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000
FXUS66 KSGX 101946
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1246 PM PDT Wed Apr 10 2024

.SYNOPSIS...
Dry and warmer weather will occur through Thursday with a building
marine layer and high temperatures near 10 degrees above average
for inland areas. An area of low pressure will move toward the
region by Friday, bringing cooler temperatures and gusty mountain/desert
winds. As the system moves over SoCal this weekend, winds will
continue for inland areas along with the highest chance for
precipitation along and west of the mountains. Subtle warming and
drying will occur by early next week.

&&

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

.SHORT TERM (Today through Friday)...
Plentiful 70s to lower 80s are seen around the lunchtime hour for
areas west of the mountains into some foothill locations. GOES
imagery features clear skies over SoCal with low clouds pushing
westward between San Clemente Island and San Diego. Confidence is
moderate to high that these low clouds impact coastal areas
sometime this evening into Thursday morning, where some spots may
see foggy conditions with visibility near one mile. The area of
high pressure that has maintained our warm and dry weather will
weaken and start to slip to the south by Thursday, providing one
last day of warmth across the area. Many inland valleys and the
high desert will reach into the 80s by the afternoon hours. NBM
output gives a low to moderate chance for some areas of the Inland
Empire to reach 90 degrees.

An area of low pressure currently over the Gulf of Alaska will
push southward along the West Coast over the next few days. This
will bring cooler and windier weather to the area by Friday. Many
areas will drop 5 to 10 degrees from Thursday to Friday, with only
a low chance of the Inland Empire seeing highs in the 80s. The
Coachella Valley and Anza Borrego Desert regions will hang onto
one more day of warm weather with highs near 90 degrees.
South/southwest winds will also increase across the mountains and
deserts during this time period as the surface pressure gradient
increases. Windiest areas will be along mountain desert slopes
into the deserts. This wind direction will favor areas of the high
desert and adjacent slopes to see the highest winds with a
moderate to high chance of seeing wind gusts over 35 MPH according
to latest NBM probabilities and ECMWF/GFS ensemble members.

&&

.LONG TERM (Saturday through Early Next Week)...
The onset timing of the of the precipitation this weekend is
becoming more clear with chances increasing by Saturday morning,
with highest chances on Saturday afternoon and night. The exact
track of the low pressure system is still in question as well as
how the long the system will hang around the region. ECMWF/GFS
guidance shows another second low forming and rotating around the
weekend system, which may produce more light showers as we head
into Sunday, while the Canadian has the system moving quicker.
Slight chances of precip were left in the forecast through most of
Sunday to capture uncertainty. In any event, this will be a
lighter rain and high elevation snow event with low to moderate
(20-40% chance) probabilities for areas west of the mountains to
see one quarter inch of rain in total. Snow levels will start near
7,000 feet early on Saturday, falling throughout the day and
landing near 5,000 feet by Sunday. The heaviest snow will fall on
Saturday with near one inch of snow expected at Big Bear.

Ensemble cluster models depict a drier and subtle warming period
by early next week. There are still some timing differences on
when the storm system moves out (best chance late Sunday). A
ridge will try to push further east toward our area, but a trough
in Canada may slip south across the West, keeping the ridge over
the ocean. Dry weather looks certain but how warm or windy we
become by next week is still yet to be seen.

&&

.AVIATION...
101935Z...Clear skies with unrestricted VIS will continue this
afternoon. Patchy coastal low clouds and fog returns to the beaches
around 00Z Thursday, reaching coastal TAF sites around 04Z then
spreading 5-10 miles inland by 14Z. Expect clearing back to the
beaches by 18Z. Bases would be 300-700 feet MSL with vis 1-5SM.

&&

.MARINE...
Patches of fog with VIS 1 nautical mile or less near the coast
tonight. 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...None.
PZ...None.

&&

$$

PUBLIC...APR
AVIATION/MARINE...PG