FXUS66 KMTR 232319
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
319 PM PST Thu Jan 23 2025
...New AVIATION, MARINE...
.SYNOPSIS...
Issued at 102 PM PST Thu Jan 23 2025
Pleasant weather continues today before a pattern change arrives
tomorrow. A cold air mass will move in, bringing some light rain
to the southern half of the cwa and cooler temperatures this
weekend.
&&
.SHORT TERM...
(This evening through Friday)
Issued at 102 PM PST Thu Jan 23 2025
Another beautiful afternoon and evening is in store as the
ridge continues to hold on. By this time tomorrow, a positively
tilted trough will move across the Bay Area, ushering in a
significant change to the pattern. A narrow band of moisture will
precede the cold air, though the PWAT anomaly looks to only max
out around 100% of normal before quickly drying. While the
moisture is not impressive, the cold air mass is legit. The 850 mb
temperature are expected to drop to the 10th percentile for this
time of year, or around the freezing mark. It's currently around
56F, for context. That means that in addition to cold mornings in
the valleys, higher elevations, and the daytime highs everywhere
will be more chilly than they have been recently. We will also get
the combination of cold and wind, that hasn't been a problem with
the recent radiational cooling dominated mornings. The minimum
surface temperature may be similar to previous nights, but with
stronger winds and less recovery during the day, it will feel more
uncomfortable through the weekend.
&&
.LONG TERM...
(Friday night through next Wednesday)
Issued at 102 PM PST Thu Jan 23 2025
At 500 mb, the trough will linger and eventually spawn a cut-off
low pressure system over the Bay Area. With the cold air aloft,
the low-level lapse rates are steeper than moist adiabatic, so
there is a chance for convection on Saturday. The problem is
moisture. Outside of the narrow band of moderate moisture on
Friday, the air mass is continental polar in nature, and will be
quite dry. Since dry air cools at a faster rate than saturated air
when lifted, the chance for buoyancy, convection, and
thunderstorms is reduced. There is still a slight chance for
thunderstorms on Saturday, however. These would likely not produce
much if any precipitation, leading to a non-zero probability of
dry thunderstorms that could spark a fire. Otherwise, we are
expecting some light rain across the Central Coast this weekend,
which may extend up the the central Bay Area. With strong offshore
winds expected in the North Bay, rain is less likely. Fortunately
it looks like Southern California will get some of this rain as
well, and the rain rates should be low enough to prevent burn scar
land slides. However, a slow moving shower could be enough to
trigger that hazard. By Monday, the low will drift into southern
California, shifting our winds back offshore and ending the chance
for rain. The rest of next week looks dry, with tremendous
uncertainty in the long wave pattern beyond next weekend.
&&
.AVIATION...
(00Z TAFS)
Issued at 319 PM PST Thu Jan 23 2025
Clear skies and dry conditions continue. Therefore, high confidence
VFR through the TAF period. Winds are relatively light through the
TAF period.
Vicinity of SFO...VFR through the TAF period. Light winds through
the TAF period with winds turning onshore Friday afternoon.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR through the TAF period. Moderate SE
drainage expected overnight with onshore winds returning Friday
afternoon.
&&
.MARINE...
(Tonight through next Tuesday)
Issued at 319 PM PST Thu Jan 23 2025
A low pressure system will develop and move southward over the
Pacific Northwest and northern California this weekend. As the low
moves southward across our coastal waters it'll cause northwest
wind gusts to increase to gale force. Expect rough to very rough
seas Friday through Sunday before wave heights begin to abate
Monday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 10 PM Friday to 10 AM PST Sunday for CAZ504.
Frost Advisory from midnight tonight to 9 AM PST Friday for
CAZ516.
PZ...Small Craft Advisory from 3 PM Friday to 9 AM PST Saturday for
Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory from 9 PM Friday to 9 AM PST Saturday for
Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras
Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory from 3 AM to 3 PM PST Friday for Pt Arena
to Pt Reyes 10-60 NM.
Gale Warning from 3 PM Friday to 9 AM PST Saturday for Pt Arena
to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...SO
MARINE...Canepa
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Prepared by Boulder-Creek.com Weather at: Thu Jan 23 20:30:02 PST 2025
From the National Weather Service
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