FXUS66 KMTR 202048

Area Forecast Discussion
National Weather Service San Francisco Bay Area
148 PM PDT Sun Jun 20 2021

.SYNOPSIS...Though warmer temperatures can still be expected
farther inland, pleasant conditions are forecast for Father`s Day
2021 as temperatures continue their cooling trend. As the marine
layer has reestablished and lower pressure develops just west of
the coast, these cool temperatures will continue for much of the
week and possibly drop below average by midweek. The next chance
for warmer temperatures looks to be next weekend with inland
areas returning to the 90s.


.DISCUSSION...as of 01:48 PM PDT Sunday...Seems appropriate that
sunny skies accompany the Summer Solstice. Most of the Bay Area is
experiencing sunny skies this afternoon, but coastal areas on the
other hand are hanging onto some clouds. Despite the inland
sunshine temperatures are actually running a few degrees cool
across the interior. 5-10 degrees cooler in fact.

As for the Willow Fire - conditions have improved a little this
afternoon with less smoke production, but satellite still shows
some heat. Nearby weather stations are still relatively hot and
dry with temps in the low 90s and RH dropping into the teens. HRRR
smoke appears to be a little over done for this afternoon, but
some smoke/haze is still possible N and E and of the Willow Fire.

For tonight...low clouds along the coast will move inland again.
Some patchy fog/drizzle will also be possible.

The upper level low pressure lurking off the CA coast will
continue to slowly drift eastward. This low will help to deepen
the night/morning marine layer and cause further
cooling/moistening of the region. Temperatures will cool a few
degrees each day through Wednesday with more widespread 60s/70s at
the coast and 70s/low 90s inland. A few of the models spit out
some precip as the low approaches over the waters and coast. This
is most likely drizzle. Therefore patchy drizzle has been added to
the forecast. Wouldn`t be surprised to see a few bucket tips
Tuesday and Wednesday mornings. The previous discussion mentioned
the possibility of thunderstorms over NorCal. Lastest guidance
stills shows some lift and moisture Monday and Tuesday, but
primarily north of the Bay Area.

The upper low meanders slowly to the NE Wednesday through Friday
keeping relatively quiet and cooler weather in places. What
happens there after is lower confidence as medium range models
shows are almost out of phase. The EC keeps the low/trough in
place and the GFS shows a robust ridge with more of a heat signal.
Ensembles fall somewhere in the middle. Given the uncertainty will
allow for a slight warming trend next weekend, but not increase
too much yet. Far interior locations have a shot at triple digit
heat once again. Stay tuned...


.AVIATION...As of 10:32 AM PDT Sunday...For the 18z TAFs. The
marine layer remains at around 1,800 ft deep per the Fort Ord
Profiler. Satellite imagery shows stratus continuing to dissipate
inland with a finger still lingering around the Golden Gate Gap as
well as along the coastline and over the waters. VFR conditions
through this evening before low clouds are expected move inland
once again. May see a little later clearing times tomorrow as the
marine layer deepens ahead of an approaching upper low. Hazy or
smoky conditions aloft look to increase this afternoon and evening
due to the Willow Fire. The latest HRRR smoke model forecast
transports smoke to the N/NE as winds aloft remain in a general
southwesterly pattern. This may occasionally reduce slant range
visibilities in some areas. Southwest to westerly winds expected
at the surface for most locations with the typical afternoon sea
breeze along the coast.

Vicinity of KSFO...VFR conditions through this evening. Moved
forward the return time tonight by a couple of hours given the
latest model runs and a deepening marine layer. MVFR/IFR
conditions then expected late tonight through mid to late tomorrow
morning. Onshore winds this afternoon around 15 kt with gusts to
20 kt.

SFO Bridge Approach...Wildfire smoke may occasionally reduce
slant range visibility, otherwise similar to KSFO.

Monterey Bay Terminals....Satellite shows stratus retreating back
towards the Monterey Bay. VFR conditions this afternoon before
IFR/LIFR cigs return by the early evening/late afternoon. Patchy
fog and drizzle possible tonight and tomorrow morning, but
confidence is low. W/NW winds through most of the period becoming
10-15 kt this afternoon.


.MARINE...as of 08:43 AM PDT Sunday...A developing weak low
pressure system over the outer to offshore waters will allow south
to southwest winds to persist through early this week. Locally
breezy southwest winds are expected north of the Bay Bridge in the
afternoons and evenings the next couple of days. Seas remain
northwest at 10 to 11 seconds along with a  marginal southerly


     .Tngt...SCA...SF Bay until 9 PM




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NWS MTR Office Area Forecast Discussion