Westminster California Weather Forecast Discussion

661
FXUS66 KSGX 120400
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
900 PM PDT Sat Oct 11 2025
.SYNOPSIS...
Cooler with night and morning low clouds through the weekend. A
low pressure system moving southward along the West Coast will
bring stronger onshore winds Monday and Tuesday along with a
chance of showers from the coast to the mountains Monday night
into Tuesday night. Gradual warming and drying with periods of
weak offshore flow Wednesday through Friday.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Evening update...
Patchy low clouds have begun to develop over the San Diego County
coastal areas this evening. A weak coastal eddy forming tonight
will help spread low clouds into Orange County and the western
valleys by early Sunday morning. Breezy west winds in the
mountains and deserts gusting to around 35-40 mph through the
passes will weaken later this evening, then surface pressure
gradients turn offshore with northerly winds developing below the
San Bernardino and Santa Ana Mountains. No impacts are expected
from these winds other than helping to clear out marine layer
clouds early. The remainder of Sunday will be fair with highs near
to slightly below seasonal normals. The marine layer will deepen
Sunday night as the next upper level trough approaches, with low
clouds spreading into the inland valleys Sunday night. Monday will
be much cooler with highs around 5 to 15 degrees below normal.
Previous discussion...
Starting Monday afternoon, an incoming shortwave trough will
begin to make its presence known in the mountains and deserts as
winds become elevated to locally strong along deserts and desert
slopes. Winds expected to peak Tuesday as the trough passes by
with lingering elevated winds into Wednesday. This system will
also be accompanied by much cooler temperatures and light
precipitation from the coasts to the mountains. As much as 15-20
degrees below average for inland areas. On that note, a dusting
of snow will be possible above 7500 feet. There is still
uncertainty in rainfall totals, but the track of the low almost
directly south from Canada should prevent any significant
precipitation totals. Generally expecting the highest amounts for
the valleys and mountains north of San Diego County, especially in
the western San Bernardino County Mountains where over an inch is
forecast. The lower deserts should remain totally rain-shadowed.
More seasonable and benign weather returns towards the end of
next week as an upper ridge expands into the area. This should
allow for the return of nighttime low marine layer clouds for
coasts and valleys as the inversion strengthens. Temps will remain
slightly below average even as high pressure builds.
&&
.AVIATION...
120300Z....Coasts/Valleys...Currently Patchy to intermittent BKN low
clouds 1,000-1,800 ft MSL along the coast. Low clouds are expected
to increase and become BKN after 04-06Z tonight and spread inland
15-20 miles by 08Z. Clouds will scatter out by 16-18Z.
Mountains/Deserts...VFR conditions expected through the TAF period.
Breezy west winds gusting 20-30 kts along desert foothills, high
desert, and the typically windy spots in low desert until 07Z
tonight. Calmer winds expected Sunday.
&&
.MARINE...
No hazardous marine conditions are expected through Monday. Tuesday,
winds will increase out of the south to southwest with gusts of 20-
25 kts possible as low pressure approaches the area.
&&
.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...SS/KW
AVIATION/MARINE...Villafane

NWS SGX Office Area Forecast Discussion