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405
FXUS66 KSGX 230543
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
943 PM PST Fri Nov 22 2024

.SYNOPSIS...
An atmospheric river currently over Northern California shifts
southward on Saturday, increasing moisture and cooling
temperatures. Very light precipitation is expected as early as
Saturday night/Sunday morning, with slightly better chances for
rain Monday through Wednesday. Any rain will move out by late
Wednesday, with warmer and drier conditions returning for the end
of next week.

&&

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

.SHORT TERM...
No significant changes to the forecast this evening as the
anticipated low clouds associated with the marine layer move into
northern San Diego County.


Previous Discussion from 1 pm Friday November 22nd.

Warm weather and sunny skies prevail this afternoon and early
evening before a deepening and more widespread marine layer
develops tonight. While cloud bases will be slightly higher than
the previous night, inland spread will be up to 10 miles before
clearing occurs late Saturday morning. As the marine clouds clear
out, a surge of moisture and clouds will move southward into
Southern California ahead of a weakening atmospheric river which
has been slamming much of the West Coast the past several days. By
the time the AR pushes down on Saturday, the moisture and energy
within this system will begin to lessen, and only meager rainfall
is expected for the weekend. Areas further north, including some
of the mountains, will be the big winners with this next event,
seeing up to 0.50" of rainfall between Saturday and Sunday, and
locally higher amounts up to 0.75". Snow levels will remain high
through the weekend, primarily above 7000-7500ft, limiting what
precipitation may be seen as snow. The 10th percentile NBM puts a
bullseye over the San Bernardino Mountains with rain totals
nearing an inch Saturday night into Sunday morning. While rain
will exist outside of the mountains this weekend, only very light
amounts are expected, with totals generally less than 0.10". Other
than the rain, periods of strong gusts out of the west to
southwest will peak around 35-40 mph for the mountain peaks and
mountain passes, with some stronger gusts along the desert slopes
as well. These stronger winds will be short lived, generally
dissolving by early Sunday morning.

The ample cloud cover and increasing moisture will cool afternoon
highs this weekend and into early next week, with temperatures
generally 5-10 degrees below normal. Another surge of moisture looks
to arrive on Monday which may hang around through Wednesday,
potentially bringing additional precipitation chances to Southern
California. This next push looks better in terms of moisture amounts
and energy, but models differ on exact location and how far south
any rain will develop. If trends push some of the better moisture
down into the area, precipitation amounts may eclipse weekend totals
with the higher terrain receiving up to an inch of rain. However, if
the models maintain the current look of a moisture cut off around LA
county, the region may end up seeing nothing. Have gone ahead with a
drier solution on the rain amounts for early next week until better
alignment is observed between the global models. Regardless of how
the precipitation shakes out, the cooler weather will prevail until
mid week with lowering heights and cloud cover. By the end of the
week, weak riding should return to the area and temperatures will
slowly recover back to near normal.

&&

.AVIATION...
230500Z...Coast/Valleys/Coastal Mountain Slopes...Patchy low clouds
(largely based around 700-1000ft MSL) are starting to fill in
offshore, primarily off the San Diego County coast, with a few
patches of lower clouds nested in the northern San Diego County
valleys. These clouds should continue to fill in and push 15-20
miles inland through 12z. Local VIS reductions possible to 0-3 SM
possible at times in valleys and where clouds intersect higher
terrain.

Clouds should largely scatter out by 16-17z Saturday
morning, though KSNA and Orange County could see clouds linger
ahead of an incoming weather system. Expansive low-mid level clouds
(with bases varying from 1500-2500ft MSL) are expected to fill in
from northwest to southeast through 18-00z Saturday afternoon,
reaching up through the coastal mountain slopes. VCSH expected in
Orange County and the Inland Empire from 22-06z Saturday
afternoon/evening and 00-08z for San Diego County. Any precipitation
should stay relatively light and any VIS reductions would be brief
and as low as 3 SM.

Mountains/Deserts...Mostly clear skies and unrestricted VIS
expected through Saturday evening.

&&

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

&&

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


&&

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

&&

$$

PUBLIC...Suk
AVIATION/MARINE...Munyan