FXUS66 KLOX 272300 CCA
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
300 PM PST FRI NOV 27 2009
.SYNOPSIS...
A COLD LOW PRESSURE SYSTEM WILL DROP DOWN THROUGH CALIFORNIA AND
IMPACT OUR AREA TONIGHT AND SATURDAY...BRINGING COLDER TEMPERATURES
...A CHANCE OF SHOWERS AND THUNDERSTORMS...AND POSSIBLY LOW
ELEVATION SNOW. BEHIND THIS COLD WEATHER SYSTEM...A WARMING TREND
WILL ENSUE WITH OFFSHORE WINDS LASTING INTO MID WEEK.
&&
.SHORT TERM (TONIGHT-SUNDAY)...THE LATEST WATER VAPOR IMAGERY PLACES
THE APPROACHING COLD UPPER LEVEL LOW PRESSURE SYSTEM VERY NEAR THE
BAY AREA. VISIBLE SATELLITE PIXS AND SURFACE OBSERVATIONS SUGGEST
THAT THE SURFACE COLD FRONT EXTENDS FROM NEAR RENO NEVADA ACROSS THE
SIERRA TO A POINT ALONG THE COAST JUST NORTH OF OUR CWA. VERY LITTLE
OR NO PRECIPITATION DEPICTED ON RADAR ACROSS THE CENTRAL VALLEY OR
CENTRAL COAST ASSOCIATED WITH THE SOUTHERN END OF THE FRONT. MOST
COMMON SENSIBLE WEATHER ELEMENT AFFECTED BY THE COLD FRONT AT THIS
TIME IS THE WINDS WHICH IMMEDIATELY INCREASE WITH THE FRONTS
PASSAGE. ANTICIPATE THIS TO CONTINUE AS THE FRONT CONTINUES TO MARCH
SOUTH INTO THE CWA. HAVE INCREASED WINDS ALONG THE COAST THIS
EVENING AND RAISED THE WIND ADVISORY FLAGS FOR THE MOUNTAINS AND
SOUTH COAST OF SANTA BARBARA COUNTY ACCORDINGLY. GUIDANCE SUGGESTS
GUSTS COULD REACH 45 MPH THROUGH AND BELOW THE PASSES OF THE SANTA
YNEZ RANGE. WINDS ALSO STRONG ACROSS THE COASTAL WATERS AND THE
ANTELOPE VALLEY. WILL HOIST GALE WARNING FOR SANTA BARBARA CHANNEL
TO GO WITH EXISTING GALES ON OUTER WATERS AND MAY NEED TO ADD WIND
ADVISORY FOR AV THIS EVENING.
AS FOR PRECIPITATION...WILL NEED TO WAIT FOR THE UPPER LOW...
INSTABILITY...AND GOOD COLD ADVECTION LATER TONIGHT AND ON SATURDAY.
18Z MODELS STILL FORECAST THIS TO TAKE AN INSIDE-OVERLAND-TRACK
WHICH WILL LIMIT PRECIPITATION ACROSS OUR CWA. PRECIPITATION WILL BE
VERY DYNAMIC IN NATURE AND GIVEN FORECAST 500 MB TEMPS OF -26C
SUGGEST THE POSSIBILITY OF THUNDERSTORMS WITH PRECIPITATION FOCUSED
ON MOUNTAIN SLOPES...BUT A CHANCE EXISTS IN ALL AREAS. AT THIS TIME
BELIEVE QPF AMOUNTS WILL BE 1/2 INCH OR LESS ALTHOUGH HIGHER AMOUNTS
WILL BE POSSIBLE IN ANY THUNDERSTORMS. SNOW LEVELS STILL LOOK LIKE
THEY WILL DROP TO NEAR 4500 FEET WITH 3-6 INCHES LIKELY THUS OUR
FIRST WINTER WEATHER ADVISORY CONTINUES FOR THE LA/VTU CO. MOUNTAINS
BUT WITH MINOR ADJUSTMENT IN TIMING.
UPPER LOW IS FORECAST TO BE OVER THE CWA ON SATURDAY WITH 500 MB
TEMPS REACHING -26C. SHOULD BE COLDEST AND CLOUDIEST DAY OF THE
ENTIRE FORECAST PERIOD WITH WINDS SLOWLY TAPERING OFF. A FAR CRY
FROM THE 80S JUST YESTERDAY AFTERNOON.
SYSTEM QUICKLY MOVES OFF TO THE SOUTH AND EAST ON SUNDAY AND A
MODERATE OFFSHORE WIND EVENT WILL ENSUE. ANY PRECIPITATION WILL
QUICKLY COME TO AN END AND GUIDANCE SUGGESTS THAT THERE WILL BE SOME
UPPER LEVEL SUPPORT FOR THIS OFFSHORE EVENT AND THUS MAY VERY WELL
SEE OFFSHORE WINDS REACHING ADVISORY LEVELS.
IF THIS WASN'T ENOUGH...LARGE SWELLS TO CONTINUE ALONG OUR COAST
WITH SURF REPORTS AT VENTURA HARBOR THIS AFTERNOON OF 7-10 FEET WITH
ISOLATED SETS TO 12 FEET! WEST FACING BEACHES BEING THE ONES MOST
AFFECTED WITH HIGH RIP CURRENT POTENTIAL. THESE ADVISORIES TO
CONTINUE THROUGH SUNDAY. SEE MARINE PRODUCTS FOR FURTHER DETAILS.
.LONG TERM (MONDAY-FRIDAY)...OFFSHORE FLOW PATTERN SHOULD BEGIN
WEAKENING FOR THE START OF THE WORK WEEK. TEMPERATURES WILL STILL
LIKELY WARM INTO MONDAY AND TUESDAY AS THE RIDGE AXIS MOVES OVER THE
REGION AND THE AIR MASS STAGNATES.
MODELS ARE STILL STRUGGLING WITH A DEVELOPING CLOSED LOW PRESSURE
SYSTEM THAT SNEAKS INTO THE EASTERN PACIFIC AND IS FORECAST BY THE
GFS TO APPROACH THE WEST COAST BY LATE WEDNESDAY OR THURSDAY UNDER A
BUILDING RIDGE IN THE EASTERN PACIFIC. 12Z ECMWF MINORS THIS SYSTEM
AND MAINTAINS A GENERAL RIDGE ALONG THE COAST. WITH A LACK OF
CONFIDENCE BETWEEN THE MEDIUM-RANGE SOLUTIONS...FORECAST REMAINS
CLOSER TO CLIMATOLOGY.
&&
.AVIATION...27/1800Z.
LOW TO MEDIUM CONFIDENCE IS CURRENT TAFS. EXPECT GUSTY WINDS TO
DEVELOP OVER THE CENTRAL COAST THIS AFTERNOON AND EVENING...BUT
BELOW 30 KTS. SHOWERS LIKELY TO ARRIVE N OF POINT CONCEPTION BEFORE
08Z...THEN S OF POINT CONCEPTION BEFORE SUNRISE. UNCERTAIN WITH
CIGS/VSBYS ASSOCIATED WITH SHOWERS...BUT WILL LIKELY STAY MVFR.
THERE IS ALSO A SLIGHT CHANCE OF TSTMS WITH THIS SYSTEM....BUT
GIVEN THE PERCENTAGE CHANCE (15-20%) WILL NOT MENTION IN CURRENT
TAFS...AND WILL CONTINUE TO MONITOR THE SITUATION CLOSELY.
KLAX...MODERATE CONFIDENCE IN CURRENT TAF. CHANCE OF SHOWERS TO
ARRIVE BEFORE SUNRISE...WITH MVFR CONDS LIKELY. THERE IS A SLIGHT
CHANCE OF TSTMS TONIGHT AS WELL...MAINLY AFTER 08Z.
KBUR...MODERATE CONFIDENCE IN CURRENT TAF. CHANCE OF SHOWERS WITH
MVFR CONDS TO ARRIVE AFTER MIDNIGHT...WITH SLIGHT CHANCE TSTMS AS
WELL.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY (SEE LAXCFWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
WINTER WEATHER ADVISORY (SEE LAXWSWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
GALE WARNING (SEE LAXMWWLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
WIND ADVISORY (SEE LAXNPWLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).
&&
$$
SYNOPSIS/PUBLIC...TRM/GOMBERG
AVIATION/MARINE...MEIER
FIRE WEATHER......GOMBERG
WWW.WEATHER.GOV/LOSANGELES
