914
FXUS66 KMTR 121900
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1200 PM PDT Tue May 12 2026

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

.KEY MESSAGES...
Updated at 1200 PM PDT Tue May 12 2026

 - Cooling trend continues today and Wednesday

 - Elevated fire weather risk for far interior San Benito and
   Monterey counties this afternoon and evening

 - Warming and drying trend resumes Thursday through the weekend

&&

.SHORT TERM...
Issued at 1200 PM PDT Tue May 12 2026
(This evening through Wednesday)

The satellite imagery shows stratus coverage across the coastal
regions and some lingering into the valleys of the Bay Area as a
thin layer of high clouds persists over the region, with gradual
clearing across the inland and Bayshore regions into the afternoon
while the coast remains socked in. Stratus coverage should rebuild
this evening and overnight but should not come as far into the
southern Salinas Valley or the North Bay valleys as we saw this
morning.

The large scale weather pattern features a departing ridge moving
into the northern and central Rockies while a trough centered on an
upper level low around 500 miles to the west of the Oregon Coast
moves in, resulting in a gradual cooling trend today into Wednesday
and an expansion of the marine layer. The latest readings from the
Bodega Bay profiler suggest a marine layer around 1500-2000 feet
thick, remaining rather consistent through the next couple of days
as the trough passes through the region. High temperatures today
will range from the upper 70s to the lower 80s in the inland
valleys, the upper 80s to lower 90s in southern Monterey and San
Benito Counties, the middle 60s to the middle 70s in the bayshore
regions, and the upper 50s to lower 60s along the Pacific coast.
Highs might be a few degrees cooler where the stratus is slower to
dissipate than the forecast or does not clear out this afternoon.
Low temperatures on Wednesday morning range from the upper 40s to
the middle 50s across the lower elevations, while Wednesday`s highs
will range from the lower 70s to the lower 80s for the inland
valleys.

As the trough moves through, the increasing pressure gradients will
result in breezy and gusty winds starting this afternoon through
Wednesday, with the gusts reaching 20 to 30 mph across the coastal
and higher elevation regions and the northern Salinas Valley.
Isolated favored regions, namely the Mayacama range and the Altamont
Pass, may reach gusts of 40 to 45 mph this evening and overnight.

Elevated fire weather risks will set up starting this afternoon
across a narrow strip of the far interior San Benito and Monterey
counties adjacent to the Central Valley. A particularly concerning
combination of gusty winds, hot temperatures, low daytime
humidities, and poor overnight humidity recoveries across this
region will result in a period of elevated fire weather concerns
across this strip through the evening hours. Any fires that start in
the drier grasses across this region may take hold and spread rather
quickly. Our neighbors in Hanford have issued a Red Flag Warning for
the adjacent zones across the western edge of Fresno County, but in
our area of responsibility. the fire weather concerns are not
widespread enough to warrant any products.

&&

.LONG TERM...
Issued at 1200 PM PDT Tue May 12 2026
(Wednesday night through next Monday)

As the trough moves out, warmer and drier weather will return to the
region with highs on Thursday and Friday in the 80s to the lower 90s
in the interior valleys, the middle 70s to lower 80s across the
Bays, and the lower to middle 60s in the Pacific coast. A second
trough coming down from the Gulf of Alaska will interrupt the
warming trend this weekend, with inland highs dipping in to the
lower 70s to lower 80s on Saturday before bouncing back to the upper
70s to middle 80s for Sunday.

Uncertainty in the forecast starts to increase in the early part of
next week as the ensemble models struggle to diagnose the
interaction between an upper level ridge and trough over the western
United States. Model ensemble means from the American GEFS, European
ECMWF, and Canadian GEPS models suggest a ridge over the eastern
Pacific and a trough over the Rockies should develop by Monday
morning, although with significant differences in the strength of
both features. However, a peek into the model ensemble clusters
reveals a significant minority of the ensemble members (around 30-
40%) show an alternate scenario where more zonal flow or troughing
develops over the West Coast, nudging the forecast towards cooler
temperatures. Past the 7-day outlook, CPC outlooks into the later
part of May show a slight lean towards temperatures above seasonal
averages, and precipitation totals near or above seasonal
averages.

&&

.AVIATION...
(18Z TAFS)
Issued at 1059 AM PDT Tue May 12 2026

A deep marine layer produced widespread stratus across the region
this morning. Stratus is receding with all sites except HAF and MRY
likely to clear by 19/20Z. Winds strengthen by the afternoon/evening
with gusts to around 20-30 knots expected along the coastline. A dry
cold front will push through tonight with moderate confidence in the
timing of cloud cover arrival. Currently kept a later stratus
arrival (09/10Z) for most sites but LAMP guidance shows some
potential for stratus to return closer to 05/06Z. This cold front
will also result in widespread gusty winds along the coast and
across the bay shoreline early tomorrow morning. For now, kept
tomorrow morning`s gusts limited to HAF, OAK, and SFO but gusts are
expected to pick up at the remaining airports after 18Z tomorrow.

Vicinity of SFO...Stratus is receding from SFO and should dissipate
by 19Z. Gusts are expected to pick up by late this morning with the
site to remain gusty through the end of the TAF period. Bumped up
the afternoon/evening gusts to 30 knots with around a 10% chance of
stronger gusts to 35 knots. We do expect gusts to ease slightly
overnight (20-25 knots) but gustier winds (30-35 knots) are expected
to return tomorrow afternoon/evening. Moderate confidence that
stratus will return around 09Z with some potential for stratus to
return as early as 03-06Z. Stratus should clear by late tomorrow
morning with VFR conditions through the end of the TAF period.

SFO Bridge Approach....Generally similar to SFO. Expect stratus to
fill in over the bay this evening and linger through late tomorrow
morning. Similar to SFO, gusty winds are expected over the bay with
the potential for sustained winds around 20 knots and gusts between
30-35 knots tomorrow afternoon/evening.

Monterey Bay Terminals...VFR at SNS through early this evening. IFR-
LIFR CIGs are expected to persist at MRY through the TAF period with
a continued stream of stratus onshore making it unlikely for MRY to
clear this afternoon. Moderate confidence in IFR-LIFR CIGs
developing again tonight with LIFR CIGs becoming more likely by
early tomorrow morning. Breezy onshore winds are expected this
afternoon/evening with gustier onshore winds to develop late
tomorrow morning and continuing through the evening.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 949 PM PDT Mon May 11 2026

Occasional strong gusts continue through tonight across the far
northern outer waters. Otherwise, a moderate to fresh northwest
breeze will continue over the waters through midweek. Seas subside
but remain moderate with 4 to 6 foot seas through midweek. Winds
increase and seas build starting mid-week with gale force winds
and wave heights in excess of 10 feet likely starting Friday and
continuing through the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Wednesday for Mry Bay.

     Small Craft Advisory from 3 PM this afternoon to 3 AM PDT
     Thursday for Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to
     Pigeon Pt 0-10 nm.

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

     Small Craft Advisory from 3 AM Wednesday to 3 AM PDT Thursday
     for Pt Pinos to Pt Piedras Blancas 0-10 nm.

&&

$$

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

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