164 
FXUS66 KLOX 100306
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
800 PM PDT SAT JUN 9 2012

.SYNOPSIS...
OFFSHORE WINDS WILL DEVELOP ACROSS INTERIOR SECTIONS OVERNIGHT INTO
SUNDAY MORNING BRINGING A WARMING AND DRYING TREND TO THE REGION.
CONTINUED WARM TEMPERATURES ACROSS INLAND AREAS THROUGH MID WEEK...WITH
TUESDAY THE WARMEST DAY. THE LATTER PART OF THE WEEK WILL HAVE A 
COOLING TREND WITH THE OVERNIGHT MARINE LAYER CLOUDS REACHING INTO THE 
VALLEYS.

&&

.SHORT TERM (TONIGHT-TUESDAY)...
UPPER LEVEL TROUGH MOVING EASTWARD INTO GREAT BASIN TONIGHT WILL
GENERATE BUILDING HIGH PRESSURE AT THE SURFACE ACROSS THE INTERIOR
DESERTS. AS THIS OCCURS...THERE WILL BE A RAPID OFFSHORE TREND
IN THE PRESSURE GRADIENTS OVERNIGHT. CURRENTLY...THE LAX-DAG GRADIENT
IS STRONGLY ONSHORE AT +7.9 MB BUT IS EXPECTED TO BE NEAR 0 OR SLIGHTLY
NEGATIVE BY SUNDAY MORNING. WHILE THE ACTUAL LAX-DAG PRESSURE GRADIENT
WILL NOT BE ALL THAT IMPRESSIVE...THE RAPID OFFSHORE TREND AND UPPER
LEVEL WIND SUPPORT WILL BE. IN FACT...LATEST 00Z NAM MODEL INDICATES
A LARGE AREA OF 40 TO 50 KNOT WINDS AT 850 MB LEVEL BETWEEN 09Z-15Z 
EARLY SUNDAY MORNING. EVEN IF THE NAM IS SLIGHTLY OVERDOING WITH 
THESE UPPER LEVEL WINDS...WE SHOULD EASILY SEE A GOOD BURST OF 
OFFSHORE WINDS IN THE MOUNTAINS DURING THIS TIME FRAME...WITH GUSTS 
GENERALLY IN THE 40 TO 50 MPH RANGE. WIND GUSTS TO AROUND 35 MPH CAN 
BE EXPECTED ACROSS THE SANTA CLARITA VALLEY. CURRENT WIND ADVISORIES 
FOR THESE AREAS LOOK GOOD. LATEST ACARS SOUNDING SHOWING MARINE 
LAYER DEPTH AROUND 1700 FEET ACROSS THE LA BASIN. WHILE THE MARINE 
LAYER DEPTH IS EXPECTED TO DECREASE SOMEWHAT OVERNIGHT INTO SUNDAY 
MORNING...APPEARS THAT GUSTY OFFSHORE WINDS OF ANY CONSEQUENCE WILL 
MAINLY BE CONFINED TO THE HIGHER VALLEY AND FOOTHILL AREAS...WITH 
LIGHTER BREEZES EVENTUALLY MAKING ITS WAY DOWN TO THE SAN FERNANDO 
VALLEY AND VENTURA COASTAL VALLEYS EARLY SUNDAY MORNING. 

PLEASE REFER TO FIRE SECTION BELOW FOR MORE DETAILS ON UPCOMING
FIRE WEATHER THREAT.

LOW CLOUDS AND FOG STILL EXPECTED TO MOVE INTO PORTIONS OF LOS
ANGELES AND VENTURA COUNTIES THIS EVENING...AS WELL AS THE SBA
CENTRAL COAST. HOWEVER...WITH INCREASING OFFSHORE INFLUENCE...SHOULD 
SEE MARINE LAYER DEPTH DECREASE LATER TONIGHT WITH LOW CLOUDS AND 
FOG GRADUALLY SCOURED OUT THROUGH THE EARLY MORNING HOURS. WARMING 
TREND ON TAP FOR MUCH OF THE REGION...WITH BIGGEST WARMING TRENDS 
EXPECTED FOR INTERIOR SECTIONS...WHERE SOME OF THE WARMEST VALLEYS 
WILL CLIMB OVER 90 DEGREES. 

*** FROM PREVIOUS DISCUSSION ***

GENERALLY TROUGHY ALOFT MONDAY AND TUESDAY...BUT WEAKER EACH 
DAY...WHICH WILL ALLOW THE AIR MASS TO WARM. MOUNTAINS AND INTERIOR 
VALLEYS WILL LIKELY RESPOND WITH WARMER TEMPERATURES...BUT COASTAL 
SECTIONS WILL REMAIN AT THE MERCY OF THE MARINE LAYER. WITH ONSHORE 
GRADIENTS INCREASING EACH DAY...THE MARINE LAYER WILL BE HERE TO 
STAY...AND IMAGINING THE LOW CLOUDS AND FOG WILL PENETRATE A LITTLE 
DEEPER INLAND EACH DAY. BREEZY ONSHORE WINDS LOOK TO RETURN TO THE 
MOUNTAINS AND DESERTS AS WELL.

.LONG TERM (WEDNESDAY-SATURDAY)...
TROUGHY PATTERN WILL CONTINUE THROUGH THE WEEK...BUT STARTING 
WEDNESDAY...THE TROUGH WILL DEEPEN THANKS TO A MORE POTENT LOW 
PRESSURE SYSTEM THAT WILL PUSH INTO THE PACIFIC NORTHWEST. THIS WILL 
BRING A GENERAL COOLING TREND...AND AN EXPANSION OF THE MARINE LAYER 
AND STRATUS. THIS SHOULD BRING MORE TYPICAL JUNE-LIKE CONDITIONS BY 
THURSDAY...WITH NEAR NORMAL TEMPERATURES...BREEZY ONSHORE 
WINDS...AND GLOOMY MORNINGS.


&&

.FIRE...
THE OFFSHORE WINDS WILL BRING HEIGHTENED FIRE WEATHER CONCERNS TO 
INTERIOR SECTIONS OF SOUTHWEST CALIFORNIA. THE GREATEST THREAT WILL 
OCCUR IN THE MOUNTAINS OF LOS ANGELES AND VENTURA COUNTIES AS WELL 
AS THE SANTA CLARITA VALLEY. THE ABOVE MENTIONED WINDS COMBINED WITH 
HUMIDITIES FALLING INTO SINGLE DIGITS BRING A SHORT PERIOD OF 
CRITICAL FIRE WEATHER CONDITIONS LATE TONIGHT THROUGH SUNDAY MORNING
TO THESE LOCATIONS. PER COORDINATION WITH LOCAL AGENCIES...A RED
FLAG WARNING WAS NOT ISSUED FOR THIS EVENT SINCE THE EXPECTED 
DURATION OF CRITICAL RED FLAG CONDITIONS WAS NOT SUFFICIENTLY LONG.

&&

.AVIATION...08/2340Z.
LOW CLOUDS LINGERING ACROSS IMMEDIATE COASTAL AREAS OF LA AND VENTURA
COUNTIES LATE THIS AFTERNOON. WITH STRONG ONSHORE FLOW IN PLACE...LOOKING
FOR EARLY RETURN OF MVFR CIGS ACROSS COASTAL AREAS THIS EVENING...SPREADING
LOCALLY INTO THE VALLEYS. DURING THE OVERNIGHT HOURS...PRESSURE GRADIENTS
EXPECTED TO TREND SHARPLY OFFSHORE WHICH WILL LIKELY RESULT IN MARINE
LAYER BECOMING MORE SHALLOW WITH TIME. THIS TREND SHOULD ALSO ALLOW
FOR AN EARLIER BURNOFF TIME OF LOW CLOUDS SUNDAY MORNING. GUSTY 
OFFSHORE BREEZES EXPECTED TO IMPACT KVNY...KPMD...AND KWJF ON SUNDAY
MORNING WITH A CHANCE OF LLWS CONDITIONS. 


KLAX...WITH LOW CLOUDS LINGERING ACROSS SANTA MONICA BAY EXPECTING
MVFR CIGS TO MOVE IN QUICKLY THIS EVENING AT KLAX. ALSO ANTICIPATING
EARLIER BURNOFF OF LOW CLOUDS SUNDAY MORNING AND COULD END UP BEING
EARLIER THAN PROJECTED 16Z TIME FRAME. 

KBUR...VFR CONDITIONS EXPECTED THROUGH PERIOD. SLIGHT CHANCE OF IFR
CIGS LATER TONIGHT. HOWEVER AT THIS POINT EXPECTING OFFSHORE TRENDS
TO KEEP LOW CLOUDS AND FOG SOUTH AND EAST OF KBUR. 

&&

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

&&

$$

PUBLIC...GOMBERG/KITTELL
AVIATION...GOMBERG
SYNOPSIS...SETO

WWW.WEATHER.GOV/LOSANGELES