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Area Forecast Discussion (AFD)

Issued by San Francisco Bay Area, CA (MTR)

FXUS66 KMTR 230016

Area Forecast Discussion
National Weather Service San Francisco Bay Area
516 PM PDT Wed May 22 2019

.SYNOPSIS...Temperatures will be on the warming trend through the
remainder of the week, yet will remain below seasonal averages. 
Unseasonably cool and unsettled conditions continue into the 
upcoming weekend with a renewed chance of rain showers as another 
system drops southward across the region. 

&& of 01:45 PM PDT Wednesday...Radar has been 
switched back to clear air mode for the time being as shower 
activity has exited to SoCal. Satellite imagery shows mostly sunny
skies across the Bay Area with widespread cumulus clouds from the
South Bay southward. Increased sunshine, warmer airmass and lack 
of precip has led to warmer temperatures this afternoon with many
locales running 5 to 10 degrees above Tuesday's maximum temps. 

Once the sun sets expect the cumulus to diminish with mainly clear
skies in the heart of the Bay Area with more clouds likely around
Monterey Bay. If the higher res models verify overnight, breezy to
gusty NE are forecast over the North and East Bay higher terrain.
Gusts over 30 mph are possible.  

The longwave pattern keeps a broad upper trough over the region 
surprisingly into early next week. Temperatures will warm a few 
more degrees on Thursday returning closer to normal. Highs will be
in the 60s to mid 70s. Several models rotate a weak shortwave 
around the base of the upper trough Thursday afternoon. There will
likely be enough lift to support a few pop up showers or an 
isolated thunderstorm over Gabilan range during peak heating. 

As noted on the previous discussion additional disturbances 
rotate around the trough as well bringing additional precip 
chances to the state. A few showers may drift westward in the 
forecast area on Friday and early Saturday. Another upper low 
takes aim at the Bay Area again late in the weekend providing a 
better chance for precip late Saturday and more so on Sunday. It 
doesn't look like a total wash out at this point for the holiday 
weekend, but more showery in nature.

Memorial Day looks cool with a few isolated showers. Warmer and
drier will develop Tuesday and Wednesday. 

&& of 5:13 PM PDT Wednesday...Mid level moisture
wrapping around an upper low over the southwest is causing  
afternoon cumulus clouds to form. The clouds are scattered but
there could be small patches where it is BKN. These clouds should
dissipate after dark. 

Strong onshore flow on the back side of the upper low will allow
stratus or stratocumulus to form late tonight. Could see SCT-BKN 
conditions at times over the Bay Area between 06Z and 16Z. West 
winds gusting to 20 kt through 04Z. 

Vicinity of KSFO...VFR through the airport evening rush. MVFR 
cigs possible over the approach between 12Z-16Z. West winds
gusting to 20 kt through 04Z.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Strong onshore flow will allow for early
MVFR cigs. MVFR cigs after 02Z at MRY and 04Z at SNS. 

&& of 04:39 PM PDT Wednesday...A large, moderate period,
late season northwest swell is moving across the waters today.
Breakers of up to around 20 feet are  possible. In addition,
increasing northwest winds with gale force  gusts are forecast
across the northern and outer waters through  the near term.
Moderate wind and seas will persist through the end of the week,
particularly in the northern outer waters. Hazardous conditions
from squared seas will exist after the winds begin to  diminish.


     .Tngt...High Surf Advisory...CAZ006-505-509-529-530
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             GLW...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 2 PM
             GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM
             GLW...Pt Arena to Pt Reyes 0-10 nm until 3 AM
             SCA...Rough Bar Advisory for SF Bar
             SCA...Mry Bay




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