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

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FXUS66 KMTR 070145

Area Forecast Discussion
National Weather Service San Francisco Bay Area
545 PM PST Sat Mar 6 2021

.SYNOPSIS... Expect dry and seasonably cool conditions today
along with locally breezy onshore winds in the afternoon. Similar
conditions are expected Sunday, except with lighter winds. A cool
weather system dropping south offshore early in the work week will
produce cool and showery weather from Monday through about
midweek, along with low snow levels and the potential for
thunderstorms on Tuesday and Wednesday. Drier and warmer
conditions are likely later in the week.

&& of 02:05 PM PST Saturday...Cooler air filtering
into the region behind last night`s cold front has kept afternoon
temperatures on the cooler side. Highs look to peak in the upper
50s and low 60s this afternoon with mostly sunny skies. Breezy and
gusty winds are set to return along coastal areas and into the
hills with peak gusts between 25 to 30 mph. These winds will back
off into the evening, making for a calm and cold night. Overnight
lows look to fall into the mid to low 40s along coast while
interior areas will back off into the mid 30s. Sunday offers
similar conditions with weaker winds and slight increases in
temperatures for both highs and lows.

The main focus in the forecast remains with a cold upper-level low
approaching the Bay Area and Central Coast early next week. There is
good confidence that this low will begin to affect the North Bay
early Monday morning, but there is potential for this system to slow
down and hold off until the afternoon. The track of this low
pressure keeps it moving southward along the shore, offering the
best chances for rain along the immediate coast, with much less rain
reaching into the East Bay and interior areas.

Fine-tuning has been been done to the official forecast to show the
potential for some convection as the rain rates increase over the Bay
Area for Tuesday. Cold air aloft with instability at the surface
creates the possibility for small hail production, with a slight,
yet unlikely chance for lightning. The convective portion of this
system could stretch into areas as far south as the Big Sur Coast
before dissipating Tuesday evening. Another factor of the forecast
that has been adjusted is the potential for accumulating snow on
higher peaks. While snow levels still look to fall below certain
peaks, the amount of moisture coupled with temperatures just barely
falling into the lower 30s, prevents significant snowfall.

Chances for rain look to continue into Wednesday afternoon for
the San Francisco Bay and could linger well into Thursday morning
for the Monterey Bay and Big Sur Coast. Some longer term model and
ensemble members show the potential for rain wrapping around the low
and prolonging rain chances for the Big Sur Coast. For now, this
seems like an unlikely scenario, and the official forecast omits
these chances, but this will be something to keep an eye on as more
higher resolution models come into range.

Forecasted rainfall totals favor coastal Mountain ranges for the
highest amounts and much less for more inland areas. The current
forecast shows 1" to 2" for higher peaks along the coast over the 3-
day period. Lower elevations along the coast are set to see 0.50" to
1", while interior areas will likely stay below 0.50". As this is
over a 3-day period and rainfall rates look mild with only brief
moments of moderate rainfall: the concern for debris flow is low.
Ponding will be possible in favored locations, but flood potential
is also low.

&& of 5:45 PM PST Saturday...For the 00Z TAFs. Post
cold frontal air mass is dry supporting VFR.

Vicinity of KSFO...VFR, west wind 20 to 25 knots decreasing to
light and variable tonight and Sunday morning. West to northwest
wind 15 to 20 knots Sunday afternoon and evening.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR, west to northwest winds 10 knots
until early to mid evening, light and variable wind late evening
trending to east to southeast overnight and Sunday morning. West
to northwest winds 10 to 15 knots resuming Sunday afternoon and

&& of 4:31 PM PST Saturday...Moderate to locally strong
northwest winds continue over the coastal waters. Strongest winds
will be along the coast where coastal jets develop. Expect these
winds through the weekend, creating locally steep fresh seas
nearshore. A pair of moderate northwest swells will move through
the waters over the coming days.


     .Tngt...SCA...SF Bay until 9 PM
             SCA...Mry Bay until 9 PM
             SCA...Pt Reyes to Pigeon Pt 0-10 nm until 9 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM
             SCA...Pt Arena to Pt Reyes 0-10 nm until 6 PM
             SCA...Pt Arena to Pigeon Pt 10-60 nm until 6 PM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 6 PM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm




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