263
FXUS66 KSGX 091108
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
308 AM PST Sun Nov 9 2025

.SYNOPSIS...
Warmer conditions expected through Monday with periods of weak
offshore flow. Locally dense fog in the coastal areas this morning
is possible again tonight into Monday morning. Cooler conditions
expected by the middle to end of next week. A windy and wet
pattern is expected to develop for the end of the week into next
weekend.

&&

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

This morning, the marine layer is a little shallower than
yesterday morning, with low clouds and fog confined to the coastal
areas. Areas of dense fog have developed in the San Diego County
coastal areas in spite of strengthening offshore flow while the
low clouds and fog have begun to clear out of portions of Orange
County. Sfc pressure gradients are trending stronger offshore
with -8.4 mb SAN-TPH, and the favored locations in the mountains
and coastal foothills are currently reporting wind gusts from 15
to 32 mph. There is about a 40 percent chance that the offshore
winds and the associated dry air will cause the fog in San Diego
County to lift before 9 am.

By Monday, as the pattern amplifies, the upper level high
pressure will be centered approximately over Southern California
with a closed upper low forming about 1500 miles west southwest of
San Diego. The building high pressure aloft and offshore flow
will continue the warming trend through Monday which will be
warmest day, with daytime high temperatures reaching the low 90s
in the inland valleys. These temperatures are about 15 degrees
above seasonal averages. The offshore flow will continue to
strengthen, with northeast to east winds peaking this
afternoon/evening and again Monday afternoon/evening. Strongest
winds will likely produce gusts of 30-45 mph in the wind-prone
locations of the mtns and coastal foothills.

For Tuesday, the high begins to weaken and the flow at the sfc
begins to turn onshore. This will bring some cooling to the
coastal areas and western portions of the inland valleys but
daytime high temperatures in the IE and parts of the San Diego
County valleys will still reach the upper 80s. The marine layer
will begin to deepen and low clouds will increase in coverage and
begin to spread inland beyond the immediate coastal areas early
Tue morning.

For Wed into next weekend...
A vigorous low pressure trough from the Gulf of Alaska will absorb
the low to our west into the mean flow, merging into an extensive
low pressure system off the coast. As this system moves inland, it
will bring much cooler conditions, stronger onshore flow,
increasing clouds and the potential for widespread rain. By next
Sunday, the potential for precip will diminish as the system moves
east into the Rockies and a high pressure ridge begins to move in
from the west.

Confidence in forecast details is still low due to the spread in
model solutions but it looks like Friday will be the coolest,
windiest day, with temperatures 5 to 15 degrees below seasonal
averages in the coastal areas and inland valleys. In those areas,
daytime high temps will be generally in the 60s. The stronger
onshore flow could produce westerly winds gusting to 40-45 mph in
the favored mtn passes and adjacent desert areas. The beginning
and ending times, and the precip amounts are still very uncertain
but about 40% of ensemble members across model platforms show some
precip by Thursday afternoon. By Friday afternoon, about 60% of
ensemble members show some precip. The NBM shows a 45-65 percent
chance for a 3-day total of one inch or more of precip from the
mtns to the coast, with the mtn slopes most likely to reach that
threshold. Snow levels could get down to about 6500 ft Friday
night so the resorts in the San Bernardino mtns could get some
fresh snow.

&&

.AVIATION...
091000Z...Coasts...Areas of FG throughout coastal SD county to the
coastal mesas up to 400 ft MSL creating widespread VIS reductions,
1/8-1/2SM. In Orange county and western portions of the Inland
Empire, low clouds are based higher, around 500-900 ft MSL, with VIS
2-5SM due to BR/HZ. Intermittent offshore flow will clear out low
clouds and FG in places.

Scattering to the coastline 14-17Z this morning. Patchy low
clouds/FG with similar bases to form along immediate coast after
about 02Z Mon, pushing up to the coastal mesas and reducing VIS 0-
2SM in even more patchy fashion than this morning.

Valleys/Mountains/Deserts...Clear skies and VFR conditions through
the period. Localized east to northeast winds through passes and
coastal slopes today, peaking tonight. Intermittent gusts 25-35 mph
in these areas.

&&

.MARINE...
Patchy fog along coastal waters reducing visibility to less than 1
nautical mile through this morning. Otherwise, gusty southwest winds
pick up late this week ahead of a weather system. Low confidence on
timing and intensity of wind and precipitation at this time, though
sustained winds in excess of 20 kts and periods of rain by late
Thursday are possible.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Dense Fog Advisory until 9 AM PST this morning for San Diego
     County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE...Westerink