000
FXUS66 KSGX 041634
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
934 AM PDT Sun Jun 4 2023

.SYNOPSIS...
Warm conditions inland today will continue before a widespread
cooling for the first half of the week. Marine layer low clouds and
fog will continue to be present for the foreseeable future for the
coast and valleys. Periods of breezy winds Monday in the mountains
and desert mountain slopes. There is a slight chance for some
convective showers to develop over the mountains and high deserts
during the first half of the week, and more patchy drizzle
possible over the coastal basin.

&&

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

Key Points:
*Below average temperatures next week from the coast to the deserts.
*Slight chance of thunderstorms in San Bernardino County mountains
 and deserts Mon-Wed.

Clouds filled in the coastal basin overnight. The marine layer
was shallower than it was yesterday morning but the inversion was
stronger today, hitting 10 degrees Celsius. Clouds should clear
out of much of the valleys by the afternoon but lower confidence
in complete clearing near the coast today. If it does clear at the
coast, it`ll likely be partial and short-lived. Highs today are
expected to be a few degrees warmer than yesterday away from the
coast with temperatures similar to a few degrees cooler at the
coast.

A trough of low pressure will position itself near central/Southern
California for the first half of the week. The increased onshore
flow will deepen the marine layer, bring gusty west winds to the
mountains and deserts slopes, and bring cooler conditions. After
today, highs for inland locations are expected to take a nose-dive
with Tuesday expected to be the coolest day of the week. Highs are
expected to be 10 to 15 degrees below average away from the coast on
Tuesday. As the low pressure system moves east for the second half
of the week, temperatures will slowly moderate but below average
temperatures are expected to continue into next weekend.

Gusty westerly winds are expected to increase tonight and continue
into Tuesday, peaking in strength on Monday. Winds will be strongest
through passes and on desert mountain slopes. Peak gusts of 40 to 50
mph expected.

The marine layer will deepen for the first half of the week. Areas
of drizzle are possible in the mornings west of the mountains.
Additionally, the incoming low may bring enough moisture and
instability to spark some thunderstorms, mainly in San Bernardino
county. Right now there is a 10-20% chance of thunderstorms
occurring over the San Bernardino County mountains and into parts
of the higher desert each afternoon Monday-Wednesday.

The mid-level pattern stays trough-y into next weekend. Global
models are hinting that another low may cut off over the region
next weekend, which would again deepen the marine layer. The
latest NBM guidance has very little deviation in temperatures day
to day for much of the region for the end of the week with
increased spread in high temperatures as we approach the end of
next weekend.

&&

.AVIATION...
041630Z...Coast/Valleys...Low clouds with bases 1500-2300 ft MSL and
tops to 2500 ft MSL will continue to clear in the valleys through
18Z with partial clearing near the coast 18Z-22Z. Local vis 3-5
miles will continue through 18Z in BR. Clouds will expand again
after 01Z Mon with bases 1500-2000 ft MSL and tops to 3000 ft MSL.
Slow clearing is likely Mon. Higher terrain will be obscured at
times.

Mountains/Deserts...Clear skies with unrestricted VIS will continue
through Monday. Gusty west winds will develop afternoon along the
desert slopes and through/east of San Gorgonio Pass with
local surface gusts 35-45 knots and associated MOD UDDFS.

&&

.MARINE...
No hazardous marine conditions are expected through Thursday.

.BEACHES...
A series of medium-to-long period south swells will bring elevated
rip currents at times this week, especially to more southerly-facing
beaches. Of particular note is a 4-foot, 16-second period swell
Wednesday, which should bring surf of 4 to 7 feet in Orange County.

&&

.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...CO
AVIATION/MARINE/BEACHES...Maxwell