817
FXUS66 KSGX 042345
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
345 PM PST Wed Mar 4 2026

.SYNOPSIS...
Cooler with breezy west winds can be expected through this evening.
Winds turn offshore by Thursday, becoming stronger for the coastal
slopes into the western valleys. The winds will bring cooler
conditions across the mountains and deserts with slightly warmer
conditions west of the mountains. Offshore winds will continue
through the weekend with a chance of precipitation for some areas by
Sunday into next Monday. A weak ridge will move over the region by
early next week, bringing drier weather.

&&

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

A trough continues to push over Northern California today. This has
contributed to a deeper marine layer that is taking its time
clearing out this afternoon. Some areas near the beaches will be
partially cloudy into the afternoon, but clouds will be expected to
move back into the coastal areas and further into the inland valleys
overnight into Thursday morning. If any fog forms, it will be over
higher terrain. The troughing pattern will also bring elevated west
winds across the mountains and deserts through this evening. Highest
winds can be expected over the northern portion of our forecast area
with mountain winds gusting near 35-50 MPH, while desert areas see
winds closer to 25-40 MPH.

The trough will move inland over the Great Basin, stalling Thursday
into Friday. This will bring northerly flow aloft, where winds will
change to an offshore pattern by Thursday morning. North winds will
funnel into the valleys and portions of the coast. NBM 75th
percentile winds show gusts primarily near 20-40 MPH across much of
this region. Areas near the foothills show winds closer to 40-50
MPH, locally higher below the Cajon Pass. Winds look to weaken some
by Thursday night, then ramp up again Friday morning.

The low pressure system associated with the longwave trough will
become cut off from the system, and meander southwestward,
eventually over northern Baja California. Since we will remain on
the west and north side of the low, offshore winds will continue
over the region through the weekend , potentially into early next
week. Strongest and most widespread winds look to occur sometime
around Saturday, when the pressure gradient is strongest. The low
will be able to pull in some moisture from Mexico, potentially
some light precipitation for the lower deserts into the mountains.
The position of the low is still unresolved in the models, where
a track too far to the south would bring mostly dry weather. NBM
chances increase near 15-30% by late Saturday night through Monday
afternoon across these regions, even west of the mountains. Model
ensembles do show light precip amounts, but these will be subject
to change as we get closer in time. After the low departs, high
pressure off the coast will begin to move over the area, with
sunnier and drier weather.

&&

.AVIATION...
042345Z....Coast/Valleys...Low clouds currently along the coast will
become more widespread through 05Z Thu. Low clouds are expected to
reach into the valleys and portions of the Inland Empire by 08Z Thu.
Bases will be 800-1800 ft overnight with some vis reductions for
elevated inland valleys. Low clouds/vis restrictions will clear 13-
16Z Thu. Gusts 20-30 kt possible below passes into portions of the
valleys through the day. Areas of LLWS shear and mod up/down drafts
expected.

Mountains/Deserts...VFR conditions will prevail through the period.
Westerly wind gusts 25-40 kts through mountain passes, along desert
slopes, and into the deserts through 12Z Thu. Isolated gusts to 55
kts through wind-prone passes and canyons. Winds will turn northerly
around 12Z Thu. Strongest winds Thu will be on the coastal slopes of
the San Bernardino mountains, High Desert, and in the Coachella
Valley. Northerly gusts 30-45 kt, locally up to 55 kt expected.
There will be areas of LLWS and mod up/down drafts.

&&

.MARINE...
Northwest winds will develop on Thursday generating choppy and
hazardous conditions. Gusts of 20 to 25 kt are expected with seas of
5 to 8 feet. A Small Craft Advisory is in effect from 7 AM to 10 PM
Thursday. No additional hazardous marine conditions are expected
through Sunday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 4 AM PST Thursday for Apple and Lucerne
     Valleys-Riverside County Mountains-San Bernardino County
     Mountains-San Diego County Deserts-San Diego County
     Mountains-San Gorgonio Pass near Banning.

PZ...Small Craft Advisory from 1 PM to 10 PM PST Thursday for Coastal
     Waters from San Mateo Point to the Mexican Border and out
     to 10 nm.

     Small Craft Advisory from 7 AM to 10 PM PST Thursday for Waters
     from San Mateo Point to the Mexican Border Extending 10 to
     60 nm out including San Clemente Island.


&&

$$

PUBLIC...APR
AVIATION/MARINE...CO

NWS San Diego (SGX) Office