738
FXUS66 KSGX 091022
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
322 AM PDT Wed Apr 9 2025

.SYNOPSIS...
Areas of late night and early morning low clouds and locally dense
fog will continue near the coast through Friday. High pressure
aloft will continue the warming trend through Friday with high
temperatures on Friday as much as 15 to 20 degrees above average
for inland areas. High pressure aloft will weaken and onshore flow
strengthen for the weekend into next week. This will spread
cooling inland with high temperatures for coastal areas cooling to
around average on Sunday with high temperatures for the deserts
still around 5 degrees above average through Tuesday. The marine
layer will deepen over the weekend with coastal low clouds
spreading farther into the valleys.

&&

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

.SHORT TERM (Today through Friday)...
High pressure aloft will continue the warming trend through Friday
with high temperatures on Friday as much as 15 to 20 degrees above
average for the mountains, inland valleys, and high desert. High
temperatures on Friday will range from around 70 near the coast
to the mid 80s to lower 90s for the Inland Empire with the lower
deserts reaching 98 to 104. NBM chances for Palm Springs to break
the existing high temperatures of 101 for Thursday and for Friday
are 69 percent on Thursday and 92 percent on Friday.

A marine layer less than 1000 feet deep will become a little
shallower into Friday morning. Satellite imagery and surface
reports show areas of low clouds and locally dense fog covering
the inner coastal waters of San Diego County and extending
locally inland along the coast. A version of the WRF with GFS
boundary conditions and a horizontal resolution of 600 meters
shows the low clouds eventually filling in across much of the San
Diego County coastal zone where a Dense Fog Advisory has been
issued through 9 AM. Low clouds and locally dense fog could also
develop this morning in southern Orange County near the coast and
in northern Orange County inland to around Interstate 5.

&&

.LONG TERM (Friday night through Tuesday)...
A coastal eddy is expected to develop on Friday night with some
deepening of the marine layer for Friday night into Saturday
morning. Greater coverage of low clouds and fog is expected with a
little greater inland spread, into the far western valleys. There
may be little or no clearing on Saturday with the low clouds
spreading into the inland valleys for Saturday night into Sunday
morning as the marine layer continues to deepen.

High pressure aloft will weaken and onshore flow strengthen for
the weekend into early next week. This will spread cooling inland
with high temperatures for coastal areas falling to around average
on Sunday with high temperatures for the deserts still around 5
degrees above average on Tuesday.

&&

.AVIATION...
090930Z...Coast...Low clouds and fog will gradually cover most
coastal areas by 14Z. Cloud bases will be 200-300 feet MSL with
tops to 400 feet MSL with VIS 0-2SM in FG. Scatter out by 15-17Z,
with some lingering low clouds/fog at the beaches thereafter. A
similar low cloud and fog scenario will repeat tonight after 08Z
into Thursday.

Otherwise...mostly clear skies with unrestricted VIS today and
tonight.

&&

.MARINE...
Areas of fog with visibility 1 NM or less this morning. Otherwise,
no hazardous marine conditions are expected through Sunday.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Dense Fog Advisory until 9 AM PDT this morning for San Diego
     County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE...MM