Tustin Foothills, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

313
FXUS66 KSGX 082043
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
143 PM PDT Thu May 8 2025

.SYNOPSIS...

A warming trend will continue into Saturday with a shallow marine
layer near the coast. High temperatures will be 10 to 20 degree
above average for areas away from the coast. A trough of low
pressure will move down the West Coast by Monday and Tuesday,
leading to much cooler weather with breezy conditions across the
mountains and deserts.

&&

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

Low clouds have diminished leading to mostly clear skies across
the region this afternoon. Temperatures have made it into the
lower 80s for the Inland Empire and lower 90s across the lower
deserts. Low clouds will reform this evening, but the marine layer
will become more shallow. This will lead to better chances for fog
near the coast and adjacent valleys, best chance over higher
terrain. The high will expand on further by Friday as 850 mb rise
another 3-5 degrees. NBM probabilities show around a 30-50% chance
of seeing triple digit heat across the Inland Empire by Friday as
highs in the upper 90s are expected. Triple digit heat will be
likely across the lower deserts with highs near 100 to 105
degrees. By Friday night into Saturday morning, there is still
some uncertainty of cloud cover near the coast as the marine
thins out. Some patchy fog may occur by Saturday morning.

Saturday will be the warmest day of the upcoming week as the area
of high pressure peaks in intensity. NBM probabilities of seeing
triple digit heat rise near 50 to 90 percent. Other areas east of
the 15 in the San Diego valleys have around the same chances in
seeing highs of at least 95 degrees. Sites that may see record
breaking heat for the day will be Palomar Mountain, Ramona, San
Jacinto, Borrego Springs, and Anaheim. The area of high pressure
pushes to the east by Sunday as a trough begins to dig southward
along the West Coast. This will bring cooling, but there still is
some uncertainty on how cool we become by Sunday as 850 mb temps
stay elevated as well as NBM percentiles showing a greater spread.
NBM was used for the forecast but changes will be made as the time
gets closer.

Confidence is growing that this trough digs fairly deep across the
state of California by Monday and Tuesday. From Sunday to Monday,
the region will cool off around 5 to 15 degrees with highs nearing
average for this time of year. The trough becomes deepest by
Tuesday, which will lead to the coolest day overall next week with
highs in the 60s and 70s for the lower elevations with 40s and 50s
across mountain communities. The trough axis passes through
Tuesday, but a troughing pattern will remain leading to highs near
to slightly below average. As the trough moves into the area
Monday and Tuesday, expect winds to increase across the mountains
and deserts with low to moderate probabilities in seeing
widespread wind gusts over 40 mph.

&&

.AVIATION...
082030..Coasts/Valleys...Low clouds have largely cleared this
afternoon, though a few clouds have stuck around the beaches of
south San Diego County. These clouds (currently based at ~600-900ft
MSL) will fill back in after 06-07z Friday, with lower bases. These
bases could be closer to 400-800ft MSL with about 5-10 miles of
inland extent. Greatest VIS obscurations along coastal mesas and
inland higher terrain though the immediate coast could see VIS down
to 2-4SM. Scattering to the beaches 15-17z Friday morning.

Otherwise...mostly clear and VFR conditions are expected today and
tonight.

&&

.MARINE...
Low clouds and patchy fog may bring visibilities to 2-4 SM over the
waters tonight into Friday morning. Otherwise, no hazardous marine
conditions are expected through Tuesday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory from 10 AM Friday to 9 PM PDT Saturday for San
     Bernardino and Riverside County Valleys-The Inland Empire.

PZ...None.

&&

$$

PUBLIC...APR
AVIATION/MARINE...Munyan