San Juan Capistrano, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

198
FXUS66 KSGX 272130
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
130 PM PST Fri Dec 27 2024

.SYNOPSIS...
A low pressure system moving inland to the north today, will bring
gusty westerly winds to the mountains and deserts through this
evening, along with widespread marine layer low clouds and patchy
drizzle west of the mountains for this afternoon and evening. An
upper ridge will build from the southwest over the weekend. This
will result in mild days and a shallow marine layer with the
potential for dense fog in the coastal areas. Offshore flow will
likely develop for Tuesday through Thursday after another trough
of low pressure moves inland to the north.

&&

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

This afternoon...Low clouds now cover most of the region west of
the mountains. It produced periods of light rain/drizzle in the LA
Basin a few hours ago, and could produce the same in other areas
through this evening before the low clouds dissipate tonight. The
onshore flow is peaking at this time and the windiest locations in
the mtn passes have reported wind gusts of 55-65 mph during the
last hour. The winds are expected to weaken tonight as the low
pressure trough to our north moves off to the east.

From previous discussion...
By Saturday morning, the trough will have moved east and a ridge
of high pressure will build in from the southwest, covering most
of the western states. This will bring warmer conditions and make
the marine layer shallower which will increase the threat of fog
in the coastal areas Saturday morning and again Sunday morning.
Daytime high temperatures will be 5-10 degrees above normal
inland away from the marine layer influence, and as much as 17
degrees above normal in the high deserts on Sunday.

A more vigorous shortwave will move inland to the north late
Sunday/Monday, displacing the ridge southward and bringing another
period of stronger onshore flow with gusty westerly winds in the
mtns and deserts. It will also lower temps a little on Monday. A
third shortwave trough will move inland on Tuesday, reaching the
Great Basin by Wednesday. A surface high following this trough
will move into the Great basin and will likely bring Santa Ana
winds to SoCal. We can expect warm, very dry and windy conditions
for Wednesday through the end of next week with a ridge of high
pressure rebuilding over the western states. Northeast to east
winds will begin to develop on Tuesday and could last into
Thursday, but the timing and strength of this event remains
uncertain due to the spread in model solutions. Currently,
numerical model guidance indicates about a 30-35 percent chance
for a moderate Santa Ana event next Wednesday.

&&

.AVIATION...
272117Z...Coast/Valleys...Low clouds based 1200-2500ft MSL with tops
to 4000 ft MSL and areas of terrain obscurations with VIS down to
1/4SM. Periods of lower bases below 1000ft MSL possible at coastal
sites between 02z-10z Saturday along with DZ, with clearing of low
clouds occurring late Saturday morning.

Mountains/Deserts...Areas of westerly winds with gusts 25-40 knots
from the mountain crests east through the desert mountain slopes and
over high deserts. Terrain below 4500 ft MSL will be locally
obscured this evening due to clouds/fog. Otherwise, high clouds.

&&

.MARINE...
Long period west-northwesterly swells will continue through early
next week. Seas will be 5-9 feet in the outer coastal waters (30-60
NM from the coast) and 3-6 feet in the inner waters (within 30 NM).
Northwest flow will strengthen slightly late this afternoon, with
gusts around 20 knots near San Clemente Island. Otherwise, no marine
hazards are expected through Tuesday.

&&

.BEACHES...
Another long period (15 to 17 seconds) northwesterly (280-290
degree) swell of 4-6 feet arrives today and continues through
Sunday, decreasing Monday. Elevated surf of 4-7 feet is expected to
continue through early next week at San Diego County beaches with
local sets to 8 feet on west-northwest facing beaches. Minor coastal
flooding is possible in vulnerable areas during morning high tides
as tides will increase this weekend, coinciding with the elevated
surf. See the Beach Hazards Statement for more information.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Sunday afternoon for San Diego
     County Coastal Areas.

     Wind Advisory until 7 PM PST this evening for Apple and Lucerne
     Valleys.

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE/BEACHES...Small