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fxus66 kmtr 180337 
afdmtr 


Area forecast discussion 
National Weather Service San Francisco Bay area California 
830 PM PDT Wednesday Mar 17 2010 


Discussion...as of 8:30 PM PDT Wednesday...in quiet weather regimes 
like we have ongoing it can be difficult to find items to discuss at 
least initially. To sum up today's weather from a subjective 
viewpoint it was a beautiful day. A few high temperatures even broke 
above the 80 degree point such as King City...Greenfield and 
Pinnacles National Monument. Large ocean swell persisted on the 
waters but are expected to gradually decline tonight and Thursday. 
All in all mostly clear skies should prevail tonight but a few 
patches of fog are possible around daybreak Thursday. 


Thursday's weather looks similar to today's but added in will be a 
Twist of offshore wind flow. Subsiding air off the local mountains 
and hills have a warming and drying effect on the airmass. Offshore 
pressure gradients will increase Thursday into Friday morning per the 
latest GFS and WRF model runs. The models agree there will be a 12 mb 
offshore gradient from wmc to sfo by early Friday morning. Forecast 
models show a dry shortwave trough sliding south along the California/Nevada 
border during this time. If the trough was a bit farther to the west 
this would normally enhance the winds over the Bay area possibly to 
the Point of needing an advisory. Locally gusty winds are expected in 
the East Bay hills and North Bay mountains Thursday and Thursday 
night but should remain below advisory levels. Fire related products 
are not seen needed at this time mainly due to higher fuel moistures. 
The strength of the offshore gradient diminishes Friday. Dry weather 
is forecast for the remainder of the period. 


&& 


Aviation...as of 4:40 PM PDT Wednesday...high pressure aloft will 
maintain mostly clear skies across the region through Thursday. 
Patchy low clouds and fog may develop near the ocean late tonight... 
but onshore flow will be too weak for any low ceilings or fog to develop 
around sf Bay. Offshore flow will begin to develop aloft late tonight 
and increase by late Thursday. These offshore winds may result in 
local low level wind shear late Thursday into Thursday night. 


Vicinity of ksfo...VFR conditions through Thursday. Winds will be 
west 15g20 kts through 04z...then gradually diminish overnight. 
Winds will turn light northeast on Thursday morning...before turning 
to the west-northwest late Thursday afternoon. Winds Thursday 
afternoon will be lighter than on Wednesday afternoon. 


Ksfo bridge approach...same as ksfo. 


Mry Bay area terminals...VFR conditions through most of the night. 
IFR ceilings may develop near kmry late tonight. If low ceilings do develop 
near Monterey Bay...they will clear by 16z Thursday. Winds will be 
light. 




Proposed policy change...effective 15z Tuesday April 6th 2010 the San 
Francisco Bay area office at Monterey will begin 3-hourly taf 
issuances for ksfo. These intermediate tafs at 03z...09z...15z...and 
21z will be issued as amendments to the tafs issued at 00z...06z... 
12z...and 18z. The intermediate tafs will be issued during a 20- 
minute window between 10 minutes before the designated issuance hour 
and 10 minutes after the hour. Comments on this proposed rule-making 
will be accepted to March 19th. Comments can be addressed to the 
webmaster at the National Weather Service at Monterey at www.Weather.Gov/sanfrancisco. 


&& 


Mtr watches/warnings/advisories... 
tonight...sca...all coastal waters. 
Small Craft Advisory...rough bar San Francisco bar. 


&& 


Climate...high temperature records for selected locations for 
March 17. 


San Francisco Bay area 


City..............temperature.....Year 
Kentfield.........87..............1914 
Moffett field.....84..............2004 
Napa..............92..............1914 
Oakland...........85..............2004 
koak Airport......81..............2004 
Richmond..........83..............2004 
ksfo Airport......82..............2004 
San Francisco.....85..............1914 
San Jose..........88..............1914 
San Rafael........84..............1972 
Santa Rosa........87..............1978 


Monterey Bay area 


City..............temperature.....Year 
Gilroy............89..............1972 
King City.........91..............2004 
Monterey..........84..............2004 
Salinas...........88..............2004 
Santa Cruz........89..............1914 


&& 


$$ 


Public forecast: canepa 
aviation/marine: Larry/dykema 
climate: sea 


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