FXUS66 KMTR 240605
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1005 PM PST Mon Feb 23 2026
...New AVIATION...
.KEY MESSAGES...
Updated at 200 PM PST Mon Feb 23 2026
- Above normal temperatures and dry conditions this afternoon
- Widespread North Bay rainfall returns tonight into Tuesday
- Warming and drying trend kicks off Wednesday
&&
.UPDATE...
Issued at 959 PM PST Mon Feb 23 2026
A long fetch of moisture extends from the tropics to northern
California and the Pacific Northwest. The precipitable water (pw)
on the evening 00z Oakland sounding increased to 0.92" which is
just above the 90th percentile in late February. A fair amount of
the pw is at or above 9 thousand feet; surface observations show
higher based ceilings near 8 to 9 thousand feet, while it is drier
below this level and some evaporation of high ceiling based rain
is taking place.
The plume of moisture is forecast to shift east and southeastward
tonight through Tuesday night, placing our forecast area within a
peak of ~ 1.4" to 1.5" pw (near the maximum for Jan and Feb on
Oakland soundings since 1948) by later Tuesday. The higher pw
corresponds to an area of increasing low level warm air advection
(upward vertical motion). This will combine with southwesterly
orographic lift (upward forced air parcels expand and cool to
saturation) and result in light to moderate rainfall. Otherwise
the 500 mb height pattern is broadly anti-cyclonic with 500 mb
heights in the 570s range which is usually not too conducive to
precipitating. By late Tuesday the focus of pw, low level warm
advection and rain chances diminish while shifting southward with
a gradual deeper layer wind shift to westerly post cool frontal
by Tuesday night. Forecast on is on track, no updates anticipated
this evening.
&&
.SHORT TERM...
Issued at 200 PM PST Mon Feb 23 2026
(This evening through Tuesday)
High clouds streaming over the region ahead of the incoming
weather system. Comfortable temperatures in the 60s across the
region with the thickest clouds over the North Bay. Moist and mild
southerly flow this evening in warm frontal structure but no
excessively strong winds forecast given the lack of cold
advection. A few stray showers late this afternoon and early
evening near the Mendocino county line otherwise mainly dry
through 10 pm tonight. Warm frontal light rains develop overnight
across the North Bay, especially Sonoma county and the coastal
hills down to Marin. Clouds and southerly winds will keep temps
mainly in the 50s overnight. Wet roads for the early morning
commute mainly for areas north of the Golden Gate.
&&
.LONG TERM...
Issued at 200 PM PST Mon Feb 23 2026
(Tuesday night through next Sunday)
Weak to moderate AR and associated warm frontal structure will
keep steady rains pointed from San Francisco northward from 12-18z
Tuesday morning with the heaviest rains continuing across Sonoma
county. Light rain will gradually shift southward across San Mateo
county and the Santa Cruz mountains during the day Tuesday with
some light rain pushing into the East Bay. The Santa Clara Valley
and points southward will see little or no rain with this system
on Tuesday. Rain will continue through the evening commute for
much of the Bay Area with wet roads but generally light winds. Rainfall
totals by late Tuesday night of 1-3 inches for the North Bay with
some some localized 4 inch totals in the Sonoma hills and around
Mt Tamalpais. Rain amounts around 1 inch in San Franciso/Oakland
with amounts tapering off to around 0.25 for San Jose. Santa Cruz
mountains may top off around 1.5 inches but the weakening nature
of the system looks to keep amounts generally light for the Santa
Cruz mountains with only 0.10-0.25 for the Santa Lucia hills in
Monterey County. So in general expect beneficial late February
rains from this system with the only place for some possible
nuisance flooding across portions of Sonoma county. However, no
signs of the system stalling or intensifying beyond Tuesday
evening so confidence remains high for no widespread flooding
impacts.
Any lingering showers end by 12z Weds with perhaps some soupy
morning fog in the moist airmass. High pressure then builds with
highs warming back into the 60s and lower 70s with mild overnight
lows generally in the 50s at least through Saturday.
Next feature of interest is a weak cutoff low that could impact
the region later Sunday into Monday. The main impact would to
drop temperatures back down to more seasonable levels with a
slight chance of instability showers though no significant
rainfall is forecast. Long range trends beyond that keep the
pattern somewhat active but not seeing any signs of notable March
storms or rainfall.
&&
.AVIATION...
(06Z TAFS)
Issued at 1005 PM PST Mon Feb 23 2026
VFR continues with areas of light rain in the North Bay. Cloud
layers increase tonight with rain spreading southward tonight and
Tuesday. Conditions MVFR-VFR Tuesday with southerly winds then
winds shifting to westerly Tuesday evening and night.
Vicinity of SFO...VFR tonight, MVFR in rain Tuesday. Wind becoming
light southeasterly tonight and Tuesday morning. South-southeasterly
wind increasing to 15 to 20 knots Tuesday, decreasing to 10 knots
Tuesday evening.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR tonight and Tuesday. VFR with light
rain Tuesday night. Light and variable winds becoming southeasterly
5 to 10 knots tonight and early Tuesday. Southeasterly winds 7 to
15 knots Tuesday becoming light and variable Tuesday night.
&&
.MARINE...
(Tonight through next Sunday)
Issued at 902 PM PST Mon Feb 23 2026
Light to moderate rain will spread farther south tonight through
Tuesday night. Winds stay breezy then ease by Wednesday. Dry
weather prevails late for the second half of the week with light
seas.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PST Tuesday for Pt Arena to Pt
Reyes 0-10 nm.
Small Craft Advisory from 3 AM to 3 PM PST Tuesday for Pt Reyes
to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 PM PST Tuesday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...RW
LONG TERM....RW
AVIATION...Canepa
MARINE...Canepa
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Prepared by Boulder-Creek.com Weather at: Tue Feb 24 00:30:03 PST 2026
From the National Weather Service
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