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Area Forecast Discussion (AFD)

Issued by San Francisco Bay Area, CA (MTR)

FXUS66 KMTR 250955

Area Forecast Discussion
National Weather Service San Francisco Bay Area
255 AM PDT Thu Apr 25 2019

.SYNOPSIS...A gradual cooling trend will continue through the 
second half of the week and into the weekend ultimately bringing 
temperatures back closer to seasonal norms.

&& of 2:55 AM PDT Thursday...Satellite imagery 
shows that coastal stratus has finally worked its way north and 
into the southern portion of the Monterey Bay. Ceilings are now 
being reported at Salinas and Monterey airports. Surface pressure 
gradients have switched to onshore, with 2.0 mb between SFO and 
SAC, and the ACV-SFO gradient now only 3.2 mb. Current 
temperatures are running cooler than yesterday at this time, and 
high temperatures today are expected to be cooler than 
yesterday's, especially near the coast. Highs today are forecast 
to range from the 70s and 80s inland, to the 60s at the coast. 

The ridge of high pressure that brought record heat to the Bay 
Area over the past couple of days will continue to gradually 
weaken over the few days. An increased onshore flow will also
continue to deepen the marine layer. This cooling trend will
continue through the weekend. Latest model guidance has slowed the
progression of the approaching cut-off low. Thus, have removed/reduced
pops for the Sunday/Monday time frame. 

&& of 10:30 PM PDT Wednesday...Evening observations 
and satellite are showing haze along the coast developing into low
clouds as the temperature drops toward the dewpoint. The upper 
ridge over the area will let a small short wave pass through it 
tonight. This in turn will allow for some deepening moisture along
with a weak onshore push. As such, the 06Z tafs maintain some low
cloud decks into several terminals, but not all. Timing and 
coverage has been adjusted toward current model guidance. Once 
this short wave clears, the low clouds should dissipate quickly 
and VFR is expected to dominate once again. This is expected to 
occur before sunrise for most locations. A more robust onshore 
push will occur as the ridge exits the region Thursday night into 

Vicinity of KSFO...VFR through the night. Some low clouds will 
loop around the east bay, but are not expected to reach SFO.

SFO Bridge Approach...Same as KSFO.

Monterey Bay Terminals...Look for low level clouds to develop this
evening across SNS and MRY. Clouds will dissipate around sunrise
Thursday. Therefore, VFR this evening -> IFR tonight -> VFR by

&& of 2:42 AM PDT Thursday...High pressure off of the 
Pacific Northwest coast will keep the strongest winds over the 
northern waters through Friday night. The high will shift westward
over the weekend with the strongest winds becoming confined to 
the northern outer waters. 


     .Tday...SCA...Pt Arena to Pt Reyes 0-10 nm until 3 AM
             SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 AM
             SCA...Pt Arena to Pt Reyes 0-10 nm from 3 PM
             SCA...Pt Arena to Pigeon Pt 10-60 nm from 3 PM




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