824
FXUS66 KSGX 180530
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
930 PM PST Mon Nov 17 2025

.SYNOPSIS... A weak storm system will move through the area later
today into early Wednesday. This will bring light to moderate rain
showers and accumulating snowfall in the mountains. There will be a
brief lull in the action on Wednesday, with sunnier but continued
cooler weather. Yet another winter storm system will move closer to
the region later on Thursday through at least Friday night, bringing
another round of rainfall and higher elevation snow. Things look to
dry out sometime early next week.

&&

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

A band of frontal precipitation is moving fairly swiftly from the
northwest to the southeast through the region. There`s been some
pretty good rain rates along parts of the coast and into the
foothills, with local rates of a third to a half an inch of rain
in about an hour. This is enough to result in some urban flooding
as well as poor visibility in heavier areas of rain/in the
mountains where areas of fog are present; use extra caution if you
need to drive this evening and avoid driving through any flooded
areas.

So far we`ve seen 0.25-0.60" in Orange County and the eastern
Inland Empire, including the western San Bernardino foothills,
0.15-0.40" along the San Diego County coastline (except for one
over-performing station near San Onofre that managed to receive
nearly an inch). Inland valleys have (so far) seen a few
hundredths to 0.20", but that should change soon as the front
continues to the east. Off-and-on showers will follow the front as
it passes out of the region overnight, continuing through most of
Tuesday. For more information, see the previous discussion.

.PREVIOUS DISCUSSION...Issued 149 PM PST Mon Nov 17 2025...
An area of low pressure has moved into Northern California, where an
associated frontal boundary continues to move through Southern
California. Light showers have been noted so far from LA to
Ventura. Showers may increase in intensity through the afternoon
and evening hours over our region as hi-res models indicate.
Hourly rain rates will peak around 0.50"/hr, but most rates will
be closer to one quarter of an inch. We are not expecting too many
impacts with this but areas that flooded from the weekend or any
other low lying/poor drainage areas may see localized ponding or
flooding. This system will be colder than the last, so snow levels
near 7,000 feet to start but lower near 5,000 feet by Tuesday
evening. A Winter Weather Advisory has been issued for areas in
the San Bernardino County mountains above 6,000 feet. A general
2-4 inches is expected around this elevation with locally over 5
inches for areas over 7,000 feet through Tuesday evening.

The exact track of this low pressure system is being a bit more
resolved in the models, where the low will move directly over our
area. This will provide a better chance of thunderstorms as the cold
core moves over the region, so areas mainly west of the mountains
will see continued isolated showers and thunderstorms into the day
on Tuesday. There will be intermittent breaks in the clouds west of
the mountains throughout the day with sunnier conditions in the
deserts. Tuesday will be a chillier day as well, with highs 10-20
degrees below average. By Wednesday, the track of this system
starts to diverge in the model guidance. Some show the system
going far enough south, giving us sunnier and drier conditions.
Others show a more interesting scenario, where the backside of the
low will produce more precipitation along the mountains into the
deserts. We will continue to watch this, as this could produce
additional desert rain and mountain snowfall.

The weather pattern continues to remain interesting as we move into
Thursday and Friday. Yet another area of low pressure looks to move
into the Southern California vicinity, where the probability of rain
and mountain snow increases once more. The exact track and
precipitation timing / amount details still somewhat uncertain,
though compared to yesterday, the model guidance is in better
agreement on the system moving over the area or off the coast, which
would give us a wetter weather setup. This will solidify a cooler
and cloudier weather pattern through the work week. High pressure
off the coast looks to move into the region sometime early next week
(Sunday or Monday), where drier and warmer weather will move into
the region.

&&

.AVIATION...
180430Z...A line of +RA/RA is moving through San Diego County and
the Inland Empire, moving eastward around 15kts. Bases 800-2000 ft
and VIS 1-3SM MSL in +RA, 2-3 kft bases and 4-6SM in -RA. Otherwise,
bases 3-5 kft. Higher terrain obscured in FG/RA/SN during the
frontal passage and through the overnight hours. Snow showers
possible in the mountains above 6,000 feet elevation between 06-13z.
Moderate confidence for -SHRA for low desert sites between 08-13z,
with VIS down to 4-6SM and bases down to 2500 ft MSL at times.

FEW-SCT bases 3-5 kft overnight into early Tuesday morning with
increasing SHRA activity across the coastal basin and mountains
after 15z. -SHRA/SHRA during the day to lower bases intermittently
to 2500 feet MSL and VIS 4-6SM. Slight chc (10-15%) TSRA after 18Z.
SHRA activity diminishes after 02z Wednesday and clouds thin out
across the region.

&&

.MARINE...
The cold front has moved through the coastal waters, yielding to
northwest winds gusting to 20-25 kts. Winds eventually weaken after
3 AM Tuesday. Check the Small Craft Advisory for details.

Showers continue through the day Tuesday, with a slight chance of
thunderstorms Tuesday afternoon. Any thunderstorm could produce
lightning, gusty erratic winds, choppy seas, and/or a waterspout. No
hazardous marine conditions are expected Tuesday night through
Thursday, but the next storm system has the potential to bring
hazardous winds and seas Thursday night and Friday.

&&

.BEACHES...
Elevated surf of 3 to 5 feet, with sets to 6 feet on west-facing
beaches is expected through Tuesday. This will generate a high risk
of rip currents.

Additionally, there is a slight chance (10-15%) of thunderstorms
Tuesday afternoon.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory until 10 PM PST Tuesday for San
     Bernardino County Mountains.

PZ...Small Craft Advisory until 2 AM PST Tuesday 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...CSP
AVIATION/MARINE...Westerink