055
FXUS66 KSGX 110937
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
237 AM PDT Sun Aug 11 2024

.SYNOPSIS...
Slightly cooler today with continued chances of thunderstorms
over the mountains and deserts. Lower thunderstorm chances on
Monday with any activity limited to the mountains. Drier with
near normal temperatures Tuesday through the end of the week.
Patchy low clouds and fog will gradually increase for the coastal
areas each night and morning.

&&

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

Low clouds remain off the coast this morning and will be patchy at
best at the beaches later this morning. Elsewhere there are
scattered high clouds developing ahead of the upper low to our
south. A gulf surge is well underway with dew points climbing
into the low 70s across the Imperial and Coachella Valleys.

The upper low and associated inverted trough will slowly move
across the Baja Peninsula today. While Precipitable Water doesn`t
change much, this wave should help increase instability due to
minor cooling aloft. Hi-res guidance continues to show more
widespread and stronger convection along the mountains and
locally into the deserts this afternoon, which could produce
locally heavy rain, gusty winds, and lightning. Precipitation
chances were increased to around 25-40 percent for the mountains
and 20-25 percent for the deserts this afternoon and early
evening. Otherwise today will be much cooler, especially in the
low deserts, with highs near seasonal normals.

Mid and upper level flow begin to turn westerly on Monday,
bringing drier air in. There may be just enough residual moisture
for isolated convection over the mountains, but chances are much
lower - generally around 10-20 percent. A weak trough pushes
through CA on Tuesday, which will continue the drying trend and
bring breezy west winds to the mountains and deserts during the
afternoon and evening. The weather pattern for much of the week
can be described as weak troughing to our north pushing into the
weak upper high over the East Pac that extends into So Cal. By the
weekend the ridge gets pushed west as more amplified troughing
develops along the West Coast. This will maintain high
temperatures near normal through the week with minor cooling
Friday into next weekend. The marine layer will gradually rebuild
with areas of night and morning low clouds and fog along the coast
and extending locally into the far western valleys.

&&

.AVIATION...
110930Z...Coast/Valleys...Mostly clear skies with some FEW-SCT
clouds near 20K ft MSL through early morning. Low clouds based near
700-1100 ft MSL offshore may impact coastal TAF sites between 12-16Z
this morning with low confidence on exact coverage. If clouds do
come ashore, local VIS 3-5 miles on higher terrain will occur. 10%
chance of ISO TSRA drifting into foothills and adjacent valleys west
of the mountains this afternoon; highest chance in SD County.

Low cloud coverage confidence higher (50-70%) in cigs reaching
coastal TAF sites later tonight, mainly after 06Z Mon based near
1000 ft MSL.

Mountains/Deserts...SCT-BKN clouds with bases around 10,000 ft MSL
develop after 16Z, followed by a 20-35 percent chance of TSRA
between 19Z Sunday and 03Z Monday. Gusty and erratic winds possible
near storms as well as MOD UDDFS.

&&

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

&&

.SKYWARN...
Skywarn activation is not requested at this time but may be needed
this afternoon. Weather spotters are encouraged to report
significant weather conditions.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...SS
AVIATION/MARINE...APR