FXUS66 KSGX 062049
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
149 PM PDT Sat Jul 6 2024

.SYNOPSIS...
Above normal high temperatures will continue through at least the
next week as persistent ridging blankets the western United
States. Highs fall a degree or two on Sunday and Monday before
warming again on Tuesday. Monsoonal moisture may reach the lower
deserts and mountains late week as the ridge axis slides eastward.

&&

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

A 598 DM ridge is centered over northern California today. Skies
have cleared, but some shallow cumulus clouds are building in the
mountains. Temperatures as of 1 PM are running cooler than Friday
afternoon across the valleys, the lower deserts and portions of 
the mountains, likely due to the elevated dew points/humidity that
is inhibiting temperatures from substantially climbing. There is 
still a moderate to high heat risk across inland areas and extreme
heat risk in the deserts, so precautions to prevent heat 
illnesses still need to be taken today.

The ridge axis that is producing this long-term heat wave slowly
weakens and progresses eastward on Sunday and Monday, allowing
highs to fall a few degrees west of the mountains both days. The 
deserts look to remain nearly steady during this time. In fact, a 
number of daily high temperature records could be broken each day 
across the lower deserts Monday through the middle of the week. 

Ensemble guidance shows increasing positive height anomalies by 
the middle of the week, leading to a noticeable uptick in highs by
Tuesday. Highs for Tuesday through Thursday will remain pretty 
steady, with highs topping out 5-8 degrees above normal at the 
coast, and 5-15 degrees above normal in the valleys, mountains and
deserts.

Forecast Highs Tuesday-Thursday:

Coast: upper-70s to low-80s.

Inland Orange/San Diego Counties: mid-80s to mid-90s, approaching
100 degrees along the foothills in San Diego County.

Inland Empire: upper-90s to mid-100s.

Mountains: upper-80s to upper-90s.

High Desert: upper-100s.

Lower Deserts: upper-110s to low-120s.

The ridge axis progresses eastward through this week, settling 
near the Four Corners region by late week. The placement of the 
ridge could lead to a turning of mid-level winds, increasing mid-
level moisture content, leading to slight chances of monsoonal 
thunderstorms. This monsoon signal begins with minor chances by 
Thursday, increasing some by Friday and Saturday per global 
ensemble guidance.

&&

.AVIATION... 
061945Z...Coast/Valleys...Mostly clear for most locations, but with 
localized patches of low clouds persisting along beaches into this 
afternoon in Orange County. Low clouds with bases 400-800 FT MSL 
will gradually move ashore 03-06z Sun. There is a 20-30% chance of 
CIGs occurring at KONT and surrounding areas overnight, best chances 
would be 12-15z Sun. Bases may lower a bit overnight, supporting 
some areas of VIS 3-5 SM in BR. Localized VIS below 1 mile where 
clouds intersect terrain. Scatter out similar to this morning, 
generally 15-17z Sun.

Mountains/Deserts...Mostly clear skies with unrestricted vis through 
Sunday.

&&

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

&&

.BEACHES...
A long-period south swell will continue to create elevated surf. The 
surf will peak today before subsiding on Sunday. Sets of 6-7 feet 
can be expected on south and southwest-facing beaches, especially in 
Orange County. Check the Beach Hazards Statement for details. 

&&

.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 Sunday afternoon for Orange 
     County Coastal Areas-San Diego County Coastal Areas.

     Excessive Heat Warning until 9 PM PDT Sunday for Riverside 
     County Mountains-San Bernardino County Mountains-San 
     Bernardino and Riverside County Valleys-The Inland Empire-
     San Diego County Mountains.

     Excessive Heat Warning until 9 PM PDT this evening for San Diego 
     County Valleys.

     Heat Advisory until 9 PM PDT this evening for Orange County 
     Inland Areas-Santa Ana Mountains and Foothills.

     Excessive Heat Warning until 9 PM PDT Wednesday for Apple and 
     Lucerne Valleys-Coachella Valley-San Diego County Deserts-
     San Gorgonio Pass Near Banning.

PZ...None.

&&

$$

PUBLIC...EA
AVIATION/MARINE...Adams