Flash Flood Warning 54, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
1052 AM PDT Tue Aug 26 2025

.KEY MESSAGES...

* Widespread showers and thunderstorms expected across the forecast
  area 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...Today through Tuesday.

A swath of light-to-moderate rain with isolated embedded
thunderstorms continues to push northward through Mohave County into
Lincoln County this morning. The associated cloud cover will work to
inhibit daytime heating in these areas, thus delaying onset of
convection this afternoon. Today, the region will undergo a minor
pattern shift. To start out the day, anomalous moisture around 200%
of normal will remain over the forecast area from southerly flow and
monsoonal moisture advection due to our proximity to the Four
Corners area of high pressure. Throughout the day, a weak shortwave
trough will approach the southern California coast, which will cut
off our moisture flow, return a dry southwest flow to the region,
and will result in a gradual decrease of PWAT values across the CWA.
That said, this shortwave will bring a couple of dynamic ingredients
to the table, including a 75-85 kt 300mb jet and cyclonic vorticity
advection. These mechanisms will provide the necessary lift to tap
into the leftover moisture and supply the region with widespread
showers and isolated thunderstorms once again. Today's primary
impact will be moderate-to-heavy rain, resulting in instances of
flash flooding. While flash flooding is possible areawide beneath
very strong thunderstorms, training storms, and/or terrain-anchored
storms, the best chances of flash flooding exist over Inyo,
Esmeralda, and central Nye counties which is also where the best
morning cloud clearing will occur. As such, issued a Flash Flood
Watch for today (9 AM to 9 PM) for these areas. Convection will
initially favor the higher terrain before pushing eastward into
nearby valley locations. Though gusty winds cannot be completely
ruled out, chances of severe-level winds (58+ mph) are less likely
than yesterday, with best odds occurring later in the day as
moisture begins to retreat.

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. Moisture
continues to retreat through the week, with precipitation chances
gradually decreasing heading into the weekend. This moisture and
associated cloud cover will help keep afternoons 5 to 8 degrees
below seasonal normals through the work week, while overnight lows
stay at-or-around normal. Seasonable temperatures expected over the
weekend.
&&

.AVIATION...For Harry Reid...For the 18Z Forecast Package...The
primary aviation concern this forecast period are multiple rounds
of thunderstorms expected to impact the region. While initially,
storms will be focused across the higher terrain, 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 18Z Forecast Package...Scattered
thunderstorms are expected across the region this afternoon and
evening. Initially, storms will generally be focused across the
higher terrain, and outflow boundaries will help to generate
storms across lower elevations. 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...Soulat
AVIATION...Phillipson

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