FXUS66 KMTR 101142
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
442 AM PDT Fri Apr 10 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1203 AM PDT Fri Apr 10 2026

 - Rain and thunderstorms through the weekend 

 - Gradual warming and drying trend next week

&&

.SHORT TERM...
Issued at 1203 AM PDT Fri Apr 10 2026
(Today and tonight)

A surface low near 37 N, -128 W in the Eastern Pacific Ocean will 
continue to trek eastward through the night. Rain showers from the 
main rain band will push into the area around 2-3 AM and push off to 
the northeast by the afternoon. Isolated rain showers/thunderstorms 
will remain possible behind it. Rainfall totals will be dependent
upon where rain showers/thunderstorms develop and thunderstorm 
development will be dependent upon where breaks in the clouds 
allow for the convective temperature to be realized. Rainfall is 
expected to be strictly beneficial. The only caveat would be for 
minor flooding in poor drainage and urban areas if a heavier rain 
shower/thunderstorm develops and/or rain showers/thunderstorms 
train. Thunderstorms will pose the risks of lightning, locally 
heavy rainfall, erratic/gusty winds, and small hail. Weak low-
level shear does not support a mention of rotation leading to 
tornadoes and/or waterspouts.

&&

.LONG TERM...
Issued at 1203 AM PDT Fri Apr 10 2026
(Saturday through Thursday)

An upper-level low in the Gulf of Alaska will dig down the West 
Coast and absorb the first low as it does so on Saturday. This will 
be a whole new ballgame as this system is much more dynamic by 
nature with the inclusion of the jet stream. The cold front will 
sweep through Saturday afternoon and evening bringing widespread 
rainfall to the region. Even with the QPF continuing to trend higher 
with 1"-2" and up to 4" in the coastal ranges when all is said and 
done, this rainfall is expected to be purely beneficial thanks (I 
guess) to the dry March that we are coming off of. The three 
ingredients for thunderstorms of lift, instability, and moisture 
will all be in place Saturday. The merging of the two lows and the 
associated cold front will offer lift, the atmosphere will 
destabilize as cold air filters in aloft, and remnant tropical 
moisture will remain in place through the cold frontal passage. 
Thunderstorms will pose the risks of lightning, locally heavy 
rainfall, erratic/gusty winds, and small hail. With the 
reintroduction of the jet stream and veering winds in the low-
levels, rotation yielding waterspouts and/or weak tornadoes is 
possible. The slower trend of returning to ridging is thanks to the 
low filling instead of remaining progressive Sunday. As a result, 
wraparound rain showers and thunderstorms are now in the forecast 
all of Sunday. Cold air with remnant moisture will allow for snow 
across the highest peaks on Sunday. Anglers should take special note 
of the expected weather and have a plan to reach safe harbor quickly 
when the weather turns. Even without thunderstorms, the marine 
conditions will deteriorate through the day Saturday. If 
thunderstorms develop, the associated wind gusts are capable of 
capsizing small vessels. Fishing leads to more lightning deaths in 
the U.S. than any other activity. When thunder roars, head indoors!

Heights will slowly begin to rise on Monday, kicking off a warming 
and drying trend. Widespread below normal temperatures are expected 
Monday before slowly rebounding to seasonal normals by Thursday. As 
we get back into the growing season, patchy frost is possible in 
sheltered locations Monday morning due to the combination of cold 
conditions and remnant moisture. The frost risk decreases through 
the week as temperatures slowly rise and drier air filters in.

&&

.AVIATION...
(12Z TAFS)
Issued at 442 AM PDT Fri Apr 10 2026

A band of moderate to heavy showers is moving slowly eastward 
over the forecast area. In addition to showers during the 12z
TAFs, there's a slight chance to chance of thunderstorms today. 
Conditions are otherwise forecast VFR-MVFR. 

Vicinity of SFO...VFR-MVFR. Showers with a convective potential
today, but will monitor radar and satellite before adding VCTS to
the TAF. Southeast wind 5 to 10 knots becoming south-southwest 10
to 15 knots in the afternoon

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR-MVFR. Showers. Southeast to southwest
winds 5 to 12 knots. 

&&

.MARINE...
(Today through Wednesday)
Issued at 435 AM PDT Fri Apr 10 2026

A low pressure system with showers and a chance of thunderstorms
will move eastward over the coastal waters and bays today. This
low will merge with an energetic low from Alaska Saturday and
Sunday. The result will be rain, heavy at times, including a
chance of thunderstorms Saturday through Sunday. High pressure
builds behind the system with fresh northwest winds developing
early next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Saturday for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras 
     Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm-SF Bay N of 
     Bay Bridge.

     Small Craft Advisory from 9 AM to 3 PM PDT Saturday for Pt Arena 
     to Pt Reyes 0-10 nm.

     Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Pigeon 
     Pt to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...Canepa
MARINE...Canepa

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Prepared by Boulder-Creek.com Weather at: Fri Apr 10 08:30:02 PDT 2026