Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 231048

Area Forecast Discussion
National Weather Service Las Vegas NV
248 AM PST Fri Feb 23 2018

.SYNOPSIS...A low pressure system over the area will result in
chilly and locally breezy conditions. The best chance of
precipitation will be over Lincoln and Mohave Counties where several
inches of snow is possible in the higher terrain. Cool and mainly
dry conditions are expected over the weekend although a weak
disturbance could bring a few snow showers to Lincoln County
Saturday night.

.SHORT TERM...Today through Sunday Night.

Upper trough which brought gusty winds to much of the area was
centered over Nevada early this morning and winds had settled down
somewhat. Some breezy conditions are still expected today as the
trough moves slowly eastward, to along the UT/NV border late this
afternoon. The strongest winds will be north/northwest winds
developing on the back side of the trough over Esmeralda, Nye and
Inyo Counties where local gusts near 40 mph are possible. I think
that overall, winds will remain below advisory levels. There is not
a lot of moisture with this system but some precipitation was noted
on radar early this morning across mainly Mohave and Lincoln
Counties. The air mass will be somewhat unstable today as the
surface heats up and with the cold pool aloft over the area.
Therefore, the potential for some decent snowfall still exists over
Lincoln and Mohave Counties and the Winter Weather Advisory remains
in effect above 4000 feet until late this afternoon. There is also a
chance of snow showers over the higher terrain of Clark, Nye and
Esmeralda Counties as well as the Sierra, but amounts in those areas
look to remain rather light. It will be a chilly day with high
temperatures roughly 15 degrees below normal. The upper trough will
weaken and shift a little more quickly eastward tonight, moving into
western Colorado by early Saturday morning. A dry northwest flow
will be over our area but there could be some lingering snow showers
over Lincoln and Mohave Counties early in the evening. A weak
shortwave trough moving through the northwest flow will reach
northeast Nevada late Saturday and into Utah Saturday evening. There
could be isolated snow showers over far northern Lincoln County late
Saturday but better chances for snow showers will be over Lincoln
County Saturday evening and possibly lingering into the overnight
hours. The remainder of the forecast area will be dry with below
normal temperatures. Dry conditions are expected Sunday and Sunday
night as a northwest flow transitions to a westerly flow.
Temperatures will moderate slightly but are expected to remain below

.LONG TERM...Monday through Thursday.
Very little change in the basic story for the extended forecast
period. The upper level disturbance arriving on Monday and into
Tuesday will likely form an upper low off the coast. As previously
mentioned the dynamics with the system will lead to some
precipitation despite low amounts of moisture. The uncertainty
with this system is its positioning over the California coast. If
the upper low sets up to too far west, much of the dynamics will
remain west of the area and decrease our chances for
precipitation. Right now, the forecast appears on track but will
need to monitor as we get closer. The system later in the week is
a bit more complex. There is disagreement between the ECMWF and
GFS on its evolution. The ECMWF digs the upper low south toward
the area. The GFS stalls the energy to the north as zonal flow
shears it out to the east. Still uncertain as to how things will
progress. We will keep a mention of precipitation over western
parts of the area in the forecast for now starting on Thursday. &&

.AVIATION...For McCarran...Light winds this morning will give way
to gusty northeasterly winds by mid-morning and last until 03z.
Also expect isolated showers to form, mainly over higher terrain,
in the afternoon as well. Winds will slacken off again in the
evening leading to an event free weekend. Another storm system
arrives on Monday and will increase winds and possibly bring
precipitation to the area.

For the rest of southern Nevada, northwest Arizona and southeast
California...Snow showers are occuring tonight from the Sierra
Nevada to central Nevada and northwest Arizona, particularly over
the higher terrain. Ceilings will generally remain above 10 kft at
TAF sites, with the exception of KBIH where CIGS will lower to
3kft or lower at time during. Gusty northwest winds at 15-25 kts
expecting on Friday afternoon with showers mainly over the higher
terrain of southern Nevada and Mohave County.

.SPOTTER INFORMATION STATEMENT...Spotter activation is not
anticipated through the weekend. Spotters are encouraged to
report any significant weather or impacts according to standard
operating procedures.


SHORT TERM...Harrison

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