435
FXUS66 KSGX 222353
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
453 PM PDT Mon Jun 22 2026

.SYNOPSIS...
Strengthening high pressure to the east will bring a warming trend
through Wednesday with moderate HeatRisk for Tuesday and Wednesday
for the deserts, mountain elevations below 500 feet, and portions
of the Inland Empire. High temperatures will warm to 5 to 10
degrees above average for inland areas. This will be followed by a
cooling trend through next weekend with high temperatures for
next Sunday as much as 8 to 12 degrees below average for the
valleys and coastal slopes of the mountains.

&&

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

.Updated Aviation Discussion for 00z TAF Package...

Current satellite imagery and 500mb analysis reveal the subtropical
ridge centered across northern Mexico has strengthened some compared
to yesterday. This favors the efficient marine layer clearing we`ve
seen this morning and also a slight uptick in afternoon
temperatures. This ridge is still progged to strengthen further,
become more broad, and nudge northward through midweek, centering
over El Paso by tomorrow. The placement of this ridge also
establishes southeasterly flow aloft, allowing for an influx of mid
level moisture into the area. The ridge and the moisture will likely
serve to limit the vertical depth and inland extent of the marine
layer through midweek. The main consequence will be the notable
warming trend, that takes afternoon temperatures 5-10 degrees above
normal by Wednesday. More importantly, the moisture will inhibit
overnight cooling, leading to mild nights, with low temperatures
running 5-10 degrees above normal as well and limiting overnight
relief from he warm daytime temperatures. This brings areas of
moderate HeatRisk into the inland valleys on Wednesday, with locally
major HeatRisk for the deserts.

With the mid level moisture in place, some shower chances are in the
forecast for Tuesday/Wednesday, but look to be fairly
inconsequential. A shortwave rounding the western edge of the ridge
on Tuesday passes west of our area, but could still provide enough
synoptic support to generate elevated showers across the area. Any
showers not over the mountains will likely be unable to overcome dry
sub-cloud air and fall as virga, with little to no measurable
precipitation in the mountains (where PoPs are 15-20%). More
surface based showers will be possible in the mountains on
Wednesday, but with the mid level moisture layer remaining fairly
thin, shower/storm duration would likely be quite short as well.
Still, a strike or two of lighting can`t be ruled out.

Ensembles continue to push a longwave trough into the Pacific
Northwest for Thursday into Friday, which should help weaken the
ridge and nudge it south/east as well as kick out the mid level
moisture. This results in a cooling trend into the weekend with the
marine layer deepening again. Temperatures return to near average
for Thurs/Fri with the potential for afternoon highs 10 degrees or
more below normal for the weekend. While there is some disagreement
in the exact timing/depth of this trough in the ensemble spread, it
appears strong enough to bring some elevated onshore wind gusts to
the region this weekend, primarily in the mountains and deserts
where gusts 30-50 mph (and locally higher) are possible.


&&

.AVIATION...
230000Z...Coast/Valleys...Low clouds based 700-1300 ft MSL expected
to develop over coastal San Diego County starting 01-03z Tue. Clouds
push into Orange County and into western valleys overnight reaching
up to 15 miles inland. 20-30% chance for clouds to reach the western
Inland Empire (KONT). Minor vis reductions (3-6SM) possible for
higher coastal terrain and western valleys (KCRQ, KL18, KSDM).
Clouds scatter to the coastline 15-18z Tue.

Mountains/Deserts...VFR conditions expected into Tue with periods of
high clouds AOA 15000 ft MSL after 19Z Tue.

&&

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

&&

.BEACHES...
Another uptick in surf expected Tuesday through Thursday with the
arrival of a 3 foot 15 to 18 second period south swell from 190 to
210 degrees. Surf of 4 to 6 ft expected. Strong rip currents
expected through the week.

&&

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


&&

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

PZ...None.

&&

$$

PUBLIC...Munyan
AVIATION/MARINE/BEACHES...KW

NWS San Diego (SGX) Office