Small Craft Advisory 36, NWS San Francisco Bay Area, CA

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1133 PM PST Fri Feb 28 2020

.SYNOPSIS...Cooler temperatures around the region over the
weekend as a cold front moves through. A chance of showers for
areas along the Central Coast, but accumulations will be minimal.
Winds will shift to the north and become breezy. The next dry,
warming trend begins on Monday as high pressure builds once again.

&&

.DISCUSSION...as of 10:17 PM PST Friday...Today was the crescendo
of daytime warmth this week that produced several more record
high temperatures. Adiabatic compressional warming under ridging
will continue to weaken tonight and switch over to expansional
cooling Saturday through Sunday as an upper level low pressure
trough arrives from the Gulf of Alaska and deepens as it moves
south along the California coast. Odd though to see the upper low's
corresponding surface low moving so far to the southwest with time
in the model forecasts, the low practically fully decoupling from
the main cold core upper trough. This is part of the reason why
there's a splitting of qpf in the forecasts, plus it doesn't help
that the low is arriving from the northwest which is often a moisture
starved trajectory. It's a race against the clock as the end of
February 2020 nears, will any of this cooling surface or aloft
produce any light sprinkles or drizzle before the month closes
out? Doesn't look like it, if not, San Francisco with zero rain
for February 2020 would tie February 1864 with zero rain.

Gusty winds will accompany this low over the weekend, it should stay
below or mostly below critical fire levels, but will be watched
closely over the weekend.

As we wait for the large scale pattern to change, am more optimistic
on 8 to 10 day 500 mb mean height forecasts across the medium range
models. There's good agreement on the pattern emerging from a stable
equilibrium wave pattern to more hemispheric long waves scenario, which
should translate into an energy potential tap equalling better chances
for rain, mountain snow as we go into March.

&&

.AVIATION...as of 9:45 PM PST Friday...Satellite image is
obscured by high clouds but low clouds have been spotted along the
coast especially around the MRY Bay Area. Approaching upper
trough should give the low clouds an onshore push. MVFR/IFR cigs
are forecast for SFO but not until after 09Z. Lower confidence on
how long the stratus stays in on Saturday but it should clear up
by midmorning as winds increase.

Vicinity of KSFO...Low cigs possible after 06Z with bases 800-1000
feet. Forecast clearing after 16Z.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...IFR cigs through 17Z at SNS and 19Z at
MRY.

&&

.MARINE...as of 9:17 PM PST Friday...An upper level trough
driving into California will bring increasing northwest winds
tonight through Sunday. Gale force winds can be expected north of
Pigeon Point as well as the Big Sur coast. Steep fresh swell from
these winds will also create hazardous conditions on the waters.
Winds will slowly decrease on Monday as the trough moves inland. A
moderate long period northwest swell will move across the waters
over the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pigeon Pt to Pt Pinos 0-10 nm from 3 AM
             GLW...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 3 AM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm

&&

PUBLIC FORECAST: Canepa
AVIATION: W Pi
MARINE: W Pi

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