000
FXUS66 KMTR 282040
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1240 PM PST Tue Nov 28 2023

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 1238 PM PST Tue Nov 28 2023

Showers developing overnight with light rainfall amounts expected
through Wednesday morning. Unsettled pattern for the rest of the
week with cooler temperatures.

&&

.SHORT TERM...
(This evening through Wednesday)
Issued at 1238 PM PST Tue Nov 28 2023

Satellite imagery shows the upper level low pressure system
approaching the region currently placed around 400 miles to the west
of San Francisco. Model consensus is for this low pressure system to
develop into an open wave as it crosses the California coast on
Wednesday, while the associated surface low remains offshore, thus
keeping most of the vertical motion offshore. Showers will start to
come onshore this evening, spreading west to east overnight.
Forecast rain amounts have increased somewhat from the previous
forecast update but are expected to remain beneficial with no
flooding concerns, with rainfall totals across the North Bay
valleys around a third to two thirds of an inch, from a tenth to
four tenths of an inch in the SF Bay Area, and a tenth to a
quarter of an inch around Monterey Bay. Coastal ranges will see
around a quarter to three quarters of an inch of rain while the
inland Central Coast sees up to two tenths of an inch or less.
Still can not rule out a chance of thunderstorms (up to 10%
probability) across the region, especially near the coast, but the
greatest probabilities lie offshore (20-30% probability). Shower
activity will begin to diminish Wednesday morning, followed by
clearer skies beginning in the afternoon.

High temperatures today range from the mid to upper 60s in the
inland valleys, to the mid 50s to lower 60s along the coast and at
higher elevations. Low temperatures will be milder than the last few
nights with most areas in the 40s, perhaps down to the mid to upper
30s ion the interior parts of Monterey and San Benito counties.
Wednesday`s highs will be cooler as the rain passes through, with
highs generally in the low to mid 60s across the lower elevations,
and into the 50s for the higher elevations.

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 1238 PM PST Tue Nov 28 2023

Unsettled weather continues through the rest of the week as
northwest flow continues in the upper atmosphere. A couple of
disturbances will come through the west coast, but the most impacts
will be felt across the Pacific Northwest into the northern parts of
California. Any rainfall in our region will generally be
concentrated in the North Bay. Current model output suggests rain
totals of up to a quarter of an inch in the North Bay coastal
ranges through the extended period.

Temperatures continue to be cool for the rest of the week, with
highs generally from the upper 50s to lower 60s and down to the
lower 50s in the higher elevations, before an upper level ridge
develops this upcoming weekend, heralding a warming trend expected
to continue through the early part of next week.

&&

.AVIATION...
(18Z TAFS)
Issued at 935 AM PST Tue Nov 28 2023

Currently VFR throughout the region. High clouds will build across
the region today, with more mid-level clouds building tonight and
Wednesday morning as a low pressure system approaches the region.
Winds will build from the south and the southwest this afternoon, up
to 10 knots at the terminals. Winds diminish in the evening hours,
turning towards the southeast and east as rain approaches the
region. Some marginal MVFR conditions are possible in the North Bay
terminals with the heaviest rain. Considered adding MVFR ceilings to
the STS and APC TAFs, but ceilings appear to be too patchy to have
good confidence in the forecast. Winds strengthen to around 8-10
knots with the best rain chances through Wednesday morning, then
diminish as the rain chances move out.

Vicinity of SFO...Generally VFR through the TAF period with possible
decreased visibility in the heaviest rain. Afternoon winds from the
southwest at up to 10 knots, diminishing in the evening before rain
arrives overnight, accompanied by winds turning to the southeast
with speeds increasing to up to 10 knots. As the low pressure system
moves out, rain chances decrease while winds turn to the east and
diminish.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR with mid- to high level clouds through
the TAF period. Breezy drainage winds at SNS turning to the north
later this morning, and southwest winds building to 10 knots at MRY,
before diminishing early this evening. Rain chances arriving early
Wednesday morning, with southeasterly winds building to 8-12 knots
through the end of the TAF period.

&&

.MARINE...
(Today through Sunday)
Issued at 935 AM PST Tue Nov 28 2023

Southerly winds steadily building today with a low pressure
system approaching the the local waters. Fresh to moderate breezes
are expected, with briefly strong breezes possible in the
northern offshore waters. Scattered showers develop late tonight
and persist through the first half of Wednesday. An isolated
thunderstorm or two is also possible. Winds will gradually
diminish and shift to northerly late Wednesday into Thursday
before strong breezes develop by Thursday night. A larger moderate
period northwest swell should arrive by late week. Weather
conditions will remain unsettled into this weekend with plenty of
cloud cover and periodic shower chances.

&&

.BEACHES...
Issued at 1238 PM PST Tue Nov 28 2023

The Coastal Flood Advisory was cancelled as tide levels are
beginning to lower after peak high tide. With astronomical tide
levels expected to be lower tomorrow, no further Coastal Flood
Advisories are expected for the rest of the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...DialH
MARINE...DialH

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NWS MTR Office Area Forecast Discussion