892
FXUS66 KSGX 030410
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
910 PM PDT Tue Jul 2 2024

.SYNOPSIS...
A prolonged heat wave will continue into next week for inland areas,
with the hottest conditions expected Friday and Saturday. A
persistent marine layer will keep temperatures near the coast from
soaring. Low clouds and fog are expected to spread into the western
valleys each night and morning.

&&

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

High temperatures Wednesday are expected to be a few degrees warmer
than today for most locations. Heat is expected to continue for the
Fourth of July with highs 3 to 5 degrees above average for the
coast and western valleys and 5 to 12 degrees above average for
inland areas. Make sure to take seek shade and drink plenty of
water if your Fourth of July plans are taking you outdoors.

Above average temperatures will continue for most areas through next
week as the ridge of high pressure lingers over the Western United
States. There is some uncertainty surrounding the position of the
ridge axis early next week, with GFS and Canadian ensemble
guidance showing the ridge axis more over the Great Basin, while
the ECMWF keeps the ridge axis over the West Coast. There is
lesser uncertainty in the strength of the ridge, with most
guidance indicating that the ridge will weaken slightly by early
next week from its peak Friday and Saturday. Major to extreme heat
risk will continue in the deserts through next Wednesday.
Moderate to locally major heat risk is expected for areas in and
west of the mountains.

From previous discussion issued at 2 PM July 2...

A strong upper ridge develops Wednesday just off the coast and
spills into CA and the West through Saturday. And I do mean strong;
a lot of guidance shows heights that reach 600 decameters over
NorCal Thursday through Saturday. Friday and Saturday right now
appear the be the hottest days. Heat warnings are in effect in all
desert regions through next Tuesday. Heat Warnings are in effect for
mountains and inland valleys Friday and Saturday. Heat Advisories
are in effect for inland Orange County and the Santa Ana Mountains
Friday and Saturday. This heat wave will be significant and long-
lasting even for early July. Temps at night will not cool off much,
so the accumulated heat risk will add to the stress on humans. The
marine layer will get more shallow for the rest of the week, with
less nocturnal coverage, but coastal clouds and fog will not go away
entirely. Max temps today through Thursday will range from 2 to 12
degrees above normal, with the greatest anomalies in the desert. On
Friday and Saturday, the hottest days, max temps will range from 6
to 15 degrees above normal. That puts Palm Springs up to 122,
flirting with the highest temps on record. The 12Z model/ensemble
guidance has a slightly better consensus on the ridge beginning to
weaken Sunday, but only slightly. This will result in a few degrees
of "cooling" for areas west of the mountains with similar to only a
degree or two "cooler" for the deserts.

&&

.AVIATION...
030330Z...Coast/Valleys...Areas of low clouds will continue to
slowly develop within 5 miles of the coast through 07Z Wed, then
spread up to 20 miles inland by 12Z Wed with BKN/OVC bases 800-1300
ft MSL and tops to 1500 ft MSL. Local VIS 1-3 miles will occur in
the coastal valleys and higher coastal terrain 08Z-16Z Wed. Most
areas will clear 15Z-18Z Wed with slow development of low clouds and
fog Wed evening.

Mountains/Deserts...Mostly clear skies with unrestricted VIS will
continue through Wed evening. Local west sfc winds will occur on the
desert slopes and through San Gorgonio Pass with gusts mostly 25 kt
or less through 08Z Wed and then again 02Z-08Z THu.

&&

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

&&

.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 and Monday. This will lead
to elevated surf with breaking wave heights up to 7 feet, mainly on
exposed south and southwest-facing beaches in Orange County. Rip and
longshore current risks will be high as well from Wednesday through
next Monday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from Thursday morning through Sunday
     afternoon for Orange County Coastal Areas-San Diego County
     Coastal Areas.

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

PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE/BEACHES...Maxwell