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

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FXUS66 KMTR 092331
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
431 PM PDT Sun Aug 9 2020

.SYNOPSIS...After warmer conditions returned to the region this
weekend, a slight cooling trend will occur during the first half of
the week, especially across the interior. Meanwhile, little change
is anticipated near the coast with the typical ebb and flow of low
clouds each night/morning.

&&

.DISCUSSION...as of 01:16 PM PDT Sunday...Weather conditions
across the region this afternoon are mainly defined by a broad
mid/upper level ridge over the Desert Southwest/Texas and a weak
low off of the central/southern California coast. This has allowed
for a compressed marine layer down to below 1,000 feet in depth
with region-wide temperatures running a few to as much as 7
degrees warmer at this hour. With this said, southerly flow at the
surface has kept low clouds along much of the coastline and up
into the northern Monterey Bay where temperatures are only in the
50s to lower 60s. Thus, the warmest conditions are likely to occur
across the interior this afternoon where 90s will be common.

Onshore flow is gradually forecast into increase early next week as
a mid/upper level trough drops southward out of British Columbia.
This will bring a slight cooling trend to the interior with only
minor day-to-day changes near the coast through midweek.
Additionally, the marine layer will likely deepen resulting in more
widespread night/morning coastal clouds spreading inland into the
valleys.

By late in the week the upper level pattern looks to return to near
what is occuring overhead today. Thus, interior locations look to
warm back into the upper 80s to 90s while coastal areas hold steady
in the 60s to lower 70s as high pressure builds over the Desert
Southwest. Additionally, moisture associated with a tropical system
off of Mexico will advect into southern and/or central California by
next weekend as it rotates around the upper level high. While
precipitation does not appear likely at this time across our region,
this is something worth keeping an eye on.

&&

.AVIATION....As of 04:31 PM PDT Sunday...for 00z TAFs. VFR
conditions across the region with onshore breezy winds. Forecast
remains on track for further compression of the marine layer,
resulting in lower bases. While most terminals are forecast to be
VFR with clear skies, terminals that will see cloud cover have a
greater risk for lower cigs and reduced vis, particularly near the
Monterey Peninsula. Skies should begin to clear by 17z for VFR
Monday with breezy onshore winds.

Vicinity of KSFO...VFR. for the remainder of Sunday and into early
Monday morning. Winds will reduce overnight. IFR conditions
placed in a TEMPO group at 11z for the chance of cloud cover over
the terminal for a few hours, being consistent with the weather
pattern that has been in place the last few days. Any clouds
should begin to lift and clear our after 16z for VFR Monday as
onshore winds increase again in the afternoon.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR for the next few hours, but cigs
begin to lower around 04Z. As the marine layer continues the
compress, models are trending more toward the likelihood of FG at
terminals with reduced vis. Skies clear after 16Z for VFR Monday
late morning, extending into the afternoon. Winds are breezy
currently, with a few strong gusts being funneled through the
Salinas Valley. Winds will ease and become calm overnight. They
will remain onshore Monday and strengthen after 19z.

&&

.MARINE...as of 02:43 PM PDT Sunday...Split flow continues with
predominately southerly winds along the coast and southern outer
waters and diminishing northerly winds in the northern outer
waters. Locally hazardous seas conditions will persist over the
northern outer waters into this evening. Meanwhile, locally breezy
winds are expected this afternoon and evening over the northern
San Francisco Bay near the Golden Gate and to the Delta. Mixed
seas will continue through the period with a short period
northwest swell and a longer period southerly swell.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...SF Bay until 9 PM
             SCA...Pt Arena to Pigeon Pt 10-60 nm until 9 PM

&&

$$

PUBLIC FORECAST: RGass
AVIATION: DK
MARINE: DRP

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