FXUS66 KSGX 091753
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1053 AM PDT Tue Jul 9 2024

.SYNOPSIS...
The hottest days for the coast and valleys will be through
Thursday with not much change for the mountains and deserts. An
influx of monsoonal moisture over the weekend could bring a slight
chance of afternoon and early evening showers and thunderstorms
for the mountains and deserts. A gradual slow cooling trend will
begin around Friday and continue into next week with Monday high
temperatures within a few degrees of average. Night and morning
coastal low clouds will spread into portions of the western
valleys at times late each night.

&&

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

.SHORT TERM...
No Significant changes to the forecast this morning as the marine
layer retreats towards the coast and heating and mixing take hold
inland. previous forecast is on track with the hottest day of the
heatwave occurring today through Thursday.

Previous discussion 331 AM PDT Tuesday July 9 2024

The hottest days for the coast and valleys are expected for today
through Thursday. Wednesday is the most likely hottest day with
high temperatures for the inland valleys of 10 to 15 degrees above
average, to 108 to 112 in the far inland valleys. There will be
minor day to day differences in high temperatures for the
mountains and deserts with widespread Extreme Heat Risk for the
deserts. Night and morning coastal low clouds will spread into the
far western valleys at times late each night. There will also be
some afternoon clouds for the mountains.

&&

.LONG TERM (Friday through Monday)...
The center of high pressure over the southwest states will move
slowly toward the north and east and in combination with a weak
low pressure system off the California coast could draw some
monsoonal moisture into the area from the southeast over the
weekend. ECMWF ensemble output has the highest precipitable water
values for Imperial over the weekend with continuing spread in
the timing of drying for the early into the middle of next week.

There is a slight chance for showers and thunderstorms for the
mountains into the adjacent deserts each afternoon and early
evening over the weekend.

High temperatures will gradually cool through the weekend and
early next week with Monday high temperatures generally within a
few degrees of average.

The marine layer will continue to moderate the heating near the
coast with night and morning coastal low clouds extending into the
far western valleys at times late each night.
&&

.AVIATION...
091700Z...Coast and Valleys...Low clouds with bases 800-1200 feet
AGL and tops to 1600 feet MSL were widespread have burned to the
beaches just prior to 17 UTC. Strong upper ridge is over Socal
through Wednesday and forecast indicates less coverage of the
marine layer clouds tonight and Wednesday morning but extensive along
the San Diego coast 10 to 15 UTC. The top of the marine layer is
forecast to lower nearly 500 feet down to about 1200 feet MSL.


Mountains/Deserts...Clear skies with unrestricted visibility will
continue through tonight. West surface winds in mountain
passes with gusts 20 knots after 22 UTC Tuesday through mountain
passes. This will lead to weak to moderate up/downdrafts over and
east of the mountains. There is smoke from the Vista wildfire near
Mt Baldy and the Lake fire in Santa Barbara
county.

&&

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

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 9 PM PDT Thursday for San
     Bernardino and Riverside County Valleys-The Inland Empire-
     San Diego County Valleys.

     Heat Advisory until 9 PM PDT Thursday for Riverside County
     Mountains-San Bernardino County Mountains.

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

     Excessive Heat Warning until 9 PM PDT Thursday for San Diego
     County Mountains.

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

PZ...None.

&&

$$

PUBLIC...Suk/17
AVIATION/MARINE...Tardy