FXUS66 KLOX 281752
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
950 AM PST SAT NOV 28 2009
...NEW AVIATION DISCUSSION...
.SYNOPSIS...
A COLD LOW PRESSURE SYSTEM WILL CONTINUE TO PUSH THROUGH THE AREA
TODAY...BRINGING COLD TEMPERATURES...SCATTERED SHOWERS...AND
THUNDERSTORMS WITH SNOW DOWN TO AROUND 4200 FEET. BEHIND THIS
SYSTEM...BREEZY CONDITIONS WILL AFFECT THE MOUNTAINS TONIGHT...AND A
SLIGHT WARMING TREND WITH OFFSHORE WINDS WILL PERSIST INTO MID WEEK.
&&
.SHORT TERM (TODAY-MON)...SATELLITE PIXS SHOW UPPER LOW SPINNING
OVER THE EASTERN SAN GABRIEL MTNS THIS MORNING WITH SEVERAL VORT
LOBES ROTATING AROUND THIS FEATURE. WHILE RAINFALL AMOUNTS FOR THE
MOST PART HAVE BEEN SPARSE ACROSS THE CWA...THERE HAVE BEEN SEVERAL
RESPECTABLE AMOUNTS ALONG OUR EASTERN BORDER AND OVER THE BORDER
WITH THE POTENTIAL FOR DECENT CONVECTION THROUGH THE DAY.
INSTABILITY IN PLACE WITH 500 MB TEMPS FORECAST TO REACH -27C BY
MIDDAY. THUS HAVE LOWERED POPS MOST AREAS BUT STILL CONTINUED THE
THREAT. SNOW LEVELS REACHING NEAR 4200 FEET WITH 2-5 INCHES REPORTED
THUS FAR. WINTER WEATHER ADVISORY LOOKS GOOD FOR NOW BUT DO HAVE
SOME CONCERN FOR TONIGHT ACROSS THE SAN GABRIELS AND UPPER PORTIONS
OF THE ANTELOPE VALLEY AS NE FLOW SETS UP FOR A POTENTIAL ADDITIONAL
UPSLOPE EVENT THERE. WILL LOOK FURTHER AT THIS FOR THE AFTERNOON
PACKAGE. HAVE DECIDED TO REMOVE THREAT OF SHOWERS AND THUNDERSTORMS
ALONG CENTRAL COAST TODAY AS PARAMETERS SHOW INSTABILITY IMPROVING
THERE AND MAIN ACTION IS OFF TO THE EAST. WINDS ALSO HAVE DIMINISHED
ACROSS THE SBA MOUNTAINS AND SBA SOUTH COAST THUS HAVE DROPPED
ADVISORY THERE EARLY. NO OTHER CHANGES AT THIS TIME.
[FROM PREVIOUS DISCUSSION]...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...
28/1800Z.
UPPER LEVEL LOW PULLING OUT TO THE SOUTHEAST. LIFR CONDS OVR MTNS
ALONG WITH STRONG WINDS AND TURBC. SHOWERS AND ISOLD TSRA OVER THE
L.A. MTNS AND DESERTS. GOOD CONFIDENCE IN TAFS.
KLAX...GOOD CONFIDENCE IN TAF. A 10 PERCENT CHC OF A SHOWER. LIGHT
EAST WINDS POSSIBLE AFTER 13Z.
KBUR...GOOD CONFIDENCE IN TAF. A 20 PERCENT CHC OF A SHOWER. LGT
TURBC SFC-070
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
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...TRM
AVIATION...RORKE
SYNOPSIS...MEIER
FWX........GOMBERG
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