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603
FXUS66 KSGX 211734
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
935 AM PST SUN DEC 21 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE PACIFIC THROUGH TUESDAY...BRINGING
WARMER CONDITIONS AND PERIODS OF GUSTY OF OFFSHORE WINDS NEAR THE
COASTAL FOOTHILLS.  THE STRONGEST OFFSHORE WINDS WILL OCCUR ON
MONDAY NIGHT AND TUESDAY MORNING...BEFORE WEAKENING INTO WEDNESDAY.
A TROUGH OF LOW PRESSURE WILL BRING COOLER CONDITIONS TO SOUTHERN
CALIFORNIA AND LOCALLY GUSTY WEST WINDS TO THE MOUNTAINS AND DESERTS
ON CHRISTMAS DAY.  HOWEVER...HIGH PRESSURE WILL REBUILD...WITH
WARMER CONDITIONS AND MORE OFFSHORE WINDS POSSIBLE FOR THE WEEKEND.

WINTER BEGINS AT 3:03 PM PST THIS AFTERNOON.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

WATER VAPOR IMAGERY SHOWS HIGH PRESSURE BUILDING ALONG 130 WEST THIS
MORNING...WITH SOUTHERN CALIFORNIA UNDER MOIST NORTHWESTERLY FLOW
ALOFT.  AS A RESULT...HIGH CLOUD COVER CONTINUES TO SPILL INTO THE
REGION TODAY...EVEN THOUGH THERE ARE MORE SUN BREAKS TODAY.  A
GRADUAL WARMING TREND WILL ALSO BEGIN TODAY...AS THE 12Z KNKX
SOUNDING SHOWS SOME MINOR WARNING NEAR THE SURFACE...WITH GREATER
WARMING ALOFT.  CURRENTLY...TEMPERATURES ARE ALREADY RUNNING 2 TO 6
DEGREES WARMER...AND EXPECT SIMILAR TRENDS WITH THE AFTERNOON
HIGHS.

THIS WARMING TREND ALONG WITH DEVELOPING OFFSHORE WINDS WILL BE THE
PREDOMINANT WEATHER STORY THROUGH TUESDAY...AS TEMPERATURES WILL RUN
BETWEEN 6 TO 12 DEGREES ABOVE NORMAL FOR BOTH MONDAY AND TUESDAY.
AS FOR THE WINDS...SURFACE GRADIENTS ARE CURRENTLY WEAKLY OFFSHORE
TO THE NORTH...BUT STILL ONSHORE TO THE EAST.  OFFSHORE GRADIENTS
WILL GRADUALLY INCREASE THROUGH MONDAY...THEN PEAK LATE MONDAY NIGHT
AND TUESDAY MORNING...BEFORE WEAKENING THROUGH WEDNESDAY.  THE UPPER
LEVEL SUPPORT ALSO REMAINS WEAK THROUGH MONDAY...BUT INCREASES
SIGNIFICANTLY MONDAY NIGHT AND TUESDAY MORNING.  THE 12Z NAM NOW
SHOWS 35 TO 45 KTS AT 850 MBS OVER THE SAN BERNARDINO AND SANTA ANA
MOUNTAINS BETWEEN 06Z AND 15Z ON TUESDAY...AND UP TO 50 KTS AT 925
MBS.  THIS LIKELY MEANS THAT THE LOCAL WRF WILL BE STRONGER...BUT
AWAIT TO SEE WHAT THE OTHER HIGH RESOLUTION MODELS DO WITH THESE
WINDS...AS IT APPEARS SOME SORT OF WIND PRODUCTS WILL LIKELY BE
NEEDED.

A TROUGH OF LOW PRESSURE WILL THEN MOVE INLAND ACROSS THE PACIFIC
NORTHWEST LATE WEDNESDAY AND CHRISTMAS DAY...SQUASHING THE RIDGE
OVER SOUTHERN CALIFORNIA.  THIS WILL BRING COOLER CONDITIONS AND THE
RETURN OF ONSHORE FLOW TO THE REGION THROUGH FRIDAY.  SOME LOCALLY
GUSTY WINDS WILL BE POSSIBLE IN THE MOUNTAINS AND DESERTS THESE DAYS
AS WELL.  HIGH PRESSURE WILL THEN REBUILD ALONG THE WEST COAST FOR
NEXT WEEKEND...WITH WARMER CONDITIONS AND MORE OFFSHORE WINDS
POSSIBLE.

&&

.AVIATION...
210950Z...COAST/VALLEYS...SCT-BKN CLOUDS WITH BASES 2000-3500 FEET
MSL WITHIN ABOUT 20 MI OF THE COAST AND AREAS OF VIS 3-5SM IN BR/HZ
IN THE VALLEYS...LOCALLY 1SM OR LESS. CLOUDS BECOMING FEW-SCT AND
VIS RESTRICTIONS CLEARING BY 15Z. OTHERWISE SCT-BKN CLOUDS AOA 15000
FT MSL AND UNRESTRICTED VIS THROUGH MON MORNING.

MTNS/DESERTS...SCT-BKN CLOUDS AOA 15000 FEET AND UNRESTRICTED VIS
THROUGH MON MORNING.

&&

.MARINE...
205 AM...COMBINED SEAS TO 8 FEET ARE POSSIBLE OVER PORTIONS OF THE
OUTER COASTAL WATERS THIS MORNING. OTHERWISE NO HAZARDOUS MARINE
WEATHER IS EXPECTED THROUGH THURSDAY.


&&

.FIRE WEATHER (FROM PREVIOUS DISCUSSION)...
OFFSHORE FLOW AND DRIER CONDITIONS WILL DEVELOP ACROSS SOUTHERN
CALIFORNIA FOR MONDAY THROUGH WEDNESDAY. GUSTY NORTHEAST WINDS WILL
DEVELOP NEAR THE COASTAL FOOTHILLS MONDAY...PEAK TUESDAY
MORNING...THEN WEAKEN INTO WEDNESDAY. HIGH TEMPERATURES WILL WARM
THROUGH TUESDAY...THEN BEGIN TO COOL WEDNESDAY. LOWEST INLAND
HUMIDITIES WILL FALL TO 10 TO 15 PERCENT FOR TUESDAY AND
WEDNESDAY...THEN RECOVER THURSDAY. INCREASED FUEL MOISTURE DUE TO
RECENT PRECIPITATION WILL LIMIT THE POTENTIAL FIRE DANGER.

&&

.SKYWARN...
SKYWARN ACTIVATION WILL NOT BE NEEDED TODAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...BEACH HAZARDS STATEMENT THROUGH TUESDAY MORNING FOR THE BEACHES
     IN THE ORANGE COUNTY COASTAL AREAS...SAN DIEGO COUNTY
     COASTAL AREAS.

PZ...NONE.

&&

$$

PUBLIC...PALMER
AVIATION/MARINE...JJT
FIRE WEATHER...17







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