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729
FXUS66 KSGX 050953
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
253 AM PDT Sun May 5 2024

.SYNOPSIS...
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A period of mostly light rain will move through the region
through the late morning followed by a mostly cloudy cool day
and a chilly night with gradual clearing. Gusty winds will
continue especially in the mountains and deserts through this
evening. Dry weather with slow warming will prevail most of next
week.
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&&

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

.SHORT TERM (Today-Tuesday)...
Scattered light showers have developed across portions of the
forecast area this morning. So far rainfall totals have mostly
been less than one-tenth inch for the coasts and valleys, and a
few stations in the San Bernardino Mountains have already picked
up over one-third inch. The band of showers will gradually shift
south and east through the morning as the cold front moves
through. Rainfall totals remain relatively unchanged - around
0.05-0.25" from the coasts to the foothills and 0.25-0.50" in the
mountains with isolated amounts near 0.75" on the south slopes of
the San Bernardino Mountains. Little if any accumulation is
expected in the deserts. A light dusting of snow is possible
above 7000 ft. Gusty west winds will continue in the mountains and
deserts this afternoon with strongest gusts around 40-50 mph,
diminishing tonight.

Once the front moves through, the remainder of the day will be
partly cloudy and cool. Highs will be a solid 15-20 degrees below
normal inland with the greatest departure in the mountains and
high desert. This means highs in the 60s for the coastal areas and
valleys, 40s in the mountains, upper 50s to low 60s in the high
desert, and mid to upper 70s in the low deserts.

The upper level low moves out on Monday with drier northwest flow
into Tuesday. Monday will be significantly warmer, followed by
minor warming on Tuesday, though still a few couple degrees below
normal. Breezy west winds develop in the mountains and deserts
each afternoon into late night, though are forecast to remain
below advisory strength. Some patchy marine layer low clouds will
develop along the coast each night, especially on Tuesday with the
development of a coastal eddy. The marine inversion will be fairly
weak though, so expect decent clearing each day even at the coast.
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&&

.LONG TERM (Wednesday-Saturday)...
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Minor warming continues into Wednesday as we remain under weak
cyclonic flow wedged between the upper ridge off the West Coast
and a large upper low over the northern Great Plains. Both
deterministic and ensemble models are coming into better agreement
with the evolution of this pattern into the latter half of the
week. A positively-tilted short wave on the back side of this low
will amplify late Wednesday, eventually splitting from the parent
low and retrograding southwestward into Thursday and Friday.
There is the potential for weak offshore flow Wednesday morning as
the short wave drives south and surface high pressure begins to
build over the Great Basin.

There are still differences in the placement and strength of the
low late in the week, resulting in increasing spread in the
temperature forecast. Since models have trended to the further
west solution, forecast now has temperatures remaining fairly
steady/not as warm for the latter half of the week. Marine layer
low clouds will continue for the coastal areas and portions of the
valleys each night and morning, potentially deepening and
spreading further inland next weekend if the upper low continues
to drift west or southwest as some ensemble members and the
deterministic models suggest.
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&&

.AVIATION...
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050930Z...Coasts/Valleys/Foothills...Low clouds cover the region
west of the mtns this morning, with bases in one layer SCT-BKN 1500-
2500 FT MSL, and another BKN-OVC 2500-4000 FT MSL. VIS reduced to 1-
3SM where low clouds and terrain intersect, obscuring higher
terrain. Scattered -SHRA will move across the region from northwest
to southeast through 21Z. Briefly lower CIGs and slightly reduced
VIS down to as low as 3SM in -SHRA. Gradually clearing after 18-20z.

Mountains/Deserts...Strong W-SW winds will continue to weaken this
morning, then decreasing through the rest of the night. Expect
another round of strong W-SW winds 20-35 kt with gusts of 45-60 kt
after 18Z. Areas of MOD-STG up/downdrafts and LLWS over/east of mtns.
SCT-BKN clouds at/abv 10000 ft MSL through this evening.
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&&

.MARINE...
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Northwest winds gusting 25 to 30 knots will continue through into
this evening, which will generate hazardous boating conditions,
especially in the outer waters. Northwest winds gusting up to 20
knots will be possible over the outer waters each afternoon and
evening for Monday through the middle of next week.
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&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
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CA...Wind Advisory until 8 PM PDT this evening for Apple and Lucerne
     Valleys-Coachella Valley-Riverside County Mountains-San
     Bernardino County Mountains-San Diego County Deserts-San
     Diego County Mountains-San Gorgonio Pass Near Banning.

PZ...Small Craft Advisory until 10 PM PDT this evening for Coastal
     Waters from San Mateo Point to the Mexican Border and out
     to 30 nm.

     Small Craft Advisory until 3 AM PDT Monday for Waters from San
     Mateo Point to the Mexican Border Extending 30 to 60 nm out
     including San Clemente Island.
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&&

$$

PUBLIC...SS
AVIATION/MARINE...PG