939
FXUS66 KMTR 272017
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
117 PM PDT Thu Mar 27 2025

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 116 PM PDT Thu Mar 27 2025

Periods of light showers and breezy winds are expected through
Monday, followed by a potentially significant system in the first
days of April.

&&

.SHORT TERM...
(This evening through Friday)
Issued at 116 PM PDT Thu Mar 27 2025

In the wake of a cold front that came through the region this
morning, satellite imagery shows a cloudy day across the Bay Area
with partial clearing across the Central Coast. Radar returns are
showing a band of showers heading across Napa County and the San
Mateo Peninsula, and heading into the East Bay, with light showers
present elsewhere in the Bay Area and Santa Cruz County. Light
showers are expected across the North Bay and Bay Area for the rest
of the day, with lingering showers overnight. A weak shortwave
trough on Friday morning may bring a few sprinkles of drizzle in the
northern reaches of Sonoma County. Breezy and gusty south winds will
continue through the evening with gusts up to 20-25 mph in most of
the Bay Area and up to 30-35 mph in the ridgelines and through gaps
and passes. These gusty winds will subside overnight, but the gusts
will resume on Friday as the winds shift to the northwest.

High temperatures through the next couple of days hover in the lower
to middle 60s in the inland valleys, to the upper 50s to lower 60s
in the coastal regions, and the upper 40s to the middle 50s in the
higher elevations. Low temperatures on Friday morning range from the
middle 40s to lower 50s across most of the region, with lows in the
upper 30s and lower 40s in the higher elevations and in southern
Monterey County.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 116 PM PDT Thu Mar 27 2025

As the shortwave trough exits on Friday morning, a transitory ridge
will move through the region, bringing us a break in the rain from
Friday afternoon through Saturday. On Sunday, an upper level low
will move into the Pacific Northwest, with the associated frontal
system bringing another shot of light rain and gusty winds to the
region. Rainfall totals for Sunday and the early part of Monday will
be around 0.5-1" across the North Bay, and around 0.1-0.5" across
the rest of the Bay Area and the Central Coast, with totals on the
higher end near the coastal ranges and near the lower end in the
interior Central Coast.

The following storm system, expected for the first couple of days of
April, is still shrouded in uncertainty, and a quick look at the
ensemble means suggests that the American GEFS ensemble model
continues to depict a stronger system than the European ECMWF
ensemble model, while the European ensemble model depicts a more
prolonged system than the one shown by the American ensemble model.
This is especially true as the forecast goes into Wednesday and the
upcoming Thursday. As of now the early estimates continue to support
widespread rain totals of 1-2 inches across the region with higher
totals possible in the higher elevations. This is still a system
where the rain totals could still fluctuate, particularly if the
models begin to coalesce on one of the two scenarios or the other.

&&

.AVIATION...
(18Z TAFS)
Issued at 1055 AM PDT Thu Mar 27 2025

A weak frontal boundary has pushed across the region earlier this
morning with another boundary approaching from the northwest late
this morning. This will bring periods of MVFR ceilings and rain
(mostly to the North Bay) to the region at times through early this
afternoon with VFR conditions expected thereafter. Overall, the rain
will be quite light today, but there could be a brief shower that
reduces visibility lower than advertised in the TAFs. West-southwest
winds are forecast to increase by early this afternoon before easing
late this evening and into early Friday morning. Rain showers will
also be possible late this evening across the Bay Area terminals
with MVFR ceilings expected across much of the region Friday morning
before clearing out by midday Friday.

Vicinity of SFO...VFR conditions have returned to the Bay Area at
this hour with west-southwest winds forecast to increase by this
afternoon. Wind gusts in the mid 20 kt range are possible from the
late morning to early afternoon at SFO. Scattered showers in the
late evening will likely be accompanied by a return of overcast
skies and MVFR ceilings. MVFR ceilings have the potential to return
Friday morning before mixing out by midday Friday.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Onshore winds are forecast to increase
through the early afternoon before easing this evening. There is the
potential for showers to move over the region late this evening and
into Friday morning, but confidence is not high enough to include in
the current TAFs. MVFR ceilings are forecast to return early Friday
morning.

&&

.MARINE...
(Today through Tuesday)
Issued at 844 AM PDT Thu Mar 27 2025

Southwest winds increase to a strong breeze across the northern
most outer waters while a moderate breeze persists across the
southern waters. Winds diminish to a moderate to fresh breeze and
become more west to northwest overnight Thursday into Friday. Seas
build and become very rough this morning with rough seas
persisting into the weekend. Multiple rounds of light to moderate
rain are expected starting today into next week as a series of
storm systems move through the region.

&&

.BEACHES...
Issued at 1055 AM PDT Thu Mar 27 2025

The long period northwest swell has arrived at the Pt. Arena and Pt.
Reyes buoys. The buoys are reporting, as of 10 AM PDT, 18 feet at 16
seconds. This swell will generate large breaking waves up to 30
feet, especially on west and northwest facing beaches, in addition
to enhanced rip currents. Inexperienced swimmers should stay out of
the water. Beachgoers should maintain a further stand-off distance
from the water than normal. Stay off of jetties and rocks, keep pets
on a leash, wear a life jacket, and never turn your back on the
ocean!

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory until 11 AM PDT Friday for CAZ006-505-509-530.

     Beach Hazards Statement through Friday morning for CAZ529.

PZ...Small Craft Advisory until 3 PM PDT this afternoon for SF Bay N
     of Bay Bridge.

     Small Craft Advisory until 9 PM PDT Friday for Mry Bay.

     Small Craft Advisory until 9 AM PDT Saturday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 AM PDT Saturday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 9 AM PDT Saturday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 PM PDT Saturday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...RGass
MARINE...RGass

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