Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 161008
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
308 AM PDT Wed Aug 16 2017

.SYNOPSIS...
An upper-level trough along the West Coast will maintain a deep
marine layer with below average highs today, and create areas of
drizzle this morning. The trough will weaken Thursday through
Saturday and create a shallower marine layer with highs closer to
seasonal normals. Upper-level low pressure next week could
continue below normal highs and a deep marine layer.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

At 3 AM PDT, water vapor imagery displayed an upper-level trough
along the West Coast, and an upper-level ridge centered around
1000 miles west of San Francisco. Lower heights from the
associated trough was creating a deep marine layer over the area,
which was evident on the fog satellite with stratus filled in west
of the mountains below 4500 ft. The deep marine layer will create
the possibility of drizzle over coastal and valley areas this
morning, and will make it difficult to clear this afternoon along
the coast.

Upper-level troughing will continue along the West Coast through
the end of the weekend, with a slight increase in heights by the
end of the week. This would translate to a shallower marine layer
than what we`ve been seeing over the past few days, and a bump up
in high temperatures closer to seasonal normals, but still below
normal.

An upper-level low then breaks off of the mean flow, and hovers
off the Southern California coast early to mid-next week. This
will help to maintain a deeper than normal marine layer, and
continue below normal high temperatures. Areas along the coast may
have trouble viewing the solar eclipse on Monday due to possible
marine layer clouds.

Mostly dry weather, with breezy afternoon/evening westerly winds
through the usual mountain passes and desert mountain slopes, will
continue through the period.

&&

.AVIATION...
161000Z...Coast/Valleys...low clouds with bases between 2000 and
2500 ft msl and tops to 3500 ft MSL will continue through 17Z.
Expect visibility restrictions of 2 sm or less where low clouds and
higher terrain intersect. The low clouds will clear slowly between
17Z and 20Z, with FEW-SCT low clouds lingering over the coast and
coastal waters between 20Z Wednesday and 03Z Thursday. Low clouds
with bases near 1800 ft msl will return to the coast and western
valleys after 03z Thursday.

Mountains/Deserts...Clear skies and unrestricted visibility is
anticipated through Thursday morning.

&&

.MARINE...
No hazardous marine weather is expected through Sunday.

&&

.BEACHES...
A building moderate period south swell (2-3 ft at 200 degrees) will
arrive in the coastal waters late Thursday and continue through the
weekend. This swell may bring elevated surf (4-6 ft) and strong rip
currents to the beaches Friday - Sunday. No products are being
issued at this time, however a Beach Hazard Statement may be
necessary later in the week.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...JJT
AVIATION/MARINE/BEACHES...BA



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