FXUS66 KMTR 221623
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
300 AM PST Thu Jan 22 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 114 AM PST Thu Jan 22 2026
- Morning fog across North and East Bay Valleys
- Sprinkles to very light rain through late Thursday morning
across Central Coast and portions of the Bay Area
- Gusty offshore winds across higher terrain of the North Bay
late Friday into Saturday
&&
.SHORT TERM...
Issued at 114 AM PST Thu Jan 22 2026
(Today and tonight)
Scattered showers continue over the marine environment and across
the Central Coast. This forecaster can confirm that very light rain
is making it to the surface in Monterey after stepping outside to
investigate. In the last six hours there was a trace of rain
reported within the Santa Lucia Range while up to a tenth of an inch
was reported to our south over the SLO county line. We still are not
anticipating much accumulation at the surface tonight with even the
NBM 90th percentile capping precipitation accumulation at a few
hundredths of an inch. Following high resolution HRRR guidance,
scattered showers are likely to persist through mid morning across
the Central Coast with showers unlikely across the Bay Area. Cannot
fully rule out a very light rain making it to the ground in the Bay
Area but it will be a lot more difficult. Aircraft soundings from
the Monterey Airport show decently moist lower levels (81% RH from 0-
0.5 km and 65% RH from 0.5-1.0 km) compared to much drier conditions
to our north at SJC (65% RH 0-0.5km and 48% RH 0.5-1.0 km). Given
the much drier air in the lower levels of the atmosphere, there is
more room for any falling precipitation to evaporate as it falls
over the Bay Area compared to over the Central Coast. There is some
potential for fog to develop across the North and East Bay Valleys
tonight. However, any dense fog should be localized due to the cut-
off low offshore helping to keep the lower levels of the atmosphere
more mixed.
The cut-off low offshore to our west will gradually move down the
California coastline Thursday. Rain chances diminish by late morning
with dry weather expected through the remainder of the day. Morning
low temperatures remain seasonal with lows in the 40s across the
lower terrain and upper 40s to low 50s across the higher elevations.
High temperatures warm by a degree or two today compared to
yesterday with highs in the low to mid 60s across the lower
elevations and mid to upper 60s across the higher elevations.
Widespread fog is possible across the interior valleys Thursday
night into Friday morning due to increased surface moisture and calm
winds.
&&
.LONG TERM...
Issued at 114 AM PST Thu Jan 22 2026
(Friday through Wednesday)
The cut-off low will continue southwards down the coastline Friday
before moving inland over Baja California and merging with a deep
upper level trough across the Central U.S. late Friday into
Saturday. In its wake, ridging redevelops across the West Coast
before becoming zonal late weekend into early next week. What does
this mean in a general sense? Dry weather and seasonal temperatures
in the upper 50s to low 60s persist for much of the upcoming week.
Morning temperatures will get progressively chillier starting
Saturday with lows dropping into the mid to upper 30s across the
region. Morning lows will trend seasonally cool through the middle
of next week.
The main thing to note for the long term forecast is that we are
expecting offshore winds to strengthen Friday night, continuing
through Saturday, across the North Bay Interior Mountains and East
Bay Hills. We know our upper level pattern is fairly quiet so we
have to turn to our surface pressure gradient to identify why we are
seeing offshore winds strengthen. Along the CA coastline we are
seeing a coastal trough develop while high pressure rebuilds across
Nevada and the Northwestern U.S. This setup is conducive for
offshore flow with a stronger pressure gradient resulting in
stronger winds. The SFO-WMC gradient shows it becoming strongly
negative (offshore) starting Friday evening and remaining that way
through the day on Saturday. The current SFO-WMC gradient is
forecast to peak around -10.8 mb early Saturday morning. There is
decent low level support for offshore winds with a low level 925 mb
northeasterly jet (peaking around 30-40 knots) located over the
interior North Bay at the same time. This brings good agreement that
we will see gusty offshore winds across the North Bay Interior
Mountains and East Bay Hills this weekend. Gusts are expected to be
between 20 to 30 mph but locally stronger gusts may occur across the
highest peaks. A few stronger gusts may mix downwards into the
neighboring valleys so forecast winds for those valleys were bumped
up slightly. The overall fire weather threat remains low but there
is still a low potential that dry, winter fuels could result in some
fire growth.
Ridging redevelops by the middle of next week but not all hope is
lost for rain lovers. The Pacific remains active with a series of
strong upper level lows developing offshore. Most of these systems
look to stay well to our north but we may see the ridge start to
break down/return of upper level troughing by the end of January
into early February. Models remain in disagreement about whether or
not we will see the ridge break down. The Euro is much more
confident that upper level troughing and rain will return while the
GFS is more pessimistic and keeps upper level ridging in place. The
Euro ensemble members nearly all show rain returning while only a
handful of GFS ensemble members do. This is still well over a week
out so make sure to stay up to date on the forecast as models come
into better agreement on ridging vs troughing.
&&
.AVIATION...
(12Z TAFS)
Issued at 259 AM PST Thu Jan 22 2026
It's VFR except for a few areas of MVFR surface visibilities. A
few passing showers continue over the north Central Coast due to
a nearby closed 500 mb low pressure system. Areas of coastal low
clouds and fog return tonight and Friday morning according to recent
HREF output.
Vicinity of SFO...VFR. Light and variable wind becoming onshore 5
to 10 knots in the afternoon and continuing onshore tonight and
Friday morning.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR with a few showers this morning.
MVFR due to low clouds developing tonight and Friday morning.
Light southeast winds becoming onshore 5 to 10 knots in the
afternoon. Light and variable winds tonight and Friday morning.
&&
.MARINE...
(Today through Tuesday)
Issued at 253 AM PST Thu Jan 22 2026
Fresh northerly breezes and building seas will develop mainly over
the northern outer waters today into Friday. Near gale force winds
from Friday morning through late Friday night over the northern
outer waters will result in hazardous conditions for small craft.
Seas will gradually ease Saturday afternoon and remain light to
moderate into the beginning of next week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PST
Saturday for Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...Canepa
MARINE...Canepa
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Prepared by Boulder-Creek.com Weather at: Thu Jan 22 08:30:03 PST 2026
From the National Weather Service
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