FXUS66 KMTR 232116
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
216 PM PDT Thu Apr 23 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1201 AM PDT Thu Apr 23 2026
- Seasonal temperatures and dry conditions return today
- Potential for rain/drizzle and slightly cooler temperatures
this weekend into early next week
- Warming trend begins early to mid next week
&&
.SHORT TERM...
Issued at 126 PM PDT Thu Apr 23 2026
(This evening through Friday)
Radar is finally quiet this afternoon after a period of somewhat
active weather. Visible satellite shows mostly clear skies around
the region with a few pop up CU hugging the hills. Increased
insolation this afternoon has led to a warmer temperatures across
the board.
Stepping back and looking at the longwave pattern over EPAC and
CONUS reveals an interesting pattern. The EPAC is highly
amplified with a solid ridge extending into E AK and W BC with a
low off the CA coast with a rex block vibe. Farther east two
pronounced upper lows spin, one north of MT and the other east of
Nova Scotia with a ridge smacked in between with an omega block
vibe. In other words a little bit of a traffic jam in the upper
atmosphere. That being said, we do see some minor movement on the
small scale and closer to home. A weak embedded shortwave/fuzzy
upper low off the CA coast is slowly moving eastward. As this
feature moves eastward high clouds will increase over the region
tonight and Friday. The higher clouds may limit fog production
tonight, but some low stratus will be possible. Interestingly,
some of the CAMs resolve some forecast 1KM radar reflectivity
tonight. Forecast is dry for Friday morning, but a few echoes may
appear on radar. Increased cloud cover will also lead to cooler
temperatures on Friday with highs dropping below seasonal averages
again.
&&
.LONG TERM...
Issued at 126 PM PDT Thu Apr 23 2026
(Friday night through next Wednesday)
A trend that emerged a few days ago is still on track for the
upcoming weekend, "wetter" and cooler. Broad troughiness remains
over region with re-enforcing upper lows. Another upper low is on
track to move over the region Friday night into Saturday and
subsequent vort maxes Saturday into Sunday. These features
combined with the northern fringes of sub-tropical moisture
pulses will lead to some drizzle/light rain showers Friday night
through Sunday morning. Not expecting much in the way of
accumulation, trace to a few hundredths. Areas most favored will
be coastal mts with enhanced low level lift. Temperatures for the
upcoming weekend will be below seasonal averages with highs in
the upper 50s and 60s.
By early next week 500mb heights begin to rebound with warming
850mb temps kicking off a gradual warming and drying trend. No
precip in the forecast Monday through Wednesday.
&&
.AVIATION...
(18Z TAFS)
Issued at 1141 AM PDT Thu Apr 23 2026
Quiet weather with some fair weather cumulus clouds popping up over
the region and high clouds passing overhead. VFR conditions will
prevail through the evening and perhaps early overnight hours for
most sites. Guidance suggests that a mix of stratus and fog will
return at some point, but there are some caveats. High clouds could
disrupt fog and stratus formation, in addition to winds. Trended
towards KAPC and KSTS seeing another night of reduced ceilings and
visibility, with KHAF likely joining them. The models are bit
divided on the expanse of the stratus and fog, thus I opted to hint
at lowering cigs for KSJC and KLVK. Medium to high confidence in the
forecast.
Vicinity of SFO...Onshore flow is expected to return this afternoon,
and increase to around 15kt around 0Z. This will last into the late
evening hours with winds falling below 10kt near or after 7Z. Quite
a few models indicate MVFR ceilings moving into the Bay, with much
of the Bay seeing MVFR cigs increase between 11-14Z and continuing
until at least 17-18Z. Opted to go with a slightly more optimistic
forecast with cigs clearing between the 17-21Z. Medium confidence in
the forecast.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR conditions prevail for the majority of
the region for the afternoon with high clouds streaming overhead and
cumulus popping up over the mountains. Much like the discussion
above, stratus and any associated fog may be dependent on the high
clouds and winds. Guidance shows Monterey Bay with ceilings around
035-050 for heights, though a few bring KMRY closer to MVFR status.
Expect this to occur just before or around sunrise, before mixing
out by mid to late morning.
&&
.MARINE...
(Today through Tuesday)
Issued at 924 AM PDT Thu Apr 23 2026
Moderate north breezes this morning will develop into a northwest
breeze this afternoon. Choppy seas at times today will begin to
subside Friday and continue into the weekend. Light rain and
drizzle return to this weekend.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt
to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos
to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 AM PDT Friday for Pt Arena to Pt
Reyes 10-60 NM.
Small Craft Advisory until 3 AM PDT Friday for Pigeon Pt to Pt
Pinos 10-60 NM.
&&
$$
SHORT TERM...MM
LONG TERM....MM
AVIATION...KR
MARINE...KR
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Prepared by Boulder-Creek.com Weather at: Thu Apr 23 14:30:03 PDT 2026
From the National Weather Service
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