Severe Thunderstorm Warning 48, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
1028 AM PDT Mon Aug 25 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 along far
  southern San Bernardino County.

* Shower and thunderstorm potential peaks on Tuesday before
  gradually decreasing throughout the remainder of the work week.

&&

.DISCUSSION...Today through Monday.

Light shower activity over southern Mohave County this morning will
provide ample cloud cover, which may inhibit daytime heating in this
region through the afternoon. Elsewhere, anomalous PWATs combined
with a series of passing vorticity maxima and clear morning skies
will provide the necessary moisture, lift, and instability necessary
for widespread shower and thunderstorm activity today. Flash
flooding may occur underneath very strong thunderstorms, underneath
training storms, and/or underneath terrain-anchored storms.
Otherwise, inverted-V soundings indicating dry air at the surface
and DCAPE approaching 1500 J/kg across the Mojave Desert and
southern Great Basin result in the added potential threats of strong
gusty winds above 50 mph and frequent lightning. The primary region
of concern today is far southern San Bernardino County including
Yucca Valley, Joshua Tree, Twentynine Palms, and State Route 62.
This afternoon, this region will experience a PWAT flux of over
1.75" combined with 500mb cyclonic vorticity advection and
corresponding CAPE values around 1000 J/kg. Forecast HRRR soundings
indicate a saturated atmospheric profile late-afternoon in south-
central San Bernardino County, with the HREF highlighting a 30-50%
chance of 1.00 inch 3-hour rainfall. Finally, this is the only part
of our forecast area the HREF has highlighted with a chance of
thunderstorm-related wind speeds over 58 mph (10%), making southern
San Bernardino susceptible to all monsoon hazards today (frequent
lightning, heavy rain, gusty winds, blowing dust, and flash
flooding).

Anomalous moisture persists across the forecast area on Tuesday,
allowing for the return of widespread showers and thunderstorms in
the late-morning and afternoon. Moisture begins to retreat Tuesday
afternoon as a pattern shift brings dry southwesterly air to the
Desert Southwest. That said, this dry southwest shift is a result of
an incoming shortwave trough, which will provide ample lift to tap
into the remnant moisture across the region. As a result, expect
continued chances of showers and thunderstorms, albeit, decreasing,
through the remainder of the work week. With the drying air,
temperatures will climb back toward seasonal normals through the
weekend.
&&

.AVIATION...For Harry Reid...For the 18Z Forecast Package...Showers
and thunderstorms will develop over the mountains by around noon.
Outflow from storms to the south will bring southernly wind to the
terminal by 19Z. Outflow boundaries will be around throughout the
afternoon and evening with primary threats will be erratic gusty
winds and briefly heavy rain with lower ceilings. Another round of
showers and thunderstorms is probable overnight into the early
morning hours Tuesday. Temperatures are forecast remain just below
100F today with even cooler temperatures on Tuesday.

For the rest of southern Nevada, northwestern Arizona and
southeastern California...For the 18Z Forecast Package... Storms
will develop over the higher terrain around noon. These storms will
produce erratic gusty winds along with locally heavy rain, lower
ceilings, and terrain obscuration. Away from thunderstorms, winds
should follow typical patterns with gusts less than 20 knots, and
conditions will be VFR through tonight.
&&

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

DISCUSSION...Soulat
AVIATION...Berc

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