Flash Flood Warning 193, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
1227 PM PDT Tue Aug 16 2022

.SYNOPSIS...Scattered showers and thunderstorms will persist
through the week as monsoonal moisture remains over the region, and
any storms will be capable of producing locally heavy rain and
flooding. With the abundant moisture in place, temperatures will
remain near to slightly below normal into the weekend.
&&

.SHORT TERM...through Wednesday night. Late morning satellite loop
showed shallow cumulus bubbling over much of the CWA, with deeper
convection beginning over the Hualapai Mountains and in southern
Esmeralda County. Surface obs showed temperatures running a few
degrees warmer than 24 hours ago, although still well below mid
August averages, and dewpoints a few degrees lower than yesterday.
With the deep moisture and some instability in place, no spot can be
completely ruled out for thunderstorm chances this afternoon and
evening, although the high resolution models are in decent agreement
that the lowest chances will be in the Death Valley region and the
lower elevations of Clark County. Models show a bit less instability
Wednesday, resulting in a bit less thunderstorm coverage as well.
However, this could be modified if any storm-scale circulation
generated today drifts nearby Wednesday. Nocturnal storm chances
look small tonight, but some of the high res models show storms
persisting Wednesday night in the southern Great Basin. Temperatures
will remain below normal thanks to the deep moisture and cloud cover.

.LONG TERM...Thursday through the weekend.

Continued southerly flow is expected across the region through the
weekend. While thunderstorms are possible Thursday afternoon, models
continue to highlight the Friday through Sunday period as period of
potentially higher impact monsoonal weather. PWAT increase across
the region to over 2 standard deviations over normal by Friday
afternoon as tropical moisture gets absorbed into mean flow.
While its hard to pin point mesoscale features this far in
advance, long range models hint at a wave moving around the main
flow Saturday into Sunday, which could enhance precipitation
chances/coverage. This potential uptick in activity and increased
risk of heavy rain leading to flash flooding is highlighted in a
few ensembles. ECMWF EFIs shows potential for anomalous QPF
through portions of Arizona into eastern portions of southern
Nevada FRI-SUN. Model ensembles also show increased probabilities
for 100 yr ARIs at times late Friday through Sunday. Finally, some
of the clusters show QPF over the ensemble means through the
weekend. While details are uncertain at this time, there is an
increasing signal for an increased thunderstorm activity, heavy
rain, and flash flooding this weekend. What is more certain is the
continuation of below-normal temperatures with the persistent
moisture and rain chances.
&&

.AVIATION...For Harry Reid...Monsoon moisture will remain in place
again today with FEW-SCT12-14k feet and SCT-BKN15-17k feet. Expect
to see thunderstorms develop over the higher terrain this afternoon,
but it's unlikely that storms will move into the valley and the main
threat will be from outflow winds. Outside of any thunderstorm
influences, winds will generally be east around 6-8 kts. Conditions
are expected to remain the same Wednesday with scattered afternoon
thunderstorms, majority remaining over the higher terrain.

For the rest of southern Nevada, northwest Arizona and southeast
California...Expecting scattered thunderstorms to develop across
much of the region this afternoon. Best chances for thunderstorms
impacts will be near KBIH where thunderstorms should be most
widespread. Convection looks to remain generally over the higher
terrain and chances are low that impacts will be felt at the area
TAF sites, expect BIH. However, any outflow winds from local
thunderstorms could impact the TAF sites into this evening. Outside
of convection, winds will in general favor diurnal wind trends,
except at KBIH where gust southeast winds are expected this
afternoon.
&&

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

SHORT TERM...Morgan
LONG TERM...Nickerson
AVIATION...Gorelow

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