223
FXUS66 KSGX 130533
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
933 PM PST Thu Nov 12 2026
.SYNOPSIS...
Cooler conditions with increased cloud coverage is expected through
early next week. Periods of rain are expected Friday through next
week. The first round is expected Friday morning, with chances of
isolated thunderstorms over the coastal waters locally into the
beaches. The next chance will be Friday evening into Saturday,
with more widespread light to locally moderate showers. In
addition to periods of rain, winds are expected to increase over
the mountains, deserts, and coastal waters. Sunday could see
mostly dry conditions with our next chances of precipitation and
increased winds Monday through Wednesday.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
...UPDATED AVIATION DISCUSSION...
Additional cooling is expected for Friday, which will bring
temperatures in most places to below average. Below average
temperatures are expected to continue through next Thursday. The
pressure gradient has begun to trend onshore ahead of an approaching
upper level low. This will lead to increased cloud coverage across
much of the coastal basin for Friday. Periods of clouds can be
expected through the weekend into early next week.
The aforementioned upper level low will dig south and move east into
Northern Baja on Friday. This will bring periods of rain to the area
by early Friday morning. The highest chances of rain for this first
period of rain are along the coast. Additionally, there is potential
for isolated thunderstorms to develop over the waters, locally into
some coastal communities. The thunderstorm chances are largely
focused to coastal waters and the coast due to the temperature
difference between sea surface temperatures (running well above
average for this time of year) and the cold temperatures associated
with the passing low pressure system. High resolution guidance is
picking up on an increase in instability with CAPE values increasing
to 500-1000 J/kg early Friday morning. There is some potential for
thunderstorms to locally reach coastal communities but atmospheric
instability drops drastically the further inland you go, which will
limit thunderstorm potential. Where thunderstorms develop, expect
erratic winds and locally heavy rain that may lead to localized
flooding. Rainfall Friday morning is generally expected to be on the
lighter side for inland areas. Isolated rainfall rates of 0.40-0.60
inches per hour are most likely to develop along the coast where
thunderstorms or heavier rain develops. Chances of rain decrease
during the day Friday, but isolated light showers at times cannot be
ruled out. Through Friday afternoon, rainfall totals will largely be
0.20 inches or less, but some isolated totals over 0.50 inch are
possible along the coast.
Rainfall chances increase again Friday evening as another upper
level low moves east through Central California. This will bring
another round of rain Friday evening into Saturday, which is
expected to be more widespread across the coast, valleys, and
mountains. Peak rainfall rates of 0.20-0.30 inches per hour are
expected during this time. Rainfall totals for the coast and
valleys will be largely 0.20-0.50 inches, with totals in the
mountains closer to 0.50-1 inch. Less than 0.10 inch is expected
in the deserts. Rainfall is expected to taper off from north to
south late Saturday morning through the early afternoon. Dry
conditions look likely for Saturday evening into Sunday. Snow
levels Friday into Saturday are expected to stay above 8000 ft,
with up to 2 inches of snow above 8500 ft.
Another low pressure system is expected to dig south along the West
Coast Monday and east late Monday into Tuesday. Ensemble guidance is
in good agreement in the timing of this trough, with lower
confidence in how far south the low will dig. The ultimate depth of
the trough will be a big influence on rainfall totals and snow
levels. NBM chances of rainfall totals exceeding 0.50 inch from
Monday morning through Wednesday morning are 30 to 45 percent for
the coast and valleys and 60-70 percent for the mountains. By
Tuesday morning, spread in NBM snow levels ranges from 5200 ft to
8300 ft.
Winds are expected to increase over the mountains and deserts with
each passing system. Expect a slight increase in winds this
evening, with a more noticeable increases Friday evening into
Saturday. Peak gusts Friday evening into Saturday will be mainly
35 to 45 mph, with gusts up to 55 mph through wind prone passes.
Winds are expected to increase again early next week with the next
trough passage, with the track of the low the main determining
factor in expected wind speeds. A more southerly track would bring
us stronger winds compared to a more northerly track.
Additional precipitation and winds are possible for the latter half
of next week, but there is low confidence in details. Continue to
monitor the forecast for more information.
&&
.AVIATION...
130530Z...Coast/Valleys...Low clouds based around 2500-4000 feet MSL
will stick around over the coastal basin tonight into Friday.
Increasing chances of -SHRA after 08Z overnight into Friday with
intermittently cigs down to 2500 feet MSL as -SHRA moves over the
area. Rain showers becoming more numerous towards 12Z with ISO TSRA
for the coastal TAF sites until around 18Z. Widespread BKN-OVC high
clouds AOA 8,000ft MSL, possibly some scatter out across the LA
basin, less likely in San Diego County. VCSH will continue for much
of Friday, even as the heavier RA comes to an end after 18Z. More
widespread low clouds and rain expected to push through the region
from north to south starting around 06Z Sat.
Mountains/Deserts...Increasing clouds AOA 10 kft through the night.
Off-and-on -SHRA over the mountains after 12Z Fri, becoming more
frequent and widespread in the late afternoon. Winds pick up after
18Z, with W/SW gusts increasing to 25-35 knots (locally 40-45 kts)
over typically windy ridges, desert foothills, and through passes.
&&
.MARINE...
Southerly winds increase tonight and Friday, turning westerly and
strengthening late Friday into Saturday. Swell and wind waves will
increase considerably at the same time, leading to steep, choppy
seas. Hazardous boating conditions are expected Friday into Saturday
afternoon, and a Small Craft Advisory is in effect for this period.
Winds and seas diminish late Saturday and Sunday, before increasing
again on Monday as the next weather system arrives. Additionally,
there will be a threat for thunderstorms Friday morning with
lightning and gusty and erratic winds all possible.
&&
.BEACHES...
A series of swells (14-15 seconds) from the west-northwest (270-280
degrees) will generate elevated surf starting Friday, which will
increase to a peak of 5 to 9 feet for west and northwest facing
beaches Saturday and Sunday. A High Surf Advisory is in effect for
these two days with dangerous conditions for both swimming and
surfing. Surf begins to wane Sunday afternoon but will remain
elevated for west-facing beaches into Monday morning. Another
northwesterly swell will arrive late Monday, extending the threat
for high surf and strong rip currents.
Additionally, there is a threat for lightning near the beaches
Friday morning with isolated thunderstorms over the waters.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory from 4 PM Friday to 10 AM PST Sunday for
Orange County Coastal Areas-San Diego County Coastal Areas.
PZ...Small Craft Advisory from 10 AM Friday to 4 PM PST Saturday for
Coastal Waters from San Mateo Point to the Mexican Border
and out to 10 nm-Waters from San Mateo Point to the Mexican
Border Extending 10 to 60 nm out including San Clemente
Island.
&&
$$
PUBLIC...CO
AVIATION/MARINE/BEACHES...APR
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