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FXUS66 KLOX 210530
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1020 PM PDT SAT SEP 20 2008

UPDATED AVIATION DISCUSSION

.SHORT TERM (TODAY-TUESDAY)...
AS EXPECTED...TEMPS WERE COOLER JUST ABOUT EVERYWHERE TODAY AS 950
MB TEMPS COOLED NEARLY 5 DEGREES FRIDAY NIGHT INTO TODAY. SOME
LINGERING HIGHER RH VALUES ACROSS THE SAN JOAQUIN VALLEY AND DECENT
NRN GRADIENTS WILL HELP TO PUSH SOME CLOUDS INTO THE NRN SLOPES OF
SBA/VTU AND WESTERN LA COUNTY MTNS OVERNIGHT. THERE COULD BE SOME
LOCALLY DENSE FOG POSSIBLE ACROSS THE GRAPEVINE AFTER MIDNIGHT.
ALSO...EXPECT SOME LOCALLY GUSTY WINDS ACROSS THE I-5 CORRIDOR WITH
NORTHWEST TO NORTH WINDS 20 TO 30 MPH WITH GUSTS TO 40 MPH POSSIBLE
OVERNIGHT. THE SANTA BARBARA COUNTY MTNS AND ADJACENT SOUTH COAST
WILL EXPERIENCE GUSTY NORTHWEST TO NORTH WINDS THIS
EVENING...SHIFTING TO THE NORTHEAST LATER THIS EVENING. THIS WILL
CONTINUE TO AFFECT THE PASSES AND CANYONS NEAR GAVIOTA AND LAS
FLORES CANYON WITH GUSTS TO 40 MPH...THEN SHIFT THE FOCUS ON THE
FOOTHILLS ABOVE MONTECITO LATER TONIGHT. PORTIONS OF THE ANTELOPE
VALLEY WILL CONTINUE SW TO W WINDS 20 TO 30 MPH WITH LOCAL GUSTS TO
45 MPH...MAINLY NEAR THE SOLEDAD CYN PASS AND LAKE PALMDALE THIS
EVENING.

NOT MUCH CHANGE IN THE UPPER PATTERN AS BROAD NW FLOW WILL PERSIST
THROUGH SUNDAY. HOWEVER...A FAIRLY SIGNIFICANT EDDY BEGINS TO
DEVELOP OVERNIGHT AS MODERATE NW FLOW ACROSS THE OUTER WATERS
PERSISTS. LOW CLOUDS SHOULD BE BETTER ORGANIZED TO AFFECT THE LA
COUNTY COASTAL AREAS...POSSIBLY MAKING INTO VTU COUNTY COASTAL AREAS
LATE. LATEST SATELLITE IMAGERY DOES SHOW A MORE ORGANIZED AREA OF
STRATUS MOVING UP INTO ORANGE COUNTY AND SHOULD REACH" onClick="return popup(this, 'notes')">REACH LA COUNTY BY
MIDNIGHT. PRETTY GOOD CONFIDENCE THAT LOW CLOUDS SHOULD STAY OUT OF
SBA COUNTY SOUTH COAST DUE TO THE NORTHERLY GRADS THIS EVENING.
LATEST AMDAR SOUNDING NEAR KLAX SHOWS MARINE LAYER NEAR 1500
FT...BUT INVERSION REMAINS QUITE WEAK DUE TO COOLER AIR ADVECTION
EARLIER. THE CENTRAL COAST SHOULD SEE SOME PATCHY LOW CLOUDS
DEVELOP...ESPECIALLY BETWEEN LOMPOC AND SANTA MARIA...BUT NOT QUITE
AS ORGANIZED AS TO THE SOUTH AS SATELLITE IMAGERY INDICATES.

TEMPS SHOULD A BIT WARMER THEN WHAT MOS GUIDANCE WAS ADVERTISING N
OF POINT CONCEPTION DUE TO WEAK OFFSHORE FLOW FORECAST IN THE
MORNING. NOT MUCH CHANGE EXPECTED FOR THE COASTAL AREAS OF LA/VTU
COUNTIES...BUT TEMPS SHOULD REBOUND A COUPLE OF DEGREES ACROSS
INLAND AREAS.

HIGH PRESSURE ALOFT WILL BEGIN TO BUILD IN FROM THE SOUTH SLOWLY ON
MONDAY...AND STRENGTHEN TO A 590 DM HIGH BY EARLY TUE.
THEREFORE...TEMPS WILL BEGIN TO WARM UP BOTH DAYS...ESPECIALLY TUE.
SFC GRADS WHICH LOOKED TO BE LIGHTLY TO MODERATE OFFSHORE A FEW DAYS
AGO...NOW LOOKS MORE WEAKLY NEUTRAL. NEVERTHELESS...THIS SHOULD HELP
TEMPS TO WARM UP INTO THE LOWER 90S ACROSS THE WARMEST INTERIOR
LOCATIONS OF THE FORECAST AREA.

...FROM PREVIOUS DISCUSSION...

.LONG TERM (WEDNESDAY-SATURDAY)...
WITH ONSHORE GRADS WEAKENING AND THE RIDGE CONTINUING ITS BUILD UP
FROM THE SOUTH...WED AND THU LOOKS TO REMAIN WARM...WITH ONE OF
THOSE DAYS BEING THE WARMEST OF THE WEEK. THE HIGH AND WEAK ONSHORE
GRADS SHOULD KEEP THE MARINE LAYER CONFINED TO THE IMMEDIATE COAST
AT BEST...WHICH FURTHER HINTS AT A WARM MIDWEEK. THERE IS A WILDCARD
IN A WEAK CUTOFF LOW TO THE WEST. THIS PATTERN WILL CREATE AN
EAST-WEST TEMP GRAD THAT MODELS CURRENTLY HAVE US SITTING IN THE
WARM SECTOR WED AND THU...BUT THIS PATTERN COULD SHIFT AND TEMPS
COULD BE A BIT COOLER. NOT ONLY THAT...BUT A WHEN QUESTION EXISTS AS
WELL...AS TO WHEN WILL THINGS FINALLY SHIFT TO THE EAST. CURRENTLY
THE GFS AND ECMWF ARE BEHAVING NICELY...WITH A TROUGH DIGGING INTO
THE LOW TO THE WEST AND PUSHING EVERYTHING EASTWARD ON FRI AND SAT.
THIS IS REFLECTED IN THE FORECAST WITH SOME COOLING...BUT CONFIDENCE
IS LOW THIS FAR OUT.

&&

.AVIATION...

21/0530Z.

MARINE LAYER ABOUT 1400 DEEP AND CAPPED BY A VERY WEAK INVERSION. A
WEAK EDDY WILL SPIN UP TONIGHT AND CIGS WILL LIKELY FORM FROM KLGB
TO KOXR AND CANNOT RULE OUT GETTING INTO KSBA (IN FACT THIS COULD BE
ONE OF THOSE TIMES WHERE KSBA GETS THE CIGS AFTER SUNRISE. CLOUDS
WILL BE MORE PATCHY IN THE VLYS. DUE TO WEAK INVERSION BURN OFF
SHOULD OCCUR NEAR MID MORNING.

KLAX...GOOD CONFIDENCE IN TAF CIGS WILL LIKELY ARRIVE WITH IN ONE
HOUR OF FCST TIME AND BURN OFF TIME IS ALSO LIKELY WITH THE SAME ONE
HOUR BLOCK.

KBUR...ONLY FAIR CONFIDENCE IN TAF. THERE IS A 40 PERCENT CHANCE OF
IFR CIGS AFTER 11Z. IF CIGS DO FORM THEY SHOULD DISSIPATE BY 16Z.

&&

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

&&

$$

PUBLIC...KAPLAN/KITTELL
AVIATION...ASR

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