Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 161127 AAA
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
427 AM PDT Fri Apr 16 2021

UPDATED McCARRAN AVIATION SECTION

.SYNOPSIS...Light scattered showers and isolated thunder possible in
the higher elevations of Lincoln County and the Sierra this
afternoon and Saturday afternoon. Elsewhere, breezy northwest winds
and partly cloudy skies expected. Through the remainder of the
weekend, temperatures will remain around seasonal averages with
breezy conditions with elevated waves expected on area lakes. The
work week will be characterized by continued afternoon breezes, dry
conditions, and warming temperatures.
&&


.SHORT TERM...Today through Sunday.

As an upper-level area of low pressure continues to push eastward,
the associated elongated trough will stretch westward across the
Desert Southwest, working as the driving weather factor for the
weekend.

With this shortwave trough, PWATs between a quarter of an inch and a
half of an inch coupled with some meager surface instability (~250-
500 J/kg) will bring the potential for light showers and isolated
thunderstorms to the higher elevations of Lincoln County and the
Sierra Nevada this afternoon. Rainfall totals are not expected to
exceed a tenth of an inch, though locally heavier rainfall is
possible with any thunderstorm development. Otherwise, dry
conditions expected across the region with breezy northwest winds 15-
25 mph.

On Saturday, this shortwave will push southward through the forecast
area, bringing chances of precipitation farther south with it.
However, there will be less moisture to tap into on Saturday,
resulting in primarily virga showers (if any). The highest chance of
precipitation reaching the ground will be along the Arizona Strip in
northern Mohave County, but even then, expecting less than 0.05" of
rainfall. Can`t rule out an isolated rumble of thunder. North to
northeasterly winds will be the primary response of this shortwave
on Saturday, with gusts 25-35 mph and corresponding wave heights on
area lakes between 1 and 2 feet.

The shortwave will exit our forecast area on Sunday, closing off
over southern Arizona, and resulting in persistent breezy conditions
and temperatures right around seasonal averages to finish out the
weekend.

.LONG TERM...Monday through Friday.

Somewhat complex forecast in the long term period as high pressure
ridging begins to build along the West Coast early in the week, but
forecast models are struggling on some of the finer details. The
first of which is a shortwave digging into the eastern Great Basin
on Monday which could reduce heights slightly and result in less
warming for the first half of the week than forecast. Alternatively,
should the shortwave be weaker or track further east, greater
warming would be expected. Thereafter, a train of smaller shortwaves
looks to move through the northwesterly flow midweek onward which
would cool temperatures back closer to seasonal normal and could
encourage some high terrain showers in the southern Great Basin. The
current forecast is somewhat of a compromise solution with warmer
temperatures than the cooler ECMWF clusters would suggest, but not
as warm as the GFS solutions which favor stronger ridging.
&&


.AVIATION...For McCarran...Direction will favor a northeast-east
direction with speeds 8-12 kts today. After 04Z, this evening there
is the potential for stronger northeast winds with gusts up to 20
kts possible. After midnight, gusts should begin to weaken with
north winds the rest of the night. SCT-BKN120 through the afternoon
and overnight.

For the rest of southern Nevada, northwest Arizona and southeast
California...Prevailing north to northeast flow through tonight with
strongest winds expected in the lower Colorado River Valley between
KIFP and KHII. Scattered showers and isolated thunderstorms will be
possible over northern Lincoln County this afternoon, while an
isolated shower can not be ruled out over the mountains near KBIH.
Associated with the showers ceiling will lower to 7-8 kft AGL.
&&


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

$$

SHORT TERM...Varian
LONG TERM...Outler
AVIATION...Pierce

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