949
FXUS66 KSGX 200922
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
222 AM PDT Mon May 20 2024

.SYNOPSIS...
A large-scale trough over western North America will persist
through this week. Temperatures will remain below seasonal
averages with gusty winds across the mountains and deserts. A
closed upper level low will move across the region on Monday,
which will bring the coolest and windiest conditions overall. Low
clouds will continue nights and mornings, retreating back to the
coast each afternoon.

&&

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

The marine layer continues to gradually fill the coastal basin
with low clouds this morning. A weak trough of low pressure to the
west will get picked up by a larger jet stream-driven trough to
the north this morning and push through SoCal today. This should
deepen the marine layer and produce patchy drizzle this morning,
most likely near the coast. Winds through mountain passes into
adjacent deserts will continue strong and gusty through this
evening, with isolated top gusts through San Gorgonio Pass
exceeding 50 mph, but more widespread gusts of 35-45 mph. As the
trough exits east, the trend will be to decrease the onshore flow
and tamp down the marine layer a little. That should bring more
sunshine west of the mountains and weaker winds in the mountains
and deserts for Tuesday and Wednesday. High temperatures in the
60s to low 70s west of the mountains today represent up to 10
degrees below normal in the valleys. Tuesday and Wednesday will
be a few degrees higher, approaching but still not achieving
normal. A very weak trough rotates through California again
Thursday into Saturday. This should deepen the marine layer again
and extend low clouds into foothills each night and morning, and
make it harder for coastal areas to get sunshine in the
afternoons. This will also boost those seasonal winds in the
mountains and deserts. The cooler weather starts Thursday, and
right now appears to bottom out Saturday, when temps will be more
than 10 degrees below normal in the valleys. Next week the mean
trough over the West appears to weaken, maybe making way for an
actual ridge of high pressure. While ensembles paint a wide range
of outcomes, most solutions indicate at least weaker low pressure
and warmer weather next week.

&&

.AVIATION...
200920Z...Coast/Valleys...Low clouds have filled in much of the
coastal basin early this morning with cigs 1500-2500 ft MSL. Vis
restrictions near coastal slopes where clouds intersect higher
terrain. Patchy -DZ possible until around 17Z this morning near the
coast and coastal slopes.

Most areas clearing by 16Z-18Z Mon with locally BKN CIGs near the
beaches this afternoon. Areas of low clouds redeveloping after 02Z,
progressing inland overnight and filling much of the coastal basin
once again. Cigs/vis similar to that of this morning.

Mountains/Deserts...Clear skies with unrestricted VIS will continue
through this evening. West winds near 15-25 kts this morning will
strenghten and expand across most locations by the afternoon hours,
where wind gusts will range from 20-35 kts, locally near 45 kts in
mountain passes.  There is around a 25 percent chance of a 30 kt
gust at KPSP from 22Z Mon to 04Z Tue. Blowing dust could locally
reduce VIS to 3-5 miles at times. Winds relaxing later Monday night.

&&

.MARINE...
No hazardous marine conditions are expected through Friday.

&&

.BEACHES...
A series of southwest swells of 2-3 ft at 16-18 seconds from 200-220
degrees will build through Monday and produce above normal surf of 3-
5 ft with locally higher sets on exposed SW facing beaches, as well
as a high risk of rip currents at all beaches. A Beach Hazards
Statement is in effect through this evening. Swell and surf will
slowly lower Wednesday and Thursday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through this evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...MM
AVIATION/MARINE/BEACHES...APR