FXUS66 KLOX 071127
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
300 AM PST MON DEC 7 2009
.SYNOPSIS...
A COLD LOW PRESSURE SYSTEM WILL BRING WINDS...RAIN...AND LOW
ELEVATION SNOW TO THE AREA TODAY THROUGH TUESDAY MORNING. A SERIES
OF SYSTEMS WILL BRING MORE CHANCES OF RAIN TO THE AREA FROM
THURSDAY THROUGH THE WEEKEND. TEMPERATURES WILL REMAIN WELL
BELOW SEASONAL NORMALS THROUGH THE WEEK...COLDEST TODAY AND TUESDAY.
&&
.SHORT TERM (TODAY-WED)...
LIGHT RAIN HAS OVERSPREAD ALL AREAS EXCEPT THE L.A. COAST. SATELLITE
WAS LOOKING UNORGANIZED FOR MOST OF THE NIGHT IS BEGINNING TO ASSUME
A LITTLE BETTER STORM LIKE APPEARANCE AS IT TAKES ON MORE OF A SW TO
NE TILT. ALL MDLS DO AGREE HOWEVER THAT THE BULK OF THE JET ENERGY
AND DYNAMICS IS GOING TO SLAM INTO SAN DIEGO COUNTY RATHER THAN L.A.
COUNTY AS THOUGHT YDY. THIS IS GOING TO DECREASE THE IMPACT OF THE
SYSTEM FOR OUT AREA AND WHILE .5 TO 1.0 INCHES OF RAIN IS STILL GOOD
MORE PLACES WILL END UP WITH .5 THAN THE 1.0. GIVEN THE TILT OF THE
STORM IT STILL LOOKS LIKE THE SOUTH FACING MTNS WILL GET UP TO 3
INCHES OF RAIN SOLELY DUE TO OROGRAPHICS. AT 18Z THE NAM SHOWS TWO
DISTINCT BLOBS OF RAIN. THE FIRST BLOB IS THE JET ENHANCED
PREFRONTAL RAINFALL WHICH COVERS MOST OF VTA AND LA COUNTY. THE
SECOND IS A NARROWER BAND ASSOC WITH THE COLD FRONT AND IS LOCATED
OVER MONTEREY COUNTY. THIS FRONTAL BAND OF RAIN SWEEPS THROUGH THE
AREA DURING THE AFTERNOON. IT WILL CONTAIN THE HEAVIEST RAINFALL
RATES...POSSIBLY REACHING A HALF INCH PER HOUR WHICH IS ENOUGH TO
TRIGGER DEBRIS FLOWS OVER THE RECENT BURN AREAS. SNOW LEVELS AHEAD
OF THE FRONT WILL BE BETWEEN 4000 AND 5000 FEET...WHICH IS ENOUGH TO
BRING SNOW TO THE GRAPEVINE. WINDS WILL INCREASE DURING THE
AFTERNOON BUT NOW WITH THE JET FURTHER SOUTH THE WINDS WILL NOT BE
AS STRONG AS ONCE THOUGHT.
THE WEATHER BEHIND THE COLD FRONT WILL BE INTERESTING. BY 06Z 537DM
THKNS ARE FORECAST THROUGH HALF OF THE COUNTY WITH 543 DM THKNS OVER
KLAX. THIS AMOUNT OF COLD AIR ADVECTION WILL BRING IN QUITE A BIT OF
GUSTY NW WINDS AND WIND ADVISORIES MAY WELL BE NEEDED FOR MANY AREAS
OF SLO AND SBA COUNTY. NO WIND PRODUCTS FOR THE MTNS OF LA AND VTA
COUNTY SINCE THE WINDS ARE WRAPPED UP IN THE WINTER STORM WARNING
BUT GUSTS TO 55 MPH WILL OCCUR BEHIND THE FRONT. THESE KINDS OF
THKNS WILL LOWER THE SNOW LEVELS TO 2000 FEET OR LOWER. BUT SINCE IT
IS QUITE DRY BEHIND THE FRONT THE AMOUNT OF SNOW FALL WILL BE
LIMITED AND MOSTLY CONFINED TO THE NORTHERN SLOPES AND INTERIOR VLYS
AS WELL AS THE FOOTHILLS OF THE ANTELOPE VLY. LOW TEMPS AND
POTENTIAL FROST AND FREEZE ISSUES WILL BE A MAJOR CONCERN TONIGHT
GUSTY WINDS WILL KEEP MOST TEMPS EVERYWHERE EXCEPT THE SOUTHERN
COASTAL ZONES IN THE MID 30S BUT ANY WIND SHELTERED AREAS COULD
EASILY SEE MIN TEMPS IN THE MID TO UPPER 20S.
TUESDAY WILL BE PARTLY CLOUDY OR EVEN MOSTLY SUNNY BEHIND THE
FRONT...BUT IT WILL BE COLD DESPITE SEEING SOME SUNSHINE MAX TEMPS
WILL BE ABOUT 15 DEGREES COLDER THAN NORMAL. CLOUDS AND SNOW SHOWERS
WILL CONTINUE ON THE NORTH SLOPES IN THE MORNING BEFORE DISSIPATING
IN THE AFTERNOON.
WEDNESDAY WILL BE A DECENT IF NOT SOME WHAT COOL DAY. A SMALL RIDGE
POPS UP AND TEMPS WILL RISE ABOUT 8 DEGREES FROM TUESDAYS VALUES.
SKIES WILL BE PARTLY CLOUDY AS MID AND HIGH LEVEL CLOUDS FROM AN
APPROACHING STORM DRIFT THROUGH THE RIDGE.
.LONG TERM (THU-SUN)...
THE GFS AND THE EC ARE IN GOOD SYNOPTIC AGREEMENT FOR THE EXTENDED
PERIOD BUT DISAGREE SOMEWHAT ON THE TIMING...LOCATION AND AMOUNTS OF
RAIN. BUT BOTH AGREE THAT THE RAIN DOOR IS OPEN. BOTH MDLS AGREE
THAT THE RIDGE WILL BREAK DOWN INTO A WESTERLY FLOW PATTERN THURSDAY
AND THAT THIS PATTERN WILL LAST THROUGH SUNDAY WITH PERHAPS A LITTLE
WAVE MOVING THROUGH SUNDAY.
THE EC FORECAST LIGHT RAIN THU AND FRI WITH HEAVIER SATURDAY AND
SUNDAY. THE GFS BRINGS LIGHT RAIN INTO THE AREA THURSDAY AND THEN
NOTHING ON FRIDAY. A LITTLE HEAVIER RAIN ON SATURDAY AND THEN
FORECASTS A MAJOR RAIN EVENT SUNDAY.
THINK WE CAN SAFELY SAY THAT WE WILL HAVE A LIGHT RAIN EVENT
THURSDAY WITH MAYBE A QUARTER TO A HALF INCH OF RAIN. SNOW LEVELS
WILL BE HIGHER THAN TODAYS STORM.
LEFT A CHANCE OF RAIN IN FOR FRIDAY. WILL JUST GIVE CHC RAIN FOR THE
WEEKEND SEEING HOW FAR OUT THE FCST IS AND THE MDLS PROPENSITY TO
CHANGE A FORECAST MAJOR STORM INTO A WEAKER ONE WITH TIME. BUT IT
WILL BE INTERESTING TO SEE HOW THESE SYSTEMS PLAY OUT.
&&
.AVIATION...
07/1200Z.
CLOUDS WILL INCREASE AND LOWER TODAY...WITH RAIN OVERSPREADING
THE AREA THIS MORNING AND LASTING THROUGH THE DAY...TAPERING TO
SHOWERS DURING THE LATE AFTERNOON OR EARLY EVENING.
DURING THE RAIN CIGS AND VIS WILL VARY GREATLY BETWEEN IFR AND LOW
MVFR CONDS BUT FEW IF ANY LIFR CONDS ARE EXPECTED.
KLAX...LOW CONFIDENCE IN EXACT CIG/VIS FCST DURING THE RAIN AS BOTH
VALUES WILL CHANGE FROM ONE MOMENT TO THE NEXT. EXPECT IFR TO LOW
MVFR CONDS. EAST WINDS AROUND 10 KTS ARE LIKELY DURING THE MORNING
WITH A 30 PERCENT CHANCE OF ARRIVING BY 12Z.
KBUR...LOW CONFIDENCE IN EXACT CIG/VIS FCST DURING THE RAIN AS BOTH
VALUES WILL CHANGE FROM ONE MOMENT TO THE NEXT. EXPECT IFR TO LOW
MVFR CONDS. WINDS WILL ALSO VARY CONSIDERABLY FROM 14Z TO 02Z.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING (SEE LAXWSWLOX).
HIGH WIND WATCH (SEE LAXNPWLOX).
FLOOD WATCH (SEE LAXFFALOX).
GALE WARNING (SEE LAXMWWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
&&
$$
PUBLIC...RORKE
AVIATION...RAT
SYNOPSIS...ASR
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