036
FXUS66 KSGX 240402
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
902 PM PDT Sat Aug 23 2025

.SYNOPSIS...
High temperatures will remain near or a little above average
through Monday. High temperatures will cool to a few degrees
below average for Tuesday through Friday. Significant monsoonal
moisture will remain in place through Tuesday with chances for
afternoon and early evening showers and thunderstorms each day,
mainly for the mountains and deserts. Drying will begin on
Wednesday and continue into next weekend with decreasing
thunderstorms chances each day. Night and morning low clouds will
mostly be limited to coastal areas through the weekend, but could
return to the western valleys for the latter half of next week.

&&

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

This evening...Radar still shows very weak echoes from the earlier
elevated showers/tstms. While it produced little in the way of
rainfall, the elevated convection and cloud cover had some
interesting effects on today`s high temperatures. It suppressed
high temperatures for most of the region but many areas west of
the mountains experienced a "Heat Burst". This was a mesoscale
event which caused the temperature to rise and fall rapidly. For
example, the temperature at our office went from 92 degrees at
noon to 100 degrees at 12:41 pm then fell back into the 80s an
hour later as the sea breeze reasserted itself. This phenomenon
also resulted in a record high temperature of 110 degrees in
Escondido. Many locations in the valleys reported higher maximum
temperatures than portions of the deserts. The debris clouds left
over will likely clear overnight and tomorrow morning which will
likely produce a more typical heating pattern and lead to chances
for afternoon and evening thunderstorms over the mountains and
deserts.

From previous discussion...
The area of high pressure over the desert southwest will weaken
slightly on Monday, where a greater push of onshore flow will
allow for a few degrees of cooling. Though the high will weaken by
the middle part of the week, monsoonal moisture will continue to
flow with greatest chances for storm activity on Tuesday. The
weakening high will also contribute to a more noticeable cooling
trend on Tuesday with highs near average. This temperature trend
will prevail through the week as the marine layer deepens, allowing
low clouds and fog to enter coastal and western valley areas each
night and morning. Moisture will begin to lessen on Wednesday and
continue to do so into next weekend, with minimal chances of
storm activity and temperatures near or a little below average.

&&

.AVIATION...
240320Z...Coast/Valleys...Virga/-SHRA dissipating by 06Z. Patchy low
clouds with bases 500-800 ft MSL developing along the coast after
08Z and spreading locally 5-10 mi inland with a 50-60% chance of
CIGS at KSAN and KCRQ 11-16Z. Chance of CIGS at KSNA is less than
20%. Vis 3-6 SM in BR/HZ where low clouds develop, locally 2 SM or
less over higher coastal terrain. Clouds and vis restrictions
clearing 16-18Z, then redeveloping early Monday morning. Otherwise
variable mid and high cloud cover at/above 15,000 ft MSL through
Sunday evening.

Mountains/Deserts...Virga/-SHRA dissipating by 06Z. 30-50% chance of
SHRA/TSRA over the mountains and deserts 18-01Z Sunday afternoon. CB
bases near 12 kft with tops to 35 kft. SHRA/TSRA may produce local
VIS of 1-3 SM, gusty and erratic winds, cloud-to-ground lightning,
and small hail. Otherwise variable mid and high clouds at/above
15,000 ft MSL through this Sunday evening.

&&

.MARINE...
The lightning threat has ended over the coastal waters this evening.
Otherwise, no hazardous marine conditions are expected through
Thursday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE...SS