948
FXUS65 KVEF 210704
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1200 AM PDT Mon Sep 21 2026

.KEY MESSAGES...

* Showers and Thunderstorms expected over Inyo, Esmeralda, Nye, and
  Lincoln County later today, persisting into tonight.

* Near normal temperatures early this week, warming back up to above
  normal mid week into next weekend.

* Potential increase in monsoonal moisture for Mohave County late
  week

&&

.DISCUSSION...through Monday.

Satellite imagery shows an upper low off the coast of Central
California, bringing high clouds to the region during the early
hours Monday morning. This system will slowly track east into
Central Nevada over the next 48 hours bringing a chance for showers
and thunderstorms over the Sierra and portions of the Great Basin
this afternoon through Tuesday. Moisture advection ahead of the
approaching trough is only marginal with PW ranging from 0.7 to 1.00
inch surging northward through the Great Basin; however forecast
soundings for Desert Rock, Tonopah, and Bishop show fairly deep
saturation through the atmospheric profile to support convective
activity. CAPE ranges from around 300-600 j/kg with higher DCAPE
values while 0-6km shear is more than enough for convection to
develop and sustain itself after sunset. Best forcing for ascent
looks to be over the Sierra and in higher terrain within Esmeralda,
Nye, and Lincoln Counties. Both 00z HRRR and RRFS are in great
agreement of convection developing in these areas after 19z, then
persisting through 06-08z at least. While moisture availability and
instability are only marginal, if storms end up training over the
same areas then flooding could become a concern around Death Valley
and into the Great Basin. DCAPE is high enough where gusty winds
will be possible in any storm along with heavy rain and lightning.
Further south toward Las Vegas, the I-15 corridor and points south,
not expecting much, if any, convection as the main forcing for
ascent remains to the north. Will have to watch if any outflow
boundaries track south toward the Las Vegas Valley Monday evening as
some hi-res guidance shifts winds around to the north. Confidence is
low if Las Vegas will see gusty winds from storm outflow, but will
monitor storm trends and evolution through the evening.

With the upper low passing overhead bringing slightly cooler air
aloft, temperatures will cool marginally behind the low on Tuesday
with most locations 3 to 6 degrees cooler than today. The low will
eject fairly quickly to the northeast on Tuesday morning but there
may be a few lingering showers into the early afternoon in Lincoln
County.

Generally, dry southwesterly flow and subtle ridging sets up for the
remainder of the week and into next week. Medium to long range
guidance is in agreement that low level temperatures will run
several degrees above normal in this upcoming pattern, resulting in
a warming trend each day mid week through the weekend. High
temperatures by Saturday reach the low 100s again in desert valleys.
Overall Heat Risk through the week remains low, with sporadic areas
of moderate. Along with warming temps, ensemble guidance is also
hinting towards a modest uptick in moisture mainly south and east of
Las Vegas on Thursday and Friday. Currently, the best chances of
precipitation associated with this moisture are around 10 to 20
percent in Mohave County.

&&

.AVIATION...For Harry Reid...For the 06Z Forecast Package...Winds
generally follow typical daily directional patterns with speeds
under 10 knots. However, southeasterly winds on Monday afternoon
increase to around 10 knots with gusts between 15 and 18 knots.
After sunset, winds shift back to the southwest and fall to under 10
knots. Cannot rule out another northerly push of winds on Monday
night due to outflow from the northwest. Mid and high cloud cover
will increase throughout the day, with bases at or above 15kft.
Showers are possible over the mountains surrounding the Las Vegas
Valley during the afternoon and evening, but these are not expected
to reach the terminal.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 06Z Forecast Package...Winds should be light
and variable for most of the area tonight. One exception is the
western Mojave Desert including KDAG, where westerly winds over 10
knots persist. Elevated southeasterly winds with gusts between 15
and 25 knots pick across most of the area during the afternoon,
lasting through sunset. At the same time, southerly winds with gusts
to around 20 knots pick up at KBIH and westerly winds of around 10
knots will continue at KDAG. Cloud cover will increase through the
day with bases at or above 10kft. Showers and thunderstorms develop
over high terrain of Inyo County, some of which may reach KBIH.

&&

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

&&

$$

DISCUSSION...Moore
AVIATION...Meltzer

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