949
FXUS65 KVEF 162223
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
325 PM PDT Sun Aug 16 2026

.KEY MESSAGES...

* Isolated showers and thunderstorms are expected this afternoon
  and early evening, mainly over the higher terrain of southern
  Nevada, southeastern California, and northwestern Arizona.

* Temperatures will steadily increase throughout the week, with
  areas of Major HeatRisk expanding by midweek, especially across
  the Colorado River Valley, Death Valley, and portions of the Las
  Vegas Valley. An Extreme Heat Watch is in effect.

&&

.DISCUSSION...

Southwesterly flow aloft persists today, with latest water vapor
imagery and 500 hPa RUC analysis indicating a weak perturbation
and fetch of mid-level moisture associated with the remnants of
Tropical Depression Hernan moving over the region. This will be
enough to maintain afternoon and early evening storm chances
despite decreased shear and instability, with convection focused
mainly over the higher terrain of San Bernardino, Clark, and
Mohave Counties. These storms will be capable of producing locally
heavy rainfall, gusty winds, and lightning. Localized flooding
also remains a concern, especially if storms develop and train
over areas that received substantial rainfall the past several
days. Any convective activity that develops this afternoon is
expected to weaken quickly through early evening. After today, a
drying trend is expected as broad mid-level ridging builds
westward over the region, yielding increased subsidence and mainly
dry conditions through midweek.

While the warming trend has already started today, the
aforementioned ridge and associated increasing thicknesses will
yield a quick return to above normal temperatures for most
locations by Tuesday. Given the climbing temperatures, widespread
Moderate HeatRisk (level 2 of 4) is expected by Tuesday, with
pockets of Major HeatRisk (level 3 of 4) concurrently developing
through the Lower Colorado River Valley and Death Valley. These
areas of Major HeatRisk will gradually expand midweek, with
temperatures peaking Wednesday into Thursday. An Extreme Heat
Watch has been issued for portions of southern Nevada,
northwestern Arizona, and southeastern California Tuesday through
Friday, with ensembles indicating possible relief from the heat in
time for the weekend as we see another uptick in monsoonal
moisture. While thunderstorm chances return to far eastern areas
as early as Thursday and Friday, details are likely to change
between now and then, thus all are encouraged to practice heat
safety this week, and check back for the latest forecast.

&&

.AVIATION...For Harry Reid...For the 00Z Forecast Package...Winds
are expected to remain light and generally follow typical daily
diurnal patterns through the TAF period. Shower activity remains
possible along the edges of the Las Vegas Valley through sunset but
is generally not expected within the airport vicinity. Similar
conditions will resume tomorrow with shower coverage decreasing even
further. Temperatures will remain near 100 through 02z tonight and
climb above 100 again Monday from 19z through 3z.


For the rest of southern Nevada, northwest Arizona and southeast
California...For the 18Z Forecast Package...Isolated showers are
possible through sunset across the higher terrain of southern Nevada
and northwest Arizona. Showers will die off quickly around sunset.
Winds across the region will remain light with the exception of the
southern Great Basin and Owens Valley, where breezy south winds are
forecast through the evening and again Monday. Cloud bases should
remain AOA 10kft AGL through the TAF period.

&&

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

&&

$$

DISCUSSION...Phillipson
AVIATION...Outler

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