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

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FXUS66 KMTR 021248

Area Forecast Discussion
National Weather Service San Francisco Bay Area
448 AM PST Tue Mar 2 2021

.SYNOPSIS...Dry and mild weather conditions will prevail over the
region through midweek with slight cooling likely late in the week.
Rain chances increase late Friday into Saturday with the potential
for unsettled conditions to persist into early next week.

&& of 03:23 AM PST Tuesday...A mid/upper level low
pressure system and associated trough remains well off of the West
Coast early this morning. It`s only impact to the region is
mid/high level clouds advecting inland across California as dry
weather conditions prevail at the surface. This system is forecast
to remain well enough offshore to maintain dry conditions over
the region before eventually dropping southward and then across
southern California on Wednesday. Day-to-day fluctuations in
temperatures are expected to be minimal through midweek, yet will
be at or above seasonal averages. Generally speaking, look for
upper 50s to lower 60s at the coast with more widespread 60s to
near 70 inland. Meanwhile, overnight lows will range from the
mid/upper 30s in the colder interior valleys with 40s elsewhere.

As the aforementioned system shifts inland over the Desert Southwest
through midweek, a mid/upper level trough will deepen over the
eastern Pacific late in the week. This system is then forecast to
shift eastward toward the West Coast late in the week potentially
bringing widespread precipitation to the region Friday night into
Saturday. However, the deterministic and most ensemble members only
indicate light precipitation for our region. Temperatures late in
the week and into the upcoming weekend will also cool as a result.

Beyond the upcoming weekend, the ensembles favor unsettled weather
conditions across our region heading into next week as troughing
persists over the eastern Pacific and along the West Coast. However,
this pattern would likely only result in light precipitation amounts
for our region. Seasonably cool conditions are also likely given
this pattern.

&& of 4:48 AM PST Tuesday...For the 12Z TAFs. VFR.
Low clouds continue to focus near a cool front very slowly
approaching the southern and central outer coastal (and offshore)
waters per recent satellite imagery and NAM output. The cool front
looks mainly elevated until later today and tonight when surface
cooling arrives based on the NAM and the air ahead of the front is
still dry to very dry. Add in today`s diurnal mixing and chances
are good the low clouds will mix out prior to reaching the north
Central Coast later today despite recent high resolution model
forecasts showing otherwise. Best chance of coastal low clouds
will be tonight and Wednesday morning as cool air advection
combines with nocturnal cooling. Not confident enough to introduce
bkn-ovc ceilings KMRY and KSNS for the 12z taf cycle, later
shifts can reassess and add ceilings if needed. Meanwhile high
clouds will continue to move in stretching out from the low
offshore, the low reaches southern California Wednesday.

Vicinity of KSFO...VFR, light and variable wind increasing to 10
knots westerly in the afternoon and early evening.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR, cool air drainage winds this morning
becoming onshore 5 to 10 knots in the afternoon and early evening.
Cool air advection and cool air drainage winds combining tonight
and Wednesday morning tending to offset low cloud development, at
least for mid to late Tuesday evening. Lower confidence cloud cover
forecast late tonight and Wednesday morning.

&& of 3:53 AM PST Tuesday...A low pressure system over
the eastern Pacific will reach southern California Wednesday.
Building northwest swell will cause hazardous sea conditions for
smaller vessels later today into the evening. A moderate period
northwest swell will then turn to long period swell late in the
week. A slow moving low pressure system arrives from the northwest
late in the week with rain this weekend.


     .Tday...SCA...Pt Arena to Pigeon Pt 10-60 nm from 12 PM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 4 PM




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