FXUS66 KSGX 220431
AFDSGX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 PM PST MON DEC 21 2009
.SYNOPSIS...AN UPPER TROUGH MOVING THROUGH WILL BRING CLOUDS AND
SCATTERED LIGHT SHOWERS TONIGHT INTO TUESDAY. THERE WILL BE STRONG
GUSTY WINDS TUESDAY AFTERNOON AND EVENING...MAINLY IN THE MOUNTAINS
AND DESERTS. HIGH PRESSURE ALOFT AND OFFSHORE FLOW WILL BRING FAIR
SKIES AND WARMER WEATHER LATER IN THE WEEK WITH LOCAL GUSTY WINDS
THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES WEDNESDAY AND
THURSDAY. ANOTHER UPPER LOW WILL BRING A CHANCE OF SHOWERS SUNDAY
AND MONDAY.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
.SHORT TERM (TONIGHT-THURSDAY)...THERE WAS LOTS OF MID TO HIGH
CLOUDINESS THIS EVENING AND ISOLATED LIGHT SHOWERS. THERE WERE ALSO
PATCHES OF LOW CLOUDS NEAR THE COAST. THE 00Z NKX SOUNDING SHOWED
THE MOISTURE IN THE MID TO UPPER LEVELS WITH STRONG WLY WINDS ALOFT.
WEAK ONSHORE GRADIENTS AND ONSHORE TRENDS.
THE PASSING UPPER TROUGH WILL CONTINUE TO BRING SCATTERED LIGHT
SHOWERS INTO TUESDAY. SHOWERS WILL INITIALLY BE SPRINKLES FROM THE
MID AND HIGH CLOUDS THEN THE FRONT WILL BRING MORE LOW LEVEL
MOISTURE W OF THE MOUNTAINS LATE TONIGHT AND TUESDAY MORNING.
RAINFALL AMOUNTS WILL GENERALLY BE LESS THAN A TENTH OF AN INCH.
STRONGER ONSHORE FLOW AND WINDS ALOFT WILL CAUSE LOCAL STRONG GUSTY
WLY WINDS TUESDAY AFTERNOON AND NIGHT. THE STRONGEST WINDS WILL BE
IN THE MOUNTAINS AND DESERTS AND OVER THE COASTAL WATERS. MOST WINDS
WILL BE ADVISORY STRENGTH...45 TO 55 MPH. HOWEVER...THERE COULD BE
ISOLATED STRONGER GUSTS ACROSS THE MOUNTAIN RIDGES THAT COULD
DESCEND INTO THE SRN DESERTS. IT WILL ALSO BE QUITE WINDY W OF THE
MOUNTAINS IN THE COASTAL AND VALLEY AREAS. COLD NLY WINDS WILL
DEVELOP LATE TUESDAY...TURNING OFFSHORE AND GRADUALLY WEAKENING
WEDNESDAY AND THURSDAY. THE OFFSHORE FLOW WILL CAUSE LOCAL GUSTY
WINDS THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES. LOCAL GUSTS
COULD GET NEAR ADVISORY STRENGTH. COOLER TUESDAY THEN A LITTLE
WARMER WEDNESDAY AND THURSDAY...ESPECIALLY W OF THE MOUNTAINS.
DESPITE THE WARMING...MAX TEMPS WILL STILL BE A LITTLE BELOW
SEASONAL IN THE COOL OFFSHORE FLOW. SKIES WILL BE MOSTLY CLEAR
TUESDAY NIGHT THROUGH THURSDAY. COOL AT NIGHT IN AREAS PROTECTED
FROM THE WINDS.
&&
.LONG TERM (FRIDAY-MONDAY)...WEAK OFFSHORE FLOW WILL CONTINUE FRIDAY
AND SATURDAY FOR FAIR SKIES AND NEAR SEASONAL TEMPS. A TROUGH
APPROACHING FROM THE W WILL BRING MORE CLOUDS AND COOLING EARLY NEXT
WEEK WITH A CHANCE PRECIP. THE EXACT TRACK OF THE LOW IS STILL
UNCERTAIN WITH THE POSSIBILITY OF SUBSTANTIAL PRECIP IF THE LOW MOVE
DIRECTLY INTO SRN CA. HOWEVER...IT COULD GO S AND LEAVE SRN CA WITH
LITTLE PRECIP.
&&
.AVIATION...
220415Z...TONIGHT THE MARINE LAYER WILL RAPIDLY DEEPEN TO 5000 FEET
BY TUESDAY MORNING. CLOUD BASES WILL LIFT TO 2500-3000 FEET MSL BY
12Z TUESDAY. INTERMITTENT LIGHT SHOWERS WILL INCREASE IN COVERAGE
BTWN 09-15Z AS THE COLD FRONT NEARS/PASSES.
EXPECT A RAPID WIND SHIFT FROM THE SOUTH TO THE WEST LATE TUESDAY
MORNING WITH THE PASSAGE OF THE COLD FRONT. STRONG...GUSTY WEST
WINDS ARE LIKELY BEHIND THE FRONT...STRONGEST BETWEEN 18Z TUESDAY
AND 00Z WEDNESDAY. WINDS NEAR THE COAST WILL BE STRONGEST. AT KSAN
SUSTAINED 15-25 KT WINDS WILL GUST TO 30 KTS AT TIMES.
THE STRONG NORTHWEST WINDS ACROSS THE MOUNTAINS WILL PRODUCE
MOUNTAIN WAVE AND ROTOR ACTIVITY OVER THE EASTERN DESERTS AT PSP AND
TRM TUESDAY AFTERNOON AND EVENING.
&&
.MARINE...
A COLD FRONT WILL RACE SOUTHWARD ACROSS THE COASTAL WATERS TUESDAY
MORNING. STRONG WEST TO NORTHWEST WINDS BEHIND THIS COLD FRONT WILL
INCREASE TO 20-30 KTS TUESDAY AFTERNOON. WINDS WILL GUST CLOSE TO 40
KTS IN THE OUTER WATERS. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED FOR
TUESDAY AND TUESDAY NIGHT.
A STEEP SHORT-PERIOD 9 FT SWELL WILL CREATE HAZARDOUS SEAS TUESDAY
AFTERNOON AND EVENING.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FOR MOUNTAINS AND DESERTS TUESDAY MORNING THROUGH
TUESDAY EVENING...SEE LAXNPWSGX.
SMALL CRAFT ADVISORY FOR COASTAL WATERS TUESDAY MORNING THROUGH LATE
TUESDAY NIGHT...SEE LAXMWWSGX.
&&
$$
PUBLIC...ATKIN
AVIATION/MARINE...MOEDE
