Rialto, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

422
FXUS66 KSGX 072047
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
147 PM PDT Wed May 7 2025

.SYNOPSIS...

Bubbling cumulus over the mountains may produce shower this
afternoon, but otherwise, sunshine and dry weather will prevail.
High pressure will move into the area through Saturday, leading to
a warming trend and shrinking marine layer with patchy fog each
morning near the coast. Much cooler weather will move into the
area as a trough of low pressure moves into the West Coast by
early next week.

&&

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

A small 570 mb area of low pressure is moving southward over the
Arizona-California border this afternoon. The backside of the
system continues to produce mid level clouds over the mountains
and deserts. Confidence continues to increase of mostly dry
weather continuing into the afternoon, but a stray shower over the
mountains may occur as mid level moisture remains somewhat elevated.
Models are in fair agreement that an area of high pressure will
move into the area by Thursday into Saturday. This will lead to a
warming trend across the region. By Saturday, inland areas will
see highs 15 to 20 degrees above average with 5 to 10 degrees
above average near the coast. Triple digit heat still remains a
viable possiblity in parts of the Inland Empire, as NBM probabilities
are moderate to high. NBM was used for forecast high temperatues,
but confidence is still moderate on how hot temperatures become.
Would not be surprised to see highs incrase a few degrees as we
move closer to the peak of the heat wave. As the ridge moves in,
the marine layer will shrink, leading to low clouds coverage only
near the coast and adjacent valleys over the next two nights. This
will lead to patchy fog in the valleys by Thursday morning, with
some coastal areas becoming foggy by Friday morning. Visibility
should not be dense overall, except in higher terrain.

Models show the ridge pushing eastward on Sunday as a trough sets
up across the West Coast. This will bring a quicker cooling trend
for the region by Sunday into early next week. Temperatures will
fall near average by Monday with even cooler conditions by
Tuesday. Model ensembles also show a chance for precipitation to
potentially move in with this system as well on Tuesday or
Wednesday of next week. NBM POPs are good for now showing a
minimal probability but the forecast will change in the coming
days.

&&

.AVIATION...
072000..Coasts/Valleys/Foothills...Satellite shows complete clearing
from the AM cloud deck has occurred with only FEW-SCT clouds over
the coastal foothills, with VFR prevailing through this evening. Low
clouds will gradually form mainly near the coast after 06-08Z
Thursday with bases 1000-1800ft MSL, significantly less inland
coverage than previous mornings. Some VIS restrictions possible,
especially for the valleys, down to 2-5SM generally after 12z. Most
clearing will occur by 17z Thursday.

Mountains/Deserts...Satellite shows cumulus based 8000-10000ft MSL
over the mountains, with a possible -SHRA or two possible through
02z Thursday. Clearing thereafter with VFR prevailing through
Thursday afternoon.

&&

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

&&

.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...APR
AVIATION/MARINE...Zuber