FXUS66 KMTR 300702
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1202 AM PDT Fri Oct 30 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1200 AM PDT Fri Oct 30 2026
- Moderate coastal flooding at high tide for Bayshore and Pacific
Coast locations through the weekend
- Seasonal to slightly below seasonal temperatures through the
extended forecast
- Potential for rain Saturday and again next week
&&
.SHORT TERM...
Issued at 1200 AM PDT Fri Oct 30 2026
(Today and tonight)
Satellite imagery is showing a pretty robust stream of high clouds
into the Bay Area and Central Coast, stemming from the remnants of a
low from the Central Pacific merging into a wider trough pattern
across the West Coast. Earlier tonight, some of the embedded
moisture gave us some rather cool cloud tops on satellite and echoes
from the KMUX radar and several stations within Monterey and San
Benito Counties have reported measurable rainfall (up to a tenth of
an inch) over the last few hours. Although shower coverage has since
decreased, chances for showers have been added to the forecast for
Monterey and San Benito Counties through the rest of the morning.
Otherwise, the weather pattern continues to be dominated by a deep
ridge that has set up across the West Coast. Morning lows will hover
in the lower to middle 40s in the North Bay valleys, which have
remained rather clear overnight, and the upper 40s to the middle 50s
across the rest of the Bay Area and Central Coast. Highs today range
from the middle to upper 60s in the inland valleys and the SF
Bayshore, the lower 70s along the warmest parts of the southern
Salinas Valley, and the upper 50s to lower 60s close to the Pacific
coast.
A combination of high astronomical tides and surge from thermal
expansion and low pressure 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 2:39 PM today, including around 1.5 ft of
surge residual.
&&
.LONG TERM...
Issued at 1200 AM PDT Fri Oct 30 2026
(Saturday through Thursday)
The trough will start to progress eastwards on Saturday, as the
trough axis digs into California and an upper level ridge behind it
starts to push it onshore and into the Great Basin. As it does, it
pulls in a couple of jet streaks eastwards. One of them will be a
meridional (north to south) jet streak that will set up to the west
of the trough, paralleling the coast of Oregon and northern
California. Quick meteorology lesson -- within a jet streak, the
balance of all the forces in the atmosphere means that there are two
regions where cyclogenesis and unsettled weather are favored. Those
two regions are on the right side of the entrance to the jet streak
(looking along the direction of wind flow) and the left side of the
exit of the jet streak. It just so happens that the left exit region
of the jet streak off Oregon and northern California will help
provide an impulse to a bit of upper level vorticity, which grows
into a bigger blob of vorticity, that pushes the trough ever more
southwards until it develops into its own low pressure system off of
southern California and the northern part of Baja California. That
is the storm system that will come into southern California and
bring some of the attendant moisture into our region. Meanwhile,
weaker low pressure systems might develop across northern California
as the jet streak approaches the coast. Rain totals look to be
around a tenth to a quarter of an inch within the far interior of
Monterey and San Benito Counties, around a few hundredths of an inch
in the rest of the Central Coast and orographically favored regions
of the coastal Bay Area, to a few sprinkles in the interior Bay Area.
The current forecast has rain coming into the interior Central Coast
Saturday morning before spreading northwards into the Bay Area later
on Saturday. Light rain and drizzle may start during trick-or-treat
hours in the SF Bay Area, but the best chances for rain lie overnight.
A low chance for thunderstorms (less than 10% probability) is
also present with this system. The conditions might be marginal,
but with a cold airmass coming with the upper level low, there
might just be enough moisture, instability, and lift to get some
convective cells in the higher elevations. K-Index values up to
25-27 degrees C would support isolated to widely scattered
thunderstorms. As a final note, high temperatures on Saturday will
dip into the middle 60s for the inland valleys, the lower 60s
close to the Bays, and the upper 50s to near 60 for the Pacific
coast.
The rain will clear out Sunday and Monday as the upper level ridge
comes across the West Coast, and highs in the inland valleys will
rise to the middle to upper 60s. Beyond that the forecast remains
uncertain. The current forecast shows some rain chances returning as
early as Tuesday as another trough or cut-off low comes into the
region, but the timing of that parent low remains uncertain and
ensemble model cluster analysis shows a potential delay of the
incoming rain until Wednesday. Rain chances linger through the end
of the seven-day outlook, but confidence in any particular scenario
remains low heading into the latter part of next week.
Coastal flooding concerns continue across Bayshore locations within
the San Pablo, San Francisco, and Monterey Bays through Sunday and
the Pacific coastal regions through Saturday. At the San Francisco
tidal gauge, high tide is expected to be 1.5 ft above normal (7.3 ft
MLLW) at 3:44 PM Saturday, and 1.0 feet above normal (6.8 ft MLLW)
at 3:59 PM Sunday, including around 1.5 ft of surge residual.
&&
.AVIATION...
(06Z TAFS)
Issued at 938 PM PDT Thu Oct 29 2026
Not much has changed from 00Z TAFs - VFR conditions will be common
place through much of Friday with mid-high level clouds. MRY and
SNS may have a passing showers or two lowering cigs below 5k.
Better chc for CIGs late Friday into Saturday.
Vicinity of SFO...VFR. Light and vrb near term, but do expect an
onshore push by this evening.
SFO Bridge Approach...Similar to SFO
Monterey Bay Terminals...VFR. Brief MVFR this evening then better
chc for MVFR CIGs Friday. Diurnal drainage overnight and then
onshore during the day.
&&
.MARINE...
(Today through Tuesday)
Issued at 1200 AM PDT Fri Oct 30 2026
Gentle to fresh northerly breezes with moderate seas will prevail
into the weekend. A long period west-northwest swell arrives this
weekend and continues into next week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 6 PM PDT Sunday for CAZ006-506-508-
529-530.
Coastal Flood Advisory until 6 PM PDT Saturday for CAZ505-509.
PZ...Small Craft Advisory until 6 PM PDT Saturday for Pigeon Pt to Pt
Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...MM
MARINE...MM
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Prepared by Boulder-Creek.com Weather at: Fri Oct 30 02:30:04 PDT 2026
From the National Weather Service
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