Mesa Grande, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

375
FXUS66 KSGX 212033
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
133 PM PDT Sat Jun 21 2025

.SYNOPSIS...
Gusty westerly winds over the mountains and into the deserts this
afternoon and evening with cooler conditions. The marine layer will
remain fairly deep overnight, reaching into the valleys. Below
average temperatures will continue early in the week, with a gradual
warming for the middle to end of the week. The marine layer will
become shallower for the middle to end of the upcoming week.

&&

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

Periods of gusty westerly winds will continue over the mountains and
into the deserts through tonight. At 1 PM, gusts were mostly 35 to
45 mph, with gusts up to 60 mph through the San Gorgonio Pass. Winds
of those speeds, potentially a little stronger are expected to
continue through tonight, diminishing by Sunday morning.

For early in the upcoming week, a long wave troughing pattern will
remain over the Western United States. That will keep high
temperatures 5 to 10 degrees below average through Tuesday. Even
remaining below average, temperatures between today and Sunday are
expected to increase 3 to 7 degrees. A brief period of offshore
winds can be expected Sunday morning on the coastal mountain slopes,
with minimal impact expected. Marine layer low clouds and fog are
expected each night and morning and will reach into the valleys.

For Wednesday through the end of the upcoming week, the upper level
troughing shifts north, allowing for weak ridging to build in. That
will bring a gradual warming. Current forecast for the end of the
week follows NBM with highs within a few degrees of normal. The
increased ridging will result in a shallower mariner layer, with
persistent coverage along the coast and less coverage expected in
the valleys.

&&

.AVIATION...
212130Z....Coast/Valleys... Clouds have mostly moved offshore this
afternoon.BKN low clouds based 2500-3500 surge back 00-03z for SD
County coast and valleys. Clouds will likely spread into Orange
County and through the Inland Empire 02-05z, though there is less
confidence in full coverage of clouds that far north compared to
this morning. VIS 1-5SM where clouds and terrain intersect,
obscuring higher terrain. With good confidence for another coastal
eddy developing tonight, there is a 60% chance low clouds get pulled
to the coast by the southeasterly flow from the eddy circulation
early Sunday, 09-13z. Any remaining cloud coverage will dissipate 14-
16z.

.Mountains/Deserts...Clear skies and unrestricted VIS through
Sunday afternoon. Strong westerly winds occurring now, with gusts 30-
50 knots this afternoon for mountain passes and locally into
deserts. These gusts are likely to produce pockets of up/downdrafts
in lee of mountains/mountain passes in addition to isold BLDU in the
desert with VIS 3-5SM at times. Winds gradually weaken tonight into
Sunday morning.

&&

.MARINE...
Aside from northwesterly wind gusts near 20 kts in the vicinity of
San Clemente Island this afternoon, no hazardous marine conditions
are expected through Wednesday.

&&

.BEACHES...
Elevated surf this afternoon, 3-5 feet sets to 6 feet for west
facing beaches.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 11 PM PDT this evening for Apple and Lucerne
     Valleys-San Diego County Deserts-San Gorgonio Pass near
     Banning.

PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE/BEACHES...Westerink