Gale Warning 16, NWS San Francisco Bay Area, CA

Area Forecast Discussion
National Weather Service San Francisco CA
1052 PM PDT Wed Mar 27 2024

...New AVIATION...

.SYNOPSIS...
Issued at 900 PM PDT Wed Mar 27 2024

Showers will end overnight. Breezy and cool Thursday with only
some isolated showers forecast. Southerly winds increase Friday
morning ahead of the next storm that will bring rain and scattered
thunderstorms to the region Friday into Saturday. Drying trend
Sunday as high pressure builds and lasts through the middle of
next week with a return to dry and seasonably mild weather.

&&

.SHORT TERM...
(Tonight through Friday)
Issued at 900 PM PDT Wed Mar 27 2024

Cold front is currently across the North Bay and will make its way
southward overnight. Cooler air aloft is starting to filter over
the region with an uptick in rain rates for the North Bay. So far
the heaviest rain has been confined to the North Bay hills with
0.75 for Mt Tamalpais and 0.04 last hour in the City. We noted a
clear frontal passage last hour at Bodega Bay buoy where the winds
abruptly shifted from southerly to westerly in an almost text
book fashion. Expect the frontal boundary and associated light
rainfall to shift north to south during the overnight hours with
lingering showers confined to the Monterey hills by sunrise and
perhaps some lingering morning drizzle around SF Bay. Roads will
be wet for the early morning commute.

The main weather story for Thursday will be chilly daytime highs
in the mid and upper 50s for most locations with some lower 60s
where the sun pokes out during the afternoon. Enough lingering
moisture and instability for there to be a few showers around,
especially in the North Bay Thursday afternoon as a weak shortwave
pivots across Oregon and far Northern California.

Attention quickly turns to next weather system with chilly temps
on Thursday night moderated by incoming mid/high clouds ahead of
the next storm.

Southerly winds will ramp up noticeably Friday morning in
response to a developing area of low pressure approaching the
waters west of the Golden Gate. Surface pressure dropping down to
around 997 mb means winds wont be nearly as strong as what we saw
with some storms of similar trajectory earlier this winter. Will
need to look at guidance overnight and at least be considering
wind advisories with future forecast updates. 925 mb winds in the
35 kt range suggest gust potential in the wind channeled valleys
could reach the 45 mph range especially with a deepening low
offshore. Saturated soils could lead trees more easily toppling.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 900 PM PDT Wed Mar 27 2024

Numerous showers and thunderstorms Friday night into Saturday as
the core of the upper low will be over the region with steep lapse
rates. Small hail will be the biggest threat but will need to at
least monitor shear profiles given the strong March sun angle and
cold air aloft.

Drying trend for Sunday as the low drops southward. High pressure
builds Monday through Weds with a return to dry weather as temps
trend above normal, back into the lower and mid 70s.

&&

.AVIATION...
(06Z TAFS)
Issued at 1047 PM PDT Wed Mar 27 2024

A cold front is currently making its way through the heart of the
Bay Area with APC and STS already seeing clearing. The cold front
will continue to drop to the southeast, bringing MVFR ceilings
and rain to the rest of the terminals. Winds will be breezy out of
the west tomorrow afternoon.

Vicinity of SFO...Currently MVFR with breezy southerly flow as the
cold front moves over the terminal. Winds will become westerly and
rain shower activity will promptly cease behind the cold front.
Winds will be breezy out of the west tomorrow afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently VFR with southwesterly flow at
MRY and VFR with northerly flow at SNS. Rain showers are beginning
to close in on the terminals with the cold frontal passage expected
by 11Z. Winds will become breezy out of the northwest after the cold
front passes with breezy westerly flow prevailing by tomorrow
afternoon.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 518 PM PDT Wed Mar 27 2024

Winds have started to strengthen and turn SW ahead of a weak cold
front approaching the coastal zones. The approaching front has
slowed down with widespread light to moderate showers expected to
begin over the coastal waters this afternoon and evening. A
second, stronger low pressure system will reach the coastal waters
Friday, bringing moderate precipitation, gusty southerly winds,
and allow for wave heights to build. This second system will
create widespread conditions that are hazardous to small crafts.
Northwesterly swell continues with a new long period northwesterly
swell arriving early next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Thursday for Mry Bay.

     Small Craft Advisory from 3 AM Thursday to 9 AM PDT Friday for
     Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory from 3 PM Thursday to 9 AM PDT Friday for
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras
     Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 9 AM Thursday to 9 AM PDT Friday for
     Pigeon Pt to Pt Pinos 10-60 NM.

&&

SHORT TERM...RW
LONG TERM....RW
AVIATION...Sarment
MARINE...AC

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