FXUS66 KMTR 091154
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
354 AM PST Tue Dec 9 2025
...New AVIATION, MARINE...
.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
&&
.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...
(12Z TAFS)
Issued at 349 AM PST Tue Dec 9 2025
Higher confidence in clearing out of the fog and stratus today for
North Bay terminals. Day-to-day change gradually improving as high
pressure builds aloft. Patchy stratus invof SF Bay providing lower
confidence there, but based on persistence forecast KOAK likely to
remain VFR.
Vicinity of SFO...Patch of stratus and fog moving along the
peninsula likely to persist through sunrise, clearing to VFR in the
few hours following. Lower chance of stratus overnight into
Wednesday morning compared to this morning. Medium confidence in
cigs holding off until just before sunrise Wednesday.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...High confidence in VFR through the TAF
period. Light drainage offshore winds overnight with light onshore
flow during the afternoons.
&&
.MARINE...
(Today through Sunday)
Issued at 349 AM PST Tue Dec 9 2025
Northwest winds increase to a strong breeze today into mid week
across the outer waters. Gentle breeze persists across the inner
coastal waters. 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...Behringer
MARINE...Behringer
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Prepared by Boulder-Creek.com Weather at: Tue Dec 9 08:30:02 PST 2025
From the National Weather Service
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