FXUS66 KMTR 020004
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
504 PM PDT Wed Apr 1 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1214 PM PDT Wed Apr 1 2026

 - Unsettled weather today and tonight with cool, gusty, and rainy
   conditions

 - Warming and drying trend kicks off Thursday with well above
   normal temperatures and moderate offshore flow into the weekend

&&

.SHORT TERM...
Issued at 1214 PM PDT Wed Apr 1 2026
(This evening through Thursday)

A gale force low pressure system off the coast of the 
Washington/Canada border and its attendant cold front will be our 
weather maker the next 24 hours. Ahead of the cold front, 
southwesterly winds will increase with gusts of 20-30 mph and up to 
40 mph in the higher terrain. Isolated pre-frontal rain showers are 
possible with the best chances for rain holding off until later this 
afternoon, slowly spreading from north to south with the cold front. 
So as far as a wet commute home goes, that will likely remain 
confined to the North Bay with the slow progression of the cold 
front. That means most of the rainfall south of the Golden Gate 
Bridge will fall overnight. Rainfall totals on the order of 0.10"-
0.25" are expected with locally higher totals in the higher terrain 
of the North Bay with the help of orographic lift and locally lower 
totals in the Interior Central Coast. Even with the over performance 
of yesterday's rainfall, no adverse impacts are expected with the 
exception of slick roadways. It is possible that today's rainfall 
over performs as well due to the recency bias of the well above 
normal temperatures and dry spell that has occurred over the last 
four weeks. This is actually a best case scenario for both water 
storage and fire weather concerns. Similar to yesterday, the best 
chances for thunderstorms will remain off to our north and east with 
our region being instability limited.

&&

.LONG TERM...
Issued at 1214 PM PDT Wed Apr 1 2026
(Thursday night through next Tuesday)

The warming and drying trend will commence right behind the cold 
front as surface high pressure noses in from the Eastern Pacific 
Ocean. This will veer winds to become northwesterly with the 
tightened surface pressure gradient yielding strong winds in exposed 
areas like the higher terrain and over the waters. Very dry air will 
get funneled in behind the cold front with PWAT values forecast to 
be between the daily minimum (0.18 inches) and tenth percentile 
(0.34 inches) for 12Z tomorrow. ECMWF and GFS ensembles are in 
agreement that the SFO-WMC pressure gradient will change from 
positive (onshore) to negative (offshore) tomorrow night, but that's 
about where the agreement ends. The uncertainty lies in how the 
aforementioned high builds into the Intermountain West and how 
strong it gets. The ECMWF deterministic and ensemble continues to 
offer a stronger solution than its GFS counterparts. Both models and 
their means show a relative minimum occurring at 5 AM Friday with 
the ECMWF ensemble mean at -9.26 mb and the GEFS ensemble mean at
-8.03 mb. 24 hours later at 5 AM Saturday, the ECMWF ensemble 
mean bottoms out at -9.91 mb while the GEFS ensemble mean is well 
on its way to relaxing at -5.50 mb. Nonetheless, confidence is 
high that a moderate offshore flow event will transpire Thursday 
night with the gradient beginning to weaken by Sunday morning and 
returning to positive by Monday. This will equate to gusts of 40 
to 50 mph in the North Bay Interior Mountains with gusts of 30 to 
40 mph in the East Bay Hills, Eastern Santa Clara Hills, and Santa
Cruz Mountains. Well above normal temperatures are expected over 
the weekend with Saturday being the warmest day of the week. 
Chances for rain may return as early as Tuesday with the help of 
an upper-level trough.

&&

.AVIATION...
(00Z TAFS)
Issued at 444 PM PDT Wed Apr 1 2026

Breezy west-southwest winds will persist out ahead of a cold front
that arrives around 04z across the North Bay and will be through 
the Monterey Bay terminals around 10Z. The mix of of MVFR/VFR cigs
will continue until after the front is through. The airmass 
behind the front is very dry with quick clearing expected to VFR,
however gusty west- northwest winds will persist through much of 
the remaining TAF period in the post-frontal environment.

Vicinity of SFO...Similar to SFO.

SFO Bridge Approach...Scattered light rain through late tonight 
out ahead and along a front that arrives in the Bay Area around
07Z. Expect a mix of MVFR/VFR cigs until the front is through and
quickly becomes VFR with gusty west-northwest winds around 09Z.

Monterey Bay Terminals...VFR conditions are expected until a cold
front arrives around 09Z with a drop into MVFR cigs until around 
12Z with scattered light rain. VFR for the remainder of the day 
once the front moves through with breezy west-northwest winds.

&&

.MARINE...
(Tonight through next Monday)
Issued at 444 PM PDT Wed Apr 1 2026

Southwesterly breezes will increase ahead of the cold front this
afternoon and veer to become fresh and northwesterly tonight. The
cold front will bring light rain this afternoon into tonight.
Widespread hazardous conditions arrive tomorrow and continue into
Friday with strong northerly breezes and rough seas. Northerly
breezes diminish and seas abate by this weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Friday for Pt Arena to Pt 
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to 
     Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.

     Small Craft Advisory from 3 AM Thursday to 3 AM PDT Friday for 
     Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 
     10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...JM
MARINE...Sarment

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Prepared by Boulder-Creek.com Weather at: Wed Apr 1 20:30:02 PDT 2026