FXUS66 KLOX 050611 AAA
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1010 PM PST FRI DEC 4 2009
UPDATE FOR NEW AVIATION DISCUSSION
.SYNOPSIS...
INCREASING CLOUDS ON SATURDAY WILL COOL TEMPERATURES A FEW
DEGREES...AND A CHANCE OF DRIZZLE WITH SOME LIGHT RAIN MAY AFFECT
SOME AREAS SATURDAY NIGHT INTO SUNDAY. A COLD LOW PRESSURE SYSTEM
DROPPING DOWN FROM THE NORTH WILL BRING RAIN AND MOUNTAIN SNOW TO
THE AREA SUNDAY NIGHT INTO MONDAY. ANOTHER STORM IS FORECAST TO
ARRIVE LATE WEDNESDAY...CONTINUING INTO THURSDAY.
&&
.SHORT TERM (TONIGHT-MON)...WEAK MARINE INVERSION LESS THAN 1000 FT
DEEP AT LAX THIS EVENING. SOME LOW CLOUDS WERE NOTED ALONG PORTIONS
OF THE CENTRAL COAST AND MAY LINGER IN THE AREA OVERNIGHT...WITH
PATCHY DENSE FOG POSSIBLE LATER TONIGHT. SOME LOW CLOUDS AND PATCHY
DENSE FOG WILL BE POSSIBLE ALONG THE COAST S OF POINT CONCEPTION
OVERNIGHT AS WELL. OTHERWISE...VARYING AMOUNTS OF HI CLOUDS WILL
PREVAIL OVER THE FORECAST AREA TONIGHT.
A BROAD UPPER LEVEL TROUGH WILL MOVE INTO CA ON SAT. THIS UPPER TROF
WILL MOVE E FOR SUN...WITH ANOTHER UPPER TROF EXPECTED TO APPROACH
SOUTHERN CA FROM THE E PAC. THIS SYSTEM WILL THEN MOVE INTO SRN CA
LATE SUN NIGHT AND MON MORNING...WITH A SHARPER UPPER TROF EXPECTED
TO MOVE INTO NORTHERN CA DURING THE DAY MON. DRY WEATHER IS EXPECTED
ACROSS THE DISTRICT SAT AND SAT NIGHT. WITH A DEEPENING MARINE LAYER
SAT NIGHT AND SUN MORNING...IT LOOKS LIKE THERE WILL BE A CHANCE OF
SOME LIGHT SHOWERS OVER PORTIONS OF VTU/L.A. COUNTIES FROM THE COAST
TO THE LOWER COASTAL SLOPES. SKIES WILL BE PARTLY CLOUDY SAT FOR THE
MOST PART THEN TURN MOSTLY CLOUDY SAT NIGHT INTO SUN. TEMPS ARE
EXPECTED TO BE A FEW DEGREES BELOW NORMAL SAT THEN SIGNIFICANTLY
BELOW NORMAL FOR SUN.
A STORM SYSTEM WILL APPROACH THE DISTRICT FROM THE E PAC SUN
NIGHT...BRINGING AN INCREASING CHANCE OF RAIN TO THE ENTIRE
DISTRICT. RAIN WILL BE LIKELY IN ALL AREAS ON MON AS THE SYSTEM
MOVES INTO THE REGION. THE COLD FRONT ASSOCIATED WITH THE STORM
SHOULD PASS THRU THE DISTRICT RATHER QUICKLY LATER MON AFTERNOON AND
EARLY MON EVENING. THE LATEST GFS AND WRF ARE BOTH INDICATING DECENT
S TO SE LOWER LEVEL FLOW AHEAD OF THE FRONT DURING THE DAY
MON...ALONG WITH DEEP MOISTURE AND HI OMEGAS. IN FACT...THE WRF
FORECASTS OMEGAS OVER 50 MICROBARS/SEC OVER PORTIONS OF VTU/L.A.
COUNTIES JUST AHEAD OF THE FRONT MON AFTERNOON...INDICATING THE
POSSIBILITY OF A PERIOD OF SIGNIFICANT RAINFALL OVER THE SBA S COAST
AND MOUNTAINS AND THRU VTU/L.A. COUNTIES...WITH GOOD OROGRAPHIC
ENHANCEMENT ON THE S AND SE FACING SLOPES. THE LATEST WRF IS
SUGGESTING RAINFALL FROM LATE SUN NIGHT THRU LATE MON COULD BE UP TO
AN INCH ALONG THE COAST AND FROM 1.50 TO 2.25 INCHES IN THE
MOUNTAINS...A BIT MORE THAN IS CURRENTLY EXPECTED. A COUPLE MORE
MODEL RUNS WILL BE NECESSARY BEFORE WE HAVE SIGNIFICANT CONFIDENCE
IN THESE MODEL FORECAST RAINFALL TOTALS. AS WE DRAW CLOSER TO THE
EVENT...AND IT APPEARS THESE HIGHER PRECIP ESTIMATES ARE
REASONABLE...THEN THERE WOULD LIKELY BE THE NEED OF A FLASH FLOOD
WATCH FOR THE RECENT BURN AREAS BELOW THE SNOW LEVEL WHICH IS
EXPECTED TO FALL GENERALLY TO NEAR 4500 FT ON MON. ABOVE THE SNOW
LEVEL...ACCUMULATING SNOW WILL BE LIKELY ON MON...BRINGING WINTRY
CONDITIONS WITH GUSTY WINDS AND POOR DRIVING CONDITIONS. A WINTER
STORM WATCH FOR THE VTU/L.A. MOUNTAINS MAY EVENTUALLY BE NEEDED FOR
THIS SYSTEM AS WELL. PLEASE SEE THE LATEST SPECIAL WEATHER STATEMENT
(LAXSPSLOX) FOR FURTHER DETAILS ON THIS UPCOMING STORM SYSTEM.
...FROM PREVIOUS DISCUSSION...
.LONG TERM (MON NIGHT-THU)...MORE COLD AIR ARRIVES MONDAY NIGHT TO
DROP THE SNOW LEVEL LOCALLY DOWN TO 2500 FEET ON THE NORTHERN SLOPES
OF THE MOUNTAINS AND IN THE ANTELOPE VALLEY. OTHER SECTIONS
VULNERABLE TO THE SNOW INCLUDE INTERIOR SAN LUIS OBISPO COUNTY. MANY
OTHER LOCALITIES WILL HAVE RATHER COLD TEMPERATURES OVERNIGHT.
POPS CONTINUE FOR TUESDAY AND TUESDAY NIGHT...ALTHOUGH THOSE PERIODS
MAY ULTIMATELY BE DRY DEPENDING ON THE TIMING OF THE THE STORM
SYSTEMS.
SPEAKING OF STORM SYSTEMS...ANOTHER STORM IS DUE WEDNESDAY AND
ESPECIALLY WEDNESDAY NIGHT INTO EARLY THURSDAY AND THIS SECOND
SYSTEM LOOKS TO BE EVEN WETTER THAN THE FIRST WITH A SUBTROPICAL
FEED OF MOISTURE THAT ORIGINATED FROM WHAT USED TO BE TYPHOON NIDA
IN THE WESTERN PACIFIC. ALTHOUGH SPECIFIC RAINFALL AMOUNTS ARE NOT
EASY TO COME BY AT THIS TIME...IF CURRENT MODEL PROJECTIONS ARE
CORRECT...THAN WE WOULD LIKELY HAVE SOME HYDROLOGIC CONCERNS AROUND
THE BURN AREAS...ESPECIALLY THE STATION BURN AREA.
&&
.AVIATION...05/0610Z...MODERATE TO HI CONFIDENCE IN CURRENT TAF
PACKAGE. LOW CLOUDS AND LIFR CONDITIONS WILL AFFECT KSBP AND KSMX AT
TIMES OVERNIGHT INTO SAT MORNING...BUT CIGS MAY SCATTER OUT AT
TIMES. FOR KPRB...THERE IS A 40 PERCENT CHANCE LOW CLOUDS AND LIFR
CONDITIONS COULD DEVELOP AT THE AIRFIELD LATE TONIGHT INTO SAT
MORNING. OTHERWISE REMAINDER OF TAFS REASONABLE.
KLAX...GENERALLY HI CONFIDENCE IN CURRENT TAF...ALTHO THERE IS A 20
PERCENT CHANCE OF IFR CIGS DEVELOPING AT TIMES LATE TONIGHT AND
EARLY SAT.
KBUR...HI CONFIDENCE IN CURRENT TAF.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
PUBLIC...SIRARD/SWEET
AVIATION...SIRARD
SYNOPSIS...BARTLING
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