Mc Kinley Firebreak, California Weather Forecast Discussion

714
FXUS66 KSGX 190338
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
838 PM PDT Thu Sep 18 2025
.SYNOPSIS...
Tropical remnants will continue to move through the area tonight
but the potential for additional showers or thunderstorms is low.
There will be gradual drying and warming for Friday and Saturday.
Another area of low pressure will form off the coast by early
next week. This may help funnel more tropical moisture into the
area, but timing and placement of any showers is uncertain. The
latter half of next week will be drier as an area of high pressure
moves over the region.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
A low pressure system to the northwest interacting with
significant amounts of moisture from the tropics in an unstable
environment produced widespread showers/tstms this afternoon. Most
of the tstms occurred over the mountains and deserts but a few
developed over the northern IE. Many storms produced periods of
heavy rainfall, and some storms produced damaging wind gusts as
well as small hail. In a few locations, gages reported rainfall
rates of between 1 and 1.5 inches per hour. There were reports of
flooded roads, mudslides and rockslides (see the Local Storm
Report products). Most of the storms have moved north or
dissipated at this hour however, the outflow from intense storms
over Imperial County has triggered some less intense storms in the
southern Coachella Valley and in the Borrego Desert. These storms
will likely weaken and dissipate over the next couple of hours.
From previous discussion...
Leftover tropical moisture could produce some showers and maybe a
few tstms north of San Diego County on Friday. Although most hi-
res models are not depicting very much in the way of precipitation.
The area of tropical moisture will push further inland across the
western part of the country, leaving SoCal completely dry by
Saturday.
Another area of low pressure will develop off the coast by
Sunday, lingering around that area into early next week. The
placement of this system will be crucial if we are to see anymore
tropical moisture. Some models suggest that this low combined
with an area of high pressure to the southwest will help funnel
tropical moisture into the area, which may produce some light
showers across the region by Sunday and Monday. The best chance of
showers look to be across western San Diego County. Otherwise,
dry weather will prevail for most this weekend into early next
week with high temperatures near average and slightly more humid
than normal. Models begin to diverge by the latter half of next
week. By Tuesday and Wednesday, high pressure may expand over the
region, bringing further warming. The area of high pressure may
stick around into the end of the week but a trough may move
through the Pac NW, providing a cooler weather pattern. The marine
layer will return to our region by this weekend into next week
with night/morning low clouds within 20 miles of the coastline.
&&
.AVIATION...
190330Z....Coast/Valleys...Patchy low clouds around 1200-1800ft MSL
late tonight into Friday morning. BKN cigs possible up to 20 miles
inland generally after 11z and clearing by 16-17z. Areas of low
clouds return to coastal areas after 03Z Saturday, primarily in San
Diego County. Slightly lower bases and less inland extent than
tonight. Minor vis reductions possible along higher coastal terrain.
.Mountains/Deserts... SCT -SHRA lingering in the deserts along with
a storm or two possible in the Coachella Valley through 06Z.
Otherwise, SCT-BKN mid level clouds based 5000-10000 ft MSL
lingering through early Friday morning may reduce vis along higher
terrain. Generally VFR conditions expected after 12Z.
&&
.MARINE...No hazardous marine conditions are expected through Monday
evening.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Flood Watch until 2 AM PDT Friday 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...PG
AVIATION/MARINE/BEACHES...KW

NWS SGX Office Area Forecast Discussion