Small Craft Advisory 157, NWS San Francisco Bay Area, CA

Area Forecast Discussion
National Weather Service San Francisco Bay Area
1028 PM PDT Tue Jul 31 2018

.SYNOPSIS...Seasonably warm and dry conditions are forecast to
continue in the interior through the week. Onshore flow and a
persistent marine layer will maintain cooler conditions near the
coast. Cooler conditions look to spread across the entire
district beginning around Sunday as high pressure weakens.

&&

.DISCUSSION...as of 9:35 PM PDT Tuesday...Smokey skies prevail
across the area this evening, as the large wildfires continue to
burn to our north and east. Most of it is aloft over us, though
locally reaching down to the surface. Latest fog product satellite
imagery shows marine stratus blanketing the coast and already
progressing well down the Salinas Valley. High temperatures this
afternoon ranged widely, from the upper 50s cooler stretches by
the ocean to 105 at the Fort Hunter Liggett RAWS site in the
interior of southern Monterey County. Around the Bay, Downtown San
Francisco only reached 61 while Concord Airport had a max of 94
degs.

Strong upper level high pressure is projected to remain basically
parked over the southwestern United States through the end of the
week. That will keep a very warm air mass aloft over us. At the
same time, a 1000 to 1500 ft deep marine layer and onshore flow
are expected to continue along the coast. The net result will be
basically persistent weather conditions, with just minor day-to-
day modulations. Will also note that concern over risk of high-
based convection is diminishing with latest model output, with the
new 00Z GFS in particular having backed off on intrusion of
midlevel subtropical moisture into southern portions of our
district on Wednesday.

In the longer term, a major pattern change appears in store,
beginning over the weekend. Models are coming into good agreement
in showing a major phase shift then occurring, with cool upper
level troughing along the west coast by the start of next week and
a major cooldown in inland temps for us.

&&

.AVIATION...as of 10:45 PM PDT Wednesday...Very similar onshore
gradients from yesterday as well as the stratus pattern on
satellite. Will keep a persistence forecast for tonight as it
seems to be working out so far. Hazy conditions from regional
wildfires expected to last through Wednesday.

Vicinity of KSFO...IFR cigs after 11Z clearing after 16Z.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...LIFR for cigs. Vsbys lowering to 3 miles
or less after 09Z. Becoming VFR at SNS after 17Z and MRY after
18Z.

&&

.MARINE...as of 10:19 PM PDT Tuesday...Gusty northwest winds will
persist across the waters through the coming days, with the
strongest winds along the immediate coast  north of Pigeon Point
and south of Point Sur. Gusty winds will  generate steep wind
waves creating hazardous sea conditions,  especially for small
vessels. Generally light swells will  continue through the
forecast period.

&&

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

&&

PUBLIC FORECAST: Blier
AVIATION: W Pi
MARINE: W Pi/DRP

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