SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDLOX 855 PM PST WED FEB 13 2002
RATHER MESSY AND ILL-DEFINED WEATHER PATTERN SETTING UP ACROSS THE
AREA FOR THE NEXT FEW DAYS. HIGH LEVEL MOISTURE BAND MOVED ACROSS THE
DISTRICT ON WEDNESDAY...AND EVEN HAD SOME SCATTERED SPRINKLES ACROSS
VENTURA AND LOS ANGELES COUNTIES LATE THIS AFTERNOON. THIS DID NOT
MEASURE AT ANY OF THE METAR OR ALERT GAUGES...WITH SEVERAL SPOTTERS
REPORTING TRACE AMOUNTS. 00Z NKX/VBG SOUNDINGS AND RECENT ACARS
SOUNDING FROM SNA INDICATE SUBSTANTIAL DRY LAYER STILL PRESENT FROM
ABOUT 950 MB UP TO 700 MB. MARINE LAYER IS SPREADING INTO THE CENTRAL
COAST AT THIS TIME...WITH LOW CIGS ALREADY REPORTED ACROSS WRN SBA
COUNTY. SOME LOW CLOUDS ALSO FORMING ALONG THE SAN DIEGO COUNTY
COAST...BUT STILL CLEAR ALONG THE LA/VTU COASTS. WEAK EDDY APPEARS TO
BE PRESENT ACROSS THE INNER WATERS...AND 00Z MESO-ETA STRENGTHENS THIS
OVERNIGHT. LOW CLOUDS SHOULD DEVELOP LATE TONIGHT ACROSS THE L.A.
COUNTY COAST...AND MAY SPREAD INTO THE VALLEYS AND FURTHER NW INTO THE
VTU/SBA S COASTS ON THU MORNING. ALONG THE CENTRAL COAST...DO NOT SEE
SUFFICIENT LOW LEVEL MOISTURE OR LIFT FOR SHOWERS TONIGHT OR THU...
AND WILL REMOVE 20 PERCENT POPS FROM THE FCST. RADAR IS SHOWING A FEW
LIGHT RETURNS OFFSHORE...SO WILL KEEP MENTION OF A FEW SPRINKLES FOR
TONIGHT AND THU AM. WILL ALSO CLEAN UP SOME EVENING WORDING FURTHER
SOUTH...AND MAKE SOME CLOUD ADJUSTMENTS FOR TNGT/THURS AS WELL.
00Z ETA IS IN GOOD AGREEMENT WITH THE PREVIOUS AVN RUN THRU FRI
MORNING...WITH WEAK UPPER LOW SITTING OFF THE CENTRAL COAST. MODELS
THEN DIVERGE...WITH ETA WEAKENING THE LOW MORE QUICKLY WHILE PUTTING
MORE ENERGY INTO THE UPSTREAM SHORTWAVE. ETA ACTUALLY CUTS THIS OFF
INTO AN UPPER LOW NEAR 37N 133W BY SAT MORNING...WHILE THE PREVIOUS
AVN KEPT THIS FEATURE AS A MORE PROGRESSIVE WAVE. MARINE LAYER DEEPENS
CONSIDERABLY THU NIGHT AND FRI...LIKELY REACHING THE COASTAL SLOPES.
FRIDAY WILL BE A RATHER MURKY AND COOL DAY...WITH THE COMBINATION OF
THE MARINE LAYER AND MID LEVEL MOISTURE FROM THE UPPER LOW KEEPING
SKIES MOSTLY CLOUDY. SOME FOG AND PATCHY DRIZZLE SEEMS LIKELY AS WELL.
WEEKEND FORECAST DEPENDS ON THE DEVELOPMENT AND MOVEMENT OF THE TWO
WEATHER SYSTEMS...THE FIRST UPPER LOW...AND THE SECOND S/W (POSSIBLY
BECOMING AN UPPER LOW AS WELL) TO THE WEST. MODELS TYPICALLY HAVE A
VERY DIFFICULT TIME HANDLING THESE TYPES OF PATTERNS...AND CONFIDENCE
IN ANY DETAILS IN VERY LOW. CURRENT FCST HAS SATURDAY CONTINUING IN
THE MURKY/DRIZZLE PATTERN...THEN A CHANCE OF RAIN ON SUNDAY AS THE
MAIN SYSTEM IS SUPPOSED TO MOVE THROUGH. IF THE SYSTEM CUTS OFF AS THE
LATEST ETA IS SUGGESTING...SATURDAY WOULD BE A NICER DAY AS WEAK S/W
RIDGING DEVELOPS AHEAD OF THE UPPER LOW...AND THE CHANCE OF RAIN WOULD
PROBABLY END UP DELAYED UNTIL MONDAY DUE TO THE SLOWER MOVEMENT OF THE
CLOSED LOW. WILL LET THE MID SHIFT REVIEW THE FULL 00Z MODEL SUITE
AND DECIDE WHETHER TO MAKE ANY ADJUSTMENTS TO THE FORECAST.
LAX 0000. JACOBSON
.LOX...NONE.