Rialto, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

107
FXUS66 KSGX 151105
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
405 AM PDT Tue Apr 15 2025

.SYNOPSIS...
Onshore flow will strengthen and the marine layer deepen the next
few days spreading cooling inland with stronger and gusty west
winds for the mountains and deserts for Wednesday and Thursday.
There could be some patchy drizzle Wednesday morning and a slight
chance of showers for Thursday. A colder low pressure system from
the north could bring a chance of showers and slight chance of
thunderstorms on Friday. Then drier with warming for next weekend
with Sunday high temperatures returning to around average.

&&

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

.SHORT TERM (Today through Thursday)...
A low pressure system to the west will move slowly toward the
east, weakening and move inland through southern California on
Wednesday night and Thursday. The marine layer has deepened to
2500 to 3000 feet with widespread low clouds over the coastal
waters extending inland across much of the San Diego County
valleys and spreading into the Inland Empire from the west and
south. The most likely location for some patchy drizzle early this
morning would be in the western San Diego County valleys where
the saturated cloud layer is deeper and cloud bases closer to the
ground.

The coast and valleys will begin to cool today with greater
cooling spreading inland on Wednesday and Thursday. With the
cooling, high temperatures in some of the higher mountains on
Thursday will be as much as 15 to 20 degrees below average with
areas near the coast a few to around 5 degrees below average.
The marine layer will continue to deepen into Wednesday and
Thursday with the coastal low clouds spreading onto the coastal
mountain slopes. A deeper saturated cloud layer should be
favorable for more widespread drizzle for the coast into the
valleys for Wednesday morning. As that weakening low pressure
system moves inland through southern California for late Wednesday
night and Thursday, it will bring a slight chance of showers from
the coast to the mountains.

&&

.LONG TERM (Friday through Monday)...
On Friday, a cold low pressure system from the north has greater
potential to bring showers along with a slight chance of
thunderstorms. Cluster analysis shows greater precipitation
potential for those ensemble members that are more amplified with
the system and farther to the west with the track allowing for
greater entrainment of Pacific moisture.

Drier weather with warming is expected for the weekend with Sunday
high temperatures warming to around average, from the lower to mid
60s near the coast to the 70s for the Inland Empire with the lower
deserts in the mid to upper 80s.

&&

.AVIATION...
151000Z...Coasts/Valleys...Low clouds based around 1500 feet MSL
with tops near 2000 feet are quickly pushing inland and is
expected to fill in the entire coastal basin in the next few
hours. VIS restrictions should remain confined to the coastal
slopes and foothills where the cloud layer intersects terrain. Low
clouds retreat to the beaches 17-19z with most if not all beaches
clearing as well during the afternoon. 30% chance of low clouds
sticking around all day for the coast in the vicinity of KSAN. Low
clouds based slightly higher expected to push inland starting
around 03z Wednesday. Deepening marine layer will allow the entire
coastal basin to easily fill in with DZ becoming possible
overnight.

Mountains/Deserts...Periods of SCT-BKN clouds based 20,000ft MSL
through 12z Wednesday. Otherwise, light winds with typical
westerly flow through the mountain passes this evening and
overnight.

&&

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

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE...KW/MM