132
FXUS66 KSGX 140544
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
944 PM PST Thu Nov 13 2025

.SYNOPSIS...
An incoming winter storm will continue to bring clouds, cooler
weather and increased chances for precipitation into Saturday.
The best chances for rainfall will be across northern areas
Friday night into Saturday, with all areas expected to receive
moderate to heavy rainfall by early Sunday, increasing the flood
threat. This system will be a warmer one, so we can expect most
mountain communities to only see light snowfall accumulations. The
storm door will remain propped open into at least the first half
of next week as a weaker system moves closer to our region.

&&

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

A low pressure system is currently centered just off the coast of
Northern California with a frontal boundary extending southward from
the CA/OR border to a few miles west of Point Conception. This is
bringing mostly light rainfall across the state, with locally
heavier rainfall in areas of orographic enhancement. Bands of
light pre-frontal showers are moving across SoCal from southwest
to northeast. At this hour, no gages are reporting measurable
precipitation southeast of Ventura County. The low and frontal
boundary will move southward closer to our region tonight into
Friday as the system stalls and the upper low elongates. We will
see increasing clouds and light showers through tonight. Model
projections depict light amounts for much of Friday across San
Diego County into the lower deserts.

From previous discussion...
A Flood Watch will go into effect for all areas from early
Saturday morning through Saturday evening as this storm system
moves over the region. This is when most areas will see the
heaviest rainfall, including a chance for thunderstorms. Any area
that sees these thunderstorms or heavier rainfall over this longer
period will see an increased risk for flooding, including near
burn scars. Model agreement is fair in having the system depart on
Sunday, leaving us with off-and-on light showers and breaks in
the clouds. Cool conditions will also accompany this system, with
highs 60-65 degrees for areas west of the mountains and 40s/50s
across the mountains.

Ensemble model guidance is in better agreement of another area of
low pressure moving southward over SoCal by Monday and Tuesday of
next week. Though the details on this are still quite uncertain,
confidence is growing in a continued cooler and wetter weather
pattern. As of now, it looks increasingly likely that this system
will not be as wet as the one we will be seeing this weekend.
Models diverge some by the latter half of next week, but consensus
continues to lead to a continued active weather pattern.

See the Hydro discussion section below for details on the rain and
snow.

&&

.AVIATION...
140515Z...Patchy -RA is moving through the coastal basin, and is
expected to continue off and on through for the next few hours.
Multiple cloud layers exist: FEW-SCT base with -RA below 1000 feet
MSL, SCT-BKN throughout coastal basin around 6-8 kft, and BKN around
10 kft. VCSH region-wide throughout tonight and Friday, with some
SHRA in mountains. Main BKN-OVC base lowering gradually down from 6-
10 kft down to 3-5 kft by Friday afternoon. RA to commence from the
north and west starting 21-23z Fri, reaching to SD County 03-06z
Sat. VIS to reduce to 3-6SM and bases locally down to 1000 ft. +RA
not anticipated until after 06z Sat.

&&

.MARINE...
A storm system will approach Friday and move through Saturday and
Sunday, boosting southerly winds and seas. Prefrontal winds could
bring wind gusts of 20-30 kts across the waters on Saturday.
Occasional heavy rain Saturday could reduce visibility. There is a
slight chance of thunderstorms Friday night through Saturday night.
A Marine Weather Statement is now in effect for these thunderstorm
chances for Friday afternoon through late Saturday and contains more
details.

&&

.HYDROLOGY...
A Pacific storm will bring increasing chances for showers tonight
into Saturday. The frontal boundary looks to slow down its
progression on Friday, so most of the precipitation that occurs
on Friday morning and afternoon will be concentrated in the LA
Basin and surrounding mountains. Rain rates with this time look
to be under one half inch per hour. The San Diego metro may
remain fairly dry for much of the day on Friday.

Once the system pushes southward and inland over our area by
late Saturday, widespread heavier rainfall can be expected over
all of Southern California. This has warranted a Flood Watch for
all areas as there is an increased risk of flooding. There is also
a chance of thunderstorms for Friday night into Saturday evening.
Scattered lighter showers will continue into Sunday.

Through Sunday, rainfall for Orange and southwestern San
Bernardino Counties is expected to range from around 3 inches
near the coast to 3 to 5 inches for the mountains, locally
exceeding 7 inches on the south facing coastal slopes. For San
Diego County into the lower deserts, the forecast is more
uncertain with the rainfall totals. Most areas near the San Diego
metro will receive 2 inches of rain in total, though some areas
may see closer to 1.5 inches. The Riverside and San Diego County
mountains will receive 3 to 4 inches with locally greater
amounts. For the high desert, 1.5 to 2.5 inches of rainfall is
expected with around 1 inch for the lower deserts.

These rainfall amounts, along with the potential for periods of
higher intensity rainfall for late Friday night through Saturday,
could produce debris flows in burn areas, significant ponding of
water on roads and highways, and urban and small stream flooding.
The current forecast for the San Diego River has the river at
Fashion Valley rising above the 7.5 foot monitor stage from 11 AM
Saturday to 9 PM Sunday, sufficient to flood low-water crossings.

Snow levels above 10000 feet will lower to around 8000 feet for
late Saturday and 6500 to 7500 feet on Sunday. There could be 3
to 6 inches of snowfall for Saturday night and Sunday, mostly
above 7500 feet with accumulations near one inch for areas below
7000 feet, including the Big Bear Lake region.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Flood Watch from late Friday night through Saturday evening for
     Apple and Lucerne Valleys-Coachella Valley-Orange County
     Coastal Areas-Orange County Inland Areas-Riverside County
     Mountains-San Bernardino County Mountains-San Bernardino
     and Riverside County Valleys-The Inland Empire-San Diego
     County Coastal Areas-San Diego County Deserts-San Diego
     County Mountains-San Diego County Valleys-San Gorgonio Pass
     near Banning-Santa Ana Mountains and Foothills.

PZ...None.

&&

$$

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