426
FXUS66 KMTR 171715
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
915 AM PST Mon Nov 17 2025

...New UPDATE, MARINE...

.KEY MESSAGES...
Updated at 1218 AM PST Mon Nov 17 2025

 - Scattered showers and a slight chance of thunderstorms will
   gradually decrease through Monday before drier weather returns
   Tuesday.

 - Next system brings more beneficial type rain late Wednesday
   through Thursday.

&&

.UPDATE...
Issued at 912 AM PST Mon Nov 17 2025

Isolated to scattered rain showers persist over the region this
morning and are likely to continue throughout much of the day. There
is also a slight chance for thunderstorms through the afternoon as
surface based and most unstable CAPE are forecast to be up to 500
J/kg. Any heavier rain showers and/or thunderstorms will be capable
of producing 0.25"-0.50" of rainfall per hour, yet these amounts are
on the high end and isolated in nature. Conditions begin to dry out
by late tonight and more so into Tuesday morning. No updates
anticpated to the ongoing forecast at this time.

RGass

&&

.SHORT TERM...
Issued at 1218 AM PST Mon Nov 17 2025
(Today and tonight)

Full scale warning operations on the watchfloor as the cold front
comes ashore. Several cells over the coastal waters have
displayed rotational velocity of 30kts, indicating a legitimate
waterspout potential. Fortunately the trend has been for these
cells to lose structure as they come ashore, but we can`t rule out
our classic landfalling waterspouts causing some damage along the
coast from San Mateo to Monterey County over the next several
hours. While narrow and fast moving, the main band of rain has
been intense, with a weather spotter in Marin reporting over six
tenths of an inch in less than an hour. These high rain rates
could cause some land slides, especially after the recent wet
weather. This threat is highest over the Pickett Burn Scar, where
a flash flood warning is in effect. Winds have been gusting to
gale force and quickly diminishing after the frontal boundary
passes. In the post frontal environment the rain will transition
to lighter scattered showers and persist through the day on a
decreasing trend before drier weather moves in overnight.

&&

.LONG TERM...
Issued at 1218 AM PST Mon Nov 17 2025
(Tuesday through Sunday)

In the wake of todays exiting system to the south we`ll see
progressive, high amplitude ridging move across central California
Tuesday and Wednesday resulting in drier conditions while
temperatures remain cooler than normal. Tuesday will be mostly sunny
area wide, with gradually increasing cloud cover on Wednesday. The
remainder of the extended forecast lacks consensus for the timing
and evolution of what appears to be a similar type storm system that
we saw overnight and today. Rain chances begin to increase across
the North Bay Wednesday evening, spreading across our whole area
during the day Thursday, and exiting to the south by early Friday
morning. Rainfall totals and winds will not be as strong as we`ve
seen the last 24hrs, however the saturated soils may bring more
risks for land/rock slides. Very high surf looks likely late
Thursday and Friday. Next weekend looks mostly dry attm, with a
signal for another upper level low bringing increasing rain
chances early next week.

&&

.AVIATION...
(12Z TAFS)
Issued at 322 AM PST Mon Nov 17 2025

A very difficult forecast for the upcoming TAF period as a surface
low or series of lows moves through the region. The wind pattern, in
particular, depends critically on the strength, location and track
of the low with cyclonic effects expected across the region. In
addition, the current winds are much lighter than what the high
resolution models depicted. Thus, confidence in the wind forecasts
is low to very low, and interests should monitor TAF updates as the
low`s evolution is refined. Ceilings remain generally MVFR to VFR
with mid-level clouds through Monday night at least, some clearing
is possible early Tuesday morning. Chances for showers also persist
through the day with the low pressure moving south. Thunderstorms
remain possible, but confidence in timing or location is too low to
include in the TAFs.

Vicinity of SFO... MVFR to VFR with mid-level ceilings through the
TAF period. Showers and a chance of thunderstorms persist through
the late evening-early overnight period. The winds will be rather
gusty, but very low confidence on wind direction, especially after
3Z as a surface low approaches the terminal.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... MVFR ceilings and a chance of showers
through the TAF period. Winds are hard to pin down owing to the
surface low passing through, but expect an

&&

.MARINE...
(Today through Saturday)
Issued at 912 AM PST Mon Nov 17 2025

Chances for scattered showers and storms linger into the evening
with shifting winds as a low pressure center moves southward along
the coast. Winds will continue to shift and increase to a strong
NW breeze through the day, building rough seas across the coastal
waters. Strong winds and rough seas will persist through Tuesday
before conditions improve for a short window Wednesday through
Thursday. A high WNW swell will arrive late Thursday into Friday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PST this evening for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras
     Blancas 0-10 nm-SF Bay N of Bay Bridge.

     Small Craft Advisory until 3 AM PST Tuesday for Pt Arena to Pt
     Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 AM PST Wednesday for Pigeon Pt to
     Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...DialH
MARINE...Murdock

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