955
FXUS66 KSGX 232040
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
140 PM PDT Thu May 23 2024

.SYNOPSIS...
Cooling through Saturday with gusty southwest to west winds in the
mountains and deserts. The strongest gusts are more likely on
Friday afternoon into Friday night. Night and morning coastal low
clouds will extend inland across all of the valleys and onto the
lower coastal slopes of the mountains with slower daytime clearing
for coastal areas. High pressure to the south will bring warming
for Sunday through Wednesday. The marine layer will become
shallower with night and morning coastal low clouds only extending
inland into portions of the valleys by the middle of next week.

&&

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

This afternoon, the marine layer low clouds were slow to clear and
much of the region west of the mtns is still covered by low
clouds, including portions of the Inland Empire. This pattern of
clearing is common with cyclonic flow aloft and a coastal eddy.
Sfc pressure gradients remain onshore with 4.2 mb SAN-DAG and 6.2
mb SAN-IPL, supporting wind gusts of 25-45 mph in the wind-prone
areas.

A low/trough embedded in the mean cyclonic flow over the western
U.S. will move inland to our north tonight and Friday and will
bring stronger onshore flow. The marine layer will deepen, cooling
will spread inland, and there will be periods of gusty southwest
to west winds for the mountains and deserts with the strongest
winds for Friday afternoon into Friday night. The additional
deepening of the marine layer to 4500-5000 feet Friday night
into Saturday morning could bring patchy drizzle at lower
elevations west of the mtns.

There will be gusty southwest to west winds in the mountains and
deserts, with the stronger winds on Friday and Saturday. The winds
will peak Friday afternoon into Friday night with gusts mostly 40
to 50 mph except in the northern Coachella Valley below the San
Gorgonio Pass where winds could gust to around 60 mph.

High temperatures today will cool a few degrees from those on
Wednesday. There will be further cooling on Friday. The deserts
will continue to cool slightly on Saturday while the coast and
valleys warm slightly. With the cooling, high temperatures for the
mountains and inland valleys will be as much as 10 to 15 degrees
below seasonal averages on Friday.

For Sunday through Wednesday...
Building high pressure to the south will compete for dominance
with the low/trough to our north and could bring warming through
the middle of next week. The greatest warming is expected for
Sunday and Monday with slight additional warming for Tuesday and
Wednesday. With the warming, high temperatures on Wednesday will
be around average for the coast and valleys and around 5 degrees
above average for the deserts, mostly in the 80s for the Inland
Empire and the upper 90s to 104 for the lower deserts. The marine
layer will gradually decrease in depth with night and morning
coastal low clouds only extending inland into portions of the
valleys by the middle of next week.

&&

.AVIATION...
232030Z...Coast/Valleys/Foothills...Low clouds with bases 2500-2900
FT MSL continue to remain in the area this afternoon. Locally
reduced vis where low clouds and terrain intersect. A coastal eddy
has developed which will limit the ability for areas near the coast
to scatter out. Some scattering out across inland areas around 18-
21z Thu. Low clouds progressing back inland after 23z Thu with
similar bases.

Mountains/Deserts...Clear skies with unrestricted VIS through
tonight. W-NW wind gusts of 20-35 kt over/east of mtns after 00z
Fri, with weak-mod up/downdrafts and LLWS over/east of the mtns.

&&

.MARINE...
Northwest winds are expected to gust near 20 knots in the outer
waters each afternoon and evening Friday through Sunday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from noon Friday to 2 AM PDT Saturday for San
     Gorgonio Pass Near Banning.

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE...Suk