Colton, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

785
FXUS66 KSGX 202027
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
127 PM PDT Sun Apr 20 2025

.SYNOPSIS...
Dry and warmer through early next week with high temperatures
near to around 5 degrees above normal inland by Monday. Gradual
cooling follows Tuesday through Saturday. Areas of night and
morning low clouds and fog continuing through next week, becoming
more widespread towards the middle of the week as the marine layer
deepens. Afternoon and evening winds will strengthen slightly
across the mountains and deserts for the latter half of the week.

&&

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

.SHORT TERM...
Besides some very thin cirrus (upper level clouds), clear skies
are present across the region, with afternoon high temperatures
near to slightly above average. Excellent weather, in this
forecaster`s opinion, to eat far too much chocolate. The marine
cloud layer will redevelop late this evening, likely patchy at
first before becoming more widespread in the small hours of Monday
morning. These clouds will clear Monday morning at a similar time
to this morning, followed by another mostly sunny day.

For the next week, weakly cyclonic flow will be in place aloft,
with a series of weak shortwaves bringing cooling temperatures, a
deepening marine layer, and brisker afternoon and evening breezes
(mostly in the mountains and deserts). Monday will see
temperatures similar to today, with slight cooling along the coast
and slight warming for the deserts, and stronger afternoon and
evening breezes compared to today in the mountains and deserts.
Rinse and repeat Tuesday with another degree or two drop in high
temperatures for the coasts and valleys, and degree or two rise
for the mountains and deserts.

The cooling trend that started along the coast will then spread
inland for the rest of the week, with slightly to about 10 degree
below average temperatures through most of the region by Thu-Fri.
Marine layer low clouds will get progressively deeper and further
inland each night, with areas of drizzle under the marine layer
possible (most likely early Friday morning) but with otherwise
very likely dry weather. Afternoon and evening breezes will
strengthen slightly again in the mountains and deserts mid to late
week.

&&

.LONG TERM...
Some degree of large-scale cyclonic flow continues to be likely
for at least the first part of the weekend, meaning cooler
temperatures would continue. Global ensemble members are split on
when a low pressure system will move into (and out of) the Great
Basin. The earlier/faster tracking models indicate ridging (and
warming) starting Sunday, while others indicate continued cool
weather with a deeper marine layer through the weekend and perhaps
Monday. Models are in better agreement in at least a weak ridge
with warmer temperatures locally by early the next week.

&&

.AVIATION...
202000Z....Coasts/Valleys...FEW-SCT low clouds 900-1500 ft MSL this
afternoon with FEW high clouds at 25000 ft MSL. Widespread low cloud
coverage is expected tonight. Low clouds will return to coastal
areas and spread into the western valleys 02-06Z Mon. Bases are
expected to be 700-1200 ft MSL. There is a 20 percent chance of low
clouds reaching KONT tonight, most likely 12Z or later. Local vis
restrictions 2-4SM near higher coastal terrain and in the valleys.
Low clouds and vis restrictions expected to clear to the beaches 16-
18Z Mon.

Mountains/Deserts...Clear skies with unrestricted VIS prevailing
through Monday.

&&

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

&&

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

&&

$$

PUBLIC...CSP
AVIATION/MARINE...CO