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000
FXUS66 KSGX 110436
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
936 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...

.Evening Update...
Patchy low clouds and fog have developed along parts of the San
Diego County coast. Based on coastal webcams fog does not appear
to be dense at this time. The 00Z KNKX sounding shows the marine
inversion based near 1100 ft. As low clouds push inland overnight,
there could be localized dense fog over the higher coastal terrain
and on the coastal mesas in both San Diego and Orange Counties.
Elsewhere skies will remain clear with light winds across the
region tonight.

&&

.SHORT TERM (Thursday through Friday)... 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...
110430Z... Patchy coastal low clouds and fog returns to the beaches
tonight, reaching coastal TAF sites around 04Z then spreading 5-10
miles inland by 14Z. Expect clearing back to the beaches by 18Z
Thursday. 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...SS/APR
AVIATION/MARINE...Suk