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NWS Technical
Weather Discussion |
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FXUS66 KMTR 280729
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1229 AM PDT Wed Oct 28 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1227 AM PDT Wed Oct 28 2026
- Moderate coastal flooding at high tide for Bayshore and Pacific
Coast locations through the week
- Seasonal to slightly below seasonal temperatures through the
extended forecast
- Potential for rain this weekend and again early to mid next
week
&&
.SHORT TERM...
Issued at 1227 AM PDT Wed Oct 28 2026
(Today and tonight)
Satellite imagery shows lingering high clouds over Monterey and
San Benito Counties with patches of stratus along parts of the
higher elevations. Some stratus expansion is possible through the
morning with some clearing after sunrise, but high level clouds
will also arrive this morning and persist into the evening hours
and beyond.
Conditions remain cool and dry as large scale troughing persists and
expands, with a cut-off low over British Columbia and a decaying low
crossing over from the Central Pacific merging to help dig the
trough axis deeper into California. Morning lows hover in the upper
30s to the middle 40s across the inland valleys, into the middle 30s
for the coldest spots in the eastern Santa Clara and interior
Central Coast mountains, and the upper 40s to lower 50s near the
coasts. Highs will remain cooler than the seasonal averages with
high temperatures in the upper 60s to lower 70s inland, the middle
60s to near 70 along the Bayshore, and the upper 50s to lower 60s at
the immediate coast. Winds will remain relatively light with a
gentle onshore push expected in the afternoon and evening hours.
Wind gusts might reach 20 mph along favored coastal areas and
through favored gaps and passes.
A combination of high astronomical tides and surge from thermal
expansion effects brings the risk of minor coastal flooding along
the Bayshore at the San Pablo, San Francisco, and Monterey Bays, and
the Pacific coast, at high tide today. At the San Francisco tidal
gauge, high tide is expected to be 1.9 ft above normal (7.7 ft MLLW)
at 12:56 PM Wednesday 10/28, including around 1.2 ft of surge
residual partially attributed to impacts from El Nino.
&&
.LONG TERM...
Issued at 1227 AM PDT Wed Oct 28 2026
(Thursday through Tuesday)
Troughing will continue to impact the region at least into the
upcoming weekend, with high temperatures dipping into the middle 60s
to lower 70s inland and the upper 50s to lower 60s near the Pacific
coast and the Bays. Gloomy and cloudy conditions continue into
Friday. The chances for rain continue to be rather low during the
Halloween weekend, with probabilities of precipitation around 10 to
30% throughout the Bay Area and Central Coast. Rainfall totals,
assuming rain does come, will remain on the beneficial side with the
latest forecast showing a few hundredths of an inch across the
southern halves of Monterey and San Benito Counties and zero
accumulating precipitation everywhere else. Even the reasonable
worst case scenario, one with a 10% probability that rain totals
will end up above the scenario, ranges from around a tenth of an
inch in the North bay to a half to three quarters of an inch for
interior Monterey and San Benito Counties.
Once we cross into the early part of next week, the meteorological
uncertainty really ratchets upwards. The current forecast shows
chances for rain continuing into the end of the 7-day outlook, but
merely looking at some of the models, say, the deterministic
European model or the European ensemble mean, would leave the
untrained user scratching their heads trying to reconcile that
forecast with the ridge that these models depict over the West
Coast. Setting aside the fact that this is where the model
reliability begins to degrade, especially for the deterministic
models, there are a few things that are going on here. The first is
that the deterministic models are depicting the formation of a cut-
off low in the central Pacific, and cut-off lows are notoriously
difficult to accurately predict as they can isolate themselves from
the large-scale flow. Indeed, the American GFS model depicts this
cut-off low coming closer to the state around this time. Looking at
ensemble model cluster analysis will support the high uncertainty as
there's not really a dominant scenario out of various solutions on
how fast the cut-off low will come into the Western United States,
and indeed it looks like the speed of the low is the main factor in
creating the uncertain ensemble space. Or in layman's terms, there
are chances for rain next week, but when the rain actually arrives
is up in the question, and that is before we try to find out where
in the state the rain will actually be the heaviest. Keep checking
back with us for more details...
Coastal flooding concerns continue across Bayshore locations within
the San Pablo, San Francisco, and Monterey Bays through Saturday
and the Pacific coastal regions through Friday. At the San
Francisco tidal gauge, high tide is expected to be 1.9 ft above
normal (7.7 ft MLLW) at 01:43 PM Thursday 10/29, 1.6 ft above
normal (7.4 ft MLLW) at 02:39 PM Friday 10/30, and 1.1 feet above
normal (6.9 ft MLLW) at 03:44 PM on Saturday 10/31, including
around 1.2 ft of surge residual partially attributed to impacts
from El Nino.
&&
.AVIATION...
(06Z TAFS)
Issued at 934 PM PDT Tue Oct 27 2026
VFR is forecast except for patchy valley fog /IFR-LIFR/ developing
tonight and Wednesday morning. Surface high pressure will build
into the Great Basin and onshore winds will shift to offshore
tonight and Wednesday morning.
Vicinity of SFO...VFR. West wind 5 to 10 knots becoming light
northeasterly Wednesday morning. West wind around 12 knots
redevelops Wednesday afternoon and evening.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR. Onshore winds 5 knots becoming
light easterly tonight and Wednesday morning, then onshore 10
knots Wednesday afternoon and early evening.
&&
.MARINE...
(Tonight through next Monday)
Issued at 926 PM PDT Tue Oct 27 2026
Northwest breezes continue this evening across the waters, with
isolated near gale force gusts occurring over the northern water
waters. Seas will continue to build in response, leading to rough
seas across exposed waters. Conditions will gradually improve
Thursday as winds decrease and seas subside.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 6 PM PDT Saturday for CAZ006-506-
508-529-530.
Coastal Flood Advisory until 5 PM PDT Friday for CAZ505-509.
PZ...Small Craft Advisory from 3 PM this afternoon to 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.
Small Craft Advisory until 2 AM PDT early this morning for
Pigeon Pt to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt
to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa
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Prepared by Boulder-Creek.com Weather at: Wed Oct 28 02:30:03 PDT 2026
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From the National Weather
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Revised:
29 Mar 2008 09:53 -0800 GMT
(Pacific) |
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