743 
FXUS66 KLOX 102343
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
440 PM PDT WED APR 10 2013

NEW AVIATION DISCUSSION

.SYNOPSIS...

A COOLING TREND WILL BEGIN THURSDAY AND CONTINUE THROUGH THE WEEKEND 
WITH THE EVENTUAL RETURN OF THE MARINE LAYER. IT WILL BE BREEZY AT 
TIMES...ESPECIALLY FOR THE CENTRAL COAST AND THE ANTELOPE VALLEY.

&&

.SHORT TERM (TODAY-SAT)...OUR OFFSHORE WIND "EVENT" HAS PRETTY MUCH 
COME AND GONE WITH A WHISPER. HAD SOME BRIEF GUSTY WINDS LAST NIGHT 
AND THIS MORNING BUT OUTSIDE OF A FEW ISOLATED SPOTS SPEEDS WERE 
WELL BELOW ADVISORY LEVELS. HOWEVER, EVEN THOUGH WINDS DIDN'T REALLY 
MATERIALIZE WE STILL GOT THE HEATING EFFECTS OF THE OFFSHORE FLOW 
WITH HIGHS JUMPING UP 5-15 DEGREES FROM YESTERDAY'S LEVELS. 

GRADIENTS EXPECTED TO TREND STRONGLY ONSHORE THURSDAY AHEAD OF THE 
NEXT LITTLE TROF ON FRIDAY. IN FACT, WILL HAVE TO MONITOR ANTELOPE 
VALLEY WINDS THURSDAY AFTERNOON AND EVENING AS THEY MAY APPROACH 
ADVISORY LEVEL OUT THERE. THE TURN TO ONSHORE THURSDAY WILL BRING 
COOLING TO ALL LOWER ELEVATION LOCATIONS, ANYWHERE FROM 10-15 
DEGREES FOR THE COAST AND 4-8 DEGREES FOR THE VALLEYS. DON'T THINK 
WE'LL SEE MUCH OF A MARINE LYR TONIGHT BUT BY FRIDAY MORNING AS THE 
TROF GETS CLOSER EXPECT A FAIRLY SUBSTANTIAL DEEPENING OF THE MARINE 
INVERSION WITH CLOUDS SURGING WELL INTO THE VALLEYS OVERNIGHT. THIS 
WILL BRING EVEN MORE COOLING TO THE AREA FRIDAY AND POSSIBLY LIMITED 
COASTAL CLEARING. THIS IS QUITE A CHANGE FROM YESTERDAY'S MODEL 
SOLUTIONS WHICH HAD ADVERTISED A FASTER INLAND PATH FOR THE TROF 
RESULTING IN OFFSHORE FLOW AND WARMER TEMPS FOR FRIDAY. SO TODAY'S 
FORECAST FOR FRIDAY IS A BIG DROPOFF FROM 24 HOURS AGO IN TERMS OF 
TEMPERATURES. 

THE TROF PASSAGE FRIDAY WILL BRING AN INCREASE IN NORTHWEST WINDS 
ACROSS THE AREA, POSSIBLY AS EARLY AS THURSDAY AFTERNOON ACROSS THE 
WESTERN PORTION OF OUR FORECAST AREA. IN FACT, WE MAY SEE ADVISORY 
LEVEL NORTH/NORTHWEST WINDS BLOWING THROUGH THE WESTERN PORTION OF 
THE SANTA YNEZ RANGE AND SRN SBA COUNTY COASTLINE LATE THURSDAY AND 
THURSDAY NIGHT. THE INCREASE IN NORTHWEST WINDS OFFSHORE WILL ALSO 
HELP AN EDDY CIRCULATION DEVELOP ACROSS THE SOUTHERN COASTAL WATERS, 
FURTHER ASSISTING THE DEEPENING TREND IN THE MARINE LYR FRIDAY 
MORNING. 

FAIRLY QUIET DAY SATURDAY. SHOULD SEE SOME LOWERING OF THE MARINE 
LYR DEPTH BEHIND THE TROF AND SOMEWHAT LESS OVERALL COVERAGE. 
COASTAL TEMPS ABOUT THE SAME BUT SLIGHTLY WARMER TEMPS EXPECTED 
INLAND. INCREASING ONSHORE GRADIENTS WILL BRING MORE GUSTY WINDS TO 
THE ANTELOPE VALLEY, POSSIBLY NEAR ADVISORY LEVELS.

.LONG TERM (SUN-WED)...ANOTHER INSIDE SLIDER TROF WILL BEING 
DROPPING INTO CALIFORNIA LATER SUNDAY. AHEAD OF THIS THE MARINE LYR 
WILL DEEPEN AND BECOME MORE WIDESPREAD SUNDAY MORNING. ANOTHER WINDY 
DAY FOR THE ANTELOPE VALLEY WITH LAX-DAG GRADIENT APPROACHING 10MB. 
MARINE LYR MAY BE SLOW TO CLEAR FOR COASTAL AREAS, WITH HIGHS 
EVERYWHERE DROPPING 4-8 DEGREES ON AVERAGE. 

THE EC SHOWS A SLIGHTLY FURTHER SOUTH AND WEST TRACK THAN THE OTHER 
MODELS, BUT STILL TOO FAR INLAND TO BRING ANY PRECIP BEYOND SOME 
MORNING DRIZZLE OR VERY LIGHT RAIN MONDAY MORNING FOR COASTAL LA 
COUNTY. THE PATTERN DOESN'T LOOK TOO DISSIMILAR TO WHAT WE SAW LAST 
MONDAY EXCEPT NOT NEARLY QUITE AS STRONG WITH THE WINDS. A VERY 
STRONG ONSHORE GRADIENT CONTINUES AND I SUSPECT MANY AREAS WILL SEE 
ADVISORY LEVEL WINDS BY MONDAY AFTERNOON. A FAIRLY COOL DAY WITH 
HIGHS MOSTLY IN THE 60S AT LOWER ELEVATIONS.

GRADIENTS RELAX SOMEWHAT TUESDAY INTO WEDNESDAY BUT ONLY A SLOW 
WARMING TREND AS THE TROF IS SLOW TO MOVE INTO THE PLAINS. 

&&

.AVIATION...

10/2340Z

VFR CONDITIONS ARE EXPECTED THROUGHOUT WITH ONLY A 20 PERCENT CHANCE 
OF IFR CIGS AT KLAX...KLGB AND KSMX OVERNIGHT. 

KLAX...VERY GOOD CONFIDENCE IN CAVU TAF WITH JUST A 20 PERCENT 
CHANCE OF IFR CIGS 12Z-16Z.

KLAX AND KBUR...HIGH CONFIDENCE IN CAVU TAF.

&&

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

&&

$$

PUBLIC...MW
AVIATION...ASR
SYNOPSIS...MW

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