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Area Forecast Discussion (AFD)

Issued by San Francisco Bay Area, CA (MTR)

FXUS66 KMTR 172153

Area Forecast Discussion
National Weather Service San Francisco Bay Area
153 PM PST Sun Feb 17 2019

.SYNOPSIS...Scattered showers will continue through this afternoon
mainly south of the San Francisco Bay Area. Clearing skies will 
allow for cold minimum temperatures tonight and into the upcoming
week. Dry weather is expected for Monday and Tuesday with a 
slight chance of showers returning by the middle of the week. 
Temperatures will remain below normal.

&& of 2:00 PM PST Sunday...Upper level low over
Nevada is bringing a cold northerly flow to the area. Scattered 
showers have developed over the higher terrain from the East Bay 
Hills south. A couple of spotters have reported small hail in the
Santa Cruz Mountains. Precip could still fall as snow above 3000

These showers will be ending tonight as drier air aloft moves 
into the area. As skies clear and winds decrease patchy fog is 
possible in the North Bay Valleys. Lows tonight will be dropping
into the mid to upper 20s in the coldest interior valleys with 
mid to upper 30s around the bay. An upper level ridge moving over 
the area will bring dry weather Monday and Tuesday. The airmass 
will start to moderate but lower humidities will allow for another
cold night Monday night with temperatures similar to Sunday 
night. Highs Monday and Tuesday will be in the 50s across the 
lowlands which is still about 5 degrees below normal. 

The next upper level trough will drop into the Pacific Northwest
on Wednesday. This system is further inland than the previous 
systems that have moved through here so it will have less moisture
to work with. Only a slight chance of showers is forecast with any
rain amounts under one-tenth of an inch. It will bring in a
reinforcement of cold air so snow levels will be very low again. 

Thursday and Friday look to be dry as there is good model
agreement. The flow will become more westerly which should put an
end to our cold wave. Medium range models indicate a system from 
the west possibly affecting our area late next weekend. 


.AVIATION...As of 9:33 AM PST Sunday...For 18Z TAFs. VFR 
conditions are forecast to prevail at most terminals over the next
24-30 hour period. The exception to this would be STS with some 
locally dense morning fog, and possibly LVK as well. Other than 
that, isolated rain showers this morning will decrease in coverage
through the day with some SCT or possibly BKN decks at/around 
3,500-5,000 ft AGL this afternoon with some cumulus/stratocumulus 
build-up. Onshore winds 10-20 kt with locally gusty conditions 
expected through the evening hours for most TAF sites.

Vicinity of KSFO...VFR conditions are forecast to prevail today.
SCT-BKN cumulus and stratocumulus decks will likely develop
between 3,500-5,000 ft for the late morning and afternoon hours.
Breezy west winds 15-20 kt with gusts near 30 kt this afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR with scattered showers this morning
dwindling in coverage as the day continues. SCT-BKN decks
3,500-5,000 ft AGL this afternoon with some cumulus and 
stratocumulus build-ups. Onshore winds this afternoon around 10-20

&& of 01:14 PM PST Sunday...Northwest winds are forecast
to prevail over the coastal waters for the next several days. The
northwest swell that arrived late Friday and Saturday will begin
to decrease today. A second long  period northwest swell train is
set to arrive during the week and  will bring with it more modest
swell heights.


     .Tngt...SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...SF Bay until 6 PM
             SCA...Mry Bay until 6 PM




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