FXUS66 KMTR 141806
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
1000 AM PST MON DEC 14 2009

.DISCUSSION...AS OF 9:00 AM PST MONDAY...SKIES ARE PARTLY CLOUDY
ACROSS THE DISTRICT WITH VALLEY FOG. CLOUDS ARE INCREASING ACROSS
THE DISTRICT AHEAD OF THE NEXT SYSTEM.

SHOWERS HAVE FINALLY ENDED ACROSS THE DISTRICT THIS MORNING. FOG IS
ALSO STARTING TO LIFT IN THE VALLEYS. HIGH CLOUDS ARE STARTING TO
MOVE OVERHEAD AS THE NEXT UPSTREAM SYSTEM APPROACHES THE COAST.
HOWEVER...BEFORE THAT IT WILL BE DRY AND COOL TODAY AS A SHORT-WAVE
RIDGE MOVES OVERHEAD.

WARM ADVECTION SETS UP IN EARNEST IN THE NORTH BAY LATER TONIGHT...
WITH GOOD ISENTROPIC LIFT IN THE NORTH BAY TUESDAY AND TUESDAY NIGHT.
HIGH TPW MOVES INTO THE NORTH BAY...GREATER THAN 1 INCH LATER TONIGHT
AND ON TUESDAY. AMSU IMAGERY IS INDC A LONG PLUME OF GREATER THAN 1
INCH TPW FROM 36/134 STRETCHING WSW WELL PAST THE DATELINE. AS THE
WARM FRONT SAGS SOUTH IT WILL LOST ITS UPPER SUPPORT. IN FACT...
MODELS ARE PRETTY MUCH WASHING OUT THE FRONT IN THE MONTEREY AREA
LATE WEDNESDAY. RAINFALL AMOUNTS COULD BE COPIOUS IN THE NORTH BAY
WITH THIS SYSTEM.

RIDGING BUILDS INTO THE DISTRICT FOR DRY WEATHER THURSDAY AND FRIDAY.
HOWEVER...THE LATEST GFS DOES BRING SOME WEAK WARM ADVECTION RAIN
LATE THUR NIGHT INTO THE NORTH BAY. AS FOR THE WEEKEND...WHEREAS THE
PREVIOUS MODEL RUNS WERE DRY...THE LATEST GFS BRINGS A SHORTWAVE
ACROSS THE DISTRICT FOR POSSIBLE SHOWERS ON SAT AND SAT NIGHT. WILL
WAIT FOR THE 12Z ECMWF BEFORE MAKING ANY CHANGES TO THE EXTENDED.

WILL BE MAKING UPDATES TO THE SHORT TERM FCST BY 10 AM.

&&

.AVIATION...AS OF 10:00 AM PST MONDAY...SKIES ARE CONTINUING TO
CLEAR ACROSS OUR AREA THIS MORNING. WINDS WILL SWITCH TO A MORE
SOUTHERLY COMPONENT BY LATER THIS AFTERNOON AS A FRONT APPROACHES
THE COAST. RAIN WILL MOVE INTO KSTS DURING THE OVERNIGHT HOURS AND
FOG IS POSSIBLE. CIGS OVER 6KFT WILL RETURN DURING THE OVERNIGHT
HOURS.

VICINITY OF KSFO...MOSTLY SOUTH TO EAST WINDS TODAY WITH SPEEDS
INCREASING BY THE AFTERNOON TO 6-10 KT. GENERALLY FEW-SCT SKIES
THROUGH THE REMAINDER OF THE DAY WITH ONLY BRIEF PERIODS OF BKN
CIGS FORECAST. ANY CIGS WOULD HAVE HEIGHTS OVER 6KFT. MODERATE TO
HIGH CONFIDENCE.

KSFO BRIDGE APPROACH...SIMILAR TO SFO. ANY CLOUDS SHOULD BE OVER
6KFT. MODERATE TO HIGH CONFIDENCE.

MRY BAY AREA TERMINALS...GENERALLY LIGHT WINDS. VFR CONDITIONS
EXPECTED ALL DAY TODAY WITH FEW-SCT SKIES. CIGS OVER 6KFT RETURN
LATE TONIGHT. MODERATE TO HIGH CONFIDENCE.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDA...SCA...PT ARENA TO PIGEON PT 10 TO 60 NM OFFSHORE
               ...PT ARENA TO PT REYES TO 10 NM
$$

PUBLIC FORECAST: MHS
AVIATION/MARINE: BELL

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO