Flash Flood Warning 26, NWS San Diego, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
200 PM PST MON DEC 20 2010

.SYNOPSIS...MOIST FLOW HEADING INTO SOUTHERN CALIFORNIA WILL BRING
PERIODS OF RAIN AND POSSIBLE FLOODING PROBLEMS THROUGH WEDNESDAY.
THE LOW PRESSURE TROUGH OVER THE EAST PACIFIC WILL FINALLY MOVE OUT
OF THE AREA WEDNESDAY NIGHT...AND BUILDING HIGH PRESSURE WILL BRING
DRY WEATHER THURSDAY INTO THE WEEKEND.

&&

.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.

RAIN HAS GOTTEN HEAVIER WITH A BAND SLOWLY MOVING SOUTHEAST THIS
AFTERNOON...AND WILL CONTINUE INTO SAN DIEGO COUNTY BY SUNDOWN. WITH
THE GROUND LESS ABLE TO ABSORB THE RAIN...MUCH OF THE RAIN WILL TURN
INTO RUNOFF. ENOUGH OF THAT WILL CAUSE SOME KIND FLOODING IN ALL ITS
FORMS...PONDING OF WATER IN STREETS...FLASH FLOODS AND DEBRIS FLOWS
MAINLY IN STEEP TERRAIN...RIVERS RISING...ETC. THE FLASH FLOOD WATCH
IS IN EFFECT AND PEOPLE SHOULD BE PREPARED. THE MOST INTENSE RAIN
APPEARS THIS AFTERNOON AND EVENING...AND AGAIN WEDNESDAY MORNING AS
THE HOSE OF MOISTURE SHIFTS AROUND A BIT. SNOW LEVELS WILL REMAIN
HIGH...BUT GRADUALLY DROPPING THROUGH WEDNESDAY WHEN SKI RESORTS
WILL PICK UP SOME GOOD SNOW FOR A SHORT TIME. WINDS WILL BE BRISK AT
TIMES...BUT NOT OVERLY STRONG. THEY WILL GET STRONGER WITH THE
FRONTAL PASSAGE WEDNESDAY MORNING. THE LONG MOISTURE PLUME DIRECTED
AT CALIFORNIA FOR FIVE DAYS NOW WILL FINALLY GET SHOVED ASIDE
TUESDAY NIGHT BY THE UPPER TROUGH OFF THE COAST WHICH FINALLY PUSHES
ASHORE. AS THE TROUGH AND ITS ASSOCIATED COLD FRONT MOVE INLAND
WEDNESDAY...THE PRECIPITATION WILL END WEDNESDAY AFTERNOON AND
EVENING. THE COLD AIR ASSOCIATED WITH THIS FRONT WILL DESTABILIZE
THE ATMOSPHERE ENOUGH TO ADD SOME THUNDERSTORMS TO THE FORECAST
WEDNESDAY. THEN HIGH PRESSURE ALOFT BUILDS TO GIVE US A FEW FAIR AND
DRY DAYS THURSDAY THROUGH CHRISTMAS. ANOTHER TROUGH HEADS INTO
CALIFORNIA SATURDAY NIGHT AND SUNDAY AND GUIDANCE HAD SHOWED PROMISE
FOR ANOTHER FRONTAL LIKE RAIN EVENT...BUT THE GUIDANCE HAS BACKED
OFF THIS IDEA FOR NOW AND THERE IS ONLY A SLIGHT CHANCE.

&&

.AVIATION...
202130Z...MODERATE TO HEAVY RAIN WILL BECOME MORE WIDESPREAD THROUGH
THIS EVENING. MVFR CIGS/VSBY WILL LOWER TO IFR/LIFR IN RAIN. RAIN
WILL TAPER OFF TO SHOWERS EARLY TUESDAY MORNING AND CONTINUE THROUGH
TUESDAY AFTERNOON. HIGHER TERRAIN WILL BE OBSCURED AT TIMES.

.MARINE...
A MODERATE WEST NORTHWEST SWELL WILL CONTINUE THROUGH TUESDAY...THEN
DECREASE ON WEDNESDAY. A SOUTHWEST WIND SWELL IS EXPECTED TODAY
THROUGH WEDNESDAY. WINDS WILL CONTINUE TO BE GUSTY AT TIMES...THEN
BECOMING QUITE STRONG LATE TUESDAY INTO WEDNESDAY AS A COLD FRONT
MOVES THROUGH WITH WINDS APPROACHING SMALL CRAFT ADVISORY CRITERIA.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

FLASH FLOOD WATCH IN EFFECT THROUGH WEDNESDAY AFTERNOON...SEE
LAXFFASGX.

SPECIAL WEATHER STATEMENT...SEE LAXSPSSGX.

&&

PUBLIC...MM
AVIATION...SS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SAN DIEGO CA
400 AM PST MON DEC 20 2010

CAZ042-043-048-050-055>058-060>062-211200-
ORANGE COUNTY COASTAL AREAS-
SAN DIEGO COUNTY COASTAL AREAS-
SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE-
SAN DIEGO COUNTY VALLEYS-
SAN BERNARDINO COUNTY MOUNTAINS-
RIVERSIDE COUNTY MOUNTAINS-
SANTA ANA MOUNTAINS AND FOOTHILLS-
SAN DIEGO COUNTY MOUNTAINS-
APPLE AND LUCERNE VALLEYS-
COACHELLA VALLEY-
SAN DIEGO COUNTY DESERTS-
400 AM PST MON DEC 20 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR
ALL OF EXTREME SOUTHWESTERN CALIFORNIA.

.DAY ONE...TODAY THROUGH TONIGHT

A LARGE PACIFIC PLUME OF MOISTURE AHEAD OF AN ADVANCING TROUGH OF
LOW PRESSURE IS EXPECTED TO BRING HEAVY RAINS AND THE POTENTIAL FOR
SERIOUS FLOODING BETWEEN LATE THIS AFTERNOON THROUGH WEDNESDAY
AFTERNOON. A FLASH FLOOD WATCH IS IN EFFECT FOR ENTIRE AREA.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

HEAVY RAINS AND THE POTENTIAL FOR SERIOUS FLOODING WILL CONTINUE
TUESDAY THROUGH WEDNESDAY AFTERNOON.

THE SAN BERNARDINO AND RIVERSIDE COUNTY MOUNTAINS COULD GET HEAVY
SNOW DOWN TO 6000 FEET TUESDAY NIGHT INTO WEDNESDAY AS THE COLD
FRONT COMES IN...AND A WINTER STORM WARNING MAY BE NEEDED THEN.

MODELS ALSO INDICATE THAT STRONG THUNDERSTORMS AND WATERSPOUTS
COULD ACCOMPANY THE COLD FRONT ON WEDNESDAY. STRONG SOUTH WINDS
ARE EXPECTED IN ADVANCE OF THE FRONT SO WIND ADVISORIES IN THE
COASTS AND VALLEYS MAY BE REQUIRED ON TUESDAY AND WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION IS NOT REQUESTED FOR THIS AREA...HOWEVER
WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS.

MACKECHNIE