Technical NOAA Weather Discussion

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