Alta Loma, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

177
FXUS66 KSGX 060336
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
836 PM PDT Thu Jun 5 2025

.SYNOPSIS...
The marine layer will stay a similar depth into tomorrow with
patchy drizzle overnight and morning, before becoming shallower
over the weekend. A gradual warming trend is expected through the
weekend, with the potential for continued warming into early next
week, followed by a cooldown thereafter.

&&

Update: The marine layer is going to continue to surge into the
inland valleys throughout the night, including the IE. There could
also be some drizzle possible, especially for the inland areas.
Throughout the next couple of days, the marine layer is going to
begin to lower and become thinner which will keep it more confined
to the coastal areas by the end of the week.

Models have not changed all that much from previous runs, and still
reveal some weak ridging going into the weekend, which will allow
for there to be a gradual warmup with temperatures getting above
average by Sunday and Monday. This should begin to break down as
there will be some troughing slowly advancing towards the region
towards the end of next week, and result in temperatures dropping
off a bit and getting back to around, or even slightly below, the
seasonal average for this time of year.

(Previous discussion submitted at 127 PM):

Visible satellite at 1 PM was showing areas of low clouds lingering
along portions of the coast and in the valleys, mainly in San Diego
County. It was also showing some cumulus cloud development over the
mountains and in the High Desert. The marine layer is expected to be
a similar depth as last night tonight into Friday morning, with
patchy drizzle likely west of the mountains. The marine layer is
expected to get shallower over the weekend as higher pressure tries
to build from the south.

Slight chances (15-20 percent) of showers and thunderstorms has been
maintained in the forecast for this afternoon for the San Bernardino
mountains and High Desert. HREF is indicating rainfall rates will
remain less than 0.30 inches per hour. The atmosphere continues to
dry out Friday through the weekend, with no additional chances of
showers/thunderstorms for at least the next week.

Conditions will warm into the weekend with increasing potential for
warming to continue into early next week. Latest guidance has
trended warmer from the valleys to the deserts for early next week.
Ensemble guidance is in better agreement that the weak low pressure
system off the California coast will weaken and move to the west
with high pressure to the south expanding into Southern California.
NBM chances for high temperatures to exceed 110 degrees in the low
deserts are the highest on Monday at 15 to 35 percent. Chances for
high temperatures to exceed 105 degrees are highest Sunday and
Monday at 80 to 95 percent. West of the mountains, chances of
exceeding 100 degrees for Monday and Tuesday are localized to the
eastern Inland Empire near 15 percent. Chances of exceeding 95
degrees are 10 to 25 percent for the valleys, with local areas in
the eastern portion of the Inland Empire closer to 65 percent on
Monday and Tuesday.

Temperatures will decrease a few degrees on Tuesday, with ensemble
guidance indicating a continued decrease in temperatures for
Wednesday and Thursday. By next Thursday, June 12, 80 percent of
ensemble solutions show an incoming trough of low pressure will push
the ridging east. Within that 80 percent, most of the uncertainty is
surrounding the amplitude of the incoming trough.

&&

.AVIATION...
060330Z....Coast/Valleys...Low clouds based 1200-1700 ft MSL with
tops to 2500-3000 ft will spread north and east to cover the coastal
basin by 10Z tonight. Areas of -DZ expected 07-17Z, bringing
periodic vis restrictions 2-5 SM in BR as well as possible lower
cigs to 700-900 ft MSL, with additional vis restrictions for higher
terrain inland. Clouds gradually clearing from inland areas as well
as coastal Orange County and far northern San Diego County 16-20Z
Fri, but coastal areas from KCRQ southwards and to about 10 miles
inland in San Diego County will likely remain BKN all day once
again. Clouds will spread across the coastal basin again after 00Z
Sat.

Mountains/Deserts...Mostly clear tonight and Friday. FEW-SCT cumulus
based at 10,000ft MSL will form 19Z Fri-01Z Sat over northern
mountains and high desert.

&&

.MARINE...
No hazardous marine conditions are expected today through Monday.

&&

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