Issued by NWS Los Angeles, CA
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000 FXUS66 KLOX 232152 AFDLOX SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 145 PM PST MON NOV 23 2009 .SYNOPSIS... GUSTY OFFSHORE WINDS AND CLEAR SKIES SHOULD SEND TEMPERATURES IN THE AFTERNOONS TO WELL ABOVE THE SEASONAL NORMALS THROUGH THURSDAY. A COLD FRONT WILL CROSS THE REGION ON FRIDAY AND WILL SHARPLY DROP THE TEMPERATURES. HIGH PRESSURE WILL BUILD IN ON SATURDAY...AND WINDS WILL SHIFT OFFSHORE ON SUNDAY FOR MOSTLY CLEAR SKIES AND A WARMING TREND. && .SHORT TERM (TONIGHT-THU)...MAIN WEATHER FOCUS IS THE DEVELOPING SANTA ANA ACROSS SOUTHERN CAL AND THE STRENGTH OF THE WIND GUSTS... WARM TEMPERATURES AND LOW HUMIDITIES FOR THE NEXT FEW DAYS. THE OFFSHORE WINDS KICKED IN EARLIER THAN EXPECTED TODAY AND TEMPERATURES HAVE ZOOMED ABOVE FORECASTS AS A RESULT. PRESSURE GRADIENTS OF -5.0MB LAX-DAG AND -10.6MB LAX-TPH CONTRIBUTED TO THE INCREASED OFFSHORE WINDS. STRONGEST GUSTS HAVE OCCURRED ALONG THE SANTA CLARA RIVER VALLEY AND NEARBY FOOTHILLS... AND ACROSS CANYON COUNTRY TOWARD THE SAN FERNANDO VALLEY. GUSTS OF 30 TO 40 MPH HAVE BEEN COMMON WITH STRONGEST WINDS OVER 60 MPH AT WILEY RIDGE...OUR NOTORIOUSLY WINDY SPOT. WRF MODEL LOW-LEVEL WINDS (AROUND 2K FT) INCREASE TO NEARLY 40KT JUST AFTER DARK ACROSS VENTURA COUNTY AND REMAIN STRONG THROUGH TUESDAY MORNING. THEREFORE...EXPECT WINDS TO BECOME MORE WIDESPREAD AND STRONGER ACROSS VENTURA AND LOS ANGELES COUNTIES TONIGHT. WILL CONTINUE ALL WIND ADVISORIES AND COASTAL AREAS SHOULD RAMP UP INTO THIS CATEGORY THIS EVENING AS PLANNED. MINIMUM TEMPERATURE FORECASTS ARE CHALLENGING FOR THE NEXT THREE NIGHTS AND WILL DEPEND SOLELY ON WIND-SHELTERING AND COULD MAKE FOR LARGE SPREADS IN SHORT DISTANCES. WINDS TEND TO WEAKEN IN THIS TYPE OF PATTERN BY LATE MORNING OR EARLY AFTERNOON...SO WILL LET ADVISORIES RIDE UNTIL THIS TIME FRAME ON TUESDAY. IT IS HIGHLY LIKELY THAT ADDITIONAL WIND ADVISORIES WILL BE REQUIRED FOR TUESDAY NIGHT AND POSSIBLY WEDNESDAY NIGHT. HAVE RAMPED UP TEMPERATURES IN THE WINDIER LOCATIONS THROUGH THANKSGIVING DAY. STILL DO NOT BELIEVE RECORDS ARE REACHABLE...BUT READINGS WILL PUSH UPPER 80S TO LOWER 90S ON THE WARMEST DAYS OF WEDNESDAY AND THURSDAY. OFFSHORE WINDS CONTINUE THROUGH THURSDAY MORNING WITH A WEAK ONSHORE SEABREEZE ATTEMPTING TO DEVELOP LATE IN THE DAY. THERE IS STILL A HEIGHTENED FIRE WEATHER CONCERN THROUGH THURSDAY DUE TO THE PERSISTENT SANTA ANA CONDITIONS...WARMER TEMPERATURES...POOR HUMIDITY LEVELS AND DRYING FUELS. A STRONGER SANTA ANA EVENT WOULD TIP THE SCALES TOWARD FIRE WEATHER WATCHES AND/OR WARNINGS. .LONG TERM (FRI-MON)...GOOD MODEL CONSISTENCY NOW WITH A LOW PRES TROUGH MOVING ACROSS THE WEST COAST ON FRIDAY. TEMPERATURES WILL BE A GOOD 15-20 DEGREES COOLER WITH DECENT HUMIDITY RECOVERY AS NORTHERLY WINDS RETURN TO THE REGION. THIS SYSTEM LOOKS DRY AND WILL BLOW OUT ANY LOW CLOUDS ALONG THE COAST. THERE COULD BE A REPEAT OF UPSLOPE CLOUDINESS ON THE NORTH SLOPES OF THE MOUNTAINS ALONG WITH A FEW SPRINKLES BEHIND THE STORM SYSTEM LATE FRIDAY OR SATURDAY. THE RIDGE BECOMES QUITE AMPLIFIED OVER THE EASTERN PACIFIC OCEAN ON SUNDAY AS A SURFACE HIGH DEVELOPS OVER THE GREAT BASIN TURNING OUR WINDS BACK TO OFFSHORE. FAIRLY GOOD CONFIDENCE IN THIS SCENARIO SO HAVE TRENDED TEMPERATURES BACK TO ABOVE NORMAL FOR DAYS 6-7. WE COULD ALSO BE LOOKING AT A STRONGER SANTA ANA WIND EVENT BY SUNDAY NIGHT-MONDAY. && .AVIATION...23/1950Z. VFR CONDITIONS WILL CONTINUE THROUGH TUESDAY...EXCEPT LATE NIGHT AND EARLY MORNING DENSE FOG AT KPRB. WIND SHEAR COULD BE A PROBLEM FOR KSBP...KBUR AND MAYBE KVNY DUE TO OFFSHORE WINDS. KLAX...VFR CONDITIONS THROUGH TUESDAY. KBUR...VFR CONDITIONS THROUGH TUESDAY. PERIODS OF LOW LEVEL WIND SHEAR. && .LOX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY (SEE LAXNPWLOX). && $$ PUBLIC...BOLDT AVIATION...SWEET SYNOPSIS...SETO WWW.WEATHER.GOV/LOSANGELES
