272
FXUS65 KVEF 061125
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
425 AM PDT Sun Sep 6 2026

.KEY MESSAGES...

* A band of showers with a chance of embedded thunderstorms will
  form along Interstate 15 this morning and afternoon.

* Drier conditions expected for Labor Day, with decreasing
  confidence in monsoonal thunderstorms through the week.

&&


.DISCUSSION...Today through Saturday.

A surge of moisture reminiscent of a winter-type system is pushing
northward in a line from San Diego through Needles into northern
Arizona early this morning thanks to moisture from Hurricane Marie.
The upper-level trough responsible for ushering this moisture into
the Desert Southwest will also guide a shortwave and an associated
115 kt 150mb jet streak into the region. The combination of these
features will result in a line of showers (and potentially embedded
thunderstorms) forming southwest-to-northeast across our forecast
area, generally along Interstate 15. This band of precipitation is
currently forecast to be quite narrow, with northwest and southeast
corners of our forecast area remaining dry - and even, for some,
experiencing mostly sunny skies. That said, minor shifts in the
position of the moisture flux could result in previously forecasted
dry locations observing measurable rainfall. Mostly cloudy skies
throughout the Mojave Desert and southeastern Great Basin this
morning will prevent much in the way of SBCAPE through the
afternoon. As a result, lift will be largely dependent on
orographics - meaning, the greatest chance of lightning and/or heavy
rainfall will be in the higher terrain. Looking at chances of
receiving 1 inch of rainfall over the next 24 hours, the HREF
continues to paint 60-70 percent over the higher elevations of Mt.
Charleston and 30-40 percent over the mountains of eastern Lincoln
County. Given the trajectory of this moisture, the Las Vegas Valley
is likely to experience a substantial amount of rain-shadowing,
resulting in much lower forecast precipitation amounts (generally
between 0.15 and 0.30 inches). That said, should the trajectory gain
a greater south-to-north component, moisture would funnel directly
into the Las Vegas Valley, resulting in greater rainfall amounts
(the 90th percentile approaches 0.50 inches). The primary concern
today will be the training of stronger cells embedded in the
precipitation band resulting in nuisance ponding or even flash
flooding, particularly in locations like Pahrump, which will
experience substantial runoff from the southwestern side of the
Spring Mountains. In general, the flash flood threat is expected to
be very isolated, if any at all, due to the stratiform nature of
this precipitation. Precipitation will gradually subside late-
afternoon into the evening.

There is decreasing confidence in the return of monsoonal
precipitation this week, as the Four Corners high shifts slightly
westward. PWATs in excess of 1 inch will remain trapped beneath the
ridge, with little instability aside from daytime heating. As a
result, cannot completely rule out isolated convection, particularly
in the mountains. Through the work week, temperatures will increase
thanks to rising heights, with the center of the high overhead by
Thursday.
&&


.AVIATION...For Harry Reid...For the 12Z Forecast Package... Cloud
cover will continue to increase through the morning, with bases
lowering to less than 10 kft AGL by mid-morning. Shower chances
increase around 12Z, with -RA prevailing by 15Z through mid-
afternoon. With shower activity overhead, expect CIGs dropping as
low as 5 kft with a slight (10-20 percent) chance of visibilities
reducing below 6 SM. Precipitation chances drop off around 03Z, with
improving ceilings into the overnight period. Otherwise, expect
elevated south-southwest winds in the afternoon, with a diurnal
pattern on Monday. Temperatures will remain below 100F through at
least Tuesday.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 12Z Forecast Package...Cloud cover will
continue to increase through the morning, with bases lowering to
less than 10 kft AGL by mid-morning, except for KBIH where FEW high
clouds are expected. KIFP and KEED can expect light shower activity
for the next couple of hours before the rain band pushes northward
to impact KDAG and the Las Vegas Valley TAF sites. Shower chances
continue for the Mojave Desert through the afternoon, with chances
tapering off quickly after 03Z with improving ceilings. Otherwise,
expect breezy south-southwest winds with the exception of the
Colorado River Valley TAF sites where gusty north winds will pick up
after 18Z.
&&


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

&&

$$

DISCUSSION...Soulat
AVIATION...Soulat

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