829
FXUS66 KSGX 161049
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
349 AM PDT Mon Sep 16 2024

.SYNOPSIS...
Well below average high temperatures will continue through
Thursday with chances for light precipitation from the coast to
the mountains, greatest this morning and again for late Wednesday
into Thursday. There will be stronger and gusty southwest to west
winds for the mountains and deserts for this afternoon and evening
with gusts of 35 to 45 mph and strongest gusts in the northern
Coachella Valley below the San Gorgonio Pass of 60 to 70 mph. Then
dry and much warmer for Friday through next weekend as high
pressure expands across California.

&&

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

.SHORT TERM (Today through Wednesday)...
The center of a low pressure system along the West Coast will move
from central California into Nevada today with a second low
pressure system moving southward along the West Coast on
Wednesday.

It will be much cooler today for inland areas with coastal areas
as few degrees cooler than Sunday with the mountains and high
desert 10 to 15 degrees cooler with high temperatures for the
mountains, high desert, and inland valleys 20 to 25 degrees below
average. High temperatures on Tuesday will be as much as 5 to 10
degrees warmer for the mountains, but with high temperatures for
the valleys and mountains still 15 to 20 degrees below average.
Only slight differences in high temperatures are expected on
Wednesday.

The marine layer has deepened to around 5500 feet with widespread
coastal low clouds extending well inland and onto the coastal
mountain slopes. Light precipitation is possible from the coastal
waters inland and onto the coastal slopes of the mountains with as
much as a few tenths of an inch of rainfall possible along the
coastal slopes of the San Bernardino County mountains. There are
lesser chances for some light precipitation again for late tonight
and again for Wednesday morning.

There will be stronger onshore flow today with stronger and gusty
southwest to west winds for the mountains and deserts for this
afternoon and evening with gusts of 35 to 45 mph and strongest
gusts in the northern Coachella Valley below the San Gorgonio Pass
of 60 to 70 mph.

&&

.LONG TERM (Thursday through Sunday)...
The next low pressure system from the north will move southward
along the coast of northern and central California on Wednesday
and inland through central and southern California on Thursday.
This will bring another chance for precipitation from the coastal
waters inland to the mountains for Wednesday night into Thursday.

For Friday through next weekend, the low pressure system over the
southwest states will weaken and move east with high pressure
over the eastern Pacific moving across California. High
temperatures will be several degrees warmer for Friday and
Saturday with high temperatures for next Sunday warming to a few
degrees above average for the deserts to around 5 degrees above
average for the coast and valleys, mostly in the 90s for the
inland valleys and 100 to 105 for the lower deserts.

&&

.AVIATION...
160930Z...Low clouds with bases varying 2000-3500 feet MSL and tops
to 5200 feet will continue to shroud the coast to mountains,
including higher terrain obscured in BR. -RA or -DZ likely anywhere,
but most likely in foothills under these clouds through 18Z.
When/where this precip occurs, vis could be reduced 0-5SM and cigs
drop to 1500 feet MSL. Partial scatter out more likely at coast
starting at 19Z and working inland, probably not scattering out much
if at all in far inland valleys. Low clouds and fog to fill in the
entire coastal basin again tonight into Tuesday, but with bases/tops
a few hundred feet lower.

Smoke from the Line, Bridge and Airport fires will continue to
reduce VIS in mountains, with hazy conditions over the Inland Empire
and parts of the deserts.

West-northwest winds will gust 40-50 knots through mountain passes,
continuing into tonight. Local moderate up/downdrafts in lee (east)
of mountain ridges.

&&

.MARINE...
No hazardous marine conditions are expected through Friday.
Although, northwest gusts around 20 knots are expected in the outer
waters this afternoon and evening and again Wednesday afternoon and
evening.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 9 PM PDT this evening for Apple and Lucerne
     Valleys.

     Wind Advisory from 11 AM this morning to midnight PDT tonight
     for San Diego County Deserts.

     Wind Advisory until midnight PDT tonight for San Gorgonio Pass
     Near Banning.

PZ...None.

&&

$$

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