FXUS66 KMTR 130616
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1116 PM PDT Tue May 12 2026
...New AVIATION...
.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
&&
.UPDATE...
Issued at 937 PM PDT Tue May 12 2026
Noticeable cooldown across the Bay Area and Central Coast this
afternoon thanks to a departing area of high pressure and solid
marine intrusion. The biggest 24 hour trends were across the
higher terrain and interior locations with some spots 5 to 15
degrees colder today than Monday. Despite the cooldown max temps
were still several degrees above seasonal averages. In addition to
the cooldown, onshore flow brought some gusty winds to the coast
and inland gaps/passes/valleys. Max gusts ranged from 25-50 mph.
Winds have eased a little since this afternoon, but still seeing
strong gusts near the Marin headlands and East Bay Hills.
No update needed this evening. While stratus is patchy at the
moment do expect some expansion as the night progresses.
MM
&&
.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...
(06Z TAFS)
Issued at 1107 PM PDT Tue May 12 2026
Breezy to gusty onshore winds will persist through a majority the
TAF period for sites along the coast. Winds are reducing into the
night, but are expected increase again late morning into the
afternoon on Wednesday. MVFR cigs continue to develop and
persisting through late morning Wednesday. The timing and coverage
of IFR/LIFR cigs is low confidence, and if reached may not
persist for long.
Vicinity of SFO...MVFR cigs are expected persist through late
morning Wednesday. Gusty onshore winds extending through much the
TAF period, peaking around 30 kts Wednesday afternoon, but winds
ease Wednesday night.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...MVFR cigs are expected to persist
through the late night, becoming IFR after and continuing through
mid-morning Wednesday. KSNS is expected to clear out Noon with
some partial clearing possible at KMRY by early afternoon.
&&
.MARINE...
(Tonight through next Sunday)
Issued at 443 PM PDT Tue May 12 2026
Hazardous marine conditions develop midweek and will continue into
next week. Winds increase through the remainder of the week with
strong to near gale force winds and occasional gale force gusts
Wednesday and Thursday. Wind driven seas will build to between 10
to 12 feet Wednesday and Thursday. Surface high pressure will
then strengthen over the eastern Pacific Friday into next week.
This will result in a strong coastal jet, widespread gale force
to potentially severe gale winds, and very high, wind driven seas
between 12 to 17 feet expected.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Wednesday for Mry Bay.
Small Craft Advisory until 3 PM 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 PM 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 PM PDT Thursday
for Pt Pinos to Pt Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...
MARINE...JM
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Prepared by Boulder-Creek.com Weather at: Wed May 13 00:30:03 PDT 2026
From the National Weather Service
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