Johnson Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

323
FXUS66 KSGX 191653
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
953 AM PDT Thu Jun 19 2025

.SYNOPSIS...
Low pressure moving inland into the western states will bring
cooling through Saturday with Saturday high temperatures as much
as 8 to 12 degrees below average for the mountains, inland
valleys, and high desert. There will gusty southwest to west winds
during the afternoons and evenings for the mountains and deserts
with the stronger gusts to 35 to 45 mph. The marine layer will
deepen with night and morning coastal low clouds spreading farther
inland to the valleys. For Sunday through Wednesday, low pressure
will weaken some, but remain across the area. High temperatures
will warm 5 to locally 10 degrees but remain below average by
around 5 degrees.

&&

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

.Morning Update...

Low clouds are quickly scattering to the coast this morning.
Expecting clouds to clear at the coast and nearshore waters again
given that the marine layer inversion continues to slowly weaken.
Temperatures today cooler than yesterday with moderate HeatRisk
becoming confined to just the low deserts. Models still indicate a
cooling trend through the weekend with increasing westerly winds
for the deserts/desert slopes as an upper trough pushes into the
PNW.


.Previous Discussion (244 AM PDT)...

.SHORT TERM (Today through Saturday)...
The marine layer has deepened to around 2000 feet with satellite
imagery showing coastal low clouds covering all of the Orange
County coastal plain and the western half of the San Diego County
valleys. Through sunrise, the low clouds may begin to spread into
far southern and far western portions of the Inland Empire.

Wednesday high temperatures were a few degrees cooler than Tuesday
for the coast and valleys. A low pressure system moving inland
into the western states will spread cooling inland through
Saturday. Saturday high temperatures will be as much as 8 to 12
degrees below average for the mountains, inland valleys, and high
desert with high temperatures ranging from around 70 near the
coast to the mid 70s to lower 80s for the Inland Empire with
around 100 for the lower deserts.

The marine layer will deepen to around 2500 feet for Saturday with
night and morning coastal low clouds spreading farther into
the valleys. Stronger onshore flow will also bring stronger and
gusty southwest to west winds for the deserts onto the desert
slopes of the mountains with the stronger gusts during the
afternoons and evenings to 35 to 45 mph.

&&

.LONG TERM (Sunday through Wednesday)...
Low pressure will weaken some, but remain across the area. High
temperatures will warm 5 to locally 10 degrees but remain below
average by around 5 degrees. The marine layer will decrease in
depth to around 1500 to 2000 feet with night and morning coastal
low clouds spreading inland into the western valleys.

&&

.AVIATION... 191530Z....Coast/Valleys...Low clouds based at around
800-1400 feet MSL and tops to 2000 feet will continue to scatter out
by 18Z. Low clouds to develop after 01Z and push inland overnight
into most of the inland valleys by 13Z Friday. Bases should be
closer to 1200-1500 feet MSL, with vis 3-5SM inland.

.Mountains/Deserts...Clear skies and unrestricted VIS through
Friday morning. Westerly winds increase after 22Z with gusts 25-40
knots through mountain passes locally into deserts, producing
pockets of up/downdrafts in lee of ridges.

&&

.MARINE...
Northwest winds may gust close to 20 knots near San Clemente Island
Friday afternoon and evening. Otherwise, no hazardous marine
conditions are expected through Monday. 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.

&&

$$

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