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000
FXUS66 KSGX 142027
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
127 PM PDT Sun Apr 14 2024

.SYNOPSIS...
A cold upper level storm will bring scattered showers to southern
California during Sunday afternoon and evening with additional
mountain snowfall. The last of the showers will occur in San
Diego county overnight. Dry and much warmer weather is forecast
Monday through Thursday under an upper level ridge of high
pressure. The warmest day is expected on Wednesday before a weak
weather system arrives for late week.

&&

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

The incoming upper trough synoptic lift is leading a band of
showers across the San Bernardino and San Gabriel mountains and
extending south across Orange County and the western Inland
Empire.

The main upper level low trough axis will swing through late this
afternoon and will bring 2 main rounds of showers with increasing
cold air aloft. There is up to 150 Joules of CAPE for the Inland
Empire and High Desert this afternoon with the main vorticity
maximum tracking through so an isolated thunderstorm especially
along the foothills in the San Gorgonio Pass this evening in the
better low level convergence areas through 9 pm. Otherwise the
last of the showers occur in San Diego county overnight in
northwest flow and also snow showers in the San Bernardino
mountains and rain showers into the Banning Pass into mid evening.
Winds already increasing this afternoon, mainly in the deserts
where gusts to 35 mph are expected in the Coachella Valley into
this evening with the weather system passage. Yesterday brought a
trace to 2 inches from 5000 to 7000 feet in the San Bernardino
mountains. An another shot of -6C air temperature at 700 mb this
afternoon and evening so snow level will briefly dip to 4500 to
5500 feet in the scattered showers for the San Bernardino and San
Jacinto mountains but a trace of snow over Palomar mountain is
possible. Coldest air stays across San Gabriel mountains and moves
west to east versus south.

Overall, northern areas will have stronger showers and much
greater coverage of precipitation today and late this afternoon
and early evening due to the track of the upper low cold pocket
and dynamics late afternoon. The last of few showers in cyclonic
cold flow ends early Monday morning in San Diego County.

Rapid warming of the air mass for Tuesday and Wednesday, reaching
14-17C at 850 mb by Tuesday afternoon and northerly flow due to a
weak short wave sliding through. Inland temperatures will soar
into the 90s for deserts with 18-20C at 850 mb level and hold
into next weekend. The far inland valleys will also warm rapidly
with 80s for Tuesday and Wednesday and very mild in surrounding
mountains.

NWP has a weak Pacific upper trough arriving late Thursday which
brings increasing southwest wind flow and cooler temperatures for
the coast and inland valleys and mountains, not much change for
lower deserts.

&&

.AVIATION...
142010Z...Coast/Valleys...Multiple cloud layers with SCT-BKN 2000-
3000 FT MSL and BKN-OVC 4000-6000 FT. -SHRA across Orange/San
Bernardino Co will spread farther S-E this afternoon. Reduced cigs
of 1000-2000 FT MSL and vis of 2-4 SM in -SHRA. Iso TSRA across
northern areas through 23z Sun. Gusty and erratic winds possible
vcty TSRA.

Mountains/Deserts...Local mountain terrain obscurations will
continue today. -SHRA/-SHSN with bases 3000-5000 FT MSL through
tonight. Gusty W-SW winds over/east of mtns, peaking 22z Sun-08z Mon
with winds of 20-30 kt, gusts of 40-50 kt. Areas of up/downdrafts
and LLWS over/east of mtns.

&&

.MARINE...
Scattered showers and northwest wind gusts up to 20 knots will
occur this afternoon and evening over the coastal waters.

&&

.SKYWARN...
Skywarn activation will not be needed today.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Weather Advisory until 8 PM PDT this evening for San
     Bernardino County Mountains.
&&
     Wind Advisory until 2 AM PDT Monday for Riverside County
     Mountains-San Diego County Deserts-San Diego County
     Mountains-San Gorgonio Pass Near Banning.

PZ...None.

&&

$$

PUBLIC...Tardy
AVIATION/MARINE...EA