156
FXUS66 KMTR 091741
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
941 AM PST Tue Dec 9 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 132 AM PST Tue Dec 9 2025

 - Tule fog and stratus will clear this afternoon

 - Quiet weather with warmer temperatures through Friday

 - Light rain possible next week

&&

.UPDATE...
Issued at 921 AM PST Tue Dec 9 2025

Made an adjustment to the high temperature forecast for the North
and East Bay regions today. It will ultimately be a race against
the clock for the stratus and when it burns off. If it runs
slower, like yesterday, temperatures will be cooler which is what
I trended towards due to the limited hours of sunshine. But if
clouds erode a touch faster, they should be a few degrees warmer,
perhaps closer to the mid to upper 50s for North Bay sites and
the low to mid 50s for interior East Bay valleys.

&&

.SHORT TERM...
Issued at 132 AM PST Tue Dec 9 2025
(Today and tonight)

Another round of morning clouds and patchy fog across the Bay Area.
The coverage is less than yesterday and these clouds will clear in
the afternoon as temperature climbs a few degrees warmer than recent
days. The prolonged ridging pattern continues with the amplitude
notching up over the next few days. The Eastern Pacific high now
extends a ridge across northern California, and there is even a
somewhat uncommon cut off high way up at 250 mb directly over the
Bay Area. This is the jet stream altitude where the average wind
speed this time of year is around 60 knots. We`ll be lucky to break
10 knots on the 12Z sounding. This vertically stacked dome of high
pressure is leading to widespread subsidence, calm winds, stagnant
surface air, and warmer than normal temperatures.

&&

.LONG TERM...
Issued at 132 AM PST Tue Dec 9 2025
(Wednesday through Monday)

While the ridge has been the main scapegoat for the ongoing Tule
Fog, the increasing ridge intensity will compress this cool moist
layer closer to the surface and limit it`s horizontal spread to the
Central Valley and colder interior valleys across the Bay Area. Air
quality may also suffer as a result. The 850 mb temperature will
climb to around 17C by Wednesday, and park there until Friday.
That`s around 10C warmer than normal, close to the average for June.
Surface temperatures will respond and warm up to 10F above normal,
pushing some clear areas of the Bay Area and Central Coast to the
mid 70s. This heat will peak on Thursday with noticeable cooling by
the weekend. Despite the warm afternoons, the dry atmosphere (PW 0.3-
0.5") and long December nights will still bring morning temperatures
into the 40s. The ridge axis will finally move through this weekend,
allowing the pattern to become more zonal. This opens the door for
some rain next week. While zonal flow doesn`t support strong storms
or atmospheric rivers, it looks likely that we`ll at least end the
dry streak sometime next week, possibly as early as Monday.

&&

.AVIATION...
(18Z TAFS)
Issued at 934 AM PST Tue Dec 9 2025

Another messy start to the day with low clouds and some fog
impacting the N, E, S, and SF Bay. Monterey Bay on the other hand
is VFR. Expect another slow clearing of cigs for the greater Bay
Area again, but still expecting some SCT late this afternoon.
Another repeat for cigs again tonight in the N and E Bay, but an
uptick in drying NE winds at 2500 ft will keep less clouds in SF
Bay.  Could even see some marginal LLWS for KOAK early tomorrow.

Vicinity of SFO...IFR conditions remain with cigs and some haze.
Cams and satellite show some clearing farther out in the Bay, but
slow going for the terminal itself. Will keep cigs through 19-20Z.
Tonight and tomorrow less conf, but VFR at the moment with drier
offshore flow.

SFO Bridge Approach...Same as SFO.

Monterey Bay Terminals...VFR

&&

.MARINE...
(Today through Sunday)
Issued at 921 AM PST Tue Dec 9 2025

High pressure off the California coast will maintain northerly
flow over the coastal waters. Winds are locally stronger south of
Point Pinos leading to hazardous conditions today. Winds will
strengthen across all outer waters later this week. A new, long
period northwesterly swell is expected by midday Wednesday,
lasting into the early weekend.

&&

.BEACHES...
Issued at 132 AM PST Tue Dec 9 2025

Long period swell will impact the coast Wednesday - Friday. This
energy brings strong rip currents, an increased risk for sneaker
waves, and large breaking waves. NW swell around 8 feet with a 15
second period will translate to breaking waves up to 15-20 feet.
These conditions may warrant a Beach Hazards Statement, particularly
with the warm weather likely luring more people to the Beach.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from Wednesday morning through Friday
     evening for CAZ006-505-509-529-530.

PZ...Small Craft Advisory until 9 PM PST this evening for Pt Pinos to
     Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...MM
MARINE...MM

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