Dust Storm and Damaging Winds in Arizona, August 22 to 23, 2025

Area Forecast Discussion
National Weather Service Las Vegas NV
406 PM PDT Fri Aug 22 2025

.KEY MESSAGES...

* Extreme Heat Warnings and Heat Advisories will continue through
  Saturday as hotter than normal temperatures continue.

* Showers and thunderstorms capable of producing strong outflow
  winds and flash flooding will be possible for areas south and east
  of I-15, with additional showers and thunderstorms possible in
  Lincoln and Inyo Counties.

* Chances for scattered showers and thunderstorms will continue
  through the weekend and into next week.

&&

.DISCUSSION...through Thursday.

Satellite imagery through the morning showed a decaying MCV
rotating into southern Nevada, with scattered light showers
developing ahead if this feature. Showers and isolated
thunderstorms are possible through the afternoon as this piece of
energy continue to move north into the Southern Great Basin, which
could bring isolated gusty winds to around 40 MPH as low levels
remain dry but weak instability develops. Further south, better
moisture and weak instability will allow for convection to develop
through the afternoon. With substantial debris clouds to limit
instability, thunderstorms should remain weak. Latest hires model
runs have backed off the coverage and impacts of this afternoon's
thunderstorms. Will continue to watch for gusty outflow winds,
especially in southern Mohave County into the Lake Havasu area
where CAPE to around 500J/Kg and decent downdraft CAPE may
develop. EVen this though, HREF has decreased probabilities for
strong easterly outflow winds, with the most likely solution being
easterly gusts 30-40MPH pushing through this evening. Blowing
dust is possible with any sudden gusty winds in Mohave County.
Anyone on Lake Havasu or Lake Mohave should stay alert for the
possibility of a sudden wind shift to the east or southeast this
evening with gusts up to 40 MPH possible, mainly between 5PM to
10PM PT/MT tonight. Any thunderstorm south of the I- 15 could also
bring heavy rain with an isolated flash flooding threat through
the afternoon, which is outlined in WPC's Day 1 Marginal Excessive
Rainfall Outlook. WIdespread flash flooding is not likely as low
levels remain fairly dry even where higher PWATs have set up. The
other area of concern this afternoon is in the Sierra where
upsloping should allow for thunderstorms to develop in the
terrain. With increasing downdraft CAPE, sudden gusty winds over
40 MPH are also possible in this area. Convection should wane
tonight, though models do show a low chance for light showers to
linger through San Bernardino through the night.

The current Heat Advisories and Extreme Heat Warnings in effect for
southern Nevada, northwestern Arizona, and southeastern California
will remain in effect through Saturday night as above normal
temperatures continue. Today and Saturday's afternoon high
temperatures will top out around 4 to 7 degrees above normal for
late August and overnight low temperatures tonight through Saturday
morning will struggle to cool, running around 6 to 13 degrees
warmer than normal. These warm overnight low temperatures will be
the primary driver behind elevated HeatRisk levels and dangerous
heat through Saturday. Temperatures will cool on Sunday and while
Major Heat Risk could linger in desert valleys such as Death Valley,
the Morongo Basin, and the Colorado River Valley- high and low on
Sunday temperatures will be cooler compared to today and Saturday,
even in these hotter locations. There is also uncertainty in the
temperature forecast as moisture continues to advect into the region
through the weekend. Will not be extending any heat products at this
time as we should effective cool through the weekend. Cooler than
normal temperatures return to the region next week.

Chances for showers and thunderstorms will continue through the
weekend, spread across the entire region as moisture becomes trapped
under an upper level ridge. With no obvious synoptic forcing,
Saturday and Sunday's convection will favor the terrain then rely
heavily on mesoscale features that develops from each day's overall
storm activity. Expect adjustments to precipitation chances each day
depending on what unfolds each day. PWATs of 0.75-1.50 inch will be
in place across the region which would bring a risk for heavy rain
and isolated flash flooding (especially where training or slow
moving storms develop). WPC has a marginal risk for excessive
rainfall across almost the entire region this weekend. In addition
to heavy rain- strong gusty winds and lightning are possible with
any thunderstorms Saturday and Sunday.

Storm chances continue into next week. Ensembles show additional
moisture increases, especially Tuesday and Wednesday. With a
shortwave potentially moving through the region around the same
timeframe, more widespread and/or higher impact precipitation is
possible if moisture and forcing are able to overlap. Ensembles show
a variety of solutions with the incoming shortwave and thus a large
spread in precipitation amounts. Will continue to monitor
precipitation chances and potential impacts next week.

&&

.AVIATION...For Harry Reid...For the 00Z Forecast Package...Showers
and isolated thunderstorms will continue to move away from the
terminals through the evening. Most likely, convective impacts have
ended and it will be dry through the first part of the night. A
stray shower, isolated lightning, and sudden gusty winds are still
possible through about 02Z this evening but it is a low risk. Light
wind patterns expected overnight into Saturday morning. The chance
for showers and thunderstorms returns on Saturday, potentially as
early as 15Z. If precipitation occurs Saturday morning, it should
decrease in coverage in the afternoon. If Saturday morning remains
primarily dry, the chance for showers and thunderstorms would shift
to the afternoon. Latest model trends would favor light isolated
showers in the morning and more robust, impactful convection in the
afternoon. Saturday convection could result in brief heavy rain,
lightning, sudden gusty outflow winds, and CIGs to 10kft.
Temperatures will exceed 100F between 18Z-05Z, peaking around 106F
Saturday.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 00Z Forecast Package...Continuing to watch the
potential for afternoon convection, with the greatest chances (20-
40%) expected across western Arizona as well as in the Sierra
through about 03Z. There is a lower chance of showers  this evening
but impacts should be minimal as convection will be isolated. Low
confidence in the Colorado River Valley forecast this evening and
early tonight and showers and thunderstorms may push in from the
east along gusty east to southeast winds between 03Z-06Z. Any
thunderstorms today could result in lightning, sudden gusty outflow
winds, and CIGs to 10kft. In general though, light winds and VFR
conditions will persist through early Saturday. Additional scattered
precipitation is expected on Saturday with showers and isolated
thunderstorms possible as early as 15Z in western Arizona into far
southern Nevada. The most widespread convection and highest impacts
should be Saturday afternoon in the Sierra through the Southern
Great Basin where sudden gusty outflow winds, lightning, brief heavy
rain, and CIGs to 10kft are possible.

&&

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

&&

DISCUSSION/AVIATION...Nickerson

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