Flash Flood Warning 214, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
137 PM PDT Sat Aug 20 2022

.SYNOPSIS...Shower and thunderstorm activity will continue through
this evening. The primary hazards with these storms will be
strong wind gusts, heavy rain causing flash flooding, and frequent
lightning. High pressure will move into and over the region,
displacing moisture eastward and providing a brief reprieve. This
break is expected to last through early next week. Moisture and
convective activity will return towards the middle of the week.
&&

.SHORT TERM...through Sunday evening.

The most recent water vapor satellite imagery shows ridging building
over California and Nevada, as well as a trough churning over
northern Utah. This upper-level setup has resulted in northwesterly
flow aloft across the forecast area. Embedded within this
northwesterly flow, is a small disturbance moving southeast along
the Inyo/Nye County line. This disturbance will likely be a key
player when it comes to shower and thunderstorm activity this
afternoon and evening. Speaking of afternoon and evening convection,
high resolution models have been consistently highlighting the
potential for 50+ mph winds in eastern Clark County, southern Mohave
County, the Colorado River Valley, and the Lake Mead National
Recreation Area this afternoon and evening. The showers and
thunderstorms responsible for these strong wind gusts will initially
pop up on the higher terrain in Clark, Lincoln, San Bernardino, and
Mohave counties early this afternoon. These storms are not expected
to remain anchored to the higher terrain and outflows produced by
them will have the potential to result in downstream storm
development. Outside of strong winds, heavy rainfall capable of
resulting in flash flooding and frequent lightning are additional
hazards posed by these storms. Convective activity is expected to
shut down from north to south, with most of the thunderstorms
dissipating by midnight tonight.

Northwesterly flow aloft will continue on Sunday as the ridge pushes
further into our forecast area. This flow will continue to push
moisture to the east, with a chance for isolated showers and
thunderstorms in eastern Mohave and Lincoln counties as well as the
higher terrain in San Bernardino and Clark counties. Any showers or
thunderstorms that do end up developing tomorrow will be driven by
daytime heating and are expected to dissipate a couple of hours
after sunset.

.LONG TERM...Monday through Saturday.

The aforementioned ridge over California and Nevada will continue to
push eastward over the forecast early next week. This eastward
movement of the ridge can be seen reflected in both PoPs and
temperatures. PoPs gradually push east and diminish each day through
mid-to-late week with temperatures gradually warming up. Even with
temperatures gradually warming up through mid-week, they will still
remain slightly below normal values for mid-August. Despite moisture
pushing out and PoPs diminishing, isolated afternoon thunderstorms
will remain possible in Mohave County. By Wednesday or Thursday the
ridge will have moved to our east, opening the door for moisture to
return to forecast area. This expected increase in moisture is
reflected in the PoPs, which begin increasing across the forecast
area on Wednesday and Thursday. Temperatures will cool down a few
degrees during the latter half of the week in response to this
influx of moisture.

&&

.AVIATION...For Harry Reid...Thunderstorms will likely develop
over the mountains around the Las Vegas Valley and move toward the
southeast during the afternoon impacting the terminal area between
22Z and 01Z with erratic wind gusts at least to 30 knots along with
brief moderate to heavy rain showers and ceilings around 10kft AGL.
Storms should dissipate around the terminal area after 01Z but
isolated storms will continue in the Mormon Mesa and Peach Springs
corridors 01Z-05Z. Typical light south-southwest winds and
decreasing clouds expected during the evening and overnight once any
outflow influences diminish. No significant weather expected in the
terminal area Sunday with light east-southeast winds as drier and
more stable air moves in. Isolated storms will occur Sunday
afternoon in the Mormon Mesa and Peach Springs corridors.

For the rest of southern Nevada, northwest Arizona and southeast
California...Scattered thunderstorms developing this afternoon will
move toward the southeast over southern Nevada, the Colorado River
Valley, and northwest Arizona. Gusty outflow winds over 30 knots are
possible with any storms and will likely impact Las Vegas Valley TAF
sites along with CO River sites EED/IFP during the afternoon or
early this evening. Storms will also produce lightning, brief heavy
rain, and CIGS to 8-10kft before dissipating by 06Z. The rest of the
region can expect just some fair weather cumulus and winds generally
less than 15 knots. Thunderstorms Sunday afternoon should be
confined to northwest Arizona and near the southern Nevada-Utah
border.

&&

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

DISCUSSION...Stessman
AVIATION...Adair

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