Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 222257

Area Forecast Discussion
National Weather Service Las Vegas NV
245 PM PST Wed Feb 22 2017

.SYNOPSIS...A cold front will move through the region this evening
bringing a few light showers to portions of the southern Great
Basin. Cooler air will also filter into the region Thursday with
below normal temperatures expected to continue through the weekend.
Unsettled weather is expected Sunday through Tuesday.

.SHORT TERM...through Friday night.

Gusty winds occurring across much of the area this afternoon ahead
of a cold front that is currently pushing through central Lincoln
and Nye Counties. Winds across the northern half of the Nevada
National Security Site have shifted to the northwest with gusts in
the 30 mph range. Stronger winds have been ahead of the front across
San Bernardino County where winds have been gusting to over 40 mph
at a few locations. Those winds are expected to continue through
this evening and will also increase in the Morongo Basin a little
later this afternoon as the front approaches. The current wind
advisories in place look good and no need to change. Winds will
gradually diminish overnight.

There have been a few light rain showers popping up across Lincoln
County in association with the front and that trend is expected to
continue. Outside of Lincoln County, dynamics look to be strong
enough to generate a few showers across Clark, southern Nye and
Northern Lincoln Counties early this evening as the front passes.
Did go ahead and expand pops to cover much of those areas with the
best shot of seeing slight scattered rain showers between 6pm and
10pm. Amounts are expected to remain light and most areas will only
likely to receive a few drops.

Cooler temperatures are expected Thursday across the area with
readings down about 10 degrees from today. These cooler temperatures
will remain into the weekend. A few showers will linger over
northern Lincoln County Thursday, but dry conditions elsewhere. Dry
conditions are expected everywhere Friday as a cool dry northwest
flow is in place.

.LONG TERM...Saturday through Wednesday.

The 12Z run of the GFS and ECMWF models have come into better
agreement and now show much less potential for widespread
precipitation Sunday, similar to what the Ecmwf solution has shown
the past few runs. They now depict a fast moving short wave trough
dropping over northern California Saturday afternoon and then it
moves quickly across southern Nevada by early Sunday morning as an
open wave. This would bring brief isolated to scattered showers with
the trough passage, and snow levels lowering to 3000-4000 feet by
Sunday morning. Pop values were decreased considerably for Sunday
based on the latest trends.

A second trough dropping down from the northwest is forecast to drop
down through the southwest states Monday and Monday night and this
may pick up a large swath of Pacific moisture and bring it inland
for a better chance of extensive precipitation Monday. However, the
18Z GFS shows this moisture getting pushed a little more to the
south in the base of the trough and only brushing our region. This
progressive open wave then exits the region by Tuesday leaving dry
and northwest flow behind it through the middle of the week. This
pattern will produce cooler than normal temperatures and periods of
gusty winds with each trough passage through the weekend and early
next week.

.AVIATION...For McCarran...A cold front pushing down through
southern Nevada this evening will bring gusty northwest winds behind
it and possibly some brief light showers and broken clouds with
bases of 8-9 Kft within the terminal area. Clouds will clear out and
northwest winds will diminish overnight but winds should remain
above 10 knots through at least Thursday morning and likely much of
the day.

For the rest of southern Nevada...northwest Arizona...and southeast
California...A cold front pushing down through southern Nevada this
evening will produce strong west winds with gusts over 40 kts
possible over the Mojave Desert of San Bernardino County this
evening. Brief isolated to scattered showers will occur across
southern Nevada and far northwest Arizona through this evening. Post-
frontal northwest wind gusts of 25-35 can be expected across much of
the region through late this evening. Skies will clear overnight and
sustained northwest winds of 10-20 knots will hold over the region

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to
report any significant weather or impacts according to standard
operating procedures.


Short Term............Gorelow
Long Term/Aviation....Adair

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