Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 252047

Area Forecast Discussion
National Weather Service San Diego CA
147 PM PDT Mon Sep 25 2023

Gradual warming is expected through the middle of the week, with
temperatures around normal for this time of year by Wednesday.
Cooler, windier, cloudier, and wetter conditions expected for the
end of the week into the weekend. Low clouds and fog will be more
confined to coastal areas and western valleys through Wednesday,
eventually filling in the coastal basin by the weekend.



Weak ridging will build over Southern California through the middle
of the week. This will bring gradually warming conditions into
Wednesday with high temperatures near to just above average for this
time of year. By Thursday a trough of low pressure from the Gulf of
Alaska will move into the Pacific Northwest. This trough will dig
far enough south to become the prevailing influence on Southern
California weather for the end of the week into the weekend. Cooler,
cloudier, wetter, and windier weather is expected. Areas of drizzle
may develop near the coast ahead of the main trough as early as
Thursday morning, with more likely chances of drizzle west of the
mountains on Friday morning as onshore flow continues to increase.

Periods of mostly light rain are expected Friday evening into Sunday
morning. Showers are most likely in the nights and mornings, but
some light showers may linger in the afternoons particularly on the
coastal slopes of the mountains. The current forecast has mostly
light rainfall, with areas west of the mountains at a tenth of an
inch or less, and totals up to a quarter of an inch on the coastal
slopes of the mountains. Forecast rainfall is subject to change as
we get closer to the weekend and model guidance becomes more aligned
with the exact track of the trough.

Even with some uncertainty regarding the precipitation chances and
amounts, confidence is higher that the trough will maintain cooler
and cloudier conditions with gusty westerly winds in the mountains
and deserts. Saturday looks like it will be the coolest day of the
week, with high temperatures up to 20 degrees below average in some
valley locations. Global ensemble members are indicating winds will
peak on Saturday in the mountains and into the deserts. There is
still uncertainty in the strength of the winds but it looks like
peak gusts will be at least 50 mph with the strongest gusts expected
through and below mountain passes into the deserts.


Mostly clear early. CIGS returning to coastal airports
03Z-07Z tonight into Tuesday. BKN-OVC012-018 at KSAN, KCRQ and KSNA
with tops near 2000 feet MSL is expected. Areas of valley Cigs
below 500 feet MSL and vis below 1 mile late tonight western
valleys. Confidence in returning around 06z this evening at KSAN is

Mountains/Deserts...Mostly clear skies and unrestricted vis
today and tonight.


Northwest winds with gusts near 20 kts in the outer waters
each afternoon through Wednesday.


Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.





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