Bryn Mawr, California Weather Forecast Discussion

383
FXUS66 KSGX 251018
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
318 AM PDT Thu Sep 25 2025
.SYNOPSIS...
The cooling trend will continue through Saturday with high
temperatures cooling to as much as 5 to 10 degrees below average
for inland areas. An area of low pressure will bring a chance for
showers and thunderstorms for Friday afternoon through Sunday
afternoon with the greater chances for the mountains and deserts
and on Saturday afternoon at 35 to 45 percent. For this afternoon
and evening, there will be gusty southwest to west winds for the
mountains and deserts with the stronger gusts to 35 to 45 mph. For
Sunday through Wednesday, below average high temperatures will
continue with slight day to day differences and overall warming of
a few degrees.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (Today through Saturday)...
A cooling trend will continue into Friday and Saturday as a slow-
moving low pressure system over central California moves into
southern California for Friday and Saturday. With the cooling,
high temperatures for Friday and Saturday will be as much as 5 to
10 degrees below average for inland areas with high temperatures
ranging from around 70 near the coast to around 80 for the Inland
Empire with the lower deserts around 90.
There will be stronger onshore flow today with gusty southwest to
west winds for the mountains and deserts with the stronger gusts
to 35 to 45 mph. The marine layer will deepen for tonight into
Friday with patchy drizzle or light showers possible over the
coastal waters into coastal areas for late tonight into Friday
morning. There is a 15 to 25 percent chance for showers and
thunderstorms for the mountains and deserts for Friday afternoon
and night.
On Saturday, the chance for showers and thunderstorms expands to
the valleys and increases to as much as 35 to 45 percent for the
mountains and deserts on Saturday afternoon. The chance for one-
half inch or more of rainfall at Big Bear has decreased to 10
percent.
&&
.LONG TERM (Sunday through Wednesday)...
The low pressure system over southern California on Friday and
Saturday will weaken and move to the east on Sunday. A 10 to 20
percent chance of showers and thunderstorms continues for the
mountains and deserts for Sunday afternoon.
A larger low pressure system will develop over the eastern Pacific
and move slowly into the western states through the middle of
next week. This will maintain below average high temperatures with
slight day to day differences.
&&
.AVIATION...
250930Z....Coasts/Valleys...Low clouds will gradually cover all
coastal areas and head into western valleys this morning. Bases of
500-900 feet MSL and vis 0-5SM over higher coastal/valley terrain.
Bases will lift by 15-16Z before scattering out by 17-19Z. Low
clouds will move ashore after 01Z and farther inland overnight into
Friday, filling most or all of the coastal basin. Bases would be
1000-2000 feet MSL with inland vis reduced 0-5SM. Areas of -DZ are
expected after 08Z Friday morning, especially along the coast,
temporarily reducing cigs/vis.
Mountains/Deserts...Mostly clear skies today and tonight, except for
SCT locally BKN clouds 10000 feet MSL over mountains and high desert
18-01Z.
&&
.MARINE...
No hazardous marine conditions are expected through Monday.
&&
.BEACHES...
Long period south swell from Hurricane Narda will arrive this
weekend. Swell of 5-6 feet with a period of 14-15 seconds will
produce high surf and strong rip currents, especially for south
facing beaches, Sunday through Tuesday. Coastal flooding and erosion
are possible, especially during high tides. Stay tuned for details
forthcoming.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
PUBLIC...17
AVIATION/MARINE/BEACHES...MM

NWS SGX Office Area Forecast Discussion