241
FXUS66 KSGX 020952
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
252 AM PDT Tue Jul 2 2024

.SYNOPSIS...
A long-duration heat wave will continue for the deserts through at
least much of next week. Friday and Saturday are expected to be
the hottest days for most areas with the only relief from the
heat toward the coast. The marine layer will slow the warming near
the coast with night and morning coastal low clouds spreading
into the western valleys late each night.

&&

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

.SHORT TERM (Today through Thursday)...
Warming will continue today and Wednesday with the heat plateauing
on Thursday with high temperatures a few degrees above average at
the coast and 5 to 10 degrees above average inland with hottest
high temperatures for the lower deserts around 119, for the
Inland Empire around 102, and for the Apple and Lucerne Valleys
around 110. The marine layer will slow the daytime warming near
the coast with night and morning coastal low clouds spreading into
the western valleys late each night.

&&

.LONG TERM (Friday through Monday)...
Strong high pressure aloft will be centered across California on
Friday and Saturday with some slight model placement and
intensity differences on Sunday and the following days with the
high not quite as strong on Monday.

There will be several degrees of warming on Friday with inland
high temperatures around 10 to 15 degrees above average with hottest
high temperatures for the lower deserts around 122, for the
Inland Empire around 112, and also for the Apple and Lucerne
Valleys around 112.

Not much change is expected for Saturday with Sunday a few degrees
cooler to around 5 degrees cooler for the valleys, then not much
change on Monday except for slight warming for the deserts.

&&

.AVIATION...
020945Z...Coast/Valleys...Low clouds spreading inland at this hour,
with bases 900-1100 ft MSL and tops to 1600 ft MSL. Low clouds have
reached up to 15 miles inland with CIG impacts currently at coastal
TAF sites. By 15Z, low clouds could reach up to 25 miles inland and
there is a 25-30 percent chance for CIG/VIS impacts at KONT by 13Z.
Local VIS will be 2-4 miles in BR over higher coastal terrain and in
the coastal valleys through 16Z. Most areas will clear to the coast
15Z-18Z, with low clouds returning vcnty coastal TAF sites 3Z-6Z
Wednesday.

Mountains/Deserts...Mostly clear skies with unrestricted VIS will
continue through this evening. West winds will return to the desert
slopes and through San Gorgonio Pass this afternoon/evening but will
be generally weaker, with most gusts 25 kt or less.

&&

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

&&

.BEACHES...
A swell of 2-3 feet from 190 degrees with a period of 16-18 seconds
will arrive at SoCal beaches as early as Wednesday morning, peak
Friday and gradually subside next Sunday. This may lead to elevated
surf with breaking wave heights of 6-7 feet, mainly on exposed south
and southwest-facing beaches in Orange County. Rip and longshore
current risks will be high the second half of this week.

&&

.CLIMATE...
This could be an historic heat wave for portions of the lower
deserts in terms of consecutive days of very hot high
temperatures.

For Palm Springs, NBM is forecasting 11+ consecutive days with
high temperatures of 115 or higher, 10+ consecutive days with 117
or higher, and 8 consecutive days with 119 or higher.

The existing records for Palm Springs are 9 consecutive days of
115+ in 2023, 5 consecutive days of 117+ in 1958, and 3
consecutive days of 119+, most recently in 2021.

The all-time record high temperature for Palm Springs is 123,
occurring most recently on June 17th, 2021. NBM has a 14 percent
chance on Friday and 20 percent chance on Saturday of tying the
existing record. NBM has a 7 percent chance on Friday and 8
percent chance on Saturday of breaking that record.

As for daily high temperature records for Palm Springs, NBM has a
69 percent chance on Friday and 78 percent chance on Saturday of
tying or breaking the existing high temperature records for those
dates and a 55 percent chance on Monday.

As for record warm daily minimum temperatures for Palm Springs,
NBM has a 77 percent chance on Friday and 90 percent chance on
Saturday of tying or breaking the existing records.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning from 11 AM Friday to 9 PM PDT Saturday
     for Riverside County Mountains-San Bernardino County
     Mountains-San Bernardino and Riverside County Valleys-The
     Inland Empire-San Diego County Mountains-San Diego County
     Valleys.

     Heat Advisory from 11 AM Friday to 9 PM PDT Saturday for Orange
     County Inland Areas-Santa Ana Mountains and Foothills.

     Excessive Heat Warning from 11 AM this morning to 9 PM PDT
     Tuesday for Apple and Lucerne Valleys.

     Excessive Heat Warning until 9 PM PDT Tuesday for Coachella
     Valley-San Diego County Deserts.

     Excessive Heat Warning until 9 PM PDT Tuesday for San Gorgonio
     Pass Near Banning.

PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE/BEACHES...PG