FXUS66 KMTR 101216
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
415 AM PST THU DEC 10 2009

.DISCUSSION...AS OF 3:17 AM PST THURSDAY...MID AND HIGH CLOUDS
CONTINUE TO STREAM ACROSS CALIFORNIA AND AS A RESULT...MORNING
TEMPERATURES ARE RUNNING AS MANY AS 10 DEGREES WARMER THAN THOSE FROM
24 HOURS AGO WITH READINGS FROM THE 30S TO MID 40S MOST AREAS.
THUS...DECIDED TO CANCEL THE FREEZE WARNING THAT WAS IN PLACE FOR THE
NORTH BAY VALLEYS AS IT SEEMS UNLIKELY AT THIS POINT THAT
TEMPERATURES THERE WILL FALL BELOW FREEZING.

MEANWHILE...KMUX RADAR CONTINUES TO SHOW ECHOES MOVING ACROSS THE
SOUTHERN TWO THIRDS OF THE DISTRICT. SO FAR...THOUGH...NO PRECIP HAS
BEEN DETECTED BY ANY AUTOMATED GAUGES. RAIN CHANCES ARE EXPECTED TO
INCREASE TONIGHT AND FRIDAY AS A SHORT-WAVE TROUGH APPROACHES THE
COAST FROM THE WEST. THIS TROUGH IS CURRENTLY LOCATED ALONG THE
135W MERIDIAN AND IS PROGGED TO REACH THE COAST BY FRIDAY MORNING.
THEN A STRONGER SYSTEM IS SLATED TO AFFECT THE DISTRICT ON SATURDAY
WHEN THE ASSOCIATED UPPER LOW FINALLY MOVES ACROSS CENTRAL
CALIFORNIA. THE QPF IS FORECAST TO INCREASE EACH DAY WITH ONLY A FEW
HUNDREDTHS EXPECTED TODAY...A COUPLE TENTHS POSSIBLE BY FRIDAY
MORNING...AND UP TO A HALF TO THREE QUARTERS OF AN INCH BY 12Z
SATURDAY. THE MAIN UPPER LOW IS FORECAST TO MOVE ACROSS DURING THE
DAY SATURDAY...SO AN ADDITIONAL INCH OR SO IS POSSIBLE ON SATURDAY...
ESPECIALLY OVER HIGHER TERRAIN AREAS. SHOWERS ARE EXPECTED TO
CONTINUE INTO SUNDAY WITH HIGH PRESSURE ALOFT BUILDING OVER THE WEST
THROUGH THE EARLY PART OF NEXT WEEK.

&&

.AVIATION...AS OF 4:15 AM PST THURSDAY...UNSETTLED WEATHER
APPROACHING THE NORTHERN AND CENTRAL COAST WILL PRODUCE VARYING
CLOUD HEIGHTS ACROSS THE REGION. HOWEVER CIGS ARE ANTICIPATED TO
REMAIN ABOVE 5000 FEET FOR THE MOST PART. SHOWERS REMAIN IN THE
VCNTY AT THIS HOURS BUT WILL QUICKLY DIMINISH IN THE NEXT COUPLE OF
HOURS. RAIN CHANCES WILL RETURN LATE THIS AFTERNOON AND EVENING AS
A MORE ORGANIZED SYSTEM APPROACHES.

VICINITY OF KSFO...EAST TO SOUTHEASTERLY WINDS EXPECTED ACROSS BAY
AREA TERMINALS TODAY. VCNTY SHOWERS REMAIN POSSIBLE THROUGH 13Z WITH
DRY CONDITIONS EXPECTED UNTIL LATE THIS AFTERNOON AND EVENING AS A
MORE ORGANIZED SYSTEM APPROACHES.

KSFO BRIDGE APPROACH...SAME AS KSFO VICINITY.

MRY BAY AREA TERMINALS...EAST TO SOUTHEASTERLY WINDS EXPECTED TODAY.
VCNTY SHOWERS REMAIN POSSIBLE THROUGH 14Z WITH DRY CONDITIONS
EXPECTED UNTIL LATE THIS AFTERNOON AND EVENING AS A MORE ORGANIZED
SYSTEM APPROACHES.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDA...NONE.
$$

PUBLIC FORECAST: SSA
AVIATION/MARINE: CW

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO