Riverside, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

217
FXUS66 KSGX 251001
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
301 AM PDT Fri Apr 25 2025

.SYNOPSIS...
Cool with a deep marine layer this weekend. Patchy drizzle is
possible along the coast this morning, followed by a chance of
showers tonight through Saturday evening. There is also a 10%
chance of thunderstorms for the mountains westward Saturday
afternoon. Gusty southwest to west winds for the mountains and
deserts this afternoon into Saturday evening with gusts to 45 to
55 mph along and below the desert slopes of the mountains. Gradual
warming next week with highs near to slightly above normal.

&&

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

Marine layer low clouds have spread into the coastal slopes and
passes this morning. Based on latest pilot reports, the cloud deck
itself is around 1000 ft thick, which is marginal for producing
marine layer drizzle. However, a weak negatively-tilted short wave
trough will lift through the area later this morning, which should
provide enough dynamics for drizzle or light showers. Otherwise
cool today with high temperatures around 5-15 degrees below
normal. Gusty southwest to west winds develop over the mountains
and deserts this afternoon and continue through Saturday night
when gusts to 45-55 mph will occur on the favored desert slopes
and below the passes.

An upper level low currently off the coast of Eureka will dig
south today, moving east across So Cal on Saturday. This will
bring a 15-50% chance of precipitation, with the highest chances
for Orange County, western Inland Empire, and the San
Bernardino/San Gabriel Mountains late Saturday morning through
Saturday afternoon. With the cold core moving overhead Saturday
afternoon, weak instability will lead to a 10% chance of
thunderstorms along and west of the mountains. Rainfall amounts
will generally be light and decrease from north to south. Some
areas in far southern San Diego County may be left with nothing.
For the most part totals will be less than 0.15" for the coasts
and valleys, and a few hundredths up to 0.25" in the mountains,
highest along the south slopes of the San Bernardino Mountains.
Isolated higher amounts are expected where thunderstorms occur.
Snow levels will fluctuate between 5000-6000 ft with totals of
1-5" above 6000 ft, highest near Mt San Antonio.

Weak troughing lingers across the region Sunday and Monday
maintaining cool weather with a deep marine layer. Highs remain
around 10-20 degrees below normal inland on Sunday, then around
3-5 degrees below normal on Monday. Ensembles in good agreement
with an upper ridge trying to nudge in from the west on Tuesday
for more significant warming and highs returning to a couple
degrees above normal, then another weak wave developing and
sweeping southeasterly across the Western US around
Wednesday and Thursday which will moderate temperatures, then
another ridge trying to build in on Friday for minor warming. The
marine layer will become more shallow Tuesday and Wednesday with
low clouds confined to the coastal areas, then deepen again on
Thursday - right in time for May Gray to begin.


&&

.AVIATION...
250945Z....Coasts/Valleys/Coastal Mountain Slopes...Clouds based at
2500-3500 feet MSL with tops near 5500 feet have filled in across
the coasts and valleys this morning with VIS reduced 0-5SM in along
the coastal mountain slopes. Patchy -DZ possible later this morning
between 10-18z with accompanying lower CIGs near 2000 feet MSL and
lower VIS 3-5SM at times. Clouds start to disperse 18-19z Friday
with BKN clouds likely persisting far inland and against the coastal
mountain foothills through the afternoon. Clouds (with similar
bases/tops) increasing again after 02z Saturday though may be
somewhat patchy in the evening, with a more uniform marine layer
expected by about 09z Saturday.

Mountains/deserts...West winds increase after 22z this afternoon,
gusting 35-45 kts, locally 50 kts, over ridges, through passes and
desert slopes. Strong up/downdrafts are likely, with isolated LLWS
and rotors in lee of mountains, such as vcnty KPSP. Otherwise, VFR
conditions prevail through Saturday.

&&

.MARINE...
No hazardous marine conditions are expected through Tuesday.

&&

.BEACHES...
Elevated surf of 3 to 6 feet with occasional sets to 7 feet Saturday
through Tuesday, peaking Sunday night and Monday. Strong rip
currents expected.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 2 PM this afternoon to 11 PM PDT Saturday for
     Apple and Lucerne Valleys-San Diego County Deserts-San
     Gorgonio Pass near Banning.

PZ...None.

&&

$$

PUBLIC...SS
AVIATION/MARINE/BEACHES...Munyan