Damaging Wind in Nevada, August 6, 2017

Area Forecast Discussion
National Weather Service Las Vegas NV
933 PM PDT Sun Aug 6 2017

.SYNOPSIS...Widespread showers and thunderstorms will continue
through this afternoon and evening in areas north of Las Vegas. A
warming and drying trend is expected to take place through the
first half of this week. Temperatures will climb back to near
normal by Tuesday/Wednesday. The next chance for increasing
moisture will take place late this week. However confidence is low
in just how far west moisture will push.
&&

.UPDATE...Showers and thunderstorms have diminished across Inyo,
Esmeralda, and most of Nye County this evening. Hi-res solutions
from the HRRR's latest run still indicate activity building back
across the aforementioned areas through midnight, as mid-
tropospheric diffluence is suggested to aid new storm development.
However, water vapor imagery has indicated drier areas moving into
the NW zones. Limited instability and capping should also inhibit
development. So, that said, I decreased PoPs across over those
areas. Lincoln County should remain the focus for activity through
midnight, as there remains decent instability and some uncapped
areas. Mid-level diffluence also expected aid storms through
midnight before nocturnal capping takes over. Storm motion will
continue along the mean westerly tropospheric flow between 10-20
knots, limiting threats of flash flooding. Southern zones will
remain dry with skies continuing to clear through the evening and
early morning. -Boothe-
&&

.AVIATION...For McCarran...Typical summertime diurnal wind pattern
expected through Monday. Mainly sct clouds with bases 12-15 kft.
Less chance of outflow winds Monday due to showers/thunderstorms but
still cannot totally rule out some outflow late in the day.

For the rest of southern Nevada, northwest Arizona and southeast
California...Typical summertime diurnal wind pattern exists for most
terminals through Monday. The exception could be BIH which may have
some gusty and erratic winds from showers/thunderstorms through 06Z
tonight and again late Monday. Ceilings should be within VFR
conditions at all terminals above 10 kft through the forecast
period.

&&

.PREV DISCUSSION...
118 PM PDT Sun Aug 6 2017

.SHORT TERM...Today through Monday.

The stage is set for a fairly active afternoon across the northern
half of the forecast area. A distinct moisture boundary extends
across the southern Inyo County line to just south of Las Vegas
east to the Arizona Strip. To the south, capping and drier air
shouldn't result in much more than cumulus fields. To the north,
better instability, upper level divergence, and a dissipating PV
anomaly will result in plenty of dynamics for scattered to
numerous thunderstorms. A secondary moisture boundary extends
along a line stretching from Tonopah to the Spring Mountains and
delineates a line of higher mid-level moisture that exists across
Nye and Lincoln counties. This will be the main area to watch for
significant rain rates this afternoon/evening. Storm motion of
around 8-15 mph will keep the threat of widespread flooding
limited to areas where training, terrain driven storms develop
(which is a real possibility). Gusty outflow winds and small hail
will also be possible with storms today. Storms are likely to
slowly diminish from south to north through the evening, with
showers and embedded storms along the northern CWA border
potentially lasting through the overnight hours.

Monday will see further drying. Showers/storms will be mainly
limited to Esmeralda, northern Inyo, northern Lincoln, and
central/northern Nye counties. Moisture will continue to decrease,
even in those areas and so too will the flood threat. As this
drying occurs, temperatures will continue to warm across the
region.
&&

.LONG TERM...Monday night through Saturday

The Pacific trough will slide north and east up and over the
southern ridge Monday night and Tuesday. Dont think we will see
much from it though as the better lift will be over northern NV.
Kept the slight chance for precipitation over the far northern
boundary of the forecast area Tuesday afternoon as a few showers
or a stray thunderstorm may drift into northern Lincoln and Nye
counties. After that, heights begin to rise and strong ridging
sets up over the desert Southwest starting Tuesday afternoon,
which will limit precipitation development through the rest of the
week. In addition, much drier air arrives Wednesday, so sunny and
dry conditions are expected for the second half of the week. Some
of the longer range models hint at moisture shifting back north
into NE AZ and Southern CA, however confidence is too low to add
any kind of precipitation chances to the forecast. Warming
temperatures are expected through the week, with slightly above
normal temps possible Wednesday and Thursday.
&&

.FIRE WEATHER...Scattered thunderstorms are possible through this
afternoon and evening over the southern Great Basin, with heavy
rain, strong winds and lightning possible. A gradual drying and
warming trend will continue through at least the middle of next
week. Temperatures will be warming to near normal by
Tuesday/Wednesday. The next chance for increasing monsoon moisture
is late this week. However, confidence in whether will push any
further east than the Colorado River Valley is low.
&&

.SPOTTER INFORMATION STATEMENT...Showers and thunderstorms are
expected in areas to the north of Las Vegas again today. Spotters
are encouraged to report any significant weather or impacts
according to standard operating procedures.
&&

SHORT TERM...Wolcott
LONG TERM....Allen
AVIATION.....Kryston

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