East Highland, California Weather Forecast Discussion

017
FXUS66 KSGX 050330
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
830 PM PDT Sat Oct 4 2025
.SYNOPSIS...
Mild, near to below normal temperatures with little day to day
change through Monday, followed by a gradual warming trend into
the middle/latter part of next week. Daily marine layer clouds will
likely make a comeback early Sunday morning, with more widespread
low clouds next week. Periods of weak offshore winds overnight
and in the mornings over mountain ridges and in the deserts will
occur through early next week. There is the potential for tropical
moisture to move into the area late in the week, bringing a
slight chance of showers, most likely over the mountains but with
the potential for more widespread activity.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.Evening Update...
Patchy low clouds continue to develop offshore this evening. These
will slowly increase in coverage overnight with some cloud cover
lingering into the morning near the coast before clearing
thereafter. Calm conditions will continue through the middle of
the week. We continue to watch Tropical Storm Priscilla to the
south. There remains great uncertainty on the exact track of this
system. The synoptic set up will be key as low pressure to the
north and high pressure to the south will dictate the system`s
path either toward our region our or out to sea. Keep an eye on
the forecast over the coming days and read below for more detailed
information.
.Previous Discussion (149 PM Saturday)...
.SHORT TERM...
A broad trough will remain over the western U.S. into early next
week, and a shortwave digging down the western side of the trough
will develop into a weak low off the south-central California
coast. This will result in a very subtle cooling west of the
mountains and subtle warming for the mountains and deserts Sunday
through Monday, but in practice temperatures will still feel very
similar to today. However, the low will bring nightly and morning
low clouds back to our coastal areas. Low clouds will struggle to
form for most of tonight, but an eddy circulation developing
early Sunday morning will moisten things up enough to get at least
patchy low clouds along the San Diego and likely northern Orange
County coastline. Low clouds Sunday and Monday nights will be
earlier to develop in the evening and more widespread overnight.
Meanwhile, a shortwave trough moving into the Intermountain West
will lead to some weakly breezy offshore flow from the east to
northeast for the mountains and deserts from the early morning
through early to mid-afternoon both Monday and Tuesday. These
winds aren`t strong enough for any major impacts, but will lead to
drier conditions in these areas than past days.
&&
.LONG TERM...
The weak closed low off the south-central coast will merge into
the broader trough and move to the northeast late Tuesday into
Wednesday as the west end of a broad high over the southern U.S.
nudges into the area. This will result in a warming trend Tuesday
through the mid to latter half of next week. Meanwhile, a large
low pressure system will drop south out of the Gulf of Alaska and
make its way down the West Coast. Simultaneously, the developing
tropical system Priscilla south of Baja California will gradually
make its way northwest through next week, likely leading to some
amount of remnant moisture moving into Southern California by late
Thursday/Friday.
There is significant differences in model output for where the
low from the northwest will set up, as well as the track of the
tropical system and how much moisture it will advect into the
area. There is the possibility for dry weather to continue all
weekend (most likely at this moment) as well as for a quite wet
weekend in some areas (currently an outside chance). This is
leading to a low confidence forecast for temperatures, winds and
possible convective rainfall for the latter part of next week.
For now, the forecast is for near the zero chances for rainfall
increasing to a small chance (10-15%) by late Thursday, followed
by slight chances (15-20%) over the mountains and parts of the
deserts and less than 15% chances elsewhere Friday and Saturday.
Any moisture would be fairly elevated at first, resulting in
those higher chances over the mountains, but if we get strong
enough forcing from troughing nearby, showers west of the
mountains would not be out of the question, as indicated by a
handful of ensemble members. Currently chances for thunderstorms
are too low to include in the forecast.
&&
.AVIATION...
050300Z....Coasts/Valleys...As of 03z Sat, clear skies prevail. Low
clouds with bases 1500-2500 ft MSL to slowly start to develop in
very patchy fashion throughout the coastal basin. Eventually, by 10-
12z tonight, confidence increases for greater BKN coverage across SD
county and coastal Orange County. Most clouds scatter out to the
coast 17-19z with a slight chance for off-and-on SCT-BKN cigs to
linger through the afternoon at the immediate SD county coastline,
including at KSAN. Clouds with similar bases will start to develop
after 00z Mon at the coast, broadening in coverage, and eventually
filling into all of SD/Orange County lowlands overnight.
Mountains/Deserts...VFR conditions will prevail into Sun night.
&&
.MARINE...
No hazardous marine conditions are expected through Wednesday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
UPDATE...APR
PUBLIC...CSP
AVIATION/MARINE...Westerink

NWS SGX Office Area Forecast Discussion