Severe Thunderstorm Warning 30, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
1133 AM PDT Tue Aug 26 2025

.KEY MESSAGES...

* Slow-moving, wet thunderstorms continue to bring an elevated risk
  of flash flooding through this evening, especially over urban
  areas and burn scars.

* Additional showers and storms are expected Wednesday, but a
  drying trend will reduce thunderstorm activity Thursday onward.

* Cooler temperatures persist until warming settles in later this
  week.

&&

.DISCUSSION...
Deep monsoonal moisture combined with sufficient afternoon heating
will provide another round of thunderstorms today. A handful of
showers and thunderstorms are already kicking up along the western
periphery of an expansive cloud deck that covers much of the Basin
and Range. Primary risk with storms today will be flash flooding,
but we can't rule out small hail, strong gusty winds, and of
course lightning concerns remain as well.

Flash Flood Concerns: A flash flood watch has been issued for much
of the Sierra and northeastern California today and will be in
effect from noon to 9pm. Heavy rain this week may have saturated the
ground for many mountain locations in the Sierra with rain amounts 1
to 3 inches. Any additional rainfall will be quick to run off due to
the already saturated soils, especially for burn areas.

Timing: With the widespread cloud deck across the Basin and Range
areas, mostly east of Highway 395, thunderstorm development will
be delayed until more clearing occurs. West of that periphery, a
handful of storms are already firing with showers near Hawthorne
and over/near Mt Rose Summit. The most widespread activity will
kick off between 1p-3p for western Nevada and spread eastward into
the Basin and Range between 2p-8p. Outflows may propagate and
kick off storms well past 8p tonight, especially across western
NV, with some simulations holding onto showers for along and south
of I80 through early Wednesday morning.

Wednesday Weather: Plan on another active day of storms and showers
with similar concerns for flash flooding, hail, lightning, and
winds. Simulations have been leaning toward less widespread
activity, but with the deep monsoon moisture in place, we will still
have quite a few storms out and about to monitor.

Thursday offers the first day of 'relief' as moisture is projected
to become more limited across the Sierra and western Nevada. Even
still with precipitable water values around 0.5-0.7", we are still
well within a thunderstorm-producing air mass. The risk may shift
from heavy rain and flash flooding to strong, dry outflow winds but
we will have to see just how much moisture scours out and how much
lingers on through the end of the week.

-Edan

&&

.AVIATION...

Scattered thunderstorms are the primary concern today, especially
between 19Z and 03Z. Heavy rain and IFR conditions, strong
outflow winds, small hail, and frequent lightning are the main
threats with any thunderstorms near regional terminals. The best
chance (40-50%) of thunderstorm impacts exists at KMMH with lesser
odds of 30-40% at other terminals.

Periods of fog and IFR conditions will return overnight and
persist at KTRK through 15-16Z before dissipating. Otherwise, VFR
conditions and areas of mid-upper clouds will prevail for tomorrow
morning.

Light rain showers may persist overnight through 12z Wednesday for
KRNO, KMEV, and KCXP.

-Salas/Edan

&&

.REV Watches/Warnings/Advisories...
NV...Flood Watch until 9 PM PDT this evening NVZ001>003.

CA...Flood Watch until 9 PM PDT this evening CAZ071>073.

&&