FXUS66 KLOX 300423
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
820 PM PST SUN NOV 29 2009
.SYNOPSIS...
TUESDAY WILL REMAIN WARM AND DRY WITH OFFSHORE WINDS...THEN SWITCH
TO THE NORMAL SEA BREEZE IN THE AFTERNOON. WEDNESDAY WILL COOL A
FEW DEGREES...WITH AROUND SEASONABLE TEMPERATURES THROUGH SATURDAY.
&&
.SHORT TERM (TONIGHT-WED)...UPPER LEVEL LOW PRESSURE SYSTEM INITIALIZED
THIS EVENING OVER THE NORTHERN GULF OF CALIFORNIA...WITH UPPER LEVEL
HIGH PRESSURE SYSTEM BUILDING OFF THE COAST OF CALIFORNIA. AS A
RESULT...FAIRLY STRONG NORTHEAST FLOW ALOFT CONTINUES THIS EVENING.
AS THE LOW PRESSURE SYSTEM EDGES EASTWARD ON MONDAY...LOOK FOR UPPER LEVEL
SUPPORT TO GRADUALLY WEAKEN.
WHILE CURRENT OBSERVATIONS SHOWING A SLIGHT DECREASE IN AREAL
COVERAGE AND INTENSITY OF WINDS THIS EVENING...MODEL CROSS SECTIONS DO SHOW
THAT OFFSHORE WINDS WILL BECOME SOMEWHAT STRONGER AND MORE
WIDESPREAD IN THE NEXT 3 TO 6 HOURS. IN ADDITION TO THE GOOD UPPER
LEVEL AND THERMAL SUPPORT...THERE WILL BE INCREASING OFFSHORE
PRESSURE GRADIENTS...WITH LAX-DAGGETT FORECASTED TO REACH -4.6 MB BY
MONDAY MORNING. ACROSS OUR FORECAST AREA...BEST UPPER LEVEL WIND AND
THERMAL SUPPORT WILL OCCUR ACROSS LOS ANGELES COUNTY...WITH WIND
ADVISORIES LOOKING GOOD FOR THE MOUNTAINS AND SANTA CLARITA VALLEY.
THESE AREAS CAN EXPECT WIND GUSTS IN THE 40 TO 50 MPH RANGE. OFFSHORE
WINDS EXPECTED TO WEAKEN CONSIDERABLY ON MONDAY AFTERNOON.
AS THE BOUNDARY LAYER TEMPERATURES EDGE UPWARD ON MONDAY...LOOK FOR THE
OFFSHORE WINDS TO BRING ADDITIONAL WARMING AND DRYING TO THE REGION.
TEMPERATURES IN MOST AREAS WILL TREND UPWARD A FEW DEGREES...WITH MANY
AREAS CLIMBING WELL INTO THE 70S...AND EVEN A FEW 80 DEGREE READINGS
LIKELY. HUMIDITY LEVELS ARE EXPECTED TO FALL INTO THE TEENS ACROSS MUCH
OF THE AREA ON MONDAY...WITH A FEW HOURS OF SINGLE DIGIT READINGS
POSSIBLE IN SOME LOCATIONS. WHEN HUMIDITY LEVELS LOWER ON MONDAY...IT
APPEARS THAT WIND SPEEDS WILL BE ON DOWNWARD TREND...THUS THERE ARE NOT
ANY RED FLAG WARNINGS PLANNED AT THIS TIME. HOWEVER...HEIGHTENED FIRE
WEATHER CONCERNS WILL CONTINUE THROUGH MONDAY.
BY TUESDAY...THE OFFSHORE FLOW IS EXPECTED TO BECOME WEAK IN THE
MORNING...THEN SWITCHING TO ONSHORE IN THE AFTERNOON. THIS WILL BRING
A COOLING TREND TO THE AREA...MOST NOTICEABLE ALONG THE COAST.
*** FROM PREVIOUS DISCUSSION ***
.LONG TERM (THU-SUN)...UPPER LEVEL LONG WAVE RIDGE WILL GRADUALLY
SHIFT NORTH WHILE SHIFTING WEST THROUGH THE PERIOD. HAVE ADDED
SLIGHT CHANCE OF LIGHT SHOWERS OVER THE ENTIRE AREA SUNDAY AS A
TROUGH DIVES SOUTH..WITHIN THE NORTH FLOW..AND PHASES WITH A WEAK
TROUGH..WITHIN THE WESTERLY FLOW OVER THE EASTERN PAC..AND MOVES
OVER THE AREA. OTHERWISE A WARMING TREND WILL LIKELY CONTINUE THU
UNDER CLEAR SKIES AND WEAK OFFSHORE WINDS. AS THE RIDGE BEGINS TO
SHIFT WEST TEMPERATURES WILL GRADUALLY COOL TO NEAR NORMAL THROUGH
SAT THEN CONTINUE TO COOL A COUPLE OF DEGREES BELOW NORMAL SUN UNDER
PARTLY CLOUDY SKIES.
&&
.AVIATION...30/0430Z.
HIGH CONFIDENCE IN CURRENT TAFS WITH CLEAR SKIES EXPECTED ACROSS THE
AREA. BREEZY CONDITIONS EXPECTED WITH LOW LEVEL WIND SHEAR AT KBUR
AND KVNY THROUGH A GOOD PORTION OF THE NIGHT.
KLAX...HIGH CONFIDENCE IN VFR CONDITIONS THROUGH SUNDAY NIGHT. WEAK
NE TO E WINDS EXPECTED TO RETURN AFTER 12Z TONIGHT...WITH SPEEDS
GENERALLY REMAINING UNDER 07 KTS.
KBUR...HIGH CONFIDENCE IN VFR CONDITIONS THROUGH SUNDAY NIGHT. LOW
LEVEL WIND SHEAR AT TIMES THROUGH MIDNIGHT OR SO.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS (SEE LAXMWWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
&&
$$
PUBLIC...GOMBERG
AVIATION...GOMBERG
SYNOPSIS...BARTLING
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