Area forecast discussion 
National Weather Service San Francisco Bay area 
151 PM PST Friday Feb 12 2016 


..very warm February weather to return Sunday through Tuesday... 


Synopsis...dry weather along with overnight coastal clouds and 
fog will continue through the weekend and into early next week. 
Slightly cooler temperatures can be expected tomorrow with warming 
then forecast for Sunday into Tuesday. Large long-period westerly 
swell will continue to impact the coast through 
Saturday...creating hazardous conditions at area 
beaches...including sneaker waves. 


&& 


Discussion...as of 2:00 PM PST Friday...mix of sun and higher 
clouds across our area today after the low clouds burned off from 
most coastal spots this morning. As expected temperatures for the 
most part are running a few degrees cooler than this time 
yesterday (especially around Monterey where we are 8 cooler than 
thursday). Guidance plus current analysis suggests clouds will 
likely return to the coast with areas of fog tonight into the 
morning hours. Synoptically a system will pass to our north 
tonight. Models had been hinting at some light rain for the North 
Bay from this feature earlier in the week, however now appears any 
precipitation will stay well to the north. Highs will be mostly in 
the middle 60s to lower 70s. 


A strong ridge of high pressure will build back into our region 
starting on Sunday along with building 850 temperatures to push highs 
back into the well above normal category. In fact, many locations 
will likely begin to approach or even set records for at least one 
of the three days. 850 mb temperatures are forecast to peak in the 17-18c 
range on Monday along with 586 dm 500 mb heights. Both of these 
values are near record for February, so forecast temperatures were 
slightly increased. Would not be surprised if many locations are 
in the 75 to 80 degree range on Monday. 


Longer range guidance continue to mostly indicate a return to rain 
from late Wednesday through Thursday as a system moves in from the 
west. Although the 12z operational GFS greatly diminished the 
precipitation, the GFS ensemble mean still favors rainfall. In 
addition, the European model (ecmwf) operation run indicates rain along with the 
Canadian. Cnrfc currently has 1/2" to 1" at the coast with 2/10" 
to 4/10" for most inland spots. Still a few days out, so those 
numbers could easily change quite a bit. 


CPC 8 to 14 day outlook does favor drier than normal conditions 
with above normal temperatures. That would take US almost to the 
end of the month. 


&& 


Aviation...as of 11:02 am PST Friday...patchy coastal low clouds 
and fog are gradually clearing otherwise high clouds are streaming 
in over the area on SW middle-upper level winds. Localized reductions 
in slant-wise visibility possible (near sunset) as a result of 
hazy and stable weather conditions. Otherwise it's high confidence 
VFR conditions today. 


Northwest winds becoming a little gusty on the immediate coastline to 
15-20 knots through the day. Inland winds mainly light/variable 
becoming locally onshore this afternoon. Sfo-SAC pressure gradient 
is presently weak onshore at 0.4 mb. 


Weak middle-upper level troughing will slide southeast over the coastal 
waters tonight. Ongoing boundary layer humidity will likely cause 
low clouds and fog to move back to the immediate coast along with 
a localized inland stratus/fog intrusion overnight. Marine layer 
presently shallow at 750-900 feet likely limiting inland intrusion 
initially this evening however overnight as the aforementioned 
trough sweeps southeast the layer may tend to deepen probably at least a 
few more hundred feet. Model trends indicate unseasonably strong 
epac high pressure through the Holiday weekend. 


Vicinity of ksfo....VFR. Light NE winds. Westerly winds to near 10 
knots is forecast to return by mid-afternoon. 


Sfo bridge approach...similar to ksfo. 


Monterey Bay area terminals...patchy low clouds and fog over the 
Monterey Bay per visible imagery. Light onshore winds likely 
bringing patchy low clouds & fog back to the area later this 
evening. Absence of upward vertical motion early this evening may 
help extend VFR conditions another couple hours than presently 
advertised for kmry and ksns..will amend shortly. Medium-high 
confidence IFR/LIFR later this evening into Saturday morning. 
Low-medium confidence clearing/VFR conditions return by late 
Saturday morning. 


&& 


Marine...as of 9:10 am PST Friday...generally light northwest 
winds will continue this morning over a building and long period 
westerly swell. By this afternoon and evening northwest winds will begin 
to increase over the waters and continue through much of the 
weekend. Unseasonably strong high pressure will continue over the 
eastern Pacific through this weekend and early next week. A cold 
frontal system will approach the coastal waters by late Wednesday 
or Thursday. 


&& 


Mtr watches/warnings/advisories... 
... Surf advisory...all coastal locations through 
8pm Saturday 
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm 
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm 
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm from 6 PM 
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm from 6 PM 
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm from 6 PM 
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm from 6 PM 
Small Craft Advisory...rough bar advisory for sf bar 


&& 


$$ 


Public forecast: Bell 
aviation: canepa 
marine: canepa/r_walbrun 




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