000
FXUS66 KMTR 032354
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
354 PM PST WED DEC 3 2008
.DISCUSSION...AS OF 2:50 PM PST WEDNESDAY...ONE MORE NIGHT OF
POSSIBLE FOG THEN LOTS OF UNCERTAINTY IN THE EXTENDED. NONE THE
LESS...FORECAST REMAINS DRY.
WHAT AN UNPRECEDENTED DAY ACROSS THE BAY AREA AS DENSE FOG COVERED
MANY VALLEYS FROM SANTA CLARA VALLEY NORTHWARD. IN FACT...MANY
LOCATIONS HELD ONTO FOG THROUGH MUCH OF THE AFTERNOON. CASE IN
POINT...SANTA ROSA HAS NOT EVEN REACHED 50 DEGREES AS OF 2PM. THAT IS
A WHOPPING 17 DEGREE DIFFERENCE FROM YESTERDAY. ELSEWHERE...PLACES
DID WARM UP AFTER THE FOG DISSIPATED...BUT MANY LOCATIONS WERE 3 TO
5 DEGREES COLDER THAN YESTERDAY.
SHORT TERM (TONIGHT-SATURDAY)...
ONE BIG DIFFERENCE TONIGHT COMPARED TO LAST NIGHT WILL BE THE LACK
OF WIDESPREAD DENSE FOG. A WEAK UPPER LOW CURRENTLY OFF THE NORCAL
COAST WILL CONTINUE TO MOVE S ALONG THE COAST TONIGHT. THIS SHOULD
KEEP THE BL BETTER MIXED PREVENTING DENSE FOG. HOWEVER...STILL THINK
THERE IS ENOUGH RESIDUAL MOISTURE FOR PATCHY FOG IN THE VALLEYS.
GENERALLY SPEAKING...TEMPERATURES ON THURSDAY WILL BE SIMILAR TO
THIS AFTERNOON WITH THE EXCEPTION OF SANTA ROSA REGION AND OTHER
LOCALES THAT HELD ONTO FOG TODAY. THESE LOCATIONS SHOULD BE MUCH
WARMER ON THURSDAY. BY LATE THURSDAY EVENING MODELS START TO SLOWLY
DIVERGE ON THE TRACK OF THE UPPER LOW...BUT THE GENERAL IDEA IS THAT
IT WILL BE NEAR 30N 130W. IF THIS PLACEMENT IS CORRECT...THE WOULD
PUT THE BAY REGION UNDER WEAK OFFSHORE FLOW WITH WARMER AND DRIER
CONDITIONS. THEREFORE...HAVE REMOVED FOG/CLOUDS MENTION THURSDAY
NIGHT AND FRIDAY NIGHT. TEMPERATURES WILL WARM SLIGHTLY THROUGH
SATURDAY.
LONG TERM (SUNDAY-WEDNESDAY)...
MEDIUM RANGE MODELS STILL DO NOT HAVE A GOOD HANDLE ON THE DETAILS
FOR THE EXTENDED PERIOD. HOWEVER..THEY DO HAVE THE SAME IDEA OF
DEVELOPING A CUT OFF LOW OFF THE SOCAL COAST. THE PLACEMENT OF THE
CUT OFF LOW STILL VARIES BY ALMOST 500 MILES ON THE ECMWF (CLOSER TO
THE COAST) COMPARED TO GFS BY THIS WEEKEND. THE LATEST RUNS KEEP THE
UPPER LOW OFF THE WEST COAST FOR MUCH OF NEXT WEEK WITH A RIDGE OVER
CA. THAT WOULD MEAN DRY CONDITIONS WITH NO PRECIP EXPECTED. LITTLE
CHANGE WAS MADE TO THE EXTENDED.
&&
.AVIATION...AS OF 3:54 PM PST WEDNESDAY...LOW CLOUDS AND FOG ARE
AGAIN EXPECTED TO AFFECT BAY AREA TERMINALS TONIGHT AS WELL AS THOSE
IN THE MONTEREY BAY AREA. ALREADY CEILINGS AND VISIBILITIES ARE
LOWERING IN THE NORTH BAY...AND THE SAME CAN BE EXPECTED AT KSFO
AND KOAK AFTER 06Z. A WEAK OFFSHORE SURFACE PRESSURE GRADIENT WILL
KEEP WINDS MOSTLY LIGHT NORTHERLY THROUGH THE EVENING.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TNGT...SCA...PT ARENA TO PIGEON PT 20 TO 60 NM
&&
$$
PUBLIC FORECAST: MM
AVIATION/MARINE: SSA
NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO
