Flash Flood Warning 56, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
Issued by National Weather Service Reno NV
300 PM PDT Tue Aug 26 2025

.KEY MESSAGES...

* Widespread showers and thunderstorms expected across the
  forecast area for the rest of today, with best chances of flash
  flooding beneath training storms or storms anchored to high
  terrain as well as across Inyo, Esmeralda, and central Nye
  counties.

* Shower and thunderstorm potential gradually decreases throughout
  the remainder of the work week, allowing for persistent below-
  normal afternoon temperatures.

&&

.DISCUSSION...Through Saturday
Debris clouds over Southern Nevada and Mohave County scattered out
through the morning per satellite imagery, with mostly sunny
skies further west. With the sun being able to peak through the
clouds, destabilization has begun with CAPE increasing through the
morning, and scattered showers with isolated thunderstorms have
already started to develop in the Sierra and the Southern Great
Basin. This trend should continue through the afternoon, with
surface based CAPE climbing to 1000-1500 J/kg allowing for
scattered convection in most areas. In addition, an incoming
shortwave will provide upper level support for sustain
thunderstorm activity (as opposed to pulse storms like we had over
the weekend). Convection should initially favor terrain then push
into nearby valleys. Some hi-res models show an axis of scattered
showers and thunderstorms developing in Inyo County this
afternoon which would then push east through Death Valley, Nye,
Clark, and western Lincoln counties this evening before decaying
tonight, so that will be a trend to watch for. The main threat
today will be heavy rain and flash flooding with PWATS sitting at
150%-200% of normal. The highest risk for flash flooding will be
in Inyo County through the Southern Great Basin where the best
upper level forcing could allow for organized thunderstorm
activity and multiple rounds of precipitation. A Flash Flood Watch
has been issued through 9pm tonight to capture this threat,
including expanding the watch into Lincoln County with the morning
package. With anomalously high moisture though, be alert as any
storm could result in heavy rain and flash flooding. Other than
rain, the downburst wind threat today will be limited due to
abundant moisture through the low and mid levels, however wet
microbursts could still produce isolated strong gusty winds.
Precipitation should diminish overnight, with mainly isolated
showers possible in Lincoln and Mohave counties.

Anomalous remnant moisture on Wednesday will allow for the return
of showers and thunderstorms in the late morning and afternoon,
but to a much lesser areal extent than the last couple of days as
drier air starts to filter into the region. While PWATS will
decrease fairly quickly, an incoming shortwave means whatever
moisture remains will allow for scattered showers and isolated
thunderstorms to develop. The heavy rain and flash flood risk will
be lower on Wednesday, however with an incoming trough there will
be a risk for sudden gusty winds as thunderstorms are able to
develop on Wednesday. Hi-res models show some destabilization in
the Southern Great Basin on Wednesday, so this may be where the
greatest risk for thunderstorms and impacts could develop
Wednesday afternoon.

Moisture continues to retreat through the week, with precipitation
and associated cloud cover weakening into the weekend. This
moisture will gradually decrease with help from afternoon S gusts.
Overnight lows stay at or around normal through the work week,
while overnight lows stay at or around normal. Seasonable
temperatures expected over the weekend.

&&

.AVIATION...For Harry Reid...For the 0Z Forecast Package...The
primary aviation concern this forecast period are multiple rounds
of thunderstorms expected to impact the region. Outflow
boundaries are expected to generate additional storms in the Las
Vegas Valley, with frequent lightning, erratic gusty outflow winds
to 30-40KT, and heavy rainfall all possible. Brief reductions to
MVFR/IFR ceilings/visibility can be expected where heavy rain
develops. Initially, a round of thunderstorms is expected this
afternoon, with a brief lull late afternoon/early evening, with a
second round expected to move from west to east across Southern
Nevada through late evening. Ceilings with storms could drop as
low as 6-8kft, though after storms diminish, VFR conditions will
prevail as ceilings lift and scatter out around 10kft. Winds away
from storms/outflow boundaries will generally remain light and
settle into expected diurnal patterns.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 0Z Forecast Package...Scattered
thunderstorms will continue across the region this afternoon and
evening. Erratic gusty outflow winds to around 30-40KT, MVFR/IFR
conditions in heavy rain, and lightning can be expected in storms
that develop. Storm activity will diminish and move from west to
east through late evening, with less confidence in thunderstorm-
related impacts further south toward the Lower Colorado River
Valley/KEED and into northwestern Arizona. Outflow boundaries will
result in variable winds, though outside of thunderstorm
influences, sustained wind speeds are expected to remain around
10KT or less. Ceilings improve quickly, becoming FEW- SCT AOA
10kft once thunderstorms end tonight.

&&

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

&&

DISCUSSION...Nickerson
AVIATION...Nickerson

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Preliminary Local Storm Report
National Weather Service Las Vegas NV
355 PM PDT Tue Aug 26 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0331 PM     Flash Flood      3 S Barstow             34.86N 117.02W
08/26/2025                   San Bernardino     CA   Law Enforcement

            Heavy rain in the area, large rocks and
            debris in the roadway and flooding across
            the roadway on SR 247 south of Barstow.
            Traffic being turned around in either
            direction.

&&

SM