Stormy Weather

FXUS66 KLOX 231851 AAA
AFDLOX

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1050 AM PST WED JAN 23 2008

UPDATED AVIATION DISCUSSION

.SHORT TERM...
06Z MDLS THREW A MONKEY WRENCH IN TO THE FORECAST AND REMINDED
EVERYONE THAT WITH A BIG WET CUT OFF LOW AN EXACT FORECAST IS NOT
VERY LIKELY AT ALL. BOTH THE 00Z AND 06Z MDLS ARE FORECASTING A BIG
EVENT OVER THE NEXT 72 HOURS...BUT THE TIMING OF THE IMPULSES DIFFER
FROM 6 TO 12 HOURS BETWEEN THE TWO RUNS. REALISTICALLY THE ABILITY
TO TIME IMPULSES EVEN 12 TO 24 HOURS OUT WITH THIS SYSTEM IS NOT
GREAT. THE BEST FORECAST TOOLS FOR THIS KIND OF SYSTEM IS THE
SATELLITE.

CURRENTLY THE LOW IS NEARLY STATIONARY AT 36.6/127.7 A LARGE
MOISTURE PLUME IS ENTRAINED INTO THE SOUTHERN FLOW OF THE LOW AND IS
DRAPED ACROSS SANTA BARBARA COUNTY. MODERATE ISOLATED HEAVY RAIN IS
FALLING ACROSS VENTURA...SANTA BARBARA...AND SLO COUNTIES. L.A.
COUNTY IS ONLY PARTLY CLOUDY LARGELY OBLIVIOUS TO THE RAIN FALLING
TO THE NW. THE LOW WILL ELONGATE AND WOBBLE A LITTLE TO THE SOUTH
LATER TODAY AND THIS WILL DRIVE THE PLUME EASTWARD INTO L.A. COUNTY.
THE FREEZING LEVEL IS AT 5000 FEET AND THE SLOW LEVEL IS A FEW
HUNDRED FEET BELOW THAT. AS THE COLD AIR BEHIND THE PLUME MOVES INTO
THE AREA THE SNOW LEVEL WILL DROP TO 4000 FEET. WITH THE SLOW MOVING
BAND OF MODERATE PRECIPITATION ONE TO TWO FEET OF SNOW IS LIKELY
THROUGH THURSDAY MORNING. JET DYNAMICS LOOK GOOD STARTING THIS
AFTERNOON ESPECIALLY OVER SBA COUNTY.

RIGHT NOW THURSDAY LOOKS LIKE A LITTLE LULL IN THE STORM WITH JUST
SCATTERED SHOWERS THOROUGH THE AREA. STILL CANNOT TOTALLY BELIEVE
THIS FORECAST AS THE UPPER LOW COULD MOVE A LITTLE SLOWER OR THE
SECOND ONE A LITTLE FASTER.

A SECOND LOW PLUNGES DOWN THE COAST FRIDAY AND SETS UP IN NEARLY THE
SAME POSITION AS TODAYS. IT AGAIN IS FORECAST TO PULL A LARGE BAND
OF MOISTURE INTO THE AREA. THERE WILL BE TWO OR THREE PERIOD OF
MODERATE TO HEAVY RAIN FROM FRIDAY AFTERNOON TO SATURDAY MORNING
WITH THIS SYSTEM. ANOTHER WINTER WARNING MAY BE NEEDED FOR THIS TIME
PERIOD. WITH SO MUCH ANTECEDENT RAINFALL FLOOD POTENTIAL WILL BE
MAXIMIZED.

ACROSS SAN LUIS OBISPO AND SANTA BARBARA COUNTIES...RAINFALL TOTALS
FROM MONDAY THROUGH THE WEEKEND ARE EXPECTED TO AVERAGE 4 TO 7
INCHES IN COASTAL AND VALLEY AREAS...AND 6 TO 12 INCHES IN THE
FOOTHILLS AND MOUNTAINS. LOCAL TOTALS IN EXCESS OF 15 INCHES ARE
POSSIBLE ALONG SOUTH AND SOUTHWEST FACING MOUNTAIN SLOPES.

IN VENTURA AND LOS ANGELES COUNTIES...RAINFALL TOTALS FROM MONDAY
THROUGH THE WEEKEND ARE EXPECTED TO AVERAGE 2 TO 4 INCHES IN COASTAL
AND VALLEY AREAS...AND 4 TO 8 INCHES IN THE FOOTHILLS AND MOUNTAINS.
LOCAL TOTALS IN EXCESS OF 10 INCHES ARE POSSIBLE ALONG SOUTH AND
SOUTHWEST FACING MOUNTAIN SLOPES.

.LONG TERM...
EC AND GFS ARE NOT IN TOO BAD AN AGREEMENT FROM SUNDAY ONWARD.
SUNDAY LOOKS LIKE SHOWERS AS THE UPPER LOW KICKS OUT. ANOTHER
NORTHWEST IMPULSE SCOOTS THROUGH MONDAY AND WILL BRING A CHANCE OF
SHOWERS TO THE WHOLE AREA BUT RAINFALL AMOUNTS WILL BE LIGHT. THE
FLOW DRYS OUT TUESDAY BUT LATER TUESDAY YET ANOTHER IMPULSE ROLLS
THROUGH AND WILL BRING A SLIGHT CHANCE OF RAIN.

&&

.AVIATION...23/1830Z...
RAIN ACTIVITY CONTINUES OVER ALL AIRFIELDS EXCEPT LA COUNTY...WHICH
SHOULD BEGIN TO SEE SOME RAIN STARTING AFTER 20Z TO 22Z. MOST OF THE
AIRPORT WILL RUN MVFR/VFR WILL CIGS ABOVE 025 AND VIS ABOVE
5SM...EXCEPT DURING BRIEF HEAVY RAINFALL UNDER THE STRONGER
CELLS...WITH CIGS NEAR 015 AND VIS NEAR 2SM. LLWS MAY BE A CONCERN
AT KOXR KLAX AND KSBA AT TIMES...BUT CONFIDENCE IS LOW TO WARRANT
MENTION. ONE THUNDERSTORM HAS ALREADY FORMED NEAR KSBA IN THE WAKE
OF THE CHANNEL ISLANDS. WOULD EXPECT ANOTHER ONE OR TWO TO FORM LIKE
THAT THROUGH THE EVENING. SIMILAR THUNDERSTORMS MAY AFFECT KLAX AND
KLGB IN THE WAKE OF CATALINA ISLAND...SOMETIME AFTER 23Z.

FOR KLAX...VFR WILL CONTINUE THROUGH MOST OF THE PERIOD...EXCEPT FOR
A PERIOD BETWEEN 23Z AND 02 OR 03Z WITH MVFR CATS DURING RAIN. VIS
MAY BRIEFLY DROP TO 2SM DURING A HEAVY SHOWER BETWEEN 22Z AND 04Z.
THUNDERSTORM MAY IMPACT AIRPORT BETWEEN 23Z AND ABOUT 06Z. WINDS
WILL REMAIN NEAR 12 KT THROUGH ABOUT 06Z. DIRECTIONS WILL REMAIN
EAST THROUGH ABOUT 20Z...BUT BEGIN TO SWING SOUTHERLY
THEREAFTER...AND MAY BECOME SOUTHWESTERLY BY 02 TO 04Z. MORE EAST
WINDS ARE POSSIBLE AFTER 12Z.

FOR KBUR...VFR CONDITIONS WILL BECOME MVFR AFTER 22Z OR SO. MAY
BRIEFLY REACH IFR DURING A HEAVY SHOWER BETWEEN 21Z AND 03Z. SE
WINDS NEAR 10 KT WILL CONTINUE THROUGH ABOUT 05Z.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING (SEE LAXWSWLOX).
FLOOD WATCH (SEE LAXFFALOX).
SMALL CRAFT ADVISORY (SEE LAXCWFLOX).
MARINE WEATHER STATEMENT (SEE LAXMWSLOX).
SPECIAL WEATHER STATEMENT (SEE LAXSPSLOX).

&&




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