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

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FXUS66 KMTR 022336

Area Forecast Discussion
National Weather Service San Francisco Bay Area
336 PM PST Tue Mar 2 2021

.SYNOPSIS...Dry and mild weather conditions continue with slight
cooling late in the week. Rain chances increase late Friday into
Saturday with the potential for unsettled conditions to persist
into early next week.

&& of 02:08 PM PST Tuesday...Fairly clear skies
continue over the region as a low pressure system spins well
offshore to our west. That system will stream some high clouds
over CA and will move southward then into SoCal. For the Bay Area
and Central CA, we`ll remain dry and mild for much of this week.
Daytime highs will range in the 60s to low 70s and overnight lows
will be in the 40s along the coast and in the 30s for the colder
inland valleys.

The big story is that we`re watching the forecast models for an
incoming cold front this weekend. Models continue to suggest that
light rain could start up in the North Bay on Friday aftn/evening
then move southward across our region through Saturday. The
heaviest rain should fall Saturday morning. Confidence remains low
on the details of rain rates, but we are monitoring the trends in
case it could impact burn scars. Rain totals will generally be
light to moderate for our CWA. Coastal mountains should have the
highest amounts around 0.5-1", but the inland areas will be much
lighter around 0.25" or less with some areas in the North Bay or
near the coast getting up to 0.4". Winds with this frontal passage
should be enhanced starting with southwesterly flow and then
turning northwesterly behind the front. Still trying to nail down
exactly how strong wind gusts could be and if the higher 925 mb
winds will mix down to the surface. Initial estimates are that
wind gusts could range 15-25 mph, locally higher over peaks and
ridges. One thing to note about the forecast is that the prior
ECMWF run was suggesting that the storm could turn into a cut-off
low and move just south of our region...which would have meant a
drier scenario for our CWA. Latest deterministic ECMWF run has
returned back to a typical trough moving inland. In addition, the
ECMWF ensemble showed 36 out of 50 members with rain and the GFS
ensemble showed 26 out of 30 members with rain, so there is less
confidence in the cut-off low being a possibility.

Showers will diminish by Saturday afternoon/evening, but we could
see some lingering light showers on Sunday, mainly in the North
Bay. Models then suggest that another storm could move in sometime
Monday or Tuesday and that unsettled weather will continue next

&& of 3:35 PM PST Tuesday...For the 00Z TAFs. VFR as
high clouds continue to push over the Bay Area. Winds continue to
diminish and will be more variable through the night. Onshore
winds, breezier closer to the coast, return on Wednesday. High
clouds prevail. The better chance for lower clouds look to be
after 00Z and outside the TAF period.

Vicinity of KSFO...VFR through the TAF period. Winds continue to
subside, becoming light and variable overnight. Increasing NW
winds Wednesday afternoon. Models hinting and lower clouds moving
into the Bay Area Wednesday evening and will be monitored.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR. A few clouds are growing off the
Gabilan Range at this hour, but prevailing SW flow aloft is
keeping it away from the terminals at this point, so continued to
keep heavy low cigs out of the tafs, but some SCT low clouds still
possible overnight. Winds switch back to NW tomorrow afternoon as
high clouds remain.

&& of 01:53 PM PST Tuesday...A low pressure system over
the eastern Pacific will move across the waters into tomorrow,
though winds will remain generally light to locally moderate.
Building northwest swell will cause hazardous seas conditions for
smaller vessels into tomorrow morning over  the outer waters.
Winds will gradually increase and turn southerly on Thursday ahead
of the next frontal system set to arrive Friday and Saturday.
Moderate northwest swell will over the next couple  of days before
a longer period northwest swell arrives late this  week.


     .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm




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