Norco, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

346
FXUS66 KSGX 031040
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
340 AM PDT Sat May 3 2025

.SYNOPSIS...
A strong area of low pressure will move into the region this
weekend into early next week. This will bring much cooler and
windier weather across inland areas along with increased chances
for precipitation across all of Southern California, where parts
of the deserts may see thunderstorms on Sunday. Rain chances
lower for areas near the coast by Monday with minimal rain chances
by Tuesday across SoCal. A building area of high pressure will
usher in warmer and drier weather by the middle and end of next
week.

&&

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

.SHORT TERM (Through Monday)...
A trough of low pressure is moving into the West Coast this
morning. Satellite imagery shows high clouds from the Southern
California Bight northward into Oregon and Washington. This has
led to another morning of deep marine layer moisture set up across
SoCal as clouds have filled in much of the coastal basin. The
atmosphere may be saturated enough again this morning for areas of
drizzle to occur closer to the coast. As the system moves closer
to the region today and evolves into stronger more potent area of
low pressure, we can expect temperatures to be slightly cooler
for inland areas vs. yesterday. The marine layer will be stingy,
where most areas near the coast will once again stay in the clouds
for much of the day. SW/W winds will increase by the afternoon
hours across the mountains and deserts as the low moves closer to
SoCal. NBM wind probabilities are moderate to high in seeing winds
over 30 mph across the high desert and over 40 mph across mtn
passes and the Anza-Borrego desert. Strongest winds will occur
Saturday afternoon and overnight, where peak gusts may near 60-65
mph in the San Gorgonio Pass and desert slopes of the mountains
in SD County. There is a 30-50% chance of seeing winds over 25 MPH
for areas of the western Inland Empire Saturday evening.

Shower chances will increase Saturday evening with a 15-40%
chance along and west of the mountains. Most of these showers look
light based on latest hi-res model guidance with inland valleys
and foothills seeing the highest chance of rainfall. As the system
passes over the region by Sunday, things get a bit more
interesting. A robust coastal eddy will keep clouds around for
much of the western valleys and coast with light showers
continuing on and off for areas of SD County into the Inland
Empire in the morning. The anomalous cold core low will also help
provide sufficient instability for a chance of thunderstorms by
Sunday afternoon across the Coachella Valley and high desert. Rain
rates may near one half of an inch, weakening as they move
southward across the northern mountains and into parts of the
Inland Empire. Rain totals will be light with valleys seeing less
than one quarter of an inch to over half an inch in the mountains.
Though the system is cold, most areas that see any appreciable
snowfall will be over 7,000 feet. As the low pushes east on
Monday, a secondary low embedded in the trough will plunge
southward. This will keep the area cool with another chance for
rain showers for far inland valleys, mountains and deserts with
areas near the coast drying out with peaks of sunshine.

Speaking of cold...bring back those jackets! While areas near the
coast will remain in the 60s through early next week, inland
locations will become much cooler as this system moves through.
Sunday will see highs 10 to locally over 20 degrees below normal
where places like Borrego Springs and Ramona could see record cold
high temperatures for the day. The calendar says May, but folks
across the mountains will stick only in the 40s and lower 50s,
while the lower deserts will struggle to reach 80 degrees Sunday
into Monday.

&&

.LONG TERM (Tuesday Onward)...

High pressure off the coast will begin to move into the area by
Tuesday, which will bring sunshine for all. This will begin a
warming trend through the week as temperatures near average by
Wednesday, going above average by Friday. Probabilities are near
50-70 percent chance in seeing highs reach 90 for areas of the
Inland Empire. Confidence is high that dry weather will remain but
lower on exactly how warm we become as we head into the middle of
the month.


&&

.AVIATION...
020930Z....Coasts/Valleys/Coastal Slopes...Low clouds with bases
1500 to 2200 ft MSL have moved inland to cover most of the coastal
basin tonight. Patchy DZ possible 10-16Z. Clouds clearing inland 16-
19Z, but remaining BKN-OVC along the coast and up to 10 mi inland
through the afternoon with bases 2000-2500 ft MSL. Clouds will
quickly fill into the coastal basin again after 00Z Sun with bases
rising to around 2500 ft MSL and tops to 5000 ft MSL. Scattered -
SHRA will move inland from east to west after 02-03Z Sun, bringing
localized reductions in cigs and vis 3-6 SM.

Desert Mtn Slopes/Deserts...FEW-SCT clouds at/above 10,000 ft MSL
and unrestricted vis through today. Southwest to west winds with
surface gusts 25-35 kt this afternoon, locally up to 45 kt below the
passes in the evening. MOD-STG up/downdrafts and areas of LLWS
possible over and east of the mountains this afternoon and evening.

&&

.MARINE...
Gusty west-northwest winds will develop over the coastal waters this
afternoon, strongest this evening through early Sunday morning. Wind
gusts around 25-30 kt over the outer coastal waters and 20 kt over
the inner coastal waters, along with combined seas of 8-11 feet in
the outer coastal waters and 7-9 feet in inner coastal waters with
steep waves are expected. Wave heights peak Sunday morning and
gradually lower Sunday afternoon into Monday. A Small Craft Advisory
remains in effect for the outer coastal waters from 11 AM today
through 11 AM Sunday for the outer coastal waters and from 11 PM
tonight to 11 PM Sunday for the inner coastal waters.

&&

.BEACHES...
A west swell of 8-11 foot swell with a 7-10 second period will
generate elevated surf and a high risk of rip currents on Sunday,
bringing hazardous swimming conditions to all beaches. Surf of 5 to
8 feet for San Diego County beaches, with local sets to 9 feet, and
3 to 6 feet for Orange County Beaches is expected. Elevated surf  3
to 6 feet may continue into Monday morning. Swell and surf lowers
later on Monday.

&&

.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 5 AM to 11 PM PDT Sunday for San Diego
     County Coastal Areas.

     Wind Advisory from 6 PM this evening to 6 AM PDT Sunday for San
     Diego County Deserts-San Gorgonio Pass near Banning.

PZ...Small Craft Advisory from 11 PM this evening to 11 AM PDT Sunday
     for Coastal Waters from San Mateo Point to the Mexican
     Border and out to 10 nm.

     Small Craft Advisory from 11 AM this morning to 11 AM PDT Sunday
     for Waters from San Mateo Point to the Mexican Border
     Extending 10 to 60 nm out including San Clemente Island.


&&

$$

PUBLIC...APR
AVIATION/MARINE...CSP