415
FXUS66 KMTR 230554
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
954 PM PST Sat Feb 22 2025

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 1111 AM PST Sat Feb 22 2025

Chance of very light rain in the North Bay tonight into Sunday and
again on Monday. Otherwise, dry and warm through the middle of next
week. Chance of rain returns later next week with a cutoff low
approaching the state, although details are still highly
uncertain.

&&

.UPDATE...
Issued at 830 PM PST Sat Feb 22 2025

Pretty mild Saturday around the Bay Area and Central Coast thanks
to mostly sunny skies (except far N Bay), warming airmass, subtle
ridging aloft. Highs topped out in the 60s to upper 70s. The
warmest locations were away from the coast/bays, especially
interior Central Coast with a few spots flirting with 80 degrees.
Today`s highs were 5 to 10 degrees above normal for late February.
If you like warmer weather you`ll like the upcoming seven day
forecast.  See below for more details.

Despite the warmer weather and sunny skies, the radar was put
into precip mode earlier in the afternoon due to showers over the
coastal waters and northern N Bay. Since this afternoon, showers
picked up in coverage over the coastal waters. As a result, an
evening update was done earlier to include showers as far south as
the South Bay and eastward to the East Bay. Not expecting much in
the way of accumulation, but enough to see a few drops reach the
ground. A weather spotter from Pleasant Hill reported light rain
and a few mPING reports in SF also mentioned rain. These light
rain showers will persist through the evening and into early
Sunday. Greatest likelihood still remains Golden Gate northward.

MM

&&

.SHORT TERM...
(This afternoon through Sunday)
Issued at 1111 AM PST Sat Feb 22 2025

Satellite imagery reveals coastal stratus lingering in the North Bay
and San Mateo Peninsula coastlines, while scattered cirrus persists
over much of the region. If there is anything vaguely exciting about
the short-term forecast for our region, it`s found up in the
northern fringes of Sonoma and Napa Counties. A plume of moisture is
impacting the Pacific Northwest, with the Eureka radar also showing
rain just offshore of the North Coast. The edges of the moisture
plume could bring light rain to the northern regions of Sonoma and
Napa counties beginning tonight into Sunday. Emphasis on light rain,
with the rainfall totals only around a few hundredths of an inch at
most.

Elsewhere in the region, the big story is dry and warm weather
through the weekend. Highs today range from the low to mid 70s today
in the inland valleys to the middle to upper 60s closer to the coast.
The low temperatures are also inching upwards for Sunday morning,
ranging from the middle 40s to the lower 50s in the lower
elevations, while Sunday`s highs reach the upper 70s across the
southern Salinas Valley, generally remaining similar to today`s
elsewhere.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 1111 AM PST Sat Feb 22 2025

Another round of light rain comes into the North Bay on Monday, with
an upper level low off the Pacific Northwest becoming more defined
in the model output since yesterday. The main impacts to the
forecast are a slight increase in rain totals in the North Bay, to
around a tenth of an inch in favored locations in the Sonoma coastal
ranges, and a dip in temperatures across the region. Monday`s highs
reach the lower 60s in the North bay valleys, the upper 60s the
middle 70s in the inland valleys elsewhere, and the lower to middle
60s along the coast. As the disturbance passes, upper level ridging
returns to the region and resumes our warming trend, with high
temperatures in the inland valleys reaching the middle to upper 70s
by Wednesday.

By the middle of the week, a trough moving through the northern
Pacific deepens and cuts off as it approaches the state. At this
point, significant differences between models, and among the
ensemble solutions from the models, make the forecast highly
uncertain. Looking at the ensemble means, the American GEFS model
places a weaker low through the Central Coast by Thursday, the
Canadian GEPS model places an even weaker low around the same place
and timeframe, while the European ECMWF model further deepens the
low, places it closer to southern California, and delays its impact
to Friday. The ensemble model cluster analysis further supports
these claims with the European ensemble members tending to support a
fully cut off low off the coast of California on Thursday, while the
American ensemble members supporting a broader trough or weaker
cutoff low that gets closer to the coast, and the Canadian ensemble
members tending to support solutions that more resemble a shortwave
trough. At this point, there is a chance for rain late Wednesday
through early Friday, but anything more specific than that would be
beyond the current state of the forecast certainty. Expect further
refinements to the forecast through the next few days.

&&

.AVIATION...
(06Z TAFS)
Issued at 954 PM PST Sat Feb 22 2025

Light, scattered showers continue to move through the North Bay with
chances diminishing farther south overnight. Low ceilings will
return across the Bay Area (for areas north of SJC and LVK)
overnight with ensemble guidance indicating at least some potential
for LIFR conditions to develop. HAF is already reporting LIFR CIGs
which adds some credence to LIFR conditions developing directly
along the coast. Leaning towards MVFR-IFR border overnight for most
inland sites but will need to keep an eye on CIGs as they start to
develop. Fog continues to look likely across the North Bay valleys
overnight with at least temporary LIFR impacts at STS. Winds will be
fairly light and at times variable overnight before moderate NW flow
returns tomorrow during the day.

Vicinity of SFO...VFR with MVFR conditions likely overnight. Highest
confidence in MVFR-IFR CIGs from 13Z to 18Z with some guidance
showing lowered ceilings persisting until 20Z. Confidence is low to
moderate but cloud ceilings have started to lower across the region
in the last few hours. Winds stay light overnight before moderate NW
flow begins during the day tomorrow.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period with some
potential for lower CIGs to develop overnight. Currently high level
clouds are approaching the Central Coast with low to moderate
confidence that MVFR to IFR-LIFR CIGs develop overnight. Night Fog
shows lower clouds developing offshore but ensemble guidance is
mixed on if it will reach MRY and SNS. Confidence continues to be
slightly higher for SNS than MRY, with LIFR CIGs possible from 09Z
to 16Z. Winds will be light overnight before moderate NW winds
develop during the day.

&&

.MARINE...
(Tonight through next Friday)
Issued at 954 PM PST Sat Feb 22 2025

Scattered light rain continues over the coastal waters through
early  Sunday morning. Winds and seas remain relatively calm
through the  weekend. There will be another chance for light rain
on Monday as  low pressure system moves into the Pacific
Northwest. Moderate  northwesterly swell returns to the coastal
waters by Tuesday  bringing waves between 10 to 14 feet at a
period of 14 seconds. This  will lead to rough seas and see a
return of hazardous conditions for  small crafts.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Kennedy
MARINE...Kennedy

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