Beaumont, California Weather Forecast Discussion

352
FXUS66 KSGX 270946
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
246 AM PDT Sat Sep 27 2025
.SYNOPSIS...
Isolated showers this morning will become stronger and more
widespread this afternoon, mainly for the mountains and deserts. A
few storms could drift into Orange County and valleys. Chances
for showers and thunderstorms decrease for Sunday, followed by dry
weather on Monday. High temperatures remain well below normal with
a deep marine layer through early next week. Gradual warming
expected Wednesday through the rest of next week.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Morning water vapor imagery shows the upper level low centered
over eastern Riverside County. Showers and thunderstorms continue
to develop near the low center and are drifting westward towards
the Coachella Valley. Light showers are also moving south over
Orange County, though no measurable precipitation has been
reported with these. No impacts expected with this morning
convection. Otherwise a deep marine layer remains in place with
low clouds covering the coastal basin. Only partial clearing is
expected this afternoon.
The upper level low remains in place today. Mid-level moisture
will continue to wrap around the north and west side of the low
and into So Cal today. As destabilization occurs late this morning
and afternoon, stronger showers and thunderstorms are expected to
develop over the mountains and high desert, drifting into the
inland valleys, Orange County, and lower deserts at times. Latest
CAMs maintain hourly rainfall rates of 0.50-1 inch per hour over
the mountains and locally into the low deserts this afternoon.
The Flood Watch has been expanded to include the San Gorgonio
Pass, Coachella Valley, and San Diego County deserts. Largest
concern is the potential for debris flows over the burn scars.
Storms will weaken this evening and eventually dissipate tonight.
While the low begins to lift out on Sunday, there is enough
residual moisture and instability for at least isolated and much
weaker showers and thunderstorms over the mountains in the
afternoon.
Weak short-wave ridging will build in behind the departing low
Sunday and Monday for minor warming, though high temperatures will
still be several degrees below normal. The marine layer will
remain around 4000 ft deep into Sunday morning, becoming slightly
shallower each night for small decreases in low cloud coverage.
A weak short-wave trough will traverse So Cal on Tuesday as long-
wave troughing remains just off the coast, bringing minor cooling
to the region. Upper level ridging builds into the Desert
Southwest for the latter half of the week, with So Cal becoming
wedged between the ridge and the upper trough off the coast. This
will allow for minor warming and a decrease in marine layer cloud
coverage. For now the forecast is dry beyond Sunday, though there
is the potential for tropical moisture to become entrained in the
southwesterly flow and into So Cal around Wednesday, but
considerable spread remains the precipitable water ensemble
forecasts.
&&
.AVIATION...
270930Z....Coasts/Valleys/Foothills...BKN-OVC clouds with varying
bases from 2000-4000 feet MSL are present through the coastal basin
this morning. Low clouds will generally rise to 3000 ft MSL or
greater 14-17Z then gradually scatter out for most areas 17-20Z. 20-
30% chance for SHRA/TSRA 19Z-01Z for the inland valleys and western
mtn foothills, including the Inland Empire. TSRA passing over a site
will bring gusty, erratic winds and brief heavy rain leading to
reduced vis 2-5 SM. Low clouds 2000-3500 ft MSL redevelop for inland
valleys and foothills after 00Z, then expand to cover the coastal
basin after 28/05Z.
Mountains/Deserts...Isolated -SHRA possible through this morning,
mainly along desert slopes, but less than 10% chance for TSRA
through 18Z. Scattered SHRA/TSRA (40-60% chance) across mountains
and deserts 18Z-03Z, including a 30% chance for TSRA at KPSP/KTRM.
TSRA passing over a site will bring gusty, erratic winds, reduced
cigs/vis with brief heavy rain, and frequent lightning.
&&
.MARINE...
No hazardous marine conditions are expected through Wednesday.
&&
.BEACHES...
South swell from Hurricane Narda will arrive this weekend. 4-5 feet
swell with a period of 12-14 seconds will produce elevated surf and
a high rip current risk Sunday through Tuesday, especially for south
facing beaches, where sets could reach 8 feet, and strong alongshore
currents at all beaches. More information can be found in our Beach
Hazards Statement, which is in effect from 6 AM Sunday until 11 PM
Tuesday.
&&
.SKYWARN...
Skywarn activation is not requested at this time, but may be
needed this afternoon.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from Sunday morning through Tuesday
     evening for Orange County Coastal Areas-San Diego County
     Coastal Areas.
Flood Watch from 11 AM PDT this morning through this evening for
     Coachella Valley-Riverside County Mountains-San Bernardino
     County Mountains-San Diego County Deserts-San Diego County
     Mountains-San Gorgonio Pass near Banning.
PZ...None.
&&
$$
PUBLIC...SS
AVIATION/MARINE/BEACHES...CSP

NWS SGX Office Area Forecast Discussion