Flash Flood Warning 57, NWS Las Vegas, NV

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

.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 00Z Forecast Package... Scattered
showers and thunderstorms will continue through the evening.
There should be two primary rounds- the first is with the ongoing
scattered thunderstorms in and around the valley which will
continue through about 01Z-02Z. These storms should diminish, but
moderate confidence for additional showers and thunderstorms to
then push in from the west at 03Z-04Z. Both rounds of storms could
contain lightning, erratic gusty outflow winds over 30KT, and
heavy rainfall. CIGS to 10kft are possible with the afternoon
convection, potentially lower to around 7000ft with the evening
showers and thunderstorms. After 06Z, all precipitation should
diminish and move away, giving way to VFR skies and dry conditions
overnight through Wednesday morning. Winds after the storms may
remain elevated with direction dependent on if evening convection
drops any outflow- but expecting light and diurnal winds to return
by 08Z no matter what happens this evening. Additional showers
and thunderstorms could develop in and around the valley Wednesday
afternoon, however coverage and chances for impacts will be lower
compared to the past few days. Outside of thunderstorm
influences, expect typical light diurnal wind trends much of the
day becoming southwest at 8-10KT around 00Z.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 00Z Forecast Package... Scattered
thunderstorms will continue across the region through this
evening. Erratic gusty outflow winds to around 30-40KT, CIGS below
8kft, visibility restriction due to 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
as convection wanes after 06Z, with VFR conditions and light
overnight winds following typical patterns expected tonight
through Wednesday morning. Additional showers and thunderstorms
could develop in and around the valley Wednesday afternoon,
however coverage and chances for impacts will be lower compared to
the past few days. Outside of thunderstorm influences, expect
typical light diurnal wind trends much of the day becoming
southwest at 8-10KT in the late afternoon and early evening.

&&

.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

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

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

0350 PM     Flash Flood      1 E Nebo Center         34.87N 116.93W
08/26/2025                   San Bernardino     CA   Public

            Significant water and debris flow across
            National Trails Highway and Nebo Street. The
            roadway was not passable.

&&

SM