450
FXUS66 KSGX 170425
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
930 PM PDT Sun Jun 16 2024

.SYNOPSIS...
Areas of smoke will occur at least through Monday, mostly due to the
Post Fire in the far northwest part of Los Angeles County.
Otherwise, near to slightly below average temperatures will occur
through the middle of the week as a trough of low pressure stays
over the western US. This will also bring breezy conditions to the
mountains and deserts along with greater low cloud coverage west of
the mountains. High pressure will reemerge later this week, leading
to above average temperatures away from the coast again.

&&

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

Update...

Areas of smoke covered the area due to several wildfires, with the
Post Fire of extreme NW LA County being the most substantial one at
over 14000 acres burned. Local west winds were gusting over 35 MPH
in the mountains and deserts, with Whitewater West RAWS in San
Gorgonio Pass registering 59 MPH around 7 PM. Areas of coastal low
clouds were occurring as well, but otherwise fair weather prevailed.
Inversion base of 1500-2000 ft MSL should allow at least some of the
low clouds to make it into the valleys overnight. NKX sounding and
surface observations showed dry air above that marine inversion, and
a few locations had minimum RHs around 10 percent or even a little
less today in the mountains and deserts. Unfortunately, north to
northwest winds will continue in LA County and bring the smoke into
our area through Monday, though HRRR Smoke model shows at least a
decrease in the near-surface decreasing near the coast with the sea
breeze early Monday afternoon, but smoke aloft will continue to
bring hazy conditions. Monday should be the coolest day this week
under the influence of the trough with slow warming on successive
days even though troughiness remains through at least around
Thursday.

From previous discussion...

Though the trough axis pushes east into the Northern Plains by the
middle of the week, the troughing pattern will persist across the
West. This is due to an amplified ridge that will build in across
the eastern part of the country this week. While the heat turns up
across the East, temperatures will be near to slightly below average
here in Southern California. The marine layer will also be deeper,
leading to greater low cloud coverage each night and morning for
areas near and adjacent to the coast and locally into the Inland
Empire. Minor day to day changes are expected in the weather pattern
per latest model ensembles Tuesday through Thursday.

The trough will weaken by Friday as high pressure expands into the
desert southwest per latest cluster model guidance. Confidence is
moderate to high that this will bring more warmer weather Friday
into the weekend. NBM guidance shows not too much spread in
ensembles, so this guidance is agreeable. Highs will start to
climb near 5 to 10 degrees again by next weekend with a shallower
marine layer.

&&

.AVIATION...
170315Z...Coast/Valleys...Low clouds increasing in coverage near the
coast at this hour. Bases are 1400-1700 ft MSL and tops are around
2200 ft MSL. CIG impacts currently only at KSAN but CIG impacts
likely at KCRQ and KSNA around 06Z-08Z. Bases will likely stay above
1000 ft MSL and rise to near 2000 ft MSL after 12Z. Low clouds will
spread 20-25 miles inland by 13Z obscuring higher terrain, with VIS
1-3SM where clouds and terrain intersect. There will be a 40-50
percent chance for CIGs at KONT and about a 30-40 percent chance at
KSBD 12Z-15Z. Expect inland clearing 15Z-17Z and clearing to the
coast 17Z-19Z

Mountains/Deserts...SKC with unrestricted VIS through tonight. W-SW
wind gusts of 20-35 knots, strongest through late tonight. WK-MOD
up/downdrafts over/E of mtns.

&&

.MARINE...
Northwest wind gusts up to 20 knots will be possible in the outer
waters again Monday afternoon. Otherwise, no hazardous marine
conditions are expected through Friday.

&&

.BEACHES...
A combination of a west swell of around 5 feet/9 seconds in the
outer waters and south swells of around 2 feet/16 seconds on Monday
will bring surf of 3-6 feet along with a high rip current risk
through Monday. The surf and rip current risk will gradually lower
on Tuesday.

&&

.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 Monday evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...Maxwell (Update)/APR (Previous Discussion)
AVIATION/MARINE...PG