FXUS66 KLOX 031145 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
345 AM PST THU DEC 3 2009

...UPDATED AVIATION SECTION...

.SYNOPSIS...

LOW CLOUDS WILL COVER THE COASTS AND SOME OF THE VALLEYS THIS 
MORNING THEN SUNNY AND COOL. WEAK OFFSHORE FLOW WILL DEVELOP 
FRIDAY...WARMING TEMPERATURES AND CLEARING OUT THE MARINE LAYER. A 
LOW PRESSURE SYSTEM WILL MOVE INTO THE AREA MONDAY...WITH RAIN 
BECOMING LIKELY.

&&

.SHORT TERM (TODAY-SAT)...
MARINE LAYER AT 3200 FEET TOPPED BY A WEAK INVERSION. GRADIENTS ARE 
OFFSHORE FROM KBFL AND TRENDING OFFSHORE FROM KDAG. ALL OF THIS HAS 
MADE THE MARINE CLOUDS VERY RELUCTANT TO FORM. THE CLOUDS SHOULD 
COVER THE COASTS BY SUNRISE AND SOME PATCHY LOW CLOUDS SHOULD OOZE 
INTO THE VALLEYS WITH THE HGT OF THE MARINE LAYER JUST WINNING OUT 
OVER THE OFFSHORE FLOW. NORTH OF POINT CONCEPTION A 1200 FOOT MARINE 
LAYER BLANKETS THE CENTRAL COAST AND THE SANTA YNEZ VALLEY. A NICE 
SURGE OF CLOUDS FROM THE SALINAS VALLEY HAS ALSO COVERED A LARGE 
PORTION OF THE INTERIOR OF SLO COUNTY WITH LOW CLOUDS AND PATCHY 
DENSE FOG. THE OFFSHORE FLOW WILL ALLOW FOR GOOD CLEAR AND BY 
AFTERNOON EVERYTHING SHOULD BE SUNNY. STILL NOT VERY WARM WITH THKNS 
NR 556 DM.

THE OFFSHORE FLOW WILL PEAK TONIGHT AND FRIDAY MORNING. NOT MUCH OF 
ANY UPPER OR THERMAL SUPPORT AND EXPECT THERE TO BE SOME 15 TO 25 
MPH CANYON WINDS WITH SOME HIGHER GUSTS. WINDS AND GUSTS WILL BE A 
LITTLE STRONGER IN THE MOUNTAINS AS USUAL. THE OFFSHORE FLOW WILL 
CHASE THE LOW CLOUDS AWAY AND SKIES WILL BE MOSTLY CLEAR. THE 
OFFSHORE FLOW AND A SLIGHT INCREASE IN HGTS WILL ALLOW FOR A SLIGHT 
WARM UP WEST OF THE MTNS WITH THE COASTS AND LOWER VLYS OF VTA AND 
LA COUNTY LIKELY HITTING THE LOWER 70S. THE MTNS AND DESERTS WILL 
LIKELY COOL A FEW DEGREES WITH SOME COLD AIR MOVING IN FROM THE EAST.

SATURDAY IS THE BIG TRANSITION DAY AS THE RIDGE COLLAPSES AND IS 
REPLACED BY DRY NW FLOW. WAY UP IN MONTANA A COLD UPPER LOW TAKES 
SHAPE AND THIS WILL EVENTUALLY AFFECT THE WEATHER HERE. BUT THE 
WEATHER HERE ON SATURDAY WILL BE PLEASANT WITH SOME MID OR HIGH 
LEVEL CLOUDS CREATING PARTLY CLOUDY SKIES...COOLER TEMPS THAN FRIDAY 
WITH LOW LEVEL FLOW NO ONSHORE AND LOWER HGTS ABOVE.

.LONG TERM (SUN-WED)...
GFS AND EC DO NOT AGREE ON THE LONG TERM FORECAST. THE GFS GIVES A 
NEW SOLUTION WITH EVERY RUN AS DOES THE GEM MDL. THE EC HAS BEEN 
THE MOST CONSISTENT MDL AND LONG TERM FCST IS BASED MOSTLY ON IT.

SATURDAY NIGHT THE UPPER LOW OVER MONTANA MOVES TO THE SOUTH AND 
WEST...THOUGH TO WHAT DEGREE DEPENDS ON WHAT MDL YOU ARE LOOKING AT. 
HGTS LOWER AND CYCLONIC FLOW OVER SO CAL INCREASES AND THIS SHOULD 
CREATE QUITE A LARGE AND DEEP MARINE LAYER COVERING ALL THE COASTS 
AND VLYS. THESE CLOUDS SHOULD SLOWLY DISSIPATE BY NOON LEAVING THE 
SKIES PARTLY CLOUDY WITH SOME MID AND HIGH LEVEL CLOUDS.

SUNDAY NIGHT THE EC MOVES THE UPPER LOW OUT INTO THE PACIFIC AND 
FLATTENS THE FLOW OVER SO CAL. THIS SOLUTION WOULD BRING IN SOME 
LIGHT RAIN TO THE AREA AND A CHC OF RAIN SEEMS LIKE A GOOD WAY TO 
GO. THE EC...GFS AND GEM ALL BRING RAIN TO THE AREA MONDAY ALTHOUGH 
THE 06Z GFS JUST CAME IN WITH A MUCH DRIER SOLN WITH THE BULK OF THE 
ENERGY STAYING INLAND. THE EC REMAINS VERY WET WITH A NICE MOIST 
PACIFIC FETCH. LIKELY POPS STILL LOOK GOOD BUT FORECASTING RAINFALL 
AMOUNTS IS NOT POSSIBLE AT THIS TIME.

THE REST OF EXTENDED DEPENDS SOLELY ON WHAT MDL ONE PICKS WITH THE 
EC CONTINUING ITS NON STOP RAIN EXPRESS AND BOTH THE CURRENT GEM AND 
GFS MDLS CALLING FOR DRY CONDS TUESDAY THROUGH WEDNESDAY MORNING 
WITH MORE RAIN ARRIVING THU AND FRI. CONTINUED BROAD BRUSHING SLGT 
CHC TO CHC POPS THROUGH THE EXTENDED TO REFLECT THE GREAT 
UNCERTAINTY. IT WILL BE HARD TO PIN THIS FORECAST DOWN UNTIL THE 
UPPER LOW SHOWS ITSELF SATURDAY AND WE CAN BEGIN TO TRACK IT AND 
COMPARE IT TO THE MDL SOLNS.

&&

.AVIATION...03/1145Z.
IFR TO MVFR CONDITIONS WILL PERSIST THROUGH AT LEAST 14Z AT 
KLGB...KSBP...AND KSMX. THERE IS A CHANCE THAT CONDITIONS AT KSBP 
AND KSMX COULD DETERIORATE TO VLIFR TO LIFR THROUGH 15Z. 
OTHERWISE...VFR CONDITIONS WILL BECOME PREDOMINANT AFTER 18Z.

KLAX...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD WITH A 40 
PERCENT CHANCE OF MVFR CONDITIONS BETWEEN 12Z AND 17Z THIS MORNING. 
ANY OFFSHORE WINDS SHOULD REMAIN LESS THAN 10 KNOTS.

KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD WITH LIGHT 
TURBULENCE POSSIBLE AFTER 18Z.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...RORKE
AVIATION...HALL
SYNOPSIS...ASR

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