441
FXUS66 KMTR 102359
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
359 PM PST Fri Jan 10 2025

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 229 PM PST Fri Jan 10 2025

A strong offshore wind event returns late tonight and continues
through Sunday morning for the higher elevations of the Bay Area
and into the Santa Cruz mountains. There may be another push of
gusty winds Monday through Tuesday. Dry weather persists through the
week.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 229 PM PST Fri Jan 10 2025

Upper level high pressure is being squashed by a shortwave trough
moving into the PacNW today, while a deep upper level trough digs
into northwestern Mexico. This leaves us with with quasi weak
troughing and more zonal upper level flow through the weekend. Gusty
north to northeast winds will be observed in response, with the
strongest winds being over the hills and higher elevations of Santa
Cruz county and the North, East, and South Bay counties as well.
Winds begin to increase late tonight and continue through Sunday
morning before weakening some. Outside of these winds, the other
concern to keep an eye are overnight low temperatures. Tonight,
the coldest areas should be across the interior areas of San
Benito and Monterey counties, including the south Salinas Valley.
Lows will range from roughly 32 to 36 degrees, though some areas
in Monterey and San Benito counties will be warmer and in the low
to mid 40s and upper 30s respectively. A Frost Advisory was
hoisted from late tonight through tomorrow morning as enough of
these highlighted areas fell into the 32 to 36 degree range. There
looks to be additional cold nights in our future, so we`ll need
to keep an eye on low temperature forecasts.

&&

.LONG TERM...
(Sunday night through next Thursday)
Issued at 229 PM PST Fri Jan 10 2025

Ensembles and cluster analysis shows troughing setting up over the
west, and an area of low pressure cutting off somewhere over
southern or central California. Unfortunately for us, there is no
rain in our future, just dry weather. Another round of breezy
winds is possible Monday into Tuesday, perhaps being more confined
to the North and East Bay areas. Much like the previous shift,
the NBM isn`t hitting Wind Advisory criteria, nor do any of the
ensembles really highlight it either. Will need to watch and see
how the hi- res models pan out and we get better determination as
to where the low situates. Outside of that, guidance does seem to
favor chilly overnight lows this week. NBM seems to be a good
solution for now to capture these temperatures, which fall into
the 30s for much of the area perhaps low 40s along the coast.

&&

.AVIATION...
(00Z TAFS)
Issued at 359 PM PST Fri Jan 10 2025

Mix of VFR and MVFR conditions expected overnight. Forecast RH
values have been trending higher than observed RH values which
decreases confidence in BKN/OVC cloud ceilings developing tonight.
The local WRF model is handling forecast RH values the best and does
show a temporary increase in RH values, after a weak cold frontal
passage this evening, between approximately 04-10Z. During this
time, scattered low level clouds are most likely but some potential
remains for lower visibilities and temporary BKN/OVC ceilings.
Removed fog from the STS TAF with the WRF model showing a sharp
decrease in RH after 10Z and winds staying more moderate around 10
knots overnight. This should keep the atmosphere more well mixed
over STS and prevent major decreases in visibility. By tomorrow
morning, VFR conditions return to all sites with gusty northerly
winds expected to develop mid to late morning through tomorrow
evening.

Vicinity of SFO...VFR through the TAF period. There is a low to
moderate chance of temporary BKN/OVC ceilings developing between 06-
10Z with the WRF model showing a temporary burst of higher RH values
(90%+) during this time. Variable, light winds continue tonight
before northerly winds strengthen mid tomorrow morning. Gusty
conditions will develop by late morning and continue through the
early evening hours with gusts up to 25 knots possible.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals...VFR becoming MVFR temporarily overnight.
WRF guidance shows increased RH values between 10-15Z which may
bring temporary BKN/OVC ceilings to MRY and SNS. LAMP guidance
agrees with this time frame and indicates MVFR conditions are the
most likely scenario. After 15Z, RH values decrease with CIGs
expected to clear. Gusty, northwesterly flow returns by late morning
with gusts to strengthen heading into the afternoon and evening
hours.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 359 PM PST Fri Jan 10 2025

Strong and gusty northerly winds will develop as a dry frontal
boundary moves through the region tonight into Saturday morning.
Wave heights will build in wake of the passing front to 10 to 15
feet and remain elevated through the weekend. The strongest winds
will be located over the northern outer waters where gale force
gusts are likely tonight and over the weekend. Seas reamin
elevated into the start of the upcoming workweek, but winds look
to reduce.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory from 5 AM to noon PST Saturday for CAZ006-
     506-508.

     Wind Advisory from midnight tonight to 10 AM PST Sunday for
     CAZ504-512-514-515.

     Frost Advisory from 1 AM to 9 AM PST Saturday for CAZ516>518.

PZ...Gale Warning from 3 AM Saturday to 3 AM PST Sunday for SF Bay N
     of Bay Bridge.

     Small Craft Advisory from 3 AM Saturday to 3 AM PST Sunday for
     Mry Bay-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 until 3 AM PST Sunday for Pt Arena to Pt
     Reyes 0-10 nm.

     Small Craft Advisory until 9 PM PST this evening for Pt Arena to
     Pt Reyes 10-60 NM.

     Gale Warning from 9 PM this evening to 3 AM PST Sunday for Pt
     Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory from 9 PM this evening to 3 AM PST Sunday
     for Pigeon Pt to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...KR
LONG TERM....KR
AVIATION...Kennedy
MARINE...RGass

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