NWS Forecast Area Discussion - San Francisco Area

FXUS66 KMTR 230010

Area Forecast Discussion
National Weather Service San Francisco Bay Area
510 PM PDT Mon Apr 22 2019

.SYNOPSIS...High pressure will continue to build over the region
resulting in well above normal temperatures through midweek.
Conditions cool slightly late in the week as onshore flow returns
and the ridge of high pressure weakens.

&& of 02:39 PM PDT Monday...Mostly sunny conditions
prevail over the region this afternoon as the last patch of
stratus over the Monterey Bay dissipates. This is a result of the
building high pressure aloft and weak offshore flow developing
over the region. Temperatures have already reached into the lower
80s in the North Bay Valleys as warmer, drier air mixes down to
the surface. For tonight, cannot rule out a few low clouds
returning near the Monterey Bay, yet mostly clear conditions are
more likely region-wide.

Much warmer conditions are forecast for Tuesday afternoon as
widespread 80s will be common inland. Cannot rule out interior
valleys of the North Bay, East Bay and portions of the Salinas
Valley reaching into the lower 90s. With the weak offshore pattern
and lack of a marine layer, 70s will be common along the coast with
even lower 80s in locations such as Santa Cruz and Big Sur. These
temperatures are a good 5-10 deg above average at the coast and 10
to as much as 20 deg in the interior. With this said, heat impacts
may reach into moderate levels during the afternoon hours across the
interior valley locations on Tuesday. However, overall risk will be
lower given modest cooling during the overnight hours. Folks
sensitive to heat should plan outdoor activities during the early
morning or late evening hours and avoid extraneous activity during
the peak heating.

The ridge aloft will remain the dominate feature heading into
Wednesday with above average temperatures ongoing, especially
inland. However, the ridge will shift eastward a bit and allow for
weak onshore flow to return to coastal areas. Thus, look for cooling
temperatures near the coast and to a lesser degree over inland areas
as well. Onshore flow will continue to increase late in the week and
result in modest cooling region-wide. Overnight/morning coastal
clouds may even return as early as Wednesday along the coast and
spread further inland later in the week.

The forecast models continue to indicate a mid/upper level low will
develop and approach the southern California coast this upcoming
weekend. This would bring an increase in cloud cover, slightly
cooler temperatures and potential for light precipitation over the
southern portion of the state. While some ensemble members bring
light QPF (around 0.01" of an inch or so) to portions of the Central
Coast, will maintain a dry forecast at this time as widespread
rainfall appears unlikely. Something worth watching nonetheless.


.AVIATION...As of 05:00 PM PDT Monday...for 00Z TAFs. VFR
conditions and clear skies prevail across the region. Light to
moderate onshore winds will gradually diminish later this evening.
Continue to expect the the San Francisco Bay Area terminals to
remain VFR through the night and into Tuesday as the north to
south pressure gradient remains pretty strong, and the boundary
layer air mass relatively dry. On the other hand, do believe
ceilings will develop overnight at the Monterey Bay terminals.

Vicinity of KSFO...VFR conditions are forecast to prevail through
the night and on Tuesday. Moderately strong onshore winds 20 to 25
kt will prevail through around sunset, then progressively

SFO Bridge Approach...Same as KSFO.

Monterey Bay Terminals...VFR conditions are expected to prevail
through the evening hours, but latest model output and
statistical guidance indicate likelihood of ceiling development
after around 06Z. Light onshore winds will become light and
variable by mid-evening.

&& of 02:57 PM PDT Monday...Moderate winds will prevail
through the evening and into the overnight hours over the coastal
waters as high pressure remains over the eastern Pacific. Winds
will gradually subside on Tuesday, though remaining locally breezy
north of Pigeon Point. Northwest swells are forecast to remain
small over the next several days.


     .Tngt...SCA...Mry Bay until 9 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM
             SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 AM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM




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NWS MTR Office Area Forecast Discussion