547
FXUS66 KSGX 192027
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
127 PM PDT Sun May 19 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...

This afternoon, the marine layer low clouds have cleared to about
25 miles offshore and much like yesterday, will return to the
coast in a couple of hours then spread inland to the coastal
slopes by about 5 am Monday. The marine layer will likely deepen,
with enough moisture to produce patchy drizzle late tonight and
early Monday morning, although accumulations are unlikely. Onshore
flow continues with sfc pressure gradients 4.2 mb SAN-DAG and 6.2
mb SAN-IPL currently producing westerly winds gusting 30-40 mph
and up to 55 mph in the windiest locations.

From previous discussion...
A closed upper low currently about 900 miles southwest of San Diego
will be drawn into the mean flow and become an open wave over SoCal
on Monday as a large-scale trough to the north deepens. This will
bring additional cooling to the region and Monday will likely be
the coolest day of the week. Temperatures will be near 5 degrees
below average across the coastal areas with up to 10 degrees below
average for inland areas. It will also strengthen the westerly
winds, especially in the mtns and adjacent desert areas where
chances are good for wind gusts over 40 mph and over 55 mph in
wind-prone mountain passes. The San Gorgonio Pass will have a
70-80% chance of wind gusts exceeding 55 mph.

The trough over the West Coast will continue, though not as
amplified as Monday. Rising heights will lead to some warmer
conditions and somewhat weaker winds over inland regions. Little
day-to-day variations in temperatures, winds and marine layer
clouds can be expected from Tuesday through the end of the week,
where we will see slightly below average temperatures and May Gray
conditions west of the mountains in the morning with general
clearing toward the coast by the afternoons. As we get into next
weekend, the consensus of model solutions shows the dominant
trough weakening and a building ridge of high pressure centered
over eastern Mexico. At this time, it seems likely that the
weather over SoCal will continue to be dominated by troughing over
western North America.

&&

.AVIATION...
191935Z...Coast/Valleys...Full clearing this morning including
beaches. Low clouds will return this evening, partially late today
23Z-02Z with sea breeze and lowering sun angle. Ceilings should
be similar in the 1000 to 2000 ft AGL range. A weather disturbance
will lift the marine layer Monday morning and lead to clearing
again. The tops near 3000 ft MSL overnight and Monday morning.

Mountains/Deserts...Clear with unrestricted vis through Monday
morning. Wind increasing with peak gusts 25 to 30 kt. There is low
chance of 35 kt gust at TRM and PSP from 23 to 04Z. Blowing dust is
possible. Strongest winds are in the mountain passes and foothills
of the Coachella valley with gust to 40 kt. Winds are enhanced by a
passing weather system on Monday.

&&

.MARINE...
No hazardous marine conditions through Thursday except for offshore
waters with wind gusts 20 knots for Monday.

&&

.BEACHES...
A series of southwest swells of 2-3 ft at 16-18 seconds from 200-220
degrees will build through Monday, producing 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 Monday evening. Swell and surf will
slowly lower on 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 Monday evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE/BEACHES...Tardy