Sugar Bowl

000
FXUS66 KSGX 220942
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
242 AM PDT Sat Aug 22 2026

.SYNOPSIS...
Monsoonal moisture will decrease this weekend, with a slight 
chance of showers and thunderstorms for the mountains and lower
deserts returning for Monday afternoon. Above average high and 
low temperatures will continue through next week. Widespread 
moderate to locally major HeatRisk for the coast, valleys, and 
mountains except near the beaches and for the higher elevations in
the mountains, with major to extreme HeatRisk for the lower 
deserts.

&&

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


...UPDATED AVIATION DISCUSSION...

A couple of record high minimum temperatures were set yesterday 
as moisture aloft and high clouds inhibit radiation cooling at 
night. A few high clouds continue this morning as patchy marine 
layer low clouds form over the coastal areas.

Numerical models remain in good agreement with respect to the
synoptic pattern. The dominant high pressure will remain in place
over the southwest US with some variations in the location of the
center and orientation of the ridge axis, with the ridge becoming
less amplified at times as a couple of major shortwave troughs
move inland over the Pacific Northwest. As a result, the marine
layer will remain shallow with low clouds restricted to the
coastal areas and little day-to-day change.

Daytime high temperatures will likely remain generally 5 to 10 
degrees above normal. Guidance also indicates that overnight low
temperatures will remain above normal. These temperature trends make
it more likely that the inland valleys, mountains and high desert 
will experience moderate HeatRisk through next week with some 
areas of Major HeatRisk. The lower deserts will likely experience
persistent Major HeatRisk through next week. The one caveat is 
that the changes in position and orientation of the high could 
result in a reduction of deep-layer moisture aloft. This will 
certainly reduce the chances for pm showers/tstms in the mtns and 
deserts but could also allow for improved radiation cooling at 
night leading to lower overnight temperatures. At this time lower
overnight temperatures seems to be a low probability of
occurrence.

&&

.AVIATION... 
220930Z...Coast...Patchy low clouds based 700-1000 ft MSL will 
become more widespread, mostly in San Diego Co, through about 12Z 
this morning, with more intermittent clouds in coastal Orange Co. 
Clouds scatter out 15-16Z. Low clouds expected to be more patchy and 
isolated when they form Sat evening, with a 20-30% chance for cigs 
in coastal San Diego Co after 09Z Sun and lower chances elsewhere. 

Otherwise...FEW to SCT clouds above 20 kft MSL through the TAF 
period.

&&

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

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory from 10 AM this morning to 8 PM PDT Monday for 
     Orange County Inland Areas-Riverside County Mountains-San 
     Bernardino County Mountains-San Bernardino and Riverside 
     County Valleys-The Inland Empire-San Diego County Mountains-
     San Diego County Valleys-Santa Ana Mountains and Foothills.

     Extreme Heat Warning until 8 PM PDT Friday for Coachella Valley-
     San Diego County Deserts-San Gorgonio Pass near Banning.

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE...CSP