081
FXUS65 KVEF 210525
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1025 PM PDT Wed Aug 20 2025

.KEY MESSAGES...

* Extreme Heat Warnings and Heat Advisories remain in effect through
  Saturday as hotter than normal temperatures stick around until the
  end of the week.

* Monsoonal moisture returns to the region, bringing increased
  chances for afternoon showers and thunderstorms as we head into
  the weekend and next week. Lightning, strong outflow winds, and
  heavy rain capable of resulting flash flooding will be possible.

&&

.DISCUSSION...through Tuesday.

With the Four Corners high now established, temperatures begin to
reach levels dangerous for most of the population. Highs across the
Mojave Desert will generally range from 105-115 while the southern
Great Basin and higher valleys top out in the 95-105 range. These
values are close to daily record highs in several locations.
Combined with warm overnight lows (mid 80s to low 90s in the lower
deserts), HeatRisk jumps to the major category in the Extreme Heat
Warning areas. The oppressive heat continues into the weekend when
monsoon moisture and cloud cover begin to suppress temperatures.

Speaking of monsoon moisture, we are already seeing it push into our
area (as evident by the increased clouds this morning). PoPs today
stay east of our area, but begin to creep into our eastern zones
tomorrow. Models have the Four Corners high becoming entrenched for
the next ~5 days, with southeasterly flow continuing to usher in
better moisture and precipitation chances. Ensemble mean PWAT values
between 1.25-1.50" should provide ample fuel for scattered
showers/storms over the weekend, though local instability will also
depend on the extent of morning cloud cover and precipitation. By
Saturday, NBM PoPs are over 40% across the area (which may be a
little heavy-handed in the valleys given the lack of obvious forcing
mechanisms) and generally stay that way through Tuesday. All monsoon
thunderstorm hazards will be possible (flash flooding, strong
outflow winds, and lightning).

&&

.AVIATION...For Harry Reid...For the 06Z Forecast Package...The
usual southwest winds less than 10 knots are expected overnight,
becoming light early Thursday morning. Easterly winds are expected
again from late Thursday morning through early afternoon, with
speeds generally below 10 knots, but one or two sporadic gusts could
occur. In the afternoon, winds should shift to southerly around 10
knots, with a few sporadic gusts not out of the question. VFR
conditions throughout. Temperatures above 100F from about 18Z to
05Z, peaking near 109F.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 06Z Forecast Package...Light breezes continue
across the area, with wind directions generally following typical
daily patterns, and gusts 20 knots or less. VFR conditions for most
of the area, except for isolated thunderstorms which could develop
over eastern Mohave and Lincoln counties Thursday afternoon.

&&

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

&&

$$

DISCUSSION...Woods
AVIATION...Morgan

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