798
FXUS66 KSGX 121818 CCA
AFDSGX

Area Forecast Discussion...CORRECTED
National Weather Service San Diego CA
1118 AM PDT Mon Oct 12 2026

.SYNOPSIS...
A low pressure system moving through the area and into the Great
Basin will maintain cool and showery weather today, with showers
ending from the northwest tonight. It will be warmer and dry for
Wednesday through Saturday with developing Santa Ana winds
strengthening for Friday into Saturday. Moderate HeatRisk could
return for the coast into the western valleys for Friday through
Sunday.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Tonight through Wednesday...

The area of low pressure is continuing to slide slowly southward
just off the coast of central California, and will propagate more
eastward by later in the day, and eventually exit the region. Until
then, there will still be a few lingering light to moderate showers,
mainly west of the mountains. A general consensus of the high res
models shows the precipitation completely coming to an end by early
tomorrow morning. Any remaining showers should not amount to anymore
than an additional tenth of an inch or less for the coastal areas
to a quarter of an inch for the mountains, with the highest
amounts expected for the western-facing coastal slopes and inland
foothills. Clearing tonight will allow for temperatures to cool
off efficiently, and lead to our coldest night in recent months,
with lows dipping down into the upper 40s to lower 50s for some of
the higher inland valleys. With antecedent rainfall, there could
also be some areas of patchy radiational fog also developing
within some of the higher valleys. High pressure will build in
over the region through tomorrow, with a gradual warming, although
highs will still be running around 10 to 15 degrees below the
seasonal average for most locations for this time of year for
tomorrow due to the colder air advection behind the low. The
marine layer for tonight will fill in slightly overnight, but
remain rather broken and dispersed, with a few isolated showers
still being possible through the early morning hours tomorrow.
Skies will further clear by tomorrow afternoon as the upper level
low pulls away from the region, with drying conditions
establishing themselves as we begin to transition into Santa Ana
conditions.

Thursday through Monday...

High pressure is going to begin to build in over the Great Basin as
the upper level low becomes stalled out over the Four Corners
Region. This will begin to establish Santa Ana conditions. By
Thursday, highs will still be slightly below average for the
mountains and deserts, although around average, and even slightly
higher for the coastal locations as offshore winds settle in over
the region. By Friday, a strong supergradient jet maxima at the 300
mb level is going to move in from the north over central CONUS, and
force the U/L low to cut off and retrograde back towards the
southwest. This will help the enhance the offshore winds on Friday
into early Saturday, with some of the coastal and inland basins
climbing to afternoon temperatures being as much as 15 degrees
above average for Friday afternoon, and possible return of
Moderate HeatRisk returning to portions of these locations. Winds
will also be rather strong and gusty for some of the higher
terrain and within mountain canyons and passes, and there might
even need to be Wind Advisories issued for a few locations, which
will be decided in the next day or two once there is better
agreement and confidence as to where these winds will be. RH
values will drop on Thursday, but then slightly increase on Friday
as the retrograded low taps into some subtropical moisture to the
south. However, fire concerns with the strong and gusty easterly
winds will remain elevated for both days. These winds will begin
to subside going into the upcoming weekend, as max temperatures
begin to flatline a bit, with a gradual cooling occurring each day
into early next week. There will also be a very slight chance of
precipitation for the mountains and deserts during the afternoon
hours on Friday as a result of some moisture being introduced,
along with a slight increase in instability, yet this will likely
remain east of our CWA. The return of onshore flow going into late
Saturday/early Sunday may result in the onset of some areas of
dense fog during the early morning hours. Otherwise, conditions
look to be rather tranquil in comparison as weak ridging returns
over the region, with the transition back into more zonal flow and
troughing upstream becoming the predominant features going into
the early part of next week.

&&

.AVIATION...
121730Z...Coast/Valleys...SCT -SHRA will continue today with cigs
2500-3000 feet MSL in -SHRA, otherwise bases 3500+ feet MSL.
-SHRA tapering off and gradually scattering out after 03Z KSNA/KONT
and after 14Z Tuesday at KCRQ/KSAN.

Mountains...SCT -SHRA will continue through 12Z Tue. BKN-OVC MVFR
cigs and obscured terrain will linger into Tue AM, with occasional
vis 2-5 SM with -SHRA. Clearing north (~07Z) to south (~12Z) tonight.

Deserts...BKN clouds based around 5000-7000 ft MSL through around
22Z. SCT clouds AOA 10000 ft MSL through Mon PM.

&&

.MARINE...
No hazardous marine conditions are expected through Saturday.

&&

.BEACHES...
High tides will slowly decrease but remain above 6.5* ft through the
Thursday high tide at 12 PM. A persistent south swell from 190
degrees with a period of 16 seconds and a west swell from 290
degrees with a 13 second period will generate surf of 4 to 6 ft,
with local sets to 7 ft through Thursday, with highest surf through
Tuesday. Minor coastal flooding remains possible through Thursday,
becoming more localized after Tuesday. Check the Coastal Flood
Advisory for details.

*Tide predictions have been corrected to reflect current trends in
actual tide observations.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 2 PM PDT Tuesday for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...Stewey
AVIATION/MARINE/BEACHES...CO

NWS San Diego (SGX) Office