Crestmore, California Weather Forecast Discussion

592
FXUS66 KSGX 180957
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
257 AM PDT Thu Sep 18 2025
.SYNOPSIS...
Moisture from the remnants of Tropical Storm Mario will peak
today, then decrease into the weekend. Showers and scattered
thunderstorms will move northward across the area today with the
mountains and deserts the most likely locations for heavier
rainfall with the most likely time for the heavier rainfall from
late morning through early evening. There will be gradual drying
and warming for Friday and Saturday. For early next week, there is
greater uncertainty with the placement of low pressure to the
northwest and high pressure to the southeast and the resulting
temperatures and the potential for tropical moisture from the
southwest to move into the area.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.SHORT TERM (Today through Saturday)...
Moisture from the remnants of Tropical Storm Mario will peak
today, then decrease into the weekend. Showers and scattered
thunderstorms will move northward across the area today with the
mountains and deserts the most likely locations for heavier
rainfall with the most likely time for the heavier rainfall from
late morning through early evening.
A Flood Watch continues for the mountains and deserts from 5 AM
PDT today to 2 AM PDT Friday. Bands of thunderstorms tracking
across the same area would be the most likely scenario for
producing heavier rainfall totals. The most likely peak hourly
rainfall is one-half to one inch with isolated maximum hourly
rainfall to 2 inches. There will be decreasing chances for
showers and thunderstorms for late tonight through Friday, limited
mostly to the mountains and deserts for Friday afternoon.
High temperatures for today will range from the mid 70s to around
80 near the coast to the 80s for the Inland Empire with the lower
to mid 90s for the lower deserts. That is as much as 10 to 15
degrees below average for the higher mountains in San Bernardino
and Riverside Counties. The coast and valleys will cool on Friday
with slight warming for the mountains and deserts.
There will be warming of a few degrees for inland areas on
Saturday. Saturday high temperatures will range from the mid to
upper 70s near the coast to the mid 80s to lower 90s for the
Inland Empire with the mid 90s to around 100 for the lower
deserts. That is generally a few degrees below average to around
5 degrees below average for the higher mountains.
&&
.LONG TERM (Sunday through Wednesday)...
There are differences in the placement of low pressure to the
northwest and high pressure to the southeast with greater spread
in the resulting high temperatures and in the potential for
tropical moisture from the southwest to move into the area.
There is a greater number of ensemble members of the GFS for the
warmer and drier solutions and a greater number of ensemble
members of the Canadian model for the cooler and wetter solutions
with about an equal weighting of ECMWF ensemble members for either
of those scenarios. The calibrated NBM has chances for showers at
around 20 percent for Sunday through Tuesday, but with low
confidence in the details.
&&
.AVIATION...
180930Z...-RA with isolated TSRA will continue to move south to
north this morning. Cloud bases will remain between 8000-12000 feet
MSL, but in areas of heavier RA, bases could briefly lower to around
3000 feet MSL with vis 1-5SM. Higher terrain intermittently
obscured. After 19Z, SHRA/TSRA shift into inland valleys, mountains,
and deserts, with decreasing chances near the coast. Some TSRA could
produce strong up/downdrafts, frequent lightning, and CB tops to 35
kft. The widespread precip moves out to the north tonight into
Friday. Variable lower clouds around 3000-5000 feet MSL will linger
into early Friday.
&&
.MARINE...There is a slight chance of thunderstorms through early
Friday morning, with the greatest chance this afternoon. Any storm
could briefly produce lightning, gusty erratic winds, and choppy
seas. Otherwise, no additional hazardous marine conditions are
expected through Monday.
&&
.BEACHES...There is a slight chance of lightning through early
Friday morning, with the greatest chance this afternoon.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Flood Watch from 5 AM PDT early this morning through late
     tonight for Apple and Lucerne Valleys-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...17
AVIATION/MARINE/BEACHES...MM

NWS SGX Office Area Forecast Discussion