344
FXUS65 KVEF 161054
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
354 AM PDT Sun Aug 16 2026

.KEY MESSAGES...

* Isolated showers and thunderstorms will be possible this afternoon
  and evening across the higher terrain of southern Nevada,
  southeastern California, and northwestern Arizona.

* Temperatures will steadily increase throughout the week, with
  areas of Moderate-to-Major HeatRisk developing across the Colorado
  River Valley, Death Valley, and portions of the Las Vegas Valley.

&&

.DISCUSSION...through Saturday.

The anomalous moisture that has helped to fuel storms over the past
few days, will decrease during the first half of the week as the
upper-level flow becomes more southwesterly-to-westerly thanks to
the ridge building over the area. However, first, this southwesterly
flow will help to advect mid-level moisture from Tropical Depression
Hernan into the region overnight. This moisture will bring increased
cloud cover to the region and a 15 to 30% chance for showers and
thunderstorms in the higher terrain of southern Nevada, San
Bernardino County, and Mohave County today. Storms today will be
less robust than those we have seen over the past few days, with the
primary concerns being localized moderate-to-heavy rain, lightning,
and erratic outflow winds. Any storms that develop will diminish
after sunset with the loss of daytime heating. Beyond today,
decreasing moisture combined with increasing large-scale subsidence
from the building ridge will result in a lull in convective activity
during the first half of the week.

As the aforementioned ridge of high pressure builds over the area,
we will see temperatures increase through the first half of the
week, with above normal temperatures returning during the latter
half of the week. Increasing temperatures will bring increasing
HeatRisk, with widespread Moderate HeatRisk across the region by
Thursday and pockets of Major HeatRisk popping up in Death Valley,
the Colorado River Valley, and the Las Vegas Valley. As ridging
builds over the area, ensemble guidance points at upper-level flow
becoming more southeasterly in northwestern Arizona, which would
open the door for moisture to creep back into the region. However,
uncertainty remains high at this time, so no promises.

&&

.AVIATION...For Harry Reid...For the 12Z Forecast Package...Winds
are expected to remain light and generally follow typical daily
diurnal patterns through the TAF period. Kept VCSH in for this
afternoon for the possibility that remnants of any storms that
develop south of the area drift into the southwestern valley, but
currently thinking that any stronger convection will stay southwest
of town. Showers and storms will diminish in the evening, with calm
winds and dry conditions expected overnight. Aside from any shower
activity, VFR conditions will prevail into Monday with bases
remaining AOA 10kft AGL. The high temperature may approach 100F
between 22Z and 01Z, but mid-level cloudiness will likely keep
readings in the upper 90s.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 12Z Forecast Package...Isolated to scattered
convection is expected again this afternoon, primarily across
southern Clark, eastern San Bernardino, and central Mohave counties.
While the current thinking is that the activity will stay out of the
Las Vegas Valley, a few remnant showers from storms southwest of
town may make it into the valley. Heavy rain and gusty outflow winds
are the main concerns near any storms. Convection should decrease
during the evening hours. Outside of any convective influences,
winds in most locations should be light. The exceptions are the
southern Great Basin and Owens Valley, where breezy south winds are
forecast. 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...Stessman
AVIATION...Planz

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