Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 221048
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
248 AM PST Sun Jan 22 2017

.SYNOPSIS...A strong low pressure system will bring widespread rain
and snow to the region along with areas of strong winds. Most
mountainous areas will receive significant snowfall. Drier and cool
conditions are then in store for Tuesday and beyond.
&&

.SHORT TERM...Today through Monday Night.

Widespread rain and mountain snow will develop today and tonight as
a strong, dynamic Pacific storm system approaches the area. This
system will continue to impact the area through Monday with
precipitation winding down Monday night as the low shears apart and
the main energy shifts east. Most mountain areas remain under a
Winter Storm Warning which still looks reasonable. The Owens Valley
was added to the warning last evening and rain did change to snow at
Bishop. The orientation of the moisture band looks to put southern
Inyo County under the gun to receive a healthy amount of
precipitation and the GEFS M-climate percentile indicates potential
for the maximum amount of 24-hour rainfall ever for this time of
year for southern portions of Death Valley. It does not take much to
get flooding in Death Valley so I decided to issue a Flood Watch for
that zone for today and tonight. The Flood Watch for Lincoln,
northeast Clark and northern Mohave Counties remains in effect for
tonight and Monday. I left the wind advisory in effect for portions
of the Mojave Desert and added the Kingman zone based on latest
guidance. This is in effect for most of today through Monday but it
looks like a good portion of the advisory area may not see advisory
level winds until tonight, especially the Las Vegas Valley and
northeast Clark.

.LONG TERM...Tuesday through Saturday.

Still expecting much quieter weather in the long term.  The extended
range starts out on Tuesday under the influence of a broad upper
level trough across the Western States, keeping our region cool and
unsettled but generally dry. The cool air aloft will support a few
instability driven snow showers mainly over the higher terrain, but
given the overall dryness of the airmass very little accumulations
are expected.  The troughing will shift east on Wednesday but the
airmass will remain cool under a cyclonic northwest flow through the
end of the week.  Temperatures will average 8-12 degrees below
normal through Friday, and potentially colder in areas where there
is fresh snow cover. Clear and cool nights will also favor strong
radiational cooling, allowing snow covered areas to get quite cold
overnight.

Ridging will build in over the weekend allowing for a cool and dry
northerly flow to take over our region with rising heights. This
will allow temperatures to creep back towards normal territory,
while also inducing northerly winds down the Colorado River Valley.
&&

.AVIATION...For McCarran...Rain and low clouds will move into the
area this morning and persist through tonight and possibly much of
Monday. Cigs 4-5 kft will be common and could at time drop to 2-3
kft. Vsby could drop to 5 miles briefly during periods of heavier
rain. Winds should mainly be southerly today and tonight but could
be southeast to even east this morning until about 18z. Wind speeds
should be below 10 knots this morning increasing to 10-15 knots this
afternoon. South winds will likely increase tonight to 20-25 knots
by 09z with gusts to 35 knots possible.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Expect widespread rain and mountain snow today through
tonight and into Monday with low cigs and vsbys at times. Mountains
will be obscured. Cigs will mainly be below 5 kft with periods of
cigs below 3 kft and vsby below 5SM. Areas of gusty south/southwest
winds are expected today through tonight with gusts 30-40 knots at
times.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
rain or snow amounts through Monday as another storm moves through
the region.
&&

$$

Short Term/Aviation...Harrison
Long Term...Outler

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