Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
FXUS66 KMTR 291727
Area Forecast Discussion
National Weather Service San Francisco Bay Area
1027 AM PDT SUN MAY 29 2016
.SYNOPSIS...Slightly cooler weather is forecast for today,
especially near the coast where there will be areas of low clouds
and fog. A warming trend is then expected for Memorial Day and
Tuesday. Warmer than normal temperatures will continue through the
end of the week. Dry weather will persist.
.DISCUSSION...As of 8:40 AM PDT Sunday...The first visible
satellite images this morning reveal mainly clear skies across
the North Bay region with patchy low clouds around the bay. Along
the coast stratus extends from the southern tip of Marin southward
along the coast. Across the southern half of the forecast area low
clouds have infiltrated well inland through coastal valleys under
a deepening 2000 foot marine layer. The last few visible frames
show stratus is beginning to erode over the southern salinas
valley with further clearing expected in the next hour or two.
Mainly sunny skies anticipated across the district by midday today
with the exception of coastal areas south of San Francisco that
will only see partial clearing.
Gradients at this hour continue to show a strong northerly
gradient of 4.9 mb from ACV to SFO and an equally strong onshore
gradient from SFO to LAS. A deepening marine layer and a
relatively strong onshore gradient will result in cooler
temperatures along the coast and locally inland. Temperatures
along the coast will experience a drop of up to 10 degrees.
Inland highs will only see a few degrees of cooling while the
North Bay region sees very little, if any.
Warmer conditions are expected on Memorial Day and Tuesday as an
upper level ridge of high pressure builds in over the region and
a surface trough currently situated over the interior shift west
along the coast. This will weaken the onshore gradient and thin
out the marine layer resulting in a quicker clearing of low clouds
in the morning and less marine influence. Patchy low clouds along
the coast may still be possible.
From previous discussion...The upper ridge axis is forecast to
move to our east by midweek as an upper trough develops off the
west coast along 135W. This should result in slight cooling on
Wednesday and Thursday. However, temperatures are expected to
remain above normal through the week. And, the models indicate
that temperatures will climb higher once again on Friday as the
upper ridge to our east strengthens. The ECMWF MOS indicates the
most pronounced warming late in the week, with SFO forecast to
reach 82 on Friday and Livermore 102.
The models agree that a weak upper low will develop off the
southern California coast late in the week and then lift gradually
to the northeast next weekend. The GFS forecasts precip across the
southeast portion of our forecast area by Saturday morning as the
low approaches. The ECMWF maintains dry conditions in all areas
until the following Monday night. Given these model differences
and the fact that this precipitation potential is still out at
day seven and beyond, will hold off on adding any explicit mention
of shower chances to the forecast just yet.
.AVIATION...as of 10:27 AM PDT Sunday...Low clouds persist over
the Monterey Bay area with KMRY and KSNS TAFs expected to keep
MVFR cigs for the next hour or so. VFR is expected in the San
Francisco Bay area through today with low clouds spreading inland
again overnight tonight.
Vicinity of KSFO...VFR today. MVFR Cigs returning tonight after
SFO Bridge Approach...Same as KSFO.
Monterey Bay Terminals...MVFR cigs through 18-19z...VFR this
afternoon. IFR/MVFR cigs return early tonight.
.MARINE...as of 8:20 AM PDT Sunday...High pressure over the
Eastern Pacific and low pressure inland will result in gusty
northerly winds today and tonight. Winds will be strongest over
the outer waters, especially north of Point Reyes. winds will
gradually decrease on Memorial Day with weakening high pressure.
a building southerly swell is anticipated to arrive early next
.Tday...SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
PUBLIC FORECAST: CW
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