Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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FXUS66 KMTR 270529

Area Forecast Discussion
National Weather Service San Francisco CA
929 PM PST Mon Feb 26 2024

...New AVIATION...

Issued at 831 PM PST Mon Feb 26 2024

Tuesday and Wednesday will be dry and chilly before an extended
period of rain, wind and overall nasty weather kicks off on
Thursday. Unsettled weather will continue through the weekend.


Issued at 830 PM PST Mon Feb 26 2024

A chilly night ahead as the interior North Bay sees Frost Advisory
criteria in the late night and into the morning. The precipitation
has pushed out of the area, with only some mid to low-level
clouds lingering behind the front. Not much else to report, aside
from the cold, it will be a calm night leading into a cool
Tuesday. The overnight forecast package will continue to make
adjustments to the next rain-maker in the late week and the next
batch of cool temperatures that will follow it.


(This evening through Tuesday)
Issued at 1204 PM PST Mon Feb 26 2024

The cold front descending from the north is colliding with an
outer rain band from the Eastern Pacific low pressure system,
creating a narrow band of moderate precipitation across San Mateo
and Alameda counties. San Francisco International Airport
recently reported the visibility as low as 2 miles, with San
Carlos down to 1 mile. Overall rain totals are still being
tallied, but the Radar images are suggesting it`s likely to
surpass our <1/10" forecast across this narrow, but highly
populated band.

The rain will taper off today, as cold dry air behind the cold
front moves in. By Tuesday morning, many areas will drop into the
high 30s or low 40s. The coldest area will be in the North Bay,
where mid-30s are expected and a frost advisory is in effect for
Tuesday morning. With the 850 mb temperature around +1C, this is a
marginal event, but the clear skies and enhanced radiational
cooling should help the surface temp drop below the 36F threshold.
After the cold morning, Tuesday will be a nice day with mostly
clear skies and mild temperatures.


(Tuesday night through next Sunday)
Issued at 1204 PM PST Mon Feb 26 2024

High pressure conditions will remain and Wednesday will be pretty
similar to Tuesday. A chilly start with clear skies and mild
afternoon temperatures.

Conditions look rather unsettled beginning Thursday and persisting
through the weekend as a stronger storm system slowly migrates
from the Gulf of Alaska towards the West Coast. Overall it`s just
going to be nasty outside with cold temperatures, gusty wind and
periods of moderate rain. That being said, the actual impacts
look mostly minor with wind gusts in the 25-35 mph range and only
a moderate amount of rainfall, spread out over a few days. The
storm total amounts are holding steady from the previous forecast,
with rain spread out over several days. Global model ensemble
members still suggest total amounts around 1-2" for the lower
elevations from Thursday through Sunday, with higher totals in the
coastal ranges. Friday and Saturday remain the target period for
when the heaviest rain is expected. This is a colder system and
snow levels will lower this weekend to roughly 2,000 ft in the
North Bay and 3,000 ft in the Central Coast region. As such, some
higher elevation ridgetop snow accumulation is possible, with the
greatest potential for this over the Santa Lucias. The higher
elevations of the Mayacamas and Diablo Range also have the
potential for snow on Saturday. There is very little chance for
low elevation snow and this should be more of a weather interest
than a weather impact. Dry weather looks to return early next
week, but the cold mornings will remain.


(06Z TAFS)
Issued at 918 PM PST Mon Feb 26 2024

Currently VFR at all TAF sites with the exception of MRY, which is
seeing the last of the low clouds as they move south out of the
area. VFR through the TAF period for all terminals after MRY
scatters out. Building high pressure will allow for clear skies and
breezy northwesterly winds.

Vicinity of SFO...Currently VFR with breezy onshore flow. VFR
through the TAF period. Winds will become light and northerly in the
early morning hours before returning to breezy northwesterly flow
tomorrow afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently MVFR with a borderline ceiling at
MRY and VFR at SNS, both terminals are experiencing breezy westerly
flow. The ceiling at MRY will scatter out shortly as the rain shower
activity pushes out of the area to the south, VFR through the TAF
period at both terminals thereafter. Winds will be breezy out of the
northwest tomorrow afternoon.


(Tonight through next Saturday)
Issued at 830 PM PST Mon Feb 26 2024

The gradient between the North Pacific High and the low pressure
over the northern Plains is responsible for a fresh northerly
breeze and moderate to rough seas across the coastal waters. By
early Tuesday, this gradient will tighten, increasing winds to a
strong northwest breeze. On Wednesday, high pressure will briefly
rebuild over the Western United States, decreasing winds and
abating seas. Conditions will deteriorate again on Thursday as a
cold front moves across the waters and a moderate to high westerly
swell arrives. Strong winds and rough seas will persist through


CA...Frost Advisory from 2 AM to 9 AM PST Tuesday for CAZ503-504-506.

PZ...Small Craft Advisory until 3 AM PST Wednesday for Pt Arena to Pt
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 AM PST Tuesday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 3 PM to 9 PM PST Tuesday for Pigeon Pt
     to Pt Pinos 0-10 nm.

     Small Craft Advisory until 9 AM PST Wednesday for Pigeon Pt to
     Pt Pinos 10-60 NM.



LONG TERM....Flynn

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