Mesa Grande, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

971
FXUS66 KSGX 270436
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
936 PM PDT Sat Apr 26 2025

.SYNOPSIS...
Cool and cloudy weather is expected through today, with light
showers and mountain snow. There will also be strong southwest to
west winds, strongest through mountain passes into deserts,
through late this evening. Fair and warmer weather will follow
most of next week, with the usual coastal clouds during the nights
and mornings. Temperatures will then cool off again late next
week into the weekend.

&&

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

No significant changes to the forecast this evening as the
previous forecast remains on track. Light showers will continue to
move across the area, but no additional significant precipitation
amounts are anticipated.

Previous discussion...
.SHORT TERM...
A low pressure system aloft is currently just west of Point
Conception, and is driving a cold front west through the area,
bringing light rain showers, mountain snow, possible afternoon
thunderstorms, and gusty southwest to west winds.

Rain totals for this event (or liquid equivalent above the snow
line) will be from about 0.05" to a third of an inch for coastal
and valley areas, a couple of hundredths to about a tenth of a
inch for the western high desert, and 0.25" to 0.75" for most
areas in the mountains with up to an inch locally on the windward
slopes of the San Bernardino and San Gabriel mountains, most of
which will fall as snow. Snow levels with the frontal
precipitation band currently making its way through the region
this afternoon are generally be between 5000 and 6000 feet, before
dropping to 4500 to 5000 feet this evening as showers become
isolated. Wet, heavy snow totals of up to 5 inches in the San
Bernardino Mountains, up to 3 inches in the Riverside Mountains,
and up to an inch or so in the San Diego Mountains is expected
between now and Sunday afternoon above 5500 feet.

The Coachella Valley and San Diego deserts, meanwhile, will
continue to largely miss out on any precipitation, but will
continue to see gusty winds through this evening. Southwest to
west winds are 25 to 40 mph over the mountains and deserts, with
gusts to 55 mph. As per usual, strongest winds are through areas
like the Banning/San Gorgonio Pass on I-10 and through Walker
Canyon on I-8, leading to difficult driving conditions, especially
for high profile vehicles.

The main low pressure system along with the front pass to the
northeast this evening, bringing an end to widespread
precipitation but with lingering showers overnight. Showers taper
off from the northwest to southeast overnight, lingering in San
Diego County longest through Sunday morning. Weaker low pressure
remains aloft into early next week, and lingering moisture and
weak lift could result in a few pop up showers over the mountains
late Sunday afternoon, but with the moisture source effectively
cut off the remainder of the region will see dry weather. This
will result in continued cooler than average temperatures region-
wide through Monday, however, albeit slightly warmer than today
will be.

&&

.LONG TERM...
Tuesday Apr 29 through Saturday May 03...
Weak high pressure builds in aloft Tuesday and part of Wednesday,
bringing noticeably warmer (near-average) temperatures, dry
weather, and average afternoon breezes. This will also make the
nightly marine layer low clouds shallower and more confined to
coastal areas. While some divergence in ensemble model solutions
exists Thursday onwards, the flow looks to split Thursday, with
high pressure over the northwest U.S. and low pressure aloft over
southern California. This won`t have much effect besides a slight
cooling along the coast Thursday that will start to spread inland
Friday and Saturday as larger scale troughing settles into the
western U.S. Near average temperatures region-wide will dip
slightly below average for areas west of the mountains Friday,
then below average temperatures are likely region-wide Saturday.
The marine layer will deepen and spread farther inland each night
and morning for the latter half of the week.

Deeper low pressure looks likely to move in Sun-Mon. Currently a
fair number of the members of both the GEFS and ECMWF ensemble are
showing light rain for around Sunday and early the next week, but
confidence this far in advance is fairly low.


&&

.AVIATION...
270400Z....Coasts/Valleys/Coastal Mountain Slopes...SCT-BKN clouds
with bases 3000-6000 ft MSL will continue through Sun evening with
higher terrain locally obscured. Local VIS 3-5 miles and local
BKN-OVC bases 2000-3000 ft MSL will occur in -SHRA through 20Z Sun,
but most VIS will remain unrestricted below the clouds.

Mountains/Deserts...Occasional west winds with gusts 20-35 kt will
continue through Sun evening, mainly from the mountain crests east
through the desert mountain slopes and locally into the deserts,
including below mountain passes. SCT -SHRA/-SHSN will occur in the
mountains through Sun with occasional mountain obscurations in
clouds. Some clearing will occur Sun evening.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory until 11 PM PDT this evening for
     Riverside County Mountains-San Bernardino County Mountains.

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

     Beach Hazards Statement from 6 AM PDT Sunday through Wednesday
     evening for Orange County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...Suk
AVIATION/MARINE...Maxwell