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000
FXUS66 KLOX 241143
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
445 AM PDT FRI MAY 24 2013

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...

A BROAD AREA OF LOW PRESSURE WILL LINGER OVER THE WEST COAST
THROUGH TUESDAY. PERSISTENT NIGHT THROUGH MORNING LOW CLOUDS AND
FOG WILL OCCUR THROUGH THE WEEKEND...CLEARING TO THE BEACHES EACH
DAY. GUSTY ONSHORE WINDS WILL DEVELOP OVER THE WEEKEND AS A
SERIES OF WEAK COLD FRONTS APPROACH THE AREA...WITH SHOWERS
POSSIBLE TUESDAY. THE AIR MASS WILL REMAIN COOL INTO MIDWEEK NEXT
WEEK...THEN A WARMING TREND SHOULD BEGIN FOR THE LATTER HALF OF
NEXT WEEK.

&&

.SHORT TERM (TODAY-SUNDAY)...

A BROAD TROUGH OF LOW PRESSURE CONTINUES TO LINGER ALONG THE WEST
COAST THIS MORNING. ONSHORE FLOW FIRMLY IN PLACE WILL CONTINUE TO
STRENGTHEN OVER THE HOLIDAY WEEKEND AS A SERIES OF WEAK COLD
FRONTS APPROACH THE AREA. STRONG ONSHORE SURFACE PRESSURE
GRADIENTS WILL LIKELY DEVELOP THROUGH SATURDAY...KEEPING MAY GRAY
TIDINGS TRUE. LOW CLOUDS AND FOG WILL LIKELY SOCK IN THE BEACHES
OVER THE WEEKEND. A WEAK COLD FRONT WASHING OUT OVER THE AREA ON
SUNDAY MAY PERMIT A LITTLE MORE CLEARING ON SUNDAY AFTERNOON FOR
THE SANTA BARBARA SOUTH COAST AND VENTURA COUNTY BEACHES...BUT
ANOTHER WEAK FRONTAL BOUNDARY WILL RE-ENFORCE THE ONSHORE FLOW
FOR MONDAY.

WITH THE WEAK BOUNDARY WASHING OUT OVER THE AREA ON SUNDAY...A
MODERATE SUNDOWNER AND INTERSTATE 5 CORRIDOR WIND EVENT COULD
DEVELOP BETWEEN SUNDAY AFTERNOON AND MONDAY MORNING. WHILE STILL
EARLY...AN ADVISORY LEVEL WIND EVENT COULD DEVELOP ACROSS THE
SOUTH COAST OF SANTA BARBARA COUNTY...THROUGH THE SANTA YNEZ
RANGE...AND THROUGH INTERSTATE 5 CORRIDOR SUNDAY.

STRONG ONSHORE GRADIENTS BETWEEN KLAX-KDAG AND KSMX-KBFL MAY
PERMIT FOR POSSIBLE ADVISORY LEVEL WINDS OUT IN THE ANTELOPE
VALLEY THROUGH THE SOLEDAD CANYON FROM SATURDAY THROUGH AT LEAST
SUNDAY. BREEZY CONDITIONS WILL ALSO BE PREVALENT ACROSS THE
INTERIOR VALLEYS INCLUDING AREAS SUCH AS PASO ROBLES AND THE
CARRIZO PLAIN.

.LONG TERM (MEMORIAL DAY-THURSDAY)...

ANOTHER COLD FRONT APPROACHING THE REGION WILL STRENGTHEN ONSHORE
SURFACE PRESSURE GRADIENTS ON MEMORIAL DAY. GALE FORCE WINDS
DEVELOPING ACROSS THE COASTAL WATERS WILL LIKELY SPILL OVER INTO
THE COASTAL SECTIONS. GUSTY WINDS COULD DEVELOP FOR MOST AREAS NORTH
OF POINT CONCEPTION...THROUGH THE SOLEDAD PASS AND INTO THE
ANTELOPE VALLEY...AND ALLOW FOR A STRONGER SUNDOWNER WIND EVENT
ON MONDAY AFTERNOON AND NIGHT. ELSEWHERE...VERY LITTLE
CLEARING...IF ANY...WILL OCCUR ON MEMORIAL DAY WITH VALLEY AREAS
LIKELY STRUGGLING TO CLEAR AS A DEEP MARINE LAYER AND STRONG
ONSHORE FLOW KEEPING A PERSISTENT MARINE INFLUENCE AND STRATUS
DECK IN PLACE.

POPS HAVE BEEN INCREASED SLIGHTLY AS THE FRONT ROLLS THROUGH
BETWEEN MONDAY NIGHT AND TUESDAY NIGHT. DUE TO THE NORTHWEST LOW-
LEVEL FLOW...THE BEST CHANCE FOR ANY RAINFALL WILL OCCUR FOR AREAS
NORTH OF POINT CONCEPTION AND ALONG THE NORTHERN SLOPES OF THE
MOUNTAINS. WITH MIXING RATIO NEAR 8 G/KG WITH THE FRONT...ENOUGH
MOISTURE IS PRESENT TO POSSIBLY ALLOW FOR SOME SHOWERS SOUTH OF
POINT CONCEPTION. SHOWERS OR MEASURABLE DRIZZLE FROM THE NIGHT
THROUGH MORNING MARINE LAYER STRATUS DECK ARE PLAUSIBLE WITH THE
PATTERN.

A WARMING TREND SHOULD OCCUR FOR THE LATTER HALF OF NEXT WEEK AS
HIGH PRESSURE ALOFT BUILDS INTO THE WEST COAST. SUNDOWNER WINDS AND
NORTHERLY WINDS THROUGH THE INTERSTATE 5 CORRIDOR ARE STILL
POSSIBLE INTO THURSDAY OR FRIDAY AS THE NORTHERLY SURFACE GRADIENT
REMAINS IN PLACE.

&&

.AVIATION...24/1200Z.

N OF POINT CONCEPTION...HIGH CONFIDENCE FOR VFR CONDS OVER THE NEXT
24 HOURS. 30 PERCENT CHANCE FOR MVFR CIGS AROUND KSMX BETWEEN
06Z-12Z LATER THIS EVENING.

S OF POINT CONCEPTION...MODERATE CONFIDENCE WITH 12Z TAFS. LOW
CLOUDS MVFR WILL FINALLY FILL IN ACROSS MUCH LA COUNTY COAST AND
VALLEYS BY 12Z. BURNOFF TIMES SHOULD BE A BIT SOONER THAN PREVIOUS
FEW DAYS...ESPECIALLY ACROSS THE LA COUNTY VALLEYS. 30 PERCENT CHANCE
THAT MVFR CIGS WILL DEVELOP A FEW HOURS AHEAD OF PREDICTED RETURN OF
LOW CLOUDS.


KLAX...HIGH CONFIDENCE FOR MVFR CIGS TO DEVELOP BETWEEN 12Z AND 14Z.
LOWER CONFIDENCE WITH STRATUS BURNOFF TIMING. +/- 2 HOURS FROM 12Z
TAF. MODERATE CONFIDENCE FOR MVFR CIGS TO RETURN AROUND 04Z THIS
EVENING. WITH THE POSSIBLY OF A DELAY A FEW HOURS.

KBUR...HIGH CONFIDENCE THAT MVFR CIGS WILL PERSIST THROUGH 18Z...BUT
COULD SEE STRATUS BURN OFF +/- AN HOUR EARLY OR LATE. LOW CLOUDS
WILL RETURN LATER TONIGHT...BUT TIMING COULD BE OFF A COUPLE OF
HOURS.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&

$$

PUBLIC...HALL
AVIATION...KAPLAN
SYNIOPSIS...HALL

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