Placentia, California Weather Forecast Discussion

103
FXUS66 KSGX 032043
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
143 PM PDT Fri Oct 3 2025
.SYNOPSIS...
Gusty winds expected over the mountains and deserts, peaking this
afternoon and overnight. Cooler conditions today, with weak offshore
winds and warming west of the mountains Saturday. Another brief cool
down for early next week, with a gradual warming possible into the
middle/end of next week.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
The strongest winds so far as of 1 PM have been in the 45 to 50 mph
range. Winds are expected to continue to increase over the mountains
and into the deserts, peaking in strength late this afternoon and
evening. Generally gusts will be 35 to 45 mph with more localized
gusts to 55 in portions of the deserts and up to 65 mph in the
northern Coachella Valley below the San Gorgonio Pass. The marine
layer is expected to be a similar depth tonight (2500-3000 feet).
However, the strength of the marine inversion is still fairly weak
and coverage of low clouds over the coast and valleys will continue
to be quite patchy tonight into Saturday morning.
The upper level low moving through California today will quickly
move into Nevada Saturday. That will bring a brief period of
northerly winds Saturday morning. Those northerly winds will be
mostly on the coastal mountain slopes and below the Cajon Pass. The
offshore winds may result in quicker clearing of any clouds that
develop in the valleys and Orange County. Onshore flow will return
by the afternoon. High temperatures will warm a few degrees west of
the mountains tomorrow, with the deserts a few degrees cooler. By
Sunday, minimal change in temperatures expected near the coast with
a few degrees of warming further inland.
A broad area of low pressure extending from the Intermountain West
will dig south early next week, which will bring slightly cooler
conditions on Monday. For the middle to end of next week, more
uncertainty enters the forecast. Ensemble guidance is about 50/50 on
whether or not a trough or a ridge will be the main influence on
Southern California`s weather. This is emphasized by the 20 degree
spread in high temperatures between the 90th and 10th percentiles of
temperature guidance. If a more troughy pattern materializes near
California, it`s possible tropical moisture may be drawn northward
into the Southwestern United States, bringing an increase in cloud
coverage and a slight chance of showers. Right now the forecast
closely follows the NBM for the middle to end of next week.
&&
.AVIATION...
032030Z....Coasts/Valleys...Low clouds will be in isolated patches
along the coast throughout the afternoon. Breezy west to northwest
winds expected this afternoon, with gusts to around 20 kts through
this evening, around 02Z Saturday. Low clouds will reform in patches
after 4/00Z with bases mostly above 2000 ft MSL. Clouds initially
form in San Diego County foothills/valleys, then spreading north
overnight, but remain patchy for most locations. Some areas of
patchy drizzle may be possible, especially for the foothills. There
will begin clearing from inland to the coast on Saturday between 15-
17Z, and scatter out at the coastline at around 18Z Saturday, or
shortly thereafter.
Mountains/Deserts...Mostly clear and VFR conditions through Friday
night. Stronger winds out of the west will continue through the late
afternoon and evening, especially for deserts and desert foothills,
with gusts generally 25-35 kts except for typically windy spots
gusting to around 45 kts. Winds slowly diminish after 06Z Saturday.
&&
.MARINE...
Northwest winds Friday afternoon and evening over the outer waters
will lead to hazardous conditions for small craft. Expecting
sustained winds 20 to 25 kts, with occasional gusts over 30 kts
possible, and choppy seas 5 to 8 feet. Winds will be strongest in
the vicinity of San Clemente Island. Winds weaken by later this
evening. No hazardous marine conditions are expected Saturday
through Monday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 11 PM PDT this evening for Apple and Lucerne
     Valleys.
Wind Advisory until 5 AM PDT Saturday for San Diego County
     Deserts.
Wind Advisory until 5 AM PDT Saturday for San Gorgonio Pass near
     Banning.
PZ...Small Craft Advisory until 11 PM PDT this evening for Waters
     from San Mateo Point to the Mexican Border Extending 10 to
     60 nm out including San Clemente Island.
&&
$$
PUBLIC...CO
AVIATION/MARINE...Stewey

NWS SGX Office Area Forecast Discussion