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

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FXUS66 KMTR 181739
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1039 AM PDT Tue May 18 2021

.SYNOPSIS...Another day of warm inland temperatures while locally
breezy conditions develop again this afternoon. A system
approaching from the northwest on Wednesday will bring gusty
northwest winds from Wednesday afternoon through Thursday, along
with well below normal temperatures. Gradual warming is forecast
from Friday through the weekend.

&&

.DISCUSSION...as of 09:20 AM PDT Tuesday...Good Tuesday morning.
Things are looking brighter today with more clear skies. Fort Ord
profiler shows marine layer has compressed to about 1800 ft.
Satellite imagery reveals some stratus along the coast and just
offshore from the SF peninsula down through the Monterey peninsula
and into the Salinas Valley. However, clouds seem to be eroding
or drifting southward pretty rapidly. Thus, widespread clear skies
are expected this afternoon with warmer temperatures compared to
yesterday, as a weak ridge lies over the state.

Winds will pick up this afternoon, especially along the coast, but
even more so tomorrow afternoon and evening, when stronger winds
will be more widespread. This is related to the upper trough over
British Columbia pushing into the PacNW. A wind advisory was
issued this morning and goes into effect 5PM Wed through 5AM
Thurs for most of the coastline (excluding Monterey Bay), North
Bay Mountains, SF Peninsula, SF Bay Shoreline, East Bay Hills,
Santa Cruz Mountains, Santa Lucia Mountains and San Benito
Mountains. Gusts 25-35 mph will be widespread with 40+ mph gusts
likely in favored coastal terrain and elevated areas. Coastal
waters will also be experiencing gale force winds. Fortunately,
fire weather concerns are low given the intrusion of marine air in
recent days, helping to moisten vegetation. Still, areas away
from the coast have not seen as much moisture and have experienced
warmer temperatures, along with record dry fuels from offshore
wind events earlier this season. So, new fire starts will be
possible. Winds will still be gusty into Thursday afternoon, but
will ease somewhat. Will have to monitor the situation Thursday to
see if an extension of the advisory is necessary.

There will be a notable cooldown with the incoming trough
Wed/Thurs with temperatures 5 to 15 degrees below normal Thursday.
Inland areas will struggle to reach 70 degrees, and 50s and 60s
will prevail near the coast. Gradual warmup will begin Friday
through the weekend, with temps returning to normal.

&&

.AVIATION...As of 10:39 AM PDT Monday...For the 18z TAFs.
Building high pressure helped clear out the skies at area
terminals a little earlier than forecast. A FEW clouds still
linger in the SF and Monterey Bays between 1500 and 2000 feet, but
otherwise VFR expected through Tuesday evening. As the pressure
gradient tightens, winds will increase and provide stronger west-
northwesterly gusts at most terminals. However, based on current
observations, the onset of the stronger winds in the TAF package
was pushed out slightly than previously forecast. Winds will begin
to diminish overnight, but remain moderately breezy. While most
terminals are expected to remain breezy through the night, LLWS is
possible for brief periods of time where surface winds quiet
momentarily. Skies should remain mostly clear overnight, with the
exception being a brief MVFR period of time early Wednesday
morning along the Central Coast. Stronger, gustier northwest winds
are expected Wednesday afternoon.

Vicinity of KSFO...VFR. Winds are northwest and breezy. Stronger
northwest winds are expected Tuesday afternoon. Models suggesting
gusts between 27 to 32 kts possible, which will obviously be
monitored through the day in case to goes above 35 kts. Winds will
diminish overnight, but remain gusty. VFR expected through the end
of the TAF period. Wednesday afternoon continues to look to be the
windiest day of the week as another stronger day of wind gusts are
expected.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...A brief patch of stratus hugging the
peninsula may make KMRY briefly go broken in the next hour, but
otherwise earlier clearing has brought VFR conditions to the
terminals. Winds are expected to increase and be gusty and from
the northwest this afternoon. As winds subside Tuesday evening,
some weak midlevel clouds are expected to develop along the
coastal ranges. There is chance for MVFR conditions early
Wednesday morning. But early clearing is expected once again for
VFR conditions on Wednesday as northwest winds increase yet again
with stronger gusts.

&&

.MARINE...as of 08:40 AM PDT Tuesday...Increasing northwest winds
through Tuesday. Winds out over the outer waters will be mostly
moderate gusts, while locally stronger winds are expected near
Point Reyes and south of Point Sur by Tuesday. These winds will
generate steep fresh swell resulting in hazardous seas conditions,
particularly for smaller vessels. Winds are then expected to
strengthen further early Wednesday morning, producing gale force
gusts in most of the northern and central waters Wednesday
afternoon and night. Winds will remain breezy for the remainder of
the week. Mixed seas will continue with a northwest swell and a
longer period southerly swell.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...SF Bay
             SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Mry Bay

&&

$$

PUBLIC FORECAST: Lorber/Bingaman
AVIATION: DK
MARINE: DK

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