Duarte Weather

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FXUS66 KLOX 221131
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
420 AM PDT WED MAY 22 2013

...UPDATED AVIATION DISCUSSION...

.SYNOPSIS...
A COOLING TREND WILL CONTINUE THROUGH THURSDAY...AND THERE WILL BE
PLENTY OF NIGHT THROUGH MORNING LOW CLOUDS AND FOG...ESPECIALLY
ACROSS VENTURA AND LOS ANGELES COUNTIES. THERE MAY BE SOME SLIGHT
WARMING ON FRIDAY...THEN BELOW NORMAL DAYTIME TEMPERATURES ARE
EXPECTED THROUGH THE HOLIDAY WEEKEND WITH NIGHT THROUGH MORNING LOW
CLOUDS AND FOG IN COASTAL AND VALLEY AREAS. WARMING MAY BEGIN ACROSS
THE REGION TUESDAY.

&&

.SHORT TERM (TODAY-FRI)...MARINE LAYER HAS DEEPENED TO AROUND 2500
FEET EARLY THIS MORNING. SOLID EDDY CIRCULATION HAS DEVELOPED
ACROSS THE INNER WATERS. CLOUDS HAVE PUSHED INTO ALL COASTAL AND
VALLEY AREAS OF L.A. COUNTY WITH THE EXCEPTION OF THE SANTA CLARITA
VALLEY...BUT CLOUDS SHOULD REACH THAT AREA BY DAYBREAK. CLOUDS HAVE
OVERSPREAD MOST OF VTU COUNTY...AND MAY EVEN REACH THE EASTERN
PORTION OF THE S COAST OF SBA COUNTY BY MORNING. NORTH OF PT
CONCEPTION...SKIES WERE GENERALLY MOSTLY CLEAR...WITH ONLY SOME
PATCHY LOW CLOUDS ACROSS PORTIONS OF THE SANTA YNEZ VALLEY AND
SOUTHERN SECTIONS OF THE CENTRAL COAST. EXPECT SKIES TO CLEAR IN
MOST AREAS LATER THIS MORNING...BUT CLOUDS WILL LIKELY LINGER AT
SOME BEACHES OF L.A. COUNTY AND POSSIBLY VTU COUNTY INTO OR THROUGH
THE AFTERNOON. THE COOLING TREND WILL CONTINUE...AND MAX TEMPS WILL
DOWN ANOTHER SEVERAL DEGREES TODAY...ESPECIALLY ACROSS THE
INTERIOR.

THE EXCEPTION TO THE COOLING TREND WILL BE ACROSS THE SOUTH COAST OF
SBA COUNTY...WHERE GUSTY NW TO N WINDS THIS AFTERNOON WILL WARM AS
THEY DESCEND FROM THE SANTA YNEZ MOUNTAINS. EXPECT TEMPS TO RISE
INTO AT LEAST THE LOWER 80S ACROSS PORTIONS OF THE S COAST OF SBA
COUNTY LATE THIS AFTERNOON OR THIS EVENING AS THE NLY WINDS DEVELOP.

AN UPPER LOW WAS LOCATED ACROSS THE PAC NW THIS MORNING...WITH A
TROUGH EXTENDING SOUTHWARD INTO CA. A VORT LOBE WILL MOVE ACROSS THE
AREA THIS AFTERNOON AND EVENING. BEHIND IT...DECENT SUBSIDENCE WILL
OVERSPREAD THE AREA. AT THE SAME TIME N-S GRADIENTS WILL STRENGTHEN
AND NW TO N WINDS WILL INCREASE THROUGH THE ATMOSPHERE. THIS SHOULD
HELP TO PRODUCE HEALTHY SUNDOWNER WINDS THRU AND BELOW PASSES AND
CANYONS OF SRN SBA COUNTY. WINDS SHOULD FIRST DEVELOP THROUGH THE
GAVIOTA PASS THIS AFTERNOON...THEN ACROSS THE REMAINDER OF THAT AREA
THIS EVENING AS THE LOW LVL FLOW TURNS FROM WEST-NORTHWEST TO A MORE
NORTHERLY DIRECTION. GUSTY WINDS WILL ALSO AFFECT THE CENTRAL COAST
THIS AFTERNOON AND EVENING...AND THE ANTELOPE VALLEY AND MOUNTAINS
OF LOS ANGELES AND VENTURA COUNTIES THIS AFTERNOON THROUGH LATE
TONIGHT. WIND ADVISORIES HAVE BEEN ISSUED FOR THESE AREAS. PLEASE
ALSO SEE FIRE DISCUSSION BELOW FOR MORE DETAILS ON THE ELEVATED FIRE
DANGER.

THE TROUGH ACROSS CA WILL SHARPEN UP A BIT TONIGHT/THU. INCREASINGLY
CYCLONIC FLOW THROUGH THE ATMOSPHERE MAY PRODUCE ENOUGH LIFT FOR
SOME DRIZZLE LATE TONIGHT/THU...MAINLY IN COASTAL AND VALLEY
SECTIONS OF L.A. AND VTU COUNTIES. HOWEVER...THE LATEST RUN OF THE
WRF MODEL ACTUALLY SHOWS THE NLY WINDS SPREADING INTO THE SANTA
CLARITA VALLEY...AND SUGGESTS MUCH LESS INLAND EXTENT OF THE LOW
CLOUDS TONIGHT/THU MORNING...KEEPING CLOUDS MAINLY IN COASTAL AND
LOWER VALLEY LOCATIONS OF L.A. AND VTU COUNTIES...WITH PATCHY LOW
CLOUDS ON THE CENTRAL COAST. CLOUDS COULD AGAIN LINGER NEAR THE
BEACHES THU AFTERNOON...MAINLY ACROSS L.A. COUNTY. 950 MB TEMPS
SUPPORT A BIT OF ADDITIONAL COOLING IN MOST AREA THU. N-S GRADIENTS
WILL REMAIN RATHER STRONG...AND EXPECT ANOTHER ROUND OF GUSTY
WINDS...POSSIBLY TO ADVISORY LEVELS IN THE SAME AREAS THAT WILL BE
WINDY TODAY.

THE UPPER LOW OVER THE PAC NW LIFTS INTO CANADA THU NIGHT AND
FRI...AND HEIGHTS ACROSS THE FCST AREA WILL BEGIN TO RISE. THIS MAY
ALLOW FOR SOME DECREASE IN MARINE LAYER DEPTH AND A REDUCTION IN
NIGHT THRU MORNING LOW CLOUDS AND FOG W OF THE MTNS. IT SHOULD ALSO
ALLOW FOR A FEW DEGREES OF WARMING ON FRI.

.LONG TERM (SAT-TUE)...ANOTHER UPPER LOW DROPS INTO THE PAC NW FRI
NIGHT AND SAT WITH RENEWED TROFFING ACROSS THE FCST AREA. WITH
DECREASING NW FLOW...EXPECT NIGHT THRU MORNING LOW CLOUDS/FOG TO
BECOME WIDESPREAD IN ALL COASTAL AND MOST VALLEY AREAS. THIS PATTERN
SHOULD CONTINUE THROUGH MONDAY...WITH LOCAL LATE NIGHT AND MORNING
DRIZZLE...AND POTENTIAL SLOW CLEARING NEAR THE BEACHES EACH DAY.
MAX TEMPS WILL LIKELY BE AT LEAST A FEW DEGREES BELOW NORMAL SAT
THRU MON. THE UPPER LOW AND ITS ASSOCD TROUGH WILL MOVE E LATE MON
AND TUE. HEIGHTS/THICKNESS WILL RISE ON TUE...AND SOME WARMING
SHOULD BEGIN.

&&

.FIRE WEATHER...
AS WINDS RAMP UP THIS AFTERNOON AND EVENING ACROSS THE SBA
SOUTH COAST AND MOUNTAINS...I-5 CORRIDOR OF THE LA/VTU COUNTY
MOUNTAINS...AND ANTELOPE VALLEY...THERE WILL BE ELEVATED FIRE DANGER
ACROSS ALL OF THESE AREAS. HUMDITIY LEVELS COULD BRIEFLY FALL BELOW
15 PERCENT ACROSS THE SBA SOUTH COAST ON THIS AFTERNOON.
SIMILAR LOW HUMIDITIES WILL LIKELY IMPACT THE I-5 CORRIDOR AND
ANTELOPE VALLEY DURING THE LATE AFTERNOON AND EVENING HOURS. AS A
RESULT...ALL OF THESE AREAS COULD EXPERIENCE BRIEF CRITICAL FIRE
WEATHER CONDITIONS...ESPECIALLY CONSIDERING THE VERY DRY FUELS FOR
THIS TIME OF YEAR. HOWEVER...IT DOES NOT APPEAR THAT DURATIONS OF
CRITICAL FIRE WEATHER CONDITIONS WILL BE MET TO ISSUE RED FLAG
WARNINGS FOR THIS EVENT.

&&

.AVIATION...22/1120Z...

OVERALL...MODERATE CONFIDENCE IN 12Z TAF PACKAGE. LATEST SATELLITE
SHOWS STRATUS SURGING ACROSS VENTURA/LA COUNTIES...WITH JUST SOME
PATCHY STRATUS ACROSS THE CENTRAL COAST. EXPECT MVFR CIGS ACROSS
VENTURA/LA COASTAL AND VALLEY TAFS THROUGH THE MORNING...WITH SOME
IFR/MVFR CIGS AT KSMX. THE STRATUS SHOULD BURN OFF DECENTLY BY EARLY
THIS AFTERNOON. FOR TONIGHT...EXPECT STRATUS TO RETURN TO THE SAME
SITES AS THIS MORNING WITH SIMILAR MVFR/IFR CIGS.

AS FOR WINDS...THERE WILL BE SOME GUSTY WEST TO NORTHWEST WINDS
ACROSS THE CENTRAL COAST...MOUNTAINS AND ANTELOPE VALLEY THIS
AFTERNOON AND TONIGHT. THE NORTHERLY WINDS WILL BE STRONG ENOUGH
ACROSS SOUTHERN SBA COUNTY TO PRODUCE SOME LLWS/TURBULENCE AT KSBA
THIS EVENING AND OVERNIGHT.

KLAX...MODERATE CONFIDENCE IN 12Z TAF. STRATUS CLEARING TODAY MAY
BE +/- 1-2 HOURS FROM CURRENT 19Z FORECAST.

KBUR...MODERATE CONFIDENCE IN 12Z TAF. STRATUS CLEARING TODAY MAY
BE +/- 1-2 HOURS OF CURRENT 18Z FORECAST.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
GALE WARNING (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).

&&

$$

PUBLIC...DB
AVIATION...RAT
FIRE...DG

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