FXUS66 KLOX 281206
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
400 AM PST SAT NOV 28 2009

UPDATED AVIATION DISCUSSION

.SYNOPSIS...

A COLD LOW PRESSURE SYSTEM WILL DROP DOWN THROUGH SOUTHERN 
CALIFORNIA TODAY...BRINGING COLDER TEMPERATURES...SCATTERED
SHOWERS AND THUNDERSTORMS WITH LOW ELEVATION SNOW. BEHIND THIS 
SYSTEM...A MODERATE WARMING TREND IS EXPECTED WITH OFFSHORE WINDS 
LASTING INTO MID WEEK.

&&

.SHORT TERM (TODAY-MON)...RATHER DYNAMIC UPPER LOW CONTINUES TO BE
THE MAIN WEATHER STORY TODAY. 00Z MODELS HANDLE THE LOW IN SIMILAR
FASHIONS...ALTHOUGH THE NAM TRACK IS A BIT FURTHER WEST THAN THE
GFS. CURRENTLY THE LOW IS OVER THE SOUTHERN SAN JOAQUIN VALLEY AND
WILL MOVE ON A SOUTHERLY TRACK THROUGH THE DAY. LOTS OF CONVECTIVE
CELLS ON THE RADAR ROTATING AROUND THE UPPER LOW WHICH SHOULD 
CONTINUE TO MOVE INTO OUR AREA THROUGH THE DAY. AT THIS TIME...IT
LOOKS LIKE THE NORTH-FACING SLOPES WILL RECEIVE THE GREATEST AMOUNT
OF PRECIPITATION DUE TO THE NORTH-SOUTH MOVEMENT OF THE CELLS AROUND
THE LOW. HOWEVER...THE ENTIRE AREA WILL BE AT RISK OF RECEIVING 
SCATTERED SHOWERS THROUGH TONIGHT. OVERALL...EXPECT PROBABLY AROUND
ONE HALF INCH OF PRECIPITATION ON NORTH FACING SLOPES...WITH LESS
THAN ONE QUARTER ELSEWHERE ACROSS THE AREA. GIVEN THE AMOUNT OF
INSTABILITY...THUNDERSTORMS WILL ALSO CONTINUE TO BE A THREAT 
THROUGH TONIGHT. IN AREAS THAT EXPERIENCE A THUNDERSTORM...RAINFALL
AMOUNTS COULD BE HIGHER THAN THE PREVIOUSLY MENTIONED ONE HALF INCH.
SNOW LEVELS SHOULD DROP TO AROUND 4000 FEET TONIGHT/SATURDAY MORNING
(AND POSSIBLY LOWER IN HEAVIER SHOWERS AND THUNDERSTORMS). SO...
MOUNTAIN AREAS SHOULD RECEIVE SEVERAL INCHES OF SNOWFALL FROM THIS
STORM. CURRENT WINTER WEATHER ADVISORY FOR THE LAX/VTU MOUNTAINS
LOOKS GOOD AT THIS TIME. ALSO...SOME OF THE HIGHER FOOTHILL AREAS
IN THE ANTELOPE VALLEY COULD SEE SOME SNOWFALL. GIVEN THE VERY 
SCATTERED NATURE OF THE PRECIPITATION...WILL NOT ISSUE ANY FLASH
FLOOD WATCHES FOR THE BURN AREAS (HOWEVER...THE RADAR WILL BE 
MONITORED VERY CLOSELY). AS THE LOW MOVES SOUTH OF THE AREA TONIGHT
THE PRECIP THREAT WILL END FROM THE NORTHWEST TO SOUTHEAST...WITH
DRY CONDITIONS EXPECTED FOR ALL AREAS BY SUNDAY MORNING. 

AS FOR WINDS...THE TRACK OF THIS SYSTEM WILL PRODUCE SOME GUSTY
NORTH WINDS TODAY ACROSS THE MOUNTAINS. CURRENTLY HAVE A WIND 
ADVISORY FOR AREAS IN AND BELOW THE SANTA YNEZ RANGE WHICH LOOK
GOOD AT THIS TIME (WINDS THROUGH THE I-5 CORRIDOR ARE INCORPORATED
INTO THE WINTER WEATHER ADVISORY). AS THE LOW MOVES SOUTHEAST TONIGHT
AND SUNDAY...THE FLOW WILL TURN TO THE NORTHEAST. AT THIS TIME...
A WEAK TO MODERATE COOL SANTA ANA WIND EVENT IS EXPECTED FOR SUNDAY 
AND MONDAY WITH ADVISORY LEVEL WINDS LIKELY FOR SOME AREAS. 

AS FOR TEMPS...TODAY WILL OBVIOUSLY BE A VERY COOL DAY ACROSS THE
AREA. WITH THE DEVELOPING NORTHEAST FLOW ON SUNDAY AND MONDAY...
WILL EXPECT A WARMING TREND...WITH MOST AREAS A FEW DEGREES ABOVE
NORMAL BY MONDAY. 

.LONG TERM (TUE-FRI)...FOR THE EXTENDED...THE 00Z GFS AND ECMWF ARE
NOT ON THE SAME PAGE...SO CONFIDENCE IN THE FORECAST IS RATHER LOW.
ON TUESDAY...BOTH MODELS INDICATE AN UPPER LOW APPROACHING THE 
EASTERN PACIFIC...THEN MOVING SOUTHEAST ON WEDNESDAY AND THURSDAY.
THE GFS IS MUCH FURTHER SOUTH WITH THE TRACK OF THE SYSTEM ( AND 
IT'S ASSOCIATED PRECIP)...KEEPING THE LOW CENTER SOUTHWEST OF THE 
AREA. HOWEVER...THE ECMWF TRACK IS FURTHER NORTH AND MOVES THE LOW 
INLAND OVER THE DISTRICT...BRINGING SOME PRECIPITATION TO THE AREA.
GIVEN THIS UNCERTAINTY...LITTLE CHANGE WAS MADE TO THE CURRENTLY
DRY AND SEASONABLE EXTENDED FORECAST. HOPEFULLY...FUTURE MODEL RUNS
WILL COME INTO BETTER AGREEMENT. 

&&

.AVIATION...28/1200Z.
MODERATE CONFIDENCE IN TAFS...BUT FINER DETAILS WILL BE TRICKY. COLD 
LOW PRESSURE AREA WILL BRING MVFR/VFR CIGS WITH THREATS OF 
-SHRA/-TSRA...BUT BOTH ASPECTS WILL CARRY LOW CONFIDENCE BEING 
RANDOM IN TIMING AND COVERAGE. IF TSRA FORMS...VIS COULD BRIEFLY 
LOWER BELOW 3SM. KWJF AND KPMD HAS A 10 PERCENT CHANCE OF BRIEF AND 
LIGHT -SN.

KLAX...MODERATE CONFIDENCE IN TAF. A SHOWER OR TWO SHOULD FORM 
BETWEEN 13Z AND 19Z...BUT WILL LIKELY STAY DRY FOR MOST OF THE TIME. 
CIGS COULD BRIEFLY LOWER TO MVFR...BUT TIMING WILL BE RANDOM. THERE 
IS AN OUTSIDE SHOT OF TSRA...WITH THE BEST WINDOW BETWEEN 14Z AND 
20Z.  

KBUR...MODERATE CONFIDENCE IN TAF. A SHOWER OR TWO SHOULD FORM 
BETWEEN 13Z AND 19Z...BUT WILL LIKELY STAY DRY FOR MOST OF THE TIME. 
CIGS WILL RANDOMLY ALTERNATE BETWEEN MVFR AND VFR...BUT SHOULD BE 
MOSTLY MVFR AFTER 14Z. THERE IS AN OUTSIDE SHOT OF TSRA...WITH THE 
BEST WINDOW BETWEEN 14Z AND 
20Z.  

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
WINTER WEATHER ADVISORY (SEE LAXWSWLOX).
GALE WARNING (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&

$$

PUBLIC...THOMPSON
AVIATION...KITTELL
SYNOPSIS...BARTLING

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