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Area forecast discussion 
National Weather Service San Francisco Bay area California 
950 PM PST Wednesday Nov 19 2008 


Discussion...as of 9:00 PM PST Wednesday...it was much cooler 
today across the district as low pressure aloft has displaced the 
upper ridge which is now over the Rocky Mountain states. Highs today 
ranged from the 50s and 60s near the coast and bays...to the 70s to 
lower 80s inland. These highs were 5 to 20 degrees cooler than 
yesterday's highs. 


A weak shortwave trough currently approaching the West Coast is 
serving to deepen the marine layer...which is now about 1600 feet 
deep. Expect low clouds and fog to spread inland once again 
tonight...although high clouds associated with the shortwave trough 
are obscuring the low clouds from satellite view at this time. This 
shortwave might bring some light rain to the North Bay on Thursday... 
although chances are small. 


From previous discussion...skies will begin to clear tomorrow night 
and should be mostly clear Friday through Saturday as surface high 
pressure builds into southern Oregon and northern California 
producing light offshore flow. The extended forecast remains tricky 
as the European model (ecmwf) and the operational GFS have not been exhibiting much 
continuity in their solutions. The GFS is not portraying as deep of 
an upper low as the European model (ecmwf) and is also much drier. Therefore...no 
significant changes have been made to the extended forecast which is 
advertising slight chance probability of precipitation in the climatologically favored 
areas. 


&& 


Aviation...as of 9:50 PM PST Wednesday...a few high clouds are 
passing across northern and central California as a trough moves 
across northern California. Areas of low clouds have moved inland 
with patches of dense fog developing later tonight. The 1800 foot 
deep marine layer will spread into the valleys overnight then back to 
the coast between 19z and 22z. 


Terminal Aerodrome forecast (tafs) format change... 


As of 0000z (november 5 2008) the National Weather Service in agreement with the FAA has 
changed the taf format to conform to international standards outlined 
in icao annex 3. The change includes the initiating of 30-hour tafs 
for high impact U.S. Airports. To accommodate the extended taf 
period...the format of all tafs have changed. The change involves 
identifying the data associated with each time group. 


Ksfo and koak are now 30-hour tafs. 


For additional information regarding the change please visit the 
aviation weather centers website: 


Http://aviationweather.NOAA.Gov/notice/taf30.Php 


&& 


Mtr watches/warnings/advisories...none. 


&& 


$$ 


Public forecast: Larry/Anderson 
aviation/marine: Evans 


National Weather Service on the web at weather.Gov/sanfrancisco