180
FXUS66 KSGX 252013
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
113 PM PDT Tue Jun 25 2024

.SYNOPSIS...
High pressure over the Desert Southwest will help bring in
southerly moisture again today, providing another chance for
isolated showers and thunderstorms across northern mountains and
deserts. As the ridge amplifies over the Southwest, moisture will
push to the east, bringing in drier but continued warm weather
through Thursday. A trough to the north will try to influence our
weather by the end of the week, leading to a slightly deeper
marine layer and temperatures a few degrees cooler by Friday and
Saturday. High pressure will make a return by early next week,
prompting slightly warmer conditions.

&&

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

Taking a look out our office window and at GOES imagery, one can
see cumulus clouds locally building over the mountains this
afternoon, most of them over the eastern San Bernardino
Mountains. Clockwise flow around an area of high pressure of the
Desert Southwest places us right on the edge of the moisture plume
today. These clouds may generate light showers or a weak
thunderstorm for areas near Big Bear into portions of the High
Desert, mainly east of Interstate 15. The ridge will amplify
across West Texas and New Mexico, swaying the moisture axis
eastward. This will lead to minimal chances for storm activity.

Warm conditions will prevail through much of the week. The ridge
to the east weakens slightly by Friday, allowing lower heights
and more zonal flow to come into the region. This will knock
temperatures down a few degrees across the area by Friday, leading
to near average daytime highs. Heat risk will lower as well,
mainly due to overnight temperatures not being as warm with lows
near to a few degrees below normal. Winds will be breezy across
the typical spots in passes into the deserts; most models
indicating winds 20-35 MPH most afternoons and evenings, highest in
the San Gorgonio Pass with gusts near 35-45 MPH. The marine layer
will also become slightly deeper by this time, with greater
coverage of low clouds and fog for areas west of the mountains.

An area of high pressure will grow and expand across the Pacific
by early next week, which will lead to another subtle warm up with
temperatures slightly above average away from the coast. This will
decrease the marine layer depth, leaving low clouds and fog to
occur closer to the coast.

&&

.AVIATION...
252000Z...Coast/Valleys...Mostly clear skies with the exception of a
few high clouds will prevail through this evening. There`s a greater
chance tonight compared to last night for lower clouds, with a 50-60
percent chance of CIGS at the coastal airports after 08Z-10Z Wed
with bases around 800-1200 ft MSL, locally down to 700 feet.
Otherwise, FEW-SCT clouds at/above 15,000 ft MSL and unrestricted
VIS through Wed morning. Any clouds that do develop at coastal TAF
sites will likely clear 16-18Z Wed. Typical afternoon breeziness
expected each afternoon.

Mountains/Deserts...There is a 15-20 percent chance of TSRA over the
San Bernardino Mountains north into the high desert this afternoon
into the early evening, with CB bases near 12,000 ft MSL and tops to
25,000 ft MSL. Gusty outflow winds and reduced VIS VCTY TSRA.
Otherwise, FEW-SCT clouds at/above 15,000 ft MSL and unrestricted
VIS through Wed morning. Typical afternoon breeziness expected each
afternoon.

&&

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

&&

.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 8 PM PDT Thursday for Apple and
     Lucerne Valleys-Coachella Valley-San Diego County Deserts-
     San Gorgonio Pass Near Banning.

PZ...None.

&&

$$

PUBLIC...APR
AVIATION/MARINE...CSP