FXUS66 KMTR 081730
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
930 AM PST TUE DEC 8 2009
.DISCUSSION...AS OF 8:38 AM PST TUESDAY...FROSTY START TO THE DAY
ACROSS MUCH OF THE CWA THIS MORNING. THE WFO RECEIVED NUMEROUS
REPORTS OF HEAVY FROST IMPACTING MANY PEOPLE THIS MORNING.
TEMPERATURES OVERNIGHT WERE NEAR RECORD LEVELS BUT A FEW DEGREES SHY
WITH MANY 20S AND 30S RECORDED. THE COLDEST OBSERVED TEMPERATURES
FROM AUTOMATED STATIONS WERE 17 DEG IN THE NORTH BAY AND 13 DEGREES
IN SAN BENITO COUNTY. TEMPERATURES ARE SLOWLY WARMING THIS MORNING
AND THE CURRENT FROST ADV/FREEZE WARNING WILL BE ALLOWED TO EXPIRE AT
9 AM. TEMPERATURES WILL BE SLIGHTLY WARMER THIS AFTERNOON COMPARED
TO YESTERDAY DUE TO INCREASED INSOLATION.
LITTLE CHANGE IS EXPECTED TONIGHT. MODEL GUIDANCE AND PROJECTED
BIAS CORRECTED MODELS ALL INDICATE A REPEAT OF LAST NIGHT. IN
FACT...MODELS EVEN SUGGEST THAT A FEW PLACES COULD BE COLDER
TONIGHT. THAT BEING SAID...WILL UPDATE THIS FORECAST THIS MORNING
TO RE-ISSUE THE FROST ADV AND FREEZING WARNING TONIGHT THROUGH
TOMORROW MORNING.
EARLY LOOK AT THE EXTENDED FORECAST CONTINUES TO LOOK UNSETTLED.
THE FIRST IN A SERIES OF STORMS WILL MOVE TOWARD THE COAST LATE
WEDNESDAY NIGHT/EARLY THURSDAY MORNING. THE MODEL TRENDS OVER THE
LAST DAY OR SO HAVE BEEN TO SLOW THE INITIAL START OF PRECIP UNTIL
WELL AFTER 00Z THURSDAY. IN FACT...THE LATEST NAM12 KEEPS ALL
PRECIP S OF THE CWA AND AFTER 12Z THURSDAY. THIS IS A BIG CONTRAST
FROM 24 HOURS AGO. THE GFS/ECM/CANADIAN HAVE A MORE NORTHWARD
EXTENT OF PRECIPITATION. THAT BEING SAID...THE BEST CHC FOR PRECIP
WILL LIKELY BE THE DAY ON THURSDAY. ANOTHER SECONDARY STORM SWINGS
THROUGH FRIDAY WITH ANOTHER CHC FOR RAIN. LAST BUT NOT LEAST WILL
BE A STRONGER THIRD STORM FOR THE WEEKEND. WIDESPREAD RAIN...POSS
HEAVY AT TIMES...IS FORECAST FOR SAT/SUN. WILL FINE TUNE THE
EXTENDED WITH THE AFTERNOON PACKAGE.
&&
.AVIATION...AS OF 9:30 AM PST TUESDAY...MOSTLY CLEAR SKIES WILL
CONTINUE ACROSS THE REGION TODAY. WINDS WILL BE LIGHT AND VARIABLE
THEN BECOME WEST TO NORTHWEST LESS THAN 10 KNOTS THIS AFTERNOON.
VICINITY OF KSFO...VFR CONDITIONS WILL PREVAIL TODAY. WINDS WILL
BECOMING WEST TO NORTHWEST LESS THAN 10 KNOTS LATER THIS AFTERNOON.
KSFO BRIDGE APPROACH...VFR.
MRY BAY AREA TERMINALS...VFR CONDITIONS EXPECTED THROUGH THE DAY.
WINDS WILL BECOME WEST TO NORTHWEST LESS THAN 10 KNOTS LATER THIS
AFTERNOON.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...NONE.
$$
PUBLIC FORECAST: MM
AVIATION/MARINE: SSA
NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
