Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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FXUS66 KMTR 301134

Area Forecast Discussion
National Weather Service San Francisco Bay Area
434 AM PDT Tue May 30 2017

.SYNOPSIS...Continued seasonably cool and breezy weather will
continue along with a chance of showers tonight into Wednesday as
an upper trough moves through. A drying and warming trend
Thursday into next weekend.

&& of 3:30 AM PDT Tuesday...Similar to yesterday, a
combination of a moderate marine layer (now around 2000 feet)
combined with continued onshore flow at the surface (over 3 MB)
from SFO to SAC) is leading to clouds for many locations.
However, interesting to note that parts of the North Bay are
actually staying cloud-free. Latest ob from Santa Rosa indicates
clear skies. Clouds are forecast to clear toward the coast late
this morning or early in the afternoon. Highs will be in the 50s
and 60s near the water with 70s to lower 80s inland. Breezy
westerly winds can also be expected.

Synoptically a trough will advance to the West Coast later today
with the axis forecast to swing through our CWA late tonight.
Moisture associated with this feature along with more
instability/PVA will likely trigger a few showers across our
region. Models have trended a bit wetter compared to 24 hours ago,
so PoPs were increased. Focus still remains on eastern and
southern sections especially around San Benito County. If that
verifies it would be opposite of how precipitation is typically
distributed. Rainfall amounts should be light -- less than a
tenth, and many urban spots will likely see little to no rainfall.

The axis will move to the east while 500 MB heights begin to
slowly rebuild going into the end of the week. This will lead to a
return of dry weather along with warmer temperatures. The ridge
is expected to further strengthen through next week with
afternoon highs likely going to above normal levels. Also worth
noting enough mixing should occur that the marine layer has a
better chance of scattering out. Coastal spots might actually have
a shot of a few days of sunny weather.


.AVIATION...04:30 AM PDT Tuesday for 12Z TAFs...Marine layer
established again and expecting impacts through AM rush. Unlike
yesterday, models are showing some improvement later this
afternoon and not an all day event. Gusty winds through much of
the forecast. For tonight, stratus is questionable as a weak
boundary moves through early Wednesday. Current thinking is to go
with some early cigs then lifting/sct early Wednesday with fropa.

Moderate confidence.

Vicinity of KSFO...IFR cigs through 20Z the scattering of cigs.
Brief lull this morning with winds, then gusty westerly winds once
again this afternoon. Low cigs will move in early tonight then
mix out early Wednesday with front.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR to MVFR this morning with cigs
lifting this afternoon with VFR. Cigs return early this evening
and may mix out close to 12z Wednesday.

&& of 04:27 AM PDT Tuesday...High pressure off the west
coast and low pressure inland will maintain gusty northerly winds
through at least Tuesday night. The gusty winds will generate
steep wind waves and fresh swell...making for adverse and
hazardous seas. Winds are forecast to decrease Wednesday as a
weak front moves through the area and the surface pressure
gradient weakens.


     .Tday...SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Mry Bay
             SCA...SF Bay from 12 PM




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