Mesa Grande, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

451
FXUS66 KSGX 260419
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
919 PM PDT Fri Apr 25 2025

.SYNOPSIS...
Cool and cloudy weather is expected through Saturday, with light
showers and mountain snow, along with strong westerly winds
strongest through mountain passes into deserts. There is a slight
chance of thunderstorms Saturday afternoon. Higher pressure will
slowly rebuild next week for seasonal and warmer weather, with the
usual coastal clouds during the nights and mornings.

&&

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

The marine layer continued to deepen this evening but at the same
time breaks in the clouds got bigger. While the breaks provided a
more colorful sunset, the almost-May gray will gather more fully
overnight. A trough of low pressure will move through SoCal
Saturday. Its approach today has already deepened the marine layer
to around 7,000 feet deep. Tonight and Saturday morning it will
bring scattered light showers mainly near the coast, with little if
any accumulation. As the trough moves in, a cold front with an
associated band of showers and isolated thunderstorms will track
through the region west to east between 11 am and 3 pm Saturday.
Thunderstorm chances are quite small. This main band will be
followed by post-frontal showers mainly in San Diego County and
mountains through the night or even into Sunday morning. Total
precipitation will range from a few hundredths near San Diego to
0.75 inch in the front range of the mountains. Any rainfall rates
will fall below thresholds of concern for flooding or any debris
flows on burn scars. Snow will fall in the mountains above 5,000
feet elevation, but will probably only stick above 6,000 feet. Up to
5 inches are expected, most likely around places like Baldy ski
resort and Running Springs. The system will also bring winds, an
easy forecast since they have already started. Gusts of 45-55 mph
with isolated gusts 65 mph over and through mountains into adjacent
deserts will continue through Saturday as the system rolls through.
Conditions dry out and warm up Sunday, although a secondary
shortwave rotates through the region on the dry side of the longwave
trough on Sunday. That will keep things cooler than normal into
Monday before high pressure builds a little better for Tuesday.
Accordingly, temperatures will climb next week as a weak high
pressure ridge seems to dominate the longwave pattern. This will
allow a more stable and seasonal marine layer to rebuild and provide
coastal low clouds during the nights and mornings. Within the ridge
there are some weak low pressure waves that won`t do much, but
would modulate temps and marine layer depth and its cloud extent and
duration. Most model guidance and ensembles tend to bring in lower
pressure for late next week, which would provide cooler and cloudier
weather Friday and beyond.

&&

.AVIATION...
260415Z....Coasts/Valleys/Coastal Mountain Slopes...SCT-BKN clouds
with bases 3000-6000 ft MSL will gradually increase overnight and
continue through Sat evening. Mountain terrain will be obscured at
times in clouds. Isolated SHRA will occur overnight and Sat morning,
then become SCT or even numerous Sat afternoon with local VIS 3-5
miles and bases locally as low as 2000 ft MSL. There is a slight
chance of TS Sat afternoon with any lightning strikes being
isolated. SHRA will be isolated/SCT Sat evening.

Mountains/Deserts...Areas of westerly winds with gusts 30-50 kt will
continue through Sat evening, strongest from the mountain crests
through the desert mountain slopes. PSP could periodic gusts 30-35
kt at times, especially Sat afternoon/evening. Isolated SHRA/SHSN
will occur in the mountains tonight and Sat morning, becoming
SCT/locally numerous Sat afternoon/evening with widespread terrain
obscurations in clouds.

&&

.MARINE...
There is a slight chance of thunderstorms over the waters Saturday
afternoon and evening which may bring brief heavy rainfall,
reduced visibility, brief gusty and erratic winds and lightning.
Otherwise, no hazardous marine conditions are expected through
Wednesday.

&&

.BEACHES...
Elevated surf of 3 to 6 feet with sets to 7 feet will occur Saturday
through Tuesday, peaking Sunday night and Monday, and highest on
south facing beaches. Strong rip currents will occur. There is a
slight chance of thunderstorms at the beaches Saturday afternoon and
evening, with lightning and gusty winds possible with any storm.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory from 9 AM to 11 PM PDT Saturday for San
     Bernardino County Mountains.

     Wind Advisory until 11 PM PDT Saturday for Apple and Lucerne
     Valleys-San Diego County Deserts-San Gorgonio Pass near
     Banning.

PZ...None.

&&

$$

PUBLIC...MM
AVIATION/MARINE/BEACHES...Maxwell