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FXUS66 KLOX 232355 AAA
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
354 PM PST MON NOV 23 2009
...UPDATED AVIATION SECTION...
.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...23/2354Z.
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD...EXCEPT FOR A
CHANCE OF LIFR TO IFR CONDITIONS AT KPRB BETWEEN 13Z AND 18Z TUESDAY
MORNING. PERIODS OF MODERATE TO STRONG TURBULENCE AND LOW-LEVEL WIND
SHEAR WILL OCCUR TONIGHT AT KOXR...KBUR...AND KVNY.
KLAX...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD WITH ANY
OFFSHORE WINDS LIKELY REMAINING 10 KT OR LESS. THERE IS A 20 PERCENT
CHANCE THAT WINDS COULD BE STRONGER THAN 10 KT BETWEEN 14Z AND 18Z
TUESDAY.
KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT TUESDAY. PERIODS OF
MODERATE TO STRONG TURBULENCE AND LOW-LEVEL WIND SHEAR ARE EXPECTED
THROUGH AT LEAST 15Z TUESDAY. THEN...WINDS ALOFT WILL WEAKEN.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
&&
PUBLIC...BOLDT
AVIATION...HALL
SYNOPSIS...SETO
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