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

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FXUS66 KMTR 180023
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
523 PM PDT Mon Jun 17 2019

.SYNOPSIS...Warmer temperatures are forecast for today and Tuesday
as high pressure strengthens over California, and onshore flow
weakens. However, warming at coastal areas will be limited due to
persistent onshore winds. Seasonable temperatures, along with
areas of night and morning low clouds, are forecast through the
end of the week and into next weekend.

&&

.DISCUSSION...as of 01:35 PM PDT Monday...Slightly compressed
marine layer, building high pressure and increasing northerly flow
all helped for an earlier burn off of the stratus deck this
morning. Even coastal section are seeing more sunshine today with
a more disorganized cloud deck hugging the coast today. The
increased sunshine and warmer airmass also translated to warmer
temperatures today. The latest 24 hour trend has many locations
running a few degrees warmer than yesterday and interior locations
as much as 10 degrees warmer.

No major changes to the overall forecast. High pressure will
continue to build over the Bay Area keep a warming trend through
Tuesday then moderating temperatures Wednesday. Night and morning
low clouds and even patchy drizzle will continue. The coverage
will clouds will decrease however with the building 500mb heights
and increasing N-S gradient. Scaled back on clouds tonight across
the North Bay Valleys and inside SF Bay. San Mateo Coast southward
into the Salinas Valley will see good coverage. Not only will
there be warm temperatures during the day overnight lows in the
hills will remain mild. Given the airmass will still be in the mid
20C range at 850 mb overnight lows in the 60s and 70s will be easy
to get in the hills.

By Wednesday and more so on Thursday a trough in the Gulf of
Alaska will pivot through the PacNW. This passing trough to the
north will flatten the overhead ridge bringing much cooler weather
to the Bay Area. In fact, temperatures on Thursday will actually
be at or below normal for many locations. A reverse in the
temperature trend occurs again Friday and into the weekend the
trough exits into the Great Basin. Not a real big warm up just
returning closer to normal.

&&

.AVIATION...as of 4:52 PM PDT Monday...For 00z TAFs. A
strengthening northerly gradient coupled with a compressing marine
layer will keep low clouds from penetrating very far inland
tonight. As a result VFR conditions are expected at all Bay Area
terminals through late this evening with the exception of KMRY
and KSNS that will possibly see low cigs develop this evening.
However confidence is low to moderate. Moderate onshore flow will
ease this evening becoming light and locally variable overnight.

Vicinity of KSFO...VFR conditions through late tonight. MVFR cigs
expected to return around 13z Tuesday morning. Clearing is
anticipated around 17z Tuesday morning. Moderate onshore winds
around 15 kt will ease this evening becoming light overnight. A
short period of offshore flow is expected between 15z- 21z Tuesday
over KSFO.

SFO Bridge Approach...Approach will be clear through tonight.
Impacts to approach should be short lived Tuesday morning with
light offshore flow aloft and shallow marine layer.

Monterey Bay Terminals...VFR conditions will continue through this
evening followed by the return of a shallow marine layer between
03z-05z tonight. Clearing is anticipated around 19z Tuesday.
Moderate onshore winds around 10-13 kt will ease this evening
becoming light and locally variable overnight.

&&

.MARINE...as of 2:20 PM PDT Monday...Gale warnings have been
posted for the northern outer waters through late Tuesday night as
strong pressure gradients are setting up near Cape Mendocino that
will keep northerly winds in place with fresh seas. As the
thermal trough sets up near the coast light southerly winds and
seas will persist across the near shore waters with generally
light winds in the bays except for locally gusty afternoon
seabreeze winds.

&&

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

&&

$$

PUBLIC FORECAST: MM
AVIATION: CW
MARINE: RWW

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