMAL THU THRU SAT...WITH THE COOLER OF THE THREE DAYS ON FRI.

***FROM PREVIOUS DISCUSSION***

.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...17/830 PM
MODERATE TO 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. WEST TO NW WINDS HAVE
INCREASED ACROSS THE WESTERN PORTION OF PZZ650-655 WITH SHORT PERIOD
SEAS BUILDING DUE TO THE STRONGER WINDS. THE SMALL CRAFT ADVISORY
FOR THE OUTER WATERS HAS BEEN EXTENDED OVER THE NEAR SHORE
WATERS...AND THE COMBINATION OF GUSTY WINDS AND CHOPPY SEAS IS
EXPECTED TO CONTINUE THROUGH LATE TONIGHT.

&&

.BEACHES...17/830 PM
LONG PERIOD SOUTHERN HEMISPHERE SWELLS CONTINUE WITH CONTRIBUTIONS
FROM A COUPLE OF DIFFERENT STORMS. THE ELEVATED SURF THAT RESULTED
FROM THE SOUTHERLY SWELLS PROMPTED ISSUANCE OF A BEACH HAZARDS
STATEMENT FOR HIGHER SURF AND STRONG RIP CURRENTS. THE SURF WILL
PERSIST THROUGH THURSDAY AND THEN BEGIN TO SUBSIDE THROUGH
FRIDAY...BUT THE RISK OF RIP CURRENTS WILL LIKELY CONTINUE THROUGH
FRIDAY AFTERNOON.

&&

.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...SIRARD/MW
AVIATION...SIRARD
MARINE/BEACHES...SMITH
SYNOPSIS...RAT

WWW.WEATHER.GOV/LOSANGELES




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.