Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 230456
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
856 PM PST Thu Feb 22 2018

.SYNOPSIS...
Small chances of light showers will continue through early Friday
morning. Brisk winds are also likely in the mountains and
deserts overnight before subsiding. The weekend looks fair before
low pressure returns next week for cold weather and showers.

&&

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

A shortwave embedded within the longwave trough over the western
U.S. will continue diving south and across Southern California
through Friday. As it does so, a few showers will continue, mainly
from the coast to the mountains through Friday morning. Snow
levels will drop to around 3500 ft overnight. A few hundredths of
an inch of precip is expected, with a few tenths of accumulating
snow possible in the mountains. The approaching trough will create
breezy west to southwest winds across the mountains and deserts
through 10 AM Friday morning. A Wind Advisory remains in effect
through the period for gusts of 40-50 mph.

Somewhat warmer weather is expected this weekend, with highs
closer to seasonal normals under northwest flow aloft. Breezy east
to northeast winds will develop overnight Friday and Sunday
nights near the coastal mountain slopes and through mountain
passes, however a quick burst of westerly winds over the mountains
and deserts is expected Saturday night as a trough digs across
the area. Strongest gusts of 45-55 mph are expected with the
trough passage Saturday evening.

Another deeper trough is forecast to move across the area late
Monday through Tuesday. Precip amounts are still uncertain at this
time as the 12Z ECMWF is around 0.50 inches wetter than the GFS.
Latest models show a break in the precip Wednesday afternoon
through Thursday afternoon, then a deeper trough heads our way for
Friday and Saturday of next week. Atmospheric moisture might be in
better supply for this system, so the potential for greater
precipitation accumulations are there. Gusty west to southwest
winds will also likely develop along the mountains and deserts
from the trough, with snow levels starting around 5000 ft.

&&

.AVIATION...
230420Z...SCT-BKN clouds and ISOLD -SHRA through Fri morning. Cloud
bases will be 2500-4000 ft MSL with tops to 8000 ft MSL with
occasional obscurations in the mountains. Showers ending by late Fri
morning with gradually clearing through the afternoon.

SW to W surface winds will increase tonight and continue through Fri
morning with areas of 20-30 kt winds and 35-45 kt gusts along the
desert mountain slopes and east of passes. UDDFS/LLWS/rotors will
occur at times over and east of the mountains through Fri morning,
including VCNTY KPSP. Winds will weaken Friday afternoon and evening.

&&

.MARINE...
West to Northwest winds 20-25 kt with gusts to 30 kt and combined
seas up to 8-9 ft with steep waves will develop later this evening
and continue through Friday evening. This will create hazardous
boating conditions. A Small Craft Advisory remains in effect through
8 PM Friday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 10 AM PST Friday 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 8 PM PST Friday for Coastal Waters
     from San Mateo Point to the Mexican Border and out to 30 nm-
     Waters from San Mateo point to the Mexican Border Extending
     30 to 60 nm out including San Clemente Island.

&&

$$

PUBLIC...Gregoria/JJT
AVIATION/MARINE...SS



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