Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 272226
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
130 PM PST SAT DEC 27 2014

.SYNOPSIS...
NEAR NORMAL CONDITIONS ARE EXPECTED FOR THE NEXT SEVERAL DAYS
NEAR THE COAST AS HIGH PRESSURE SURFACE AND ALOFT DOMINATES THE
LOCAL WEATHER. BELOW NORMAL TEMPERATURES OVERNIGHT WILL CONTINUE
INLAND AREAS THROUGH THE REST OF THE WEEKEND WITH FROST IN SOME
WIND-SHELTERED LOCATIONS AGAIN TONIGHT. OTHERWISE...CLEAR SKIES.
INCREASING CLOUDS BEGINNING LATE SUNDAY AFTERNOON INTO MONDAY POINTS
TOWARD WARMER NIGHTS IN THE VALLEYS EARLY IN THE WEEK AS A STORM
SYSTEM APPROACHES. ON TUESDAY...THE STORM WILL BRING AN INCREASING
CHANCE OF RAIN AND SNOW TO THE REGION. THUNDERSTORMS WILL ALSO BE
POSSIBLE TUESDAY NIGHT AND WEDNESDAY. THIS STORM FROM THE GULF OF
ALASKA WILL BE A COLD STORM ...WITH SNOW LEVELS POSSIBLY DOWN AROUND
2000 FEET AT TIMES MIDWEEK. THE STORM SHOULD MOVE OUT ON
THURSDAY...BUT TEMPERATURES WILL CONTINUE BELOW SEASONAL NORMALS.

&&

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

.SHORT TERM...
FINALLY WE SEE THE DROPOFF IN THE WINDS AS THE FREMONT CANYON WIND
GUSTS FALL TO ONLY INTO THE 20S. THE DRY AIRMASS BROUGHT FROSTY
CONDITIONS THIS MORNING...AND SHOULD AGAIN BRING FROSTY CONDITIONS
TO SOME AREAS TONIGHT INTO SUNDAY.

SUNDAY AFTERNOON AND EVENING SHOULD MARK THE BEGINNING OF A
TRANSITION PERIOD BETWEEN CLEAR...DRY OFFSHORE FLOW CONDITIONS AND
THE MOIST...CLOUDY ONSHORE FLOW CONDITIONS. RAPID DEVELOPMENT OF A
DEEP MARINE LAYER SHOULD KEEP THE COASTAL AREAS FROM SEEING DENSE
FOG THAT NORMALLY FOLLOWS A PERIOD OF OFFSHORE WINDS. THE LOCAL WRF
INDICATES A SIGNIFICANT MARINE PUSH OF LOW CLOUDS EARLY EVENING ON
MONDAY. BUFKIT ALSO SHOWS THE MARINE LAYER DEEPENING UP TO OVER 3000
FEET DEEP BY SUNRISE ON MONDAY.

&&

.LONG TERM...
A LOW ORIGINATING IN THE GULF OF ALASKA WILL MOVE INTO CANADA...THEN
DROP ALMOST STRAIGHT SOUTH TO OUR AREA. IT WILL BE BRINGING SOME
COLD WEATHER TO THE REGION...WITH PRECIPITATION AS WELL. THE GFS
ENSEMBLE PLACES THE LOW OVER THE SOUTHERN SIERRAS BY LATE WEDNESDAY
EVENING WITH A GOOD TAP INTO THE EASTERN PACIFIC. THIS EVENT LOOKS
TO BE A RATHER CONVECTIVE ONE...SO PRECIPITATION AMOUNTS WILL BE
VERY TRICKY TO PREDICT. THE ECMWF IS SLOWER MOVING IT OUT THAN THE
GFS IS...AND PER THE ECMWF IT LOOKS LIKE THE STORM COULD LINGER INTO
THURSDAY MORNING...THEN BEGIN TO PUSH EAST...LEAVING SOME GUSTY
NORTH TO NORTHEAST WINDS IN ITS WAKE. CONTINUED COOL CONDITIONS CAN
BE EXPECTED FRIDAY...THEN DRY WEATHER INTO THE WEEKEND.

&&

.AVIATION...
272030Z...CLEAR SKIES AND UNRESTRICTED VIS THROUGH 290000Z.
WINDS...ARE A BIT DIFFICULT...BUT CONTINUE TO DIMINISH AND REMAIN
BELOW LEVELS TO GREATLY IMPACT OPERATIONS.

&&

.MARINE...
WINDS CONTINUE TO DIMINISH...BUT WILL BECOME MORE ONSHORE THROUGH
THE BEGINNING OF THE WEEK WITH A CHANCE OF SHOWERS BY LATE TUESDAY.

&&

.SKYWARN...
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM PST SUNDAY FOR THE
     SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND
     EMPIRE...SAN DIEGO COUNTY VALLEYS.

     FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM PST SUNDAY FOR THE
     SAN DIEGO COUNTY DESERTS.

     FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM PST SUNDAY FOR THE
     COACHELLA VALLEY.

PZ...NONE.

&&

$$

PUBLIC...SMALL
AVIATION/MARINE...PIERCE








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