FXUS66 KMTR 100705
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1205 AM PDT Fri Apr 10 2026

...New SHORT TERM, LONG TERM...

.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...
(06Z TAFS)
Issued at 1003 PM PDT Thu Apr 9 2026

MVFR-IFR stratus is developing at the coast and moving inland 
through the next few hours, and will be reinforced overnight by the 
first band of showers expected to arrive sometime Friday morning. As 
the showers pass, ceilings should lift to become generally VFR-MVFR, 
along with isolated to scattered thunderstorms across the region, 
with the best chances focused on the North Bay and East Bay on 
Friday afternoon and evening. Have decided to go ahead and put VCTS 
in for the STS, APC, and LVK TAFs for the 18-00Z time period, but 
note that this is a lower confidence forecast. Chances for 
thunderstorms decrease on Friday evening, but scattered showers 
remain possible through the end of the TAF period, with another band 
of widespread rainfall expected after the end of the TAF period on 
Saturday afternoon through Sunday. Onshore wind flow will continue 
to diminish tonight, with light winds overnight before moderate 
southwest winds prevail through much of Friday. Gustier winds are 
expected where thunderstorms do develop.

Vicinity of SFO... VFR conditions continue through the next couple 
of hours. MVFR conditions will set up overnight as a band of showers 
passes through the terminal area through Friday morning, with VFR 
conditions with mid-level clouds returning once the showers pass. 
Friday afternoon should see a moderate southwesterly flow develop 
through the evening. There is around a 25-35% chance of 
thunderstorms at the terminal Friday afternoon and evening, but 
confidence is too low to put VCTS or PROB30 in the TAF at this time. 
Chances for showers continue through the end of the TAF period.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... MVFR stratus is developing around the 
terminals with a "sucker hole" at present around MRY, with a band of 
showers expected to pass through the region through the course of 
Friday morning. VFR conditions return as the showers pass with 
breezy southwest winds developing Friday afternoon. There is a 20-
35% probability of thunderstorm development at the terminals Friday 
afternoon and evening, but confidence is too low to put VCTS or 
PROB30 in the TAF at this time. Chances for showers continue through 
the end of the TAF period, with a low confidence forecast that winds 
at the terminals will abate overnight with potential development of 
MVFR stratus.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 1003 PM PDT Thu Apr 9 2026

Unsettled weather is expected Friday through the weekend,
including increasing winds, building seas, and a few rounds of
thunderstorms. Thunderstorms will be capable of producing frequent
lightning, gusty and erratic winds, localized heavy rain, small
hail, and waterspouts. Gentle to moderate south to southwest winds
will become fresh to strong by Saturday, with occasional near
gale force gusts. Winds become westerly late Saturday and
northerly by late Sunday as the low pressure system passes near
the northern waters. Fresh north winds last through midweek.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Gale Watch from Saturday morning through late Saturday night for 
     Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt 
     Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...DialH
MARINE...DialH

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Prepared by Boulder-Creek.com Weather at: Fri Apr 10 00:30:02 PDT 2026