Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 221746
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
946 AM PST Thu Feb 22 2018

.SYNOPSIS...
Small chances of light showers will continue through early Friday
morning. Brisk winds are also likely this afternoon through
tonight, especially in the mountains and deserts. 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...

At 9 AM PST, water vapor satellite imagery displayed an upper-
level low centered over eastern Washington, with an upper-level
trough digging across northern California. Lower heights aloft
will continue a slight chance of light showers over and west of
the mountains today, with high temperatures 5-15 degrees below
normal. Snow levels will rise to 4000-5000 ft this afternoon. A
few hundredths of an inch of precip is expected, with a few
tenths of accumulating snow possible in the mountains through this
afternoon. The approaching trough will create breezy west to
southwest winds across the mountains and deserts late this morning
through Friday morning. A Wind Advisory remains in effect from 10
AM this morning through 10 AM Friday morning for gusts of 40-50
mph. Showers will become more scattered tonight through Friday
morning, especially over San Diego County. Snow levels will lower
again to around 3500 ft, with up to a tenth of an inch of
precipitation and up to one inch of snowfall in the mountains
expected.

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 40-50 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 and timing are still
unclear. The latest GFS is now dry mid to late next week, with
another system moving across the region for next weekend. The 00Z
ECMWF has SoCal much wetter next week, so lower Pops will remain
in the forecast for the time being.

&&

.AVIATION...
221700Z...SCT-BKN clouds will prevail from the mountains west to the
coast through Fri morning with mostly ISOLD -SHRA. Cloud bases will
be 2500-4000 ft MSL with tops to 8000 ft MSL with occasional
obscurations in the mountains. Most vis below the clouds will remain
above 6 miles.

SW to W surface winds will increase today and continue through Fri
morning with areas of 20-30 kt winds and 35-45 kt gusts in the
mountains and deserts, especially the desert mountain slopes and
east of passes. UDDFS/LLWS/rotors will occur at times over and east
of the mountains this afternoon through Fri morning, including VCNTY
KPSP.

&&

.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 this afternoon 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 from 2 PM this afternoon to 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...JJT
AVIATION/MARINE...Maxwell



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