Weather

810 
fxus66 kmtr 061134 
afdmtr 


Area forecast discussion 
National Weather Service San Francisco Bay area California 
434 am PDT Monday Oct 6 2008 


Discussion...as of 2:40 am PDT Monday...satellite imagery as well as surface 
observation indicate low clouds along the coast and into the North Bay and Santa 
Clara valleys. Fog is being reported at Santa Rosa. The feet Ord 
profiler is not indicate a marine inversion. 


Temperatures this early morning range from the upper 40s to lower 60s across 
the district. The gradient picture indicate a weak northerly gradient of 
1.6 mb between Arcata-sfo and a weak onshore gradient of 1.1 mb 
between sfo-SAC. 


The 06z NAM has a good handle on the moist boundary layer responsible 
for the low clouds. The clouds will dissipate back to the coast this 
morning leading to sunny skies this afternoon. Ridging continues to build 
into the state from the eastern Pacific...pushing the storm track 
into Washington and British Columbia. Temperatures should warm the next 
couple of days as the low level flow turns to the north with weak 
surface ridging into Oregon. The most significant warm-up will be in 
the North Bay where the flow will be downslope. 


A stronger shortwave will dive into the Pacific northwest on Thursday. 
Starting Thursday through next weekend the European model (ecmwf) and the GFS begin to 
diverge. The European model (ecmwf) digs the trough into the Great Basin by Saturday 
whereas the GFS is weaker with the shortwave and digs it into the 
plains. The 00z GFS ensembles are indicate a variety of solutions...so 
will have to wait for later runs to sort the out the details. The 
European model (ecmwf) would bring cooler temperatures to the district with 850 mb temperatures of 
5-6c by 00z Sunday. The GFS is significantly warmer with 850 mb temperatures 
of 16c by 00z Sunday. With the big differences between the models 
have made little changes to the extended forecast. Both model solutions 
would lead to dry weather for the district. 


Winds during the week could become an issue. Both medium range models 
increase 925 mb winds Thursday into the weekend with 30-40 knots offshore 
winds in the north and East Bay hills. This will need to be monitored 
closely by both the public and fire weather communities. 


&& 


Aviation...as of 4:20 am PDT Monday...the latest satellite fog 
product is showing stratus moving into the San Francisco Bay from 
the ocean. The stratus has made its way into the East Bay and south 
into the Santa Clara Valley. Ksfo and koak are both reporting ceilings 
at 700 to 800 feet with no reductions to visibility. Expect IFR 
conditions to prevail until about 1700 UTC at which point the middle 
level winds will turn offshore and begin to dry the marine layer 
out. After the initial clearing VFR will prevail for the remainder 
of the forecast. 


Monterey Bay area terminals...clear skies are evident on the 
satellite fog product around the Monterey Bay area this morning. 
However...there is a hint of stratus in the Salinas valley. At this 
point anticipate VFR to prevail through the forecast period with 
the help of middle level offshore flow. Patchy IFR conditions 
are possible between 1200 to 1600 UTC especially in the Salinas 
valley. 


&& 


Mtr watches/warnings/advisories... 
... 
$$ 


Public forecast: mhs 
aviation/marine: Larry 




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