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000
FXUS66 KSGX 250400
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
900 PM PDT Wed Apr 24 2024

.SYNOPSIS...
A deep marine layer; gusty winds in the mountains and deserts; and
cooler conditions will prevail through Friday. Patchy drizzle or
light rain is expected each night and morning west of the mountains.
Gusty southwest to west winds will peak each afternoon and evening
in the mountains and deserts through Friday. Winds will weaken
through the weekend. Drier and warmer with a shallower marine layer
expected early next week.

&&

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

.Evening Update...
High clouds are streaming in over the high desert as low clouds
fill in much of the coastal basin this evening. Latest HRRR model
guidance indicates drizzle and light showers will develop mainly
after midnight, lasting until the mid morning hours. Winds have
been gusty this evening as the trough axis moves over Southern
California. Peak wind gusts have been mainly near 30-40 MPH across
mountains and deserts, with highest gusts near 60 MPH in the San
Gorgonio Pass and near In-Ko-Pah in San Diego County.

Graypril will continue for much of the day on Thursday for those
west of the mountains, especially away from the coast per latest
HREF model guidance. The deep marine layer will maintain itself
into Friday, so the chance for drizzle and light showers will once
again occur Thursday night into Friday morning. Winds will also
continue to be gusty across the mountains into the deserts on
Thursday and Friday as well. Friday will see the strongest winds
with these areas seeing peak wind gusts 40-55 MPH. Not all is
lost, as a brighter and warmer weekend is in store!

.Previous Discussion (133 PM PDT Wednesday)...
Low clouds are expected to fill in the coastal basin again
tonight into Thursday morning. Deep marine layer moisture combined
with lift from a low pressure system passing through Southern
California and Northern Baja will generate areas of drizzle and
light rain this evening and overnight. The greatest coverage is
expected to be in the coast and valleys in San Diego County and
along the coastal mountain slopes. Any accumulations for the coast
and valleys will be light, with 0.10 inches or less expected. On
the coastal mountain slopes, around 0.25 inch is expected. Marine
layer low clouds may become patchier Thursday night into Friday
morning, but areas of drizzle or light rain are still possible.
Dry conditions expected for the weekend into early next week.

Gusty southwest to west winds are expected in the mountains and
deserts through Friday. Peak winds gusts will be 50 to 65 mph. Gusts
could locally reach up to 75 mph through the San Gorgonio Pass.
Winds will peak each afternoon and evening. Winds will gradually
decrease in the the weekend, with weaker winds expected early next
week.

Cooler conditions expected for inland areas Thursday, with a few
degrees of warming on Friday for the coast. High temperatures will
be as much as 10 to 15 degrees below average on Thursday for the
mountains and valleys. A warming trend is expected for Saturday
through Monday with not much change on Tuesday. Weak high pressure
aloft is expected to prevail but there are some model differences
for early in the week which would impact the strength of the onshore
flow and the depth of the marine layer. This uncertainty creates
greater spread of the high temperature forecasts for locations in
the coast and valleys. If the warming develops, high temperatures
would be near average for most locations on Sunday with high
temperatures on Monday and Tuesday 3 to 7 degrees above average.

&&

.AVIATION...
250400Z...Coast/Valleys...Widespread BKN/OVC stratus will prevail
through 18Z Thu with bases 2000-4000 ft MSL and tops to 6500 ft MSL
and with higher terrain obscured. Local VIS 3-5 miles will occur
below the clouds in -DZ/-SHRA, mainly 09Z-18Z Thu. SCT/BKN stratus
will prevail with bases 2500-5000 ft MSL 18Z Thu-03Z Fri, with
increasing stratus again after 03Z Fri.

Mountains/Deserts...Areas of terrain obscurations will continue
at times along the coastal mountain slopes through Thu evening
with cloud tops to 7500 ft MSL and (09Z-18Z Thu) areas of -DZ/-SHRA.
Areas of west winds with surface gusts 30-50 kt will occur from the
mountain crests east through the mountain slopes and into the
deserts through Thu evening. VIS will be unrestricted on the desert
slopes/deserts.

&&

.MARINE...
No hazardous marine conditions are expected through Thursday night.
Stronger winds and choppy seas arrive Friday morning and continue
into Saturday morning, likely generating hazardous conditions,
especially in the outer waters. There is a period Friday night
(mainly mid-evening to a little after midnight) when there is
around a 25 percent chance of gale force winds near San Clemente
Basin Buoy. There is a gale watch in effect from 5 PM Friday
through 3 AM Saturday for this possibility, though there is
high confidence of winds reaching Small Craft Advisory strength.


&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 11 PM PDT Friday for Apple and Lucerne
     Valleys-Coachella Valley-Riverside County Mountains-San
     Bernardino County Mountains-San Diego County Deserts-San
     Diego County Mountains-San Gorgonio Pass Near Banning.

PZ...Gale Watch from Friday afternoon through late Friday night for
     Waters from San Mateo Point to the Mexican Border Extending
     30 to 60 nm out including San Clemente Island.


&&

$$

PUBLIC...APR
AVIATION/MARINE...Maxwell