Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 261651
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
951 AM PDT Thu Apr 26 2018

.SYNOPSIS...
Gradually cooler through the weekend, with increasing low clouds
spreading inland to the coastal mountain slopes. Expect stronger
onshore flow with strong and gusty southwest to west winds in the
mountains and deserts during the afternoons and evenings. For
Monday and Tuesday...cooler with stronger onshore flow and gusty
northwest to west winds in the mountains and deserts, further
deepening of the marine layer with small chances for light
precipitation along and west of the mountains.

&&

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

This morning...the marine layer is about 1600 ft deep and
overnight low clouds and fog had spread about 20 miles inland,
reaching the foothills. Clearing is now progressing from the
inland edges toward the coast and sunny skies are expected at the
coast by 11 am, although some low clouds could linger at the
beaches into the afternoon.

A low pressure system currently off the coast of northern CA/OR
will move slowly inland during the weekend. This will bring
stronger onshore flow to Southern California with slow cooling
spreading inland.

That low pressure system will draw subtropical moisture with some
mid and high clouds into Southern California today...decreasing tonight
and Friday. As the marine layer slowly deepens...night and
morning low clouds and fog will spread inland to the coastal
slopes Friday through the weekend. Stronger onshore flow will
also bring periods of gusty southwest to west winds in the
mountains and deserts during the afternoons and evenings.

For early next week...the global models are in better agreement
with a low pressure system from the northwest that will move into
Southern California Tuesday. This will bring additional cooling
for Monday and Tuesday. There will be stronger and gusty
northwest to west winds in the mountains and deserts. The marine
layer will deepen onto the coastal mountain slopes. There are
small chances for light precipitation west of the mountains early
Monday and slightly greater chances for light precipitation along
and west of the mountains for Tuesday into early Wednesday.

For next Thursday and Friday...An upper level ridge building in
from the west will bring fair and warmer weather with lighter
winds and a shallower marine layer.

&&

.AVIATION...
261630Z...Coast/Valleys...The 12Z KNKX Miramar sounding showed an 8
deg C marine layer inversion. Stratus, with bases from 1500-2000 ft
MSL and tops to 2500 ft MSL, will continue to clear to the coast
this morning. Low VIS of 3-5 SM HZ will improve to P6SM by early
afternoon, with VFR conditions expected through early this evening.
Low clouds, with slightly higher tops and bases, will redevelop
along the coast this evening, and push into the far inland valleys
by late tonight.

Mountains/Deserts...Local surface west northwest wind gusts of 30-40
kt will occur late this afternoon through tonight over portions of
the desert mountain slopes and through San Gorgonio Pass.

&&

.MARINE...
No hazardous marine conditions are expected through tonight.
Stronger onshore flow will create gusty westerly winds which could
cause choppy and hazardous seas Friday through Monday, mainly in the
outer waters. A Small Craft Advisory may be needed through the
period.

&&

.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...PG
AVIATION/MARINE...JJT



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