000
FXUS66 KMTR 211730
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
930 AM PST SAT NOV 21 2009

.DISCUSSION...AS OF 845 AM PST SATURDAY...THE FIRST VISIBLE
SATELLITE IMAGE OF THE DAY IS SHOWING MOSTLY CLEAR SKIES ACROSS THE
AREA THIS MORNING. OVER NIGHT LOWS WERE PRETTY CHILLY LAST NIGHT
BEHIND THE DEPARTING COLD FRONT. THE CHILLIEST AREA WAS OF COURSE
THE NORTH BAY VALLEYS WITH LOWS IN THE LOW TO MID 30S. SONOMA
COUNTY AIRPORT MADE IT TO 32 DEGREES AND WAS REPORTING FREEZING FOG
THIS MORNING. MEANWHILE NAPA AIRPORT MADE IT DOWN TO 36 DEGREES
AND ALSO REPORTED A BRIEF PERIOD OF FREEZING FOG.

TONIGHT WILL NOT BE QUITE AS CHILLY IN THE NORTH BAY VALLEYS WITH
SOME MID AND UPPER LEVEL CLOUDS EXPECTED TO MOVE IN THIS EVENING.
THESE CLOUDS WILL FORM IN RESPONSE TO A COLD FRONT BRUSHING BY THE
AREA OVERNIGHT. THIS FRONT WILL ALSO BRING A SLIGHT CHANCE OF
PRECIPITATION TO NAPA AND SONOMA COUNTIES. THE FORECAST CONTINUES
TO DRY OUT TOMORROW AS A RIDGE OF HIGH PRESSURE BUILDS OVER THE
EASTERN PACIFIC.

TEMPERATURES ARE EXPECTED TO WARM UP A BIT THIS WEEK WITH THE
RIDGE OF HIGH PRESSURE PUSHING 500 MB HEIGHTS TO 578 DM MONDAY
AFTERNOON. THIS WILL RESULT IN TEMPERATURES WARMING TO MID 60S
MONDAY AND POSSIBLY THE LOW 70S BY TUESDAY. THE WARMEST TEMPERATURES
WILL MOST LIKELY BE IN THE SOUTHERN SALINAS VALLEY WITH KING CITY
REACHING 72 DEGREES BY MID WEEK.

THANKSGIVING DAY LOOKS TO BE MOSTLY DRY AND PLEASANT. HOWEVER...THE
0000 UTC ECMWF AND 1200 UTC GFS MODELS DO BEGIN TO DIVERGE ON THEIR
SOLUTIONS BY THURSDAY. THE ECMWF INSISTS ON DROOPING A TROUGH OF
LOW PRESSURE ACROSS NORTHERN CALIFORNIA RESULTING IN A SLIGHT CHANCE
OF PRECIPITATION FOR THE NORTH BAY AREA. MEANWHILE THE OPERATIONAL
GFS IS SLOWER WITH THIS FEATURE AND APPEARS TO LIFT THE TROUGH
NORTHWARD INTO BC SPARING THE AREA OF PRECIPITATION THANKSGIVING
DAY AND INTO THE HOLIDAY WEEKEND.

.AVIATION...AS OF 930 AM PST SATURDAY...CLEAR SKIES ARE EXPECTED
TODAY WITH ONLY HIGH CLOUDS MOVING ACROSS LATER TODAY. THE
SOUTHERN EDGE OF A WEAK FRONT WILL BRING AN INCREASE IN CLOUDS TO
THE NORTH BAY ALONG WITH A CHANCE OF SHOWERS OVERNIGHT.

VICINITY OF KSFO...VFR CONDITIONS THROUGH TODAY. WEST WINDS AOB 10
KT EXPECTED THIS AFTERNOON.

KSFO BRIDGE APPROACH...VFR.

MONTEREY BAY TERMINALS...VFR CONDITIONS TODAY AND TONIGHT.
LIGHT WEST WINDS EXPECTED.

.MTR WATCHES/WARNINGS/ADVISORIES...
    .TDA...SCA FOR HAZ SEAS PT ARENA TO PIGEON PT 10-60 NM UNTIL 2 PM
        ...SCA PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM
        ...SCA PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
        ...SCA STARTING 1 PM PIGEON PT TO PT PINOS 0-10 NM
        ...SCA FOR ROUGH BAR CONDITIONS UNTIL 2 PM

PUBLIC FORECAST LARRY
AVIATION/MARINE SSA

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO