SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDLOX 315 AM PST WED JAN 3 2001
OFFSHORE FLOW CONTINUES ACROSS THE REGION. WINDS ON TUES STAYED UP
UNUSUALLY LATE INTO THE AFTERNOON AND EVENING AS A JET STREAK PASSED
OVERHEAD...BUT HAVE MORE RECENTLY DROPPED DOWN AS IS TYPICAL OF SANTA
ANA EVENTS DURING THE OVERNIGHT HOURS. GOOD SUBSIDENCE STILL NOTED ON
WATER VAPOR PIX...AND ACARS SOUNDINGS INDICATE 20 KT WINDS AT 850 MB
OVER ONT/LAX. LAST REPORT FROM LAG PK HAD GUSTS TO 45 KT...AND WINDS
STILL GUSTING 45 TO 55 MPH AT A FEW MTN LOCATIONS AS WELL. EXPECT WINDS
TO INCREASE AND BECOME MORE WIDESPREAD AGAIN EARLY THIS MORNING...AND
WILL CONTINUE WIND ADVISORIES FOR ALL OF LOS ANGELES AND VENTURA
COUNTIES...EXCEPT FOR THE LA COAST AND THE ANTELOPE VALLEY. WILL HAVE
TO MONITOR WIND SPEEDS CLOSELY THIS MORNING FOR POSSIBLE UPGRADE TO
HIGH WIND WARNINGS IN SOME ZONES.
MODELS IN GOOD AGREEMENT ON THE BROAD SCALE FEATURES THRU THURS...WITH
UPPER RIDGE HOLDING OVER CENTRAL CA AS WEAK UPPER LOW DRIFTS SLOWLY WSW
FROM THE NRN BAJA TO SOMEWHERE AROUND 30N 130W BY THU EVENING. ON THE
SMALLER SCALE...MESO-ETA ONCE AGAIN THE MODEL OF CHOICE TONIGHT AS IT
HAS A BETTER HANDLE ON THE TERRAIN AND HAS BEEN DOING A GOOD JOB WITH
THE PRESSURE GRADIENTS AND LOW LEVEL WIND FORECASTS. MESO-ETA MAINTAINS
GOOD SUPPORT FOR THE WINDS THROUGHOUT TODAY...AND THERE IS ANOTHER
UPPER FEATURE EVIDENT ON WV SATELLITE PIX IN WRN UTAH WHICH IS MOVING
SW TOWARD THE REGION. THESE FACTORS COULD SERVE TO EXTEND THE STRONGER
WINDS THROUGH MUCH OF THE DAY ONCE AGAIN...AND WILL EXTEND THE WIND
ADVISORIES THROUGH 4 PM. GRADIENTS REMAIN STRONGLY OFFSHORE TONIGHT/THU
AM...BUT UPPER SUPPORT IS QUITE A BIT WEAKER. THERE WILL PROBABLY BE
ADVISORY WINDS AT LEAST AT SOME OF THE FAVORED LOCATIONS LATE TONIGHT
AND THU AM...BUT THERE SHOULD BE A SIGNIFICANT BREAK IN THE WINDS THIS
EVENING...AND WILL LEAVE DECISION ON EXTENDING SOME WIND ADVRYS INTO
THU TO THE DAY SHIFT. OTHERWISE...VERY WARM TEMPS EXPECTED TODAY FOR
THE COASTS AND LOWER VALLEYS...AND SOME RECORD HIGHS WILL LIKELY BE
TIED OR BROKEN ESPECIALLY AT COASTAL LOCATIONS SUCH AS LAX...OXR...AND
SBA. HIGH VALLEYS...MOUNTAINS AND DESERTS WILL REMAIN COOLER HOWEVER AS
SOME COLD ADVECTION CONTINUES. TEMPS SHOULD EVEN OUT ON THURS...WITH
COASTAL PLAIN COOLING DOWN A BIT...INTERMEDIATE VALLEYS ABOUT THE SAME
AND FAR INLAND LOCATIONS WARMING UP SLIGHTLY. SKIES WILL REMAIN CLEAR
THROUGH THURS AS HIGH CLOUDS REMAIN NORTH OF THE AREA AND LOW CLOUDS
STAY FAR OFFSHORE.
EXTENDED...FRIDAY FORECAST IS SOMEWHAT UNCERTAIN AS AVN AND ETA
DISAGREE ON THE MOVEMENT OF THE OLD UPPER LOW TO OUR SOUTH. AVN BRINGS
THIS FEATURE CLOSE TO SRN CA BY FRI AM WHILE ETA LINGERS IT WELL
OFFSHORE. AVN ACTUALLY SPITS OUT PRECIP ACROSS SGX FORECAST AREA ON
FRIDAY...BUT FEEL THIS IS UNLIKELY SINCE MOISTURE IS ALL MID AND HIGH
LEVEL...WITH VERY DRY LOW LVLS THANKS TO THE OFFSHORE FLOW. SAT/SUN
FORECAST TO BE A NONDESCRIPT PATTERN WITH A SLIGHT UPPER WEAKNESS
REMAINING IN THE AREA. TREND FOR THIS WEEKEND SHOULD BE FOR INCREASING
NIGHT/MORNING MARINE STRATUS NEAR THE COASTS...AND COOLER TEMPS. MORE
SIGNIFICANT HAPPENINGS MON/TUE AS GLOBAL MODELS CONTINUE TO ADVERTISE
PATTERN SHIFT TO A ZONAL FLOW ACROSS THE PACIFIC...WITH A FAIRLY DEEP
TROF MOVING INTO THE WEST COAST. MRF IS STILL INCONSISTENT FROM RUN TO
RUN WITH THE STRENGTH OF THIS TROF...BUT THE VARIOUS MODELS HAVE COME
INTO BETTER AGREEMENT TONIGHT ON THE OVERALL PATTERN SHIFT AND THAT
SOME SORT OF TROF WILL IN FACT DEVELOP. WILL INTRODUCE CHANCE OF RAIN
INTO THE CENTRAL COAST ZONES FOR MON/TUE...BUT WILL KEEP THINGS DRY
SOUTH OF POINT CONCEPTION FOR NOW.
LAX 000. JACOBSON
.LAX...WIND ADVISORY...SEE LAXNPWLAX.
SMALL CRAFT ADVISORY...SEE LAXCWFLAX.