FXUS66 KMTR 110501
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1001 PM PDT Fri Apr 10 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1220 PM PDT Fri Apr 10 2026
- Rain and thunderstorms through the weekend
- Gradual warming and drying trend next week
&&
.SHORT TERM...
Issued at 1220 PM PDT Fri Apr 10 2026
(This evening through Saturday)
A mid/upper level low pressure system remains about 100 miles off of
the northern California coast. This feature has resulted in
widespread rain showers across our region the past 24 hours with the
North Bay picking up between 0.25"-1.25". Lesser amounts have been
reported south of the North Bay, but some coastal and mountain
locations have received up to 0.75". Overall, this has been greater
than originally forecasted. This band of rain showers continues to
shift inland and the threat for rain showers and thunderstorms will
persist throughout the afternoon and evening, especially as day time
heating increases surface based CAPE to between 500-1000 J/kg. Any
thunderstorm will be capable of producing lightning, locally heavy
rainfall, erratic/gusty winds, and small hail. Weak low-level wind
shear does not support a mention of rotation that would lead to
tornadoes and/or waterspouts through this evening. Rain showers and
a slight chance of thunderstorms will continue into the night, yet
chances for both trend downward overnight.
An approaching mid/upper level low is forecast to drop out of the
Gulf of Alaska on Saturday and move inland Sunday afternoon across
northern California. This is when we have all three ingredients for
thunderstorms: lift, instability, and moisture. Some of the higher
resolution and conviction-allowing models (CAMs) such as the RRFS
indicate the potential for a narrow cold-frontal rainband (NCFR) to
move across the Bay Area and Central Coast Saturday afternoon and
evening. This will be when we have the greatest potential for
rotating cells that may produce waterspouts and/or weak tornadoes.
In coordination with the Storm Prediction Center, we have been
upgraded to a Marginal Risk of severe thunderstorms on Saturday. The
greatest potential being the threat of wind exceeding 40 knots.
From previous forecaster: "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!"
&&
.LONG TERM...
Issued at 1220 PM PDT Fri Apr 10 2026
(Saturday night through next Thursday)
The rainfall amounts continue to trend higher today through Sunday
with 0.50"-0.75" in the southern Salinas Valley, 1"-2" across much
of the Bay Area and Central Coast, and up locally up to 4" in the
coastal ranges. However, this rainfall will be mostly beneficial
with no widespread river flooding anticipated. However, we can still
see ponding of water on roadways, minor urban and small stream
flooding, and flooding of poorly drained areas. This will be
especially so if any heavier showers and/or thunderstorms develop
and train over any one given area.
Post-frontal rain showers and isolated thunderstorm will continue
into Sunday as a colder air mass settles into the region. This is
when we may see snow fall across the higher peaks across the region,
however little to no snow accumulation is expected. Lingering rain
showers and isolated thunderstorms may persist into early Monday
morning before a warming and drying trend resumes by Monday
afternoon. Slightly below normal temperatures are expected Monday
afternoon before rebounding to near seasonal averages by Thursday
and Friday.
&&
.AVIATION...
(06Z TAFS)
Issued at 1000 PM PDT Fri Apr 10 2026
Isolated to scattered showers persist across the region, some
rather strong in the North and East Bay, with low end VFR-MVFR
conditions across the terminals. The forecast tonight is rather
difficult with convective activity playing a huge role in the
current uncertainties in the forecast. The southwest winds will
diminish somewhat across the terminals through the night, with some
shower activity persisting through Saturday morning. Southwesterly
winds will increase on Saturday as a narrow cold frontal rain band
(NCFR) passes through the region in the evening hours. As the band
comes through, the most intense winds are expected with gusts of 30-
35 kt or more possible, especially along the coast and through
favored gaps. Behind the NCFR, shower activity continues through
Sunday morning.
Vicinity of SFO... MVFR ceilings and shower activity continue
through the overnight period, with ceilings lifting to VFR
after sunrise. Winds will come from the southwest through the TAF
period, with the winds dramatically strengthening through Saturday
afternoon and evening as the narrow cold frontal rain band
approaches and passes through the terminal. Wind gusts of 35 kt or
above as the NCFR passes can not be ruled out. Winds will slightly
diminish once the NCFR passes, with showers continuing around the
terminal area.
SFO Bridge Approach... Similar to SFO.
Monterey Bay Terminals... VFR conditions with mid- to high level
cloud cover and scattered showers through the next couple of hours.
MVFR conditions are possible overnight, with VFR conditions
returning after sunrise. Showers will come into the region on
Saturday morning, with the narrow cold frontal rain band expected to
arrive Saturday evening close to the end of the TAF period.
Southwest winds expected through the TAF period, with gentle winds
overnight, and breezy winds with strong gusts returning Saturday
afternoon as the NCFR approaches.
&&
.MARINE...
(Tonight through next Thursday)
Issued at 1000 PM PDT Fri Apr 10 2026
Isolated to scattered showers remain in the forecast tonight. The
next round of precipitation arrives late Saturday into Sunday, as
the next weather system arrives. Increasing winds and rough seas
are expected, with isolated gale force gusts from Point Reyes to
Point Sur. High pressure builds behind the system with fresh
northwest winds developing early next week, as seas abate to
become moderate through mid 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...RGass
LONG TERM....RGass
AVIATION...DialH
MARINE...DialH
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Prepared by Boulder-Creek.com Weather at: Fri Apr 10 22:30:02 PDT 2026
From the National Weather Service
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