000
FXUS66 KLOX 200544 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1045 PM PDT FRI SEP 19 2008

.SHORT TERM (TODAY-MON)...
TEMPERATURES COOLED DOWN RATHER SIGNIFICANTLY ACROSS PORTIONS OF THE
SLO INTERIOR VALLEYS WHERE PASO ROBLES ONLY REACHED 76 DEGREES
TODAY. MOST OTHER INTERIOR LOCATIONS WERE DOWN BETWEEN 3-5 DEGREES
AS BOUNDARY LAYER TEMPS COOLED A BIT AND THICKNESS LVLS DROPPED IN
THE WAKE OF A WEAK FRONTAL BOUNDARY THAT MOVED INLAND OVERNIGHT.
MOST LA/VTU SBA COUNTY VALLEYS REMAINED IN THE 80S. WHILE LOW CLOUDS
WERE ABSENT OVERNIGHT AND THIS MORNING...DOWNTOWN WAS ABLE WARM UP
AS HIGH AS PALMDALE TO 86 DEGREES.

CURRENTLY...SKIES ARE MOSTLY CLEAR SOUTH OF POINT CONCEPTION...WHILE
A BAND OF CLOUDS ASSOCIATED WITH A WEAK TROF WITH CIGS OF NEAR 5000
FT IS BEGINNING TO SURGE INTO THE CENTRAL COAST THIS EVENING. HARD
TO TELL THE EXTENT OF CLOUD COVERAGE OVERNIGHT...BUT MODELS SUGGEST
THAT CLOUDS SHOULD MOVE INTO THE SALINAS RIVER VALLEY OVERNIGHT. NOT
ANTICIPATING ANY FOG DUE TO HIGH CLOUD BASES. LATEST AMDAR SOUNDING
NEAR KLAX INDICATED MARINE LAYER NEAR 800 FT...BUT WITH APPROACHING
WEAK TROF...MARINE LAYER SHOULD DEEPEN WHILE INVERSION WEAKENS
OVERNIGHT. NAM-WRF IS ADVERTISING EDDY CIRCULATION TO HELP SPIN UP
SOME STRATUS ACROSS LA/VTU COUNTY COASTAL AREAS OVERNIGHT. FEEL THAT
THERE WILL BE SOME PATCHY LOW CLOUDS ACROSS LA COUNTY AFTER
MIDNIGHT...AND POSSIBLY VTU COUNTIES. WITH INVERSION WEAKENING...LOW
CLOUDS COULD POP UP RANDOMLY ACROSS PORTIONS OF LA/VTU COUNTY
COASTAL AREAS...BUT SHOULD REMAIN PATCHY IN NATURE. KEPT SKIES CLEAR
FOR SBA SOUTH COAST OVERNIGHT...BUT WITH A FEW BANDS OF CLOUDS NEAR
POINT CONCEPTION...A MINI EDDY COULD DEVELOP BETWEEN SBA AND THE
CHANNEL ISLANDS LATER TONIGHT. HOWEVER...THERE IS A DECENT NORTHERLY
GRADIENT BETWEEN KSBA-KSMX WHICH SHOULD KEEP THE SANTA BARBARA SOUTH
COAST CLEAR.

SATURDAY LOOKS TO BE A FEW DEGREES COOLER...ALTHOUGH 950 MB TEMPS DO
NOT CHANGE MUCH...BUT ONSHORE FLOW INCREASES ACROSS THE REGION.
EXPECT MOST VALLEY LOCATIONS TO BE IN THE MID 80S. WHILE THE COASTAL
AREAS REMAIN FROM THE UPPER 60S AND 70S TO AROUND 80 INLAND AREAS.
A MORE IMPRESSIVE EDDY DEVELOPS ACROSS THE SO CAL BIGHT SAT NIGHT
AND SHOULD REACH" onClick="return popup(this, 'notes')">REACH THE COASTAL VALLEYS KEEPING TEMPS COOLER THAN AVG
ON SUNDAY. THERE CONTINUES TO BE A DECENT NORTHERLY GRADIENT
AFFECTING THE SANTA BARBARA COUNTY MTNS AND SBA SOUTH COAST WHICH
SHOULD BRING ADDITIONAL LOCAL GUSTY NORTHWEST TO NORTH WINDS ACROSS
THE USUAL WINDY PASSES AND CANYONS NEAR GAVIOTA TO MONTECITO. MODELS
ALSO PICK UP SOME LOCAL NORTHERLY WINDS 15 TO 30 MPH ACROSS THE I-5
CORRIDOR LATE SAT NIGHT INTO EARLY SUNDAY MORNING WITH A FEW CLOUDS
POSSIBLE PUSHED UP AGAINST THE NRN SLOPES OF THE VTU/WESTERN LA
COUNTY MTNS EARLY SUNDAY MORNING. THERE COULD BE A FEW DEGREES OF
WARMING ACROSS THE INTERIOR PORTIONS OF THE FORECAST AREA AS WEEK
UPPER RIDGE SLOWLY BUILDS IN FROM THE SOUTHWEST. HOWEVER A CATALINA
EDDY SHOULD PERSIST SUNDAY NIGHT INTO MONDAY CONTINUING TO LEAVE THE
COASTAL AREAS RELATIVELY COOL FOR MONDAY.

...FROM PREVIOUS DISCUSSION...

.LONG TERM (TUE-FRI)...WARMING TREND STILL ON TRACK FOR THE MIDDLE
OF NEXT WEEK. GFS HAS BACKED OFF SLIGHTLY ON THE OFFSHORE FLOW FOR
WED AND THU BUT GRADIENTS SHOULD AT LEAST BE NEAR NEUTRAL IF NOT
SLIGHTLY OFFSHORE. STILL THINK THE GFS IS UNDERDOING THE WARMING AT
950 AS WELL THE MOS GUIDANCE HIGHS. GIVEN THE STRENGTH OF THE UPPER
HIGH AND NEAR NEUTRAL OR SLIGHTLY OFFSHORE SURFACE GRADIENTS, HIGHS
SHOULD BE CLOSE TO 100 IN THE VALLEYS AND CLOSE TO 90 ACROSS THE
INLAND COASTAL PLAIN. FOR THIS REASON CURRENT FORECAST CONTINUES TO
BE WARMER THAN MOS GUIDANCE. WARMING TREND SHOULD END FRI AS ANOTHER
TROF APPROACHES THE COAST AND HIGH PRESSURE MOVES EAST.

&&

.AVIATION...20/0545Z.


KLAX...THERE IS A 70 PERCENT CHANCE OF LOW CLOUDS AND FOG WITH
IFR OR LOW MVFR CIGS AND MVFR VSBYS BETWEEN 11Z AND 17Z.

KBUR...HIGH CONFIDENCE IN CLEAR SKIES THROUGH SATURDAY.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).

&&

$$

PUBLIC...KAPLAN/WOFFORD
AVIATION...SWEET

WWW.WEATHER.GOV/LOSANGELES