655
FXUS66 KSGX 200500
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1000 PM PDT Sun Apr 19 2026

.SYNOPSIS...
Cooler west of the mountains today as onshore flow returns but
warmer inland away from the marine layer influence. A low
pressure system moving into California brings cooler and breezy
conditions Monday through the middle of the week, along with a
slight chance of precipitation Tuesday afternoon into Wednesday
morning. Cool weather and breezy onshore flow persist into next
weekend.

&&

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

This afternoon, high clouds are streaming over the region in southwest
flow ahead of a weak upper level disturbance embedded in the cyclonic
flow around an extensive low pressure system southeast of the Gulf
of Alaska. The patchy low clouds in the coastal areas and valleys
from this morning have dissipated. Temperatures are mostly a little
higher than at this time yesterday except at low elevations west
of the mountains where onshore flow is spreading the cooler
maritime air inland. High temperatures today will be near or a few
degrees above seasonal averages.

The low pressure system south of the Gulf of AK will move inland
across CA through Wednesday, with the closed upper low well to
our north. This will bring widespread cooling with strengthening
onshore flow producing gusty southwest to west winds, mainly in
the mountains and deserts where gusts of 45-50 mph will likely
occur late Tue into early Wed. Height falls aloft ahead of the
approaching low will enable the marine layer to deepen tonight
into Monday morning, with increasing low clouds spreading farther
into the inland valleys.

SoCal will be on the southern periphery of the low pressure
system, with limited moisture available for precipitation. Any
precipitation is likely to fall between late Tuesday and early
Wednesday. Current precipitation estimates are for a trace to a
few hundredths of an inch in the valleys and coastal areas,
although many locations will get no precipitation. The coastal
slopes of the San Bernardino Mountains could get about 0.15 inch
of precipitation. The snow level will fall to about 6500-7000 ft
on Wed morning but any significant snow accumulations is unlikely.

This system will also bring strong and gusty southwest to west
winds to the mtns and deserts. The winds will be strongest between
Tue afternoon and Wed morning when gusts of 45-50 mph, locally to
55 mph, are expected in the mtn passes and on adjacent desert
slopes.

The upper level trough axis will move east on Wed morning and the
winds will begin to weaken while colder air filters in from the
northwest. Wednesday will likely be the coolest day with high
temperatures near or a few degrees below normal in the coastal
areas and low deserts while in the mountains, temperatures could
be as much as 12 degrees below normal.

SoCal will remain under the influence of broad upper level
troughing for the latter half of the week into next weekend. We
can expect temperatures near or a little below seasonal averages
with a deep marine layer and onshore flow producing breezy
conditions in the mtns and deserts.

&&

.AVIATION...
200600Z...Coast/Valleys...Very patchy low clouds near 1000-1600ft
MSL have begun to develop over the waters and near the coast this
evening. These clouds are expected to gradually increase in coverage
and spread onshore over the next several hours. Clouds will likely
continue to be patchy for some time, with only intermittent CIGs at
first, but should become more uniform after 09z. Clouds expected to
spread 20-25 miles inland by 12z, with a 30% chance for impacts
vcnty KONT/KSBD from 12-16z. Low clouds scatter out around 15-17z
Monday, with increasing high level clouds afterwards.

Mountains/Deserts...Elevated westerly to southwesterly winds with
gusts 15-25 kts will continue to weaken over the next few hours.
Wind gusts 20-30 kts pick back up again by 00z Tuesday the
mountains, desert slopes, and deserts. Otherwise, VFR conditions
expected through the TAF period.

&&

.MARINE...
No hazardous marine conditions are expected through Tuesday.
Elevated onshore (northwesterly) wind gusts near 20-25 knots are
possible Wednesday afternoon into early Thursday morning, which
would bring elevated, choppy seas. Another, briefer round of gusts
to around 20 knots Thursday afternoon and evening would be more
localized to the far outer waters near San Clemente Island.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE...Munyan

NWS San Diego (SGX) Office