Technical NOAA Weather Discussion

FXUS66 KMTR 112335
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
435 PM PDT Sat Apr 11 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 109 PM PDT Sat Apr 11 2026

 - Rain showers and isolated thunderstorms are forecast to 
   increase this afternoon and evening

 - Rain showers and thunderstorm chances linger into Monday morning 

 - A warming and drying trend returns through the remainder of 
   the work week

&&

.SHORT TERM...
Issued at 109 PM PDT Sat Apr 11 2026
(This evening through Monday)

Rain showers and isolated thunderstorms remain in the forecast 
through early afternoon. Then, as a surface low approaches the 
northern California coast, a narrow cold-frontal rainband (NCFR) is 
forecast to approach the North Bay between 2 PM - 5 PM, 4 PM - 7 PM 
across the Bay Area, and 6 PM - 9 PM across the Central Coast. Along 
and ahead of the NCFR is when we have the greatest potential for 
damaging wind gusts exceeding 40 kt out over the ocean and bays. 
This will also be when we have the greatest potential for rotating 
cells that may produce waterspouts and/or weak tornadoes. Wind gusts 
are also expected to reach up to or exceed 50 mph along the coast 
and in the higher terrain during the aforementioned timeframes. Any 
stronger convection will be capable of producing stronger wind 
gusts. Again, much of our region remains under a Marginal Risk for 
sever weather today.  

The aforementioned low pressure system is forecast push into 
northern California later tonight and become quasi-stationary 
through Sunday. Thus, scattered to numerous rain showers and 
isolated thunderstorms will prevail through Sunday and into early 
Monday morning as a colder/unsettled air mass moves into the region. 
This colder air mass will result in a low end potential for the 
region's highest peaks to see snowfall through Monday morning. 
However, little to no snow accumulations are forecast at this time. 

&&

.LONG TERM...
Issued at 109 PM PDT Sat Apr 11 2026
(Monday night through next Friday)

The colder air mass will result in chilly temperatures across the 
interior both Monday and Tuesday mornings especially over the North 
Bay Valleys and interior Central Coast. Temperatures are currently 
forecast to be in the low-to-upper 30s in these areas with low 40s 
to near 50 degrees F elsewhere across the region. There is the 
potential for frost each morning across these interior regions, 
especially in the wind sheltered areas. Temperatures rebound to near 
seasonal averages by Thursday and Friday as ridging builds in from 
the eastern Pacific. 

&&

.AVIATION...
(00Z TAFS)
Issued at 434 PM PDT Sat Apr 11 2026

The forecast remains challenging for the TAF period with a frontal 
rain band currently coming into the region. Within the North Bay and 
San Mateo Peninsula, MVFR-IFR conditions are in place with steady 
rainfall through the band. Ahead of the rainband, across the 
interior East Bay and South Bays and the Central Coast, a mixed band 
of VFR to MVFR conditions prevails as isolated to scattered showers 
persist. Expect increasing southerly winds through the next few 
hours as the most intense rain approaches the region through 06Z, 
with IFR conditions and gusts to 30-40 kt expected. Behind the 
frontal rain band, gradual improvement is expected, although winds 
remain gusty and scattered showers continue through the end of the 
TAF period. Overall forecast confidence remains low to moderate.

Vicinity of SFO... Gusty southeast to south winds in addition to wet 
runways will make for challenging conditions at the terminal this 
evening into Sunday. Low-end VFR to MVFR conditions at present as 
the terminal sits in the frontal rain band. The most intense 
conditions are expected within the next couple of hours as the 
frontal rain band approaches, with gusts of 30-35 kt expected as it 
passes through. Will also need to monitor chances for lightning as 
well. Steady rain will transition to more scattered showers through 
the overnight hours into Sunday.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR-MVFR conditions through the next few 
hours with the approaching rain band coming into the region. Most 
intense rain is expected to arrive around 03-04Z, accompanied by 
MVFR-IFR conditions and the gustiest south to southwest winds of 
around 20-25 kt. Overnight, steady rain will transition to 
scattered showers through the end of the TAF period. Winds will 
generally be rather gusty from the southwest through the night, 
with some LLWS concerns at SNS as surface winds decouple from the 
flow aloft. 

&&

.MARINE...
(Tonight through next Thursday)
Issued at 434 PM PDT Sat Apr 11 2026

Dangerous conditions will exist over the coastal waters through
this evening as a potent line of storm moves through. Stronger
developed storms will be capable of producing gusty winds,
lightning, brief heavy rain, and a waterspout. Conditions will
gradually improve overnight, but scattered showers and locally
gusty winds remain through Sunday. 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 until 3 PM PDT Sunday for Mry Bay-Pt Reyes 
     to Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.

     Small Craft Advisory until 9 PM PDT this evening for Pt Arena to 
     Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory until 9 AM PDT Sunday for 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...RGass
LONG TERM....RGass
AVIATION...DialH
MARINE...MM

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Prepared by Boulder-Creek.com Weather at: Sat Apr 11 20:30:02 PDT 2026
From the National Weather Service