212 
FXUS66 KLOX 151032
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
230 AM PST THU NOV 15 2012

.SYNOPSIS...

A COLD LOW WILL APPROACH THE AREA TODAY...BRINGING THE THREAT OF 
PRECIPITATION TO THE REGION THROUGH SUNDAY NIGHT. COOLER 
TEMPERATURES CAN BE EXPECTED THROUGH THE WEEKEND. FOR NEXT WEEK 
DRY CONDITIONS ARE EXPECTED WHILE TEMPERATURES CLIMB TO NEAR NORMAL. 

&&

.SHORT TERM (TODAY-SAT)...OVERALL...00Z MODELS IN VERY GOOD SYNOPTIC 
AGREEMENT THROUGH THE PERIOD. AT UPPER LEVELS...LOW CURRENTLY NEAR 
33N 138W WILL MOVE EASTWARD TODAY...THEN OPEN UP INTO A TROUGH THAT 
WILL MOVE INLAND ACROSS THE WEST COAST FRIDAY/SATURDAY. NEAR THE
SURFACE...A GENERAL SOUTHEAST TO SOUTH FLOW WILL PREVAIL THROUGH THE
PERIOD. 

FORECAST-WISE...NO MAJOR CHANGES TO PREVIOUS THINKING. MAIN ISSUE
WILL BE THE RAIN CHANCES THROUGH THE PERIOD. A BROAD DIFFLUENT 
SOUTHERLY FLOW TODAY WILL BRING IN PLENTY OF MOISTURE/CLOUDS AND 
PROVIDE ENOUGH LIFT TO PRODUCE SOME LIGHT SHOWERS JUST ABOUT 
ANYWHERE THROUGH THIS EVENING. LATE TONIGHT/FRIDAY...A DISTURBANCE
WILL MOVE ACROSS THE AREA...BRINGING A DECENT CHANCE OF RAINFALL
TO THE AREA (ESPECIALLY SLO/SBA COUNTIES). THEN ANOTHER DISTURBANCE 
WILL SWEEP ACROSS THE AREA ON SATURDAY...BRINGING AN ADDITIONAL 
THREAT OF PRECIP. MODELS DO DISAGREE WITH THE AMOUNT OF RAINFALL AS 
THE NAM IS DRIER/SLOWER THAN EITHER THE GFS OR ECMWF. GIVEN THE FACT
THAT ALL MODELS HAVE BEEN PRETTY CONSISTENT LAST COUPLE OF DAYS...WILL
SKEW THE FORECAST TOWARD A MIDDLE GROUND BETWEEN THE DRIER NAM AND 
THE WETTER GFS/ECMWF. MODELS DO HINT AT SOME INSTABILITY OVER THE
NORTHERN COASTAL WATERS FRIDAY/SATURDAY. SO...WOULD NOT BE SURPRISED 
TO SEE AN ISOLATED THUNDERSTORM...BUT BELIEVE THE THREAT IS LOW 
ENOUGH AT THIS TIME TO KEEP THUNDER OUT OF THE OFFICIAL FORECAST. 

AS FOR RAINFALL AMOUNTS THROUGH SATURDAY...THE HIGHEST PRECIP 
AMOUNTS ARE ANTICIPATED TO BE ACROSS SLO/SBA COUNTIES...AS WELL
AS FAVORED SOUTH-FACING SLOPES. THROUGH SATURDAY NIGHT...INITIAL
RAINFALL ESTIMATES WILL GENERALLY RANGE BETWEEN 0.25 AND 0.75 INCHES 
WITH SOUTH AND SOUTHWEST FACING SLOPES POSSIBLY RECEIVING LOCALLY 
HIGHER AMOUNTS. SNOW LEVELS WILL REMAIN RATHER HIGH THROUGH THE 
WEEKEND (ABOVE 7000 FEET)...SO ONLY THE HIGHEST PEAKS WILL HAVE ANY 
LIGHT ACCUMULATIONS. 

WITH THE CLOUD COVER AND ANTICIPATED RAINFALL...TEMPS WILL BE ON A 
COOLING TREND THROUGH THE PERIOD WITH ALL AREAS DROPPING BELOW 
SEASONAL NORMS. NO MAJOR WIND ISSUES ARE ANTICIPATED. THERE WILL BE 
SOME GUSTY SOUTHERLY WINDS ACROSS THE AREA FRIDAY/SATURDAY...BUT 
NOTHING THAT SEEMS TO BE WIDESPREAD ADVISORY CRITERIA.  

.LONG TERM (SUN-WED)...OVERALL...00Z MODELS CONTINUE TO BE IN GOOD 
SYNOPTIC AGREEMENT THROUGH THE PERIOD. AT UPPER LEVELS...TROUGH WILL 
REMAIN OVER THE AREA ON SUNDAY...THEN A MORE ZONAL FLOW WILL DEVELOP 
MONDAY THRU WEDNESDAY. NEAR THE SURFACE...WEAK ONSHORE FLOW PATTERN 
WILL PREVAIL SUNDAY/MONDAY...THEN A WEAK DIURNAL PATTERN WILL 
DEVELOP TUESDAY/WEDNESDAY (OFFSHORE AT NIGHT...AND ONSHORE DURING 
THE DAY).

FORECAST-WISE...NOTHING TOO EXCITING IN THE OFFING. THERE WILL 
CONTINUE TO BE A THREAT OF LIGHT SHOWERS SUNDAY/SUNDAY NIGHT...THEN 
DRY CONDITIONS WILL PREVAIL MONDAY THRU WEDNESDAY. TEMPS WILL REMAIN
COOL ON SUNDAY...THEN WILL BEGIN A GRADUAL WARMING TREND MONDAY THRU 
WEDNESDAY. HOWEVER EVEN BY TUESDAY AND WEDNESDAY...AFTERNOON TEMPS 
WILL STILL LIKELY BE A COUPLE DEGREES BELOW SEASONAL NORMS. 

&&

.AVIATION...15/1145Z...

WILL BE UPDATED WITH THE 12Z TAF PACKAGE. 

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
NONE

&&

$$

PUBLIC...RAT
AVIATION...KJ
SYNOPSIS...SETO

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