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

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000
FXUS66 KMTR 240012
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
412 PM PST Mon Jan 23 2017

.SYNOPSIS...Scattered showers and isolated thunderstorms will
continue overnight through early Tuesday morning with perhaps some
isolated showers into Tuesday afternoon. Drying trend Tuesday
night through Wednesday. Another weak front moves through
Wednesday night into Thursday morning with a chance for some light
rain. High pressure builds Friday through the weekend with a
return of mild daytime highs but some cool overnight lows.

&&

.DISCUSSION...as of 2:57 PM PST Monday...Numerous showers
continue this afternoon with isolated t-storm still possible. Next
well defined upstream shortwave is near Cape Mendocino. Its
modeled to mainly pass over the ocean waters tonight but close
enough to keep shower threat going especially near the coast and
coastal hills. Given the cold air aloft still could see some
localized heavy downpours as cells pass over. Lots more sunshine
by Tuesday afternoon but still need to keep isolated shower threat
in the forecast especially over the hills.

Drying trend then Tue night through Weds afternoon as brief high
pressure builds. Models now trending more consistent and wetter
(relative speaking) with a chance of rain late Weds night through
about 12-18z thursday (would impact the Thur morning commute with
some more light rain).

Confidence increasing for drying trend then Thursday afternoon
through the weekend with a strong ridge building. 584 dm high
builds over the area by the weekend with warming 850 mb temps.
It may be hard to get some of the warmth to mix to the surface if
low level easterly flow from the central valley brings tule fog or
damp air towards the east bay/delta.

Dry weather then continues through early next week. Some hints of
a return to wet weather by around early February and this is
supported by the just updated cpc 8-14 day outlook.

&&

.AVIATION...As of 3:52 PM PST Monday...Scattered showers will
prevail across the region this evening as a low pressure system
slides down the coast. An isolated thunderstorm cannot be ruled
out but confidence is low as to when and where they will pop up
therefore have kept VCTS out of the TAFs and will monitor the
radar closely this evening. Scattered to broken mid-level cigs
anticipated through the period. Conditions will improve Tuesday as
this system slides south and high pressure builds in. Moderate
confidence.

Vicinity of KSFO....Mid-level VFR cigs around 3500-5000 feet
expected through much of the period. A passing shower cannot be
ruled out this evening therefore have left VCSH in the TAF through
late tonight. Light west winds will gradually veer to the east
overnight and persist through much of the day Tuesday. Moderate
confidence.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Mid-level VFR cigs around 3000-5000 feet
expected through much of the period. A passing shower cannot be
ruled out this evening therefore have left VCSH/-SHRA in the TAF
through late tonight. Light southwest winds will gradually veer
to the east overnight and persist through Tuesday morning. Winds
will turn onshore once again Tuesday afternoon. Moderate
confidence.

&&

.MARINE...as of 03:51 PM PST Monday...A low pressure system will
track down the coast and move through our waters tonight. This
will lead to scattered showers and possibly a few thunderstorms.
Large westerly swell will persist through Tuesday morning.
Another long period swell will move into our region on Wednesday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...High Surf Advisory...CAZ006-505-509-529-530
             SCA...Mry Bay
             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...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Rough Bar Advisory for SF Bar until 3 AM

&&

$$

PUBLIC FORECAST: RWW
AVIATION: CW
MARINE: Bell


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