High Wind Watch 2, NWS Los Angeles, CA

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
845 PM PST WED JAN 28 2009

...UPDATED AVIATION DISCUSSION...

.UPDATE...LATEST NAM-WRF AND GFS MODEL SOLUTIONS ARE STARTING TO
STRENGTHEN THE OFFSHORE FLOW TONIGHT...AND PACKAGE WILL BE UPDATED
TO UPGRADE THE LOS ANGELES AND VENTURA COUNTY MOUNTAINS AND THE
SANTA MONICA RANGE TO A HIGH WIND WARNING. CURRENT SURFACE GRADIENTS
NEAR -6 MB BETWEEN KLAX-KBFL AND KSBA-KBFL ARE SOMEWHAT UNDERDONE
BY THE MODELS. NAM-WRF AND GFS HAVE INTENSIFIED 850 AND 950 MB
THERMAL GRADIENTS IN THE CURRENT MODELS SOLUTIONS...WITH NAM-WRF
950 MB THERMAL GRADIENTS PEAKING AROUND 11 DEGREES CELSIUS BETWEEN
THE ANTELOPE VALLEY AND THE SOUTHERN CALIFORNIA BIGHT. GFS 850 MB
THERMAL GRADIENTS ARE EQUALLY IMPRESSIVE DUE TO THE COARSENESS OF
THE MODEL...PEAKING AT 7 DEGREES CELSIUS BETWEEN THE MOJAVE DESERT
AND THE SANTA BARBARA CHANNEL. GFS AND NAM-WRF BOTH BRING A
STRONG AREA OF SUBSIDENCE OVER THE AREA BETWEEN 12Z AND 18Z
THURSDAY...AND THIS VERIFIES WELL WITH THE CURRENT WATER VAPOR
IMAGERY WITH AREA OF SUBSIDENCE STARTING TO DEVELOP OVER NORTHERN
CALIFORNIA. SOME CONCERN THAT WIND ADVISORIES MAY ALSO BE NEEDED
FOR THE FOOTHILLS OF SAN LUIS OBISPO AND SANTA BARBARA COUNTY AS
LATEST NAM INDICATE SOME STRONGER THERMAL GRADIENTS AT 975 MB AND
950 MB...ALONG WITH A INCREASING STRONGER SURFACE PRESSURE
GRADIENT BETWEEN KSMX- KBFL. FOR NOW...NO WIND HEADLINES WILL BE
ISSUED FOR THE SAN LUIS OBISPO AND SANTA BARBARA FOOTHILLS...BUT
WINDS WILL BE BUMPED UP IN THE CURRENT PACKAGE.

LATEST NAM-WRF 950 MB TEMPERATURES INITIALIZED WELL AND CURRENT
PACKAGE SEEMS AGREEABLE AS FAR AS TEMPERATURES FOR THURSDAY AND
BEYOND FOR AREAS SOUTH OF POINT CONCEPTION. HOWEVER FOR THE
CENTRAL COAST WITH SOME STRONGER GRADIENTS DEVELOPING AND
OFFSHORE FLOW BEING MUCH STRONGER...UPDATES WILL REFLECT CONCERN
FOR A POSSIBLE WARMER DAY ALONG THE CENTRAL COAST BUMPING
TEMPERATURES TO NEAR THE 80 DEGREE MARK FOR SOME AREAS.

&&

.PREV DISCUSSION... /ISSUED 345 PM PST WED JAN 28 2009/

SHORT TERM (TODAY-SAT)...INCREASING OFFSHORE FLOW TONIGHT WILL LEAD
TO ADVISORY LEVEL NORTHEAST WINDS ACROSS PORTIONS OF VENTURA AND LOS
ANGELES COUNTIES THROUGH FRIDAY. MAY EVEN GET SOME PEAK WINDS NEAR
60 AT THE USUAL WINDY SPOTS THROUGH THE HIGHWAY 126 AND 118
CORRIDORS. WINDS SHOULD START DEVELOPING TONIGHT WITH ADVISORY LEVEL
WINDS IN THE MOUNTAINS AND VALLEYS BY SUNRISE. HAVE ALSO INCLUDED
THE LA/VTU COUNTY COAST IN THE ADVISORY AND WINDS THERE MAY PICK UP
BY SUNRISE BUT MORE LIKELY CLOSER TO 9 AM. ELSEWHERE, LOCALLY BREEZY
CONDITIONS ARE POSSIBLE, ESPECIALLY THE ANTELOPE VALLEY DURING THE
NEXT TWO AFTERNOONS. TEMPS WILL BE ON THE WAY UP WITH 70S AND EVEN
SOME LOWER 80S ACROSS THE COAST AND VALLEYS BY FRIDAY.

STRONGEST WINDS ARE EXPECTED THURSDAY AS UPPER SUPPORT IS SLIGHTLY
WEAKER ON FRIDAY. HOWEVER, GRADIENTS ARE JUST AS STRONG SO IT SHOULD
STILL BE QUITE WINDY.

OFFSHORE FLOW WEAKENS SAT, BUT DRY AND WARMER THAN NORMAL TEMPS
EXPECTED TO CONTINUE. HIGHS WILL BE DOWN A FEW DEGREES SAT BUT
STILL WELL ABOVE NORMAL.

LONG TERM (SUN-WED)...LITTLE CHANGE SUNDAY. THEN MODELS SHOW A
SLIGHT INCREASE IN OFFSHORE FLOW AGAIN EARLY NEXT WEEK. THIS SHOULD
RESULT IN A FEW DEGREES OF WARMING MONDAY AND POSSIBLY A RETURN TO
MORE WIND ADVISORIES. MODELS DIVERGE TUE-WED WITH THE GFS CONTINUING
TO SHOW A CUTOFF LOW SLOWLY APPROACHING THE COAST WHILE THE ECMWF
KEEPS IT FARTHER OFFSHORE. THE EC HAS HAD A BETTER TRACK RECORD,
PARTICULARLY WITH REGARD TO THESE CUTOFF LOWS SO IM INCLINED TO
FAVOR THIS SOLUTION, WHICH WOULD MAINTAIN ABOVE NORMAL TEMPS THROUGH
AT LEAST THE MIDDLE OF NEXT WEEK AND CLEAR SKIES. IT ISNT UNTIL AT
LEAST NEXT WEEKEND BEFORE THE EC BRINGS THE TROF TO THE COAST, BUT
THE GFS SOLUTION WOULD CERTAINLY RESULT IN AN EARLIER COOL DOWN AND
CHANCE OF RAIN.

&&

.AVIATION...29/0440Z.

MODERATE SANTA ANA WIND EVENT WILL KEEP ALL TAF SITES VFR THROUGH
THE PERIOD. NORTHEAST WINDS...AND ASSOCIATED WIND SHEAR AND
TURBULENCE...WILL BE ISSUES AT THE USUAL LOCATIONS SUCH AS KVNY...
KBUR AND KOXR. IN ADDITION...KWJF AND KPMD WILL SEE SOME GUSTY
NORTHEAST WINDS THURSDAY AFTERNOON.

KLAX...HIGH CONFIDENCE IN 06Z TAF. OFFSHORE FLOW WILL KEEP THE
AIRFIELD VFR THROUGH THE PERIOD. CHANCE OF SOME LIGHT EASTERLY
WINDS THURSDAY MORNING AFTER 14Z...WITH WIND SPEEDS BELOW 10 KT.

KBUR...HIGH CONFIDENCE IN 06Z TAF. OFFSHORE FLOW WILL KEEP THE
AIRFIELD VFR THROUGH THE PERIOD. SOME SIGNIFICANT LLWS AND
TURBULENCE WILL BE LIKELY THURSDAY MORNING...AFTER 15Z...AS
THE NORTHEAST FLOW BEGINS TO PEAK IN STRENGTH.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING (SEE LAXNPWLOX).
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

PUBLIC...HALL/WOFFORD
AVIATION...RAT

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