711
FXUS65 KVEF 031155
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
455 AM PDT Wed Sep 3 2025

.KEY MESSAGES...

* Monsoonal moisture remains in place today before slowly
  retreating eastward out of the region, shifting the best
  precipitation chances further east each day.

&&

.DISCUSSION...Today through Tuesday.

Monsoonal moisture will surge farther north into the southern Great
Basin today. Meanwhile, a vorticity lobe will stretch along the
California-Nevada state line today, providing ample forcing aloft to
sustain widespread showers and thunderstorms again this afternoon.
Yesterday, morning convection overachieved, and resulted in thick
cloud cover through the morning and early-afternoon, which
resulted in a more stable environment than expected, thus fewer
thunderstorms than forecast. Today, clearing will slowly occur
through the morning, eventually exposing our southern zones to
sunlight. The resultant daytime heating will allow CAPE values to
increase to 500- 1000 J/kg across eastern San Bernardino County,
southern Clark County, southern Mohave County, and the Colorado
River Valley. Despite ample mid-and-upper level moisture, forecast
HRRR soundings continue to show dry air at the surface across our
southern zones, so gusts between 35 and 45 mph cannot be ruled
out with stronger thunderstorms. Additional threats include
frequent lightning, locally heavy rainfall, and isolated instances
of flash flooding this afternoon. Though forcing aloft is best in
the southwestern Great Basin - primarily across Esmeralda County
- morning cloud cover will keep that area relatively stable
through the day. We still expect moisture to gradually retreat
southeastward from our forecast area through the remainder of the
week and into the weekend; however, the speed at which the
moisture retreats has been delayed somewhat due to Hurricane
Lorena approaching Baja California. Daytime heating and remnant
forcing aloft coupled with this moisture return PoPs to our
eastern zones each day heading into the weekend.

&&

.AVIATION...For Harry Reid...For the 12Z Forecast
Package...Passing showers will linger across the Las Vegas Valley
for the first couple hours of the forecast period, with ceilings
improving through the morning. Another round of showers and
thunderstorms is expected this afternoon, with the most likely
window for impacts at the terminal from late afternoon through mid
evening. Erratic gusty winds associated with storms and outflow
boundaries, along with lightning strikes and brief/transient
MVFR/IFR conditions in heavy rain can be expected with storms that
develop. Late evening and overnight, convective activity will
wane, with winds generally remaining light and variable outside of
any convective influences. VFR conditions otherwise prevail, with
temperatures remaining under 100 degrees.


For the rest of southern Nevada, northwest Arizona and southeast
California...For the 12Z Forecast Package...Lingering showers
moving northwestward across the area will gradually diminish
through this morning, with low ceilings across the Lower Colorado
River Valley expected to improve through sunrise. Another round
of showers and thunderstorms is expected to develop this
afternoon through mid evening, initially over higher terrain
before moving across lower elevations, with lower confidence in
development across western San Bernardino County and southern
portions of the Lower Colorado River Valley, including KEED.
Erratic gusty winds, lightning, and brief MVFR/IFR conditions in
heavy rain are expected with storms that develop, with outflow
winds possible away from storms. Outside of convective influences,
winds will generally remain under 10KT and be somewhat variable
this afternoon onward, with VFR conditions prevailing.

&&

.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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