649
FXUS66 KSGX 201713
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
913 AM PST Thu Nov 20 2025

.SYNOPSIS...
Another system arrives today, delivering heavy rainfall tonight
into Friday afternoon. Up to an inch of rainfall possible for
coast/valleys, higher in the foothills and mountains. Periods of
heavy snowfall in the mountains, especially early Friday morning,
with snow levels around 6000-6500ft where 5-10+ inches of snow may
accumulate. The slow moving system will allow precipitation to
linger into Saturday. Drier weather with a very slow warming trend
sets in for the end of the weekend into early next week, warming
to near normal by Wednesday.

&&

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

.UPDATE...
Currently clear skies with a few light showers in the outer coastal
waters, moving southeast. Light rainfall will begin to move in as
early as late morning from north to south, spreading across San
Diego County this evening with pre-frontal showers and intensifying
tonight into Friday morning. Snow levels currently 6000ft will rise
to 6500ft as the core of the moisture moves across tonight, falling
back to 6000ft late Friday morning/Friday afternoon. With periods of
heavy rainfall tonight, total accumulations today through Saturday
may reach around 1-1.5" for coast/valleys and around 2" for
foothills/mountains. Those above the snow level will see around 4-8"
of snow, and those above 7500ft may see upwards of 14" through
Saturday. A Winter Storm Warning is in effect.

.PREVIOUS FORECAST FROM 244 AM...
.SHORT TERM (Today through Saturday)...
Early this morning, scattered showers will develop over the
coastal waters and spread into coastal areas with rainfall of
one-tenth inch or less. For this afternoon, scattered mostly
light showers could develop in advance of a colder low pressure
system moving southward just off the California coast.

The most widespread and heaviest precipitation is expected with
the cold front this evening with showers continuing overnight.
There is also a slight chance of thunderstorms for tonight. The
snow level will rise to around 7000 feet for late this afternoon,
then fall to around 5500 to 6000 feet for early Friday morning.
The snow level will then gradually rise to around 7000 feet for
late Saturday afternoon. South to southeast winds will develop
and strengthen ahead of the cold front for late this afternoon and
evening across the coastal waters and adjacent coastal areas with
gusts to 25 to 30 mph.

Through Saturday, rainfall and liquid-equivalent above the snow
level could range from around 1 inch at the coast to 1.5 to 2
inches for the mountains with locally greater amounts. Chances for
one inch or more of rainfall or liquid-equivalent above the snow
level through Friday night ranges from around 30 percent near the
coast to 50 to 70 percent in the mountains. Through Friday
afternoon, snowfall of 3 to 6 inches is expected from 6000 to 7000
feet, 6 to 10 inches from 7000 to 7500 feet, and 10 to 14 inches
above 7500 feet. Scattered snow showers will continue for Friday
night into Saturday with additional snowfall of 2 to 5 inches.

&&

.LONG TERM (Sunday through Wednesday)...
There will be high pressure off the West Coast with generally
northwest flow aloft across California. There will be dry weather
with a warming trend for Sunday through Thanksgiving. High
temperatures on Sunday of a few to around 5 degrees above average
will warm through Thanksgiving with Thanksgiving high temperatures
a few degrees above average to 4 to 8 degrees above average for
the inland valleys and San Diego County mountains.

High temperatures on Sunday will range from the lower to mid 60s
near the coast to the mid 60s to around 70 for the valleys with
the lower to mid 70s for the lower deserts. High temperatures on
Thanksgiving will range from around 70 near the coast to the 70
for the valleys with the mid to upper 70s for the lower deserts.

&&

.AVIATION...
201700Z...SCT-BKN low clouds 2500-3500 feet MSL continue into
afternoon, with increasing SCT -SHRA. A wide band of moderate
precipitation moves across the region from northwest to southeast
from 00-12Z Fri. Expecting widespread MVFR cigs/vis through the
coastal basin with a brief period of IFR conditions (cigs below 1000
ft and VIS 1-3SM) with the passage of the heaviest precip. Slight
chance TSRA (10-20%) at coastal sites. -SHRA in the deserts, but
generally VFR conditions expected. Mtns shrouded in FG through the
night. Cigs/vis improving to generally to VFR in the coastal basin
after the band passes. Lingering SCT SHRA and ISO TSRA will create
intermittent MVFR conditions for all areas on Friday.

&&

.MARINE...
Strengthening southerly winds this afternoon will turn westerly
tonight with gusts to 25 knots, generating choppy seas. Check the
Small Craft Advisory for details. There is also a slight chance of
thunderstorms this evening through Friday afternoon. Any
thunderstorm could bring lightning, gusty winds, choppy seas, and a
waterspout.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Storm Warning from 4 PM this afternoon to 4 PM PST Friday
     for Riverside County Mountains-San Bernardino County
     Mountains.

PZ...Small Craft Advisory from 4 PM this afternoon to 2 AM PST Friday
     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...Zuber
AVIATION/MARINE...KW