244
FXUS65 KVEF 181919
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1219 PM PDT Mon Aug 18 2025

.KEY MESSAGES...

* Extreme Heat Warnings and Heat Advisories mid-to-late week as
  temperatures increase to well-above seasonal normals.

* Anomalous moisture will increase precipitation potential over area
  mountains mid-to-late week, with chances spreading across the
  region over the weekend.

&&


.DISCUSSION...Today through Monday.

Today will be the coolest day of the forecast period, as a ridge of
high pressure over the southern states expands westward. Through the
week, this westward progression will increase heights over our
forecast area, allowing afternoon high temperatures to climb to 6 to
10 degrees above seasonal normals. Due to the high confidence of
this heat, went ahead and upgraded the Extreme Heat Watch over the
region to Heat Advisories in the Spring Mountains, Esmeralda County,
and central Nye County, and Extreme Heat Warnings elsewhere
Wednesday through Saturday. The only zones without heat-related
headlines include the eastern Sierra Slopes and the White Mountains
in Inyo County, as temperatures will be more moderate in those
higher elevations. Over the weekend, a trough will push through the
western states, which will deamplify the ridge and cool temperatures
across the Desert Southwest. There remains some uncertainty of the
timing of this trough, with forecast high temperatures on Saturday
jumping up several degrees from the previous forecast package. As
such, went ahead and kept the heat headline through Saturday, as
overnight lows will remain unseasonably warm (struggling to drop
below 90 degrees in valley locations), and afternoon highs have the
potential to over-achieve.

As the aforementioned ridge of high pressure spreads westward
through the work week, there will be a brief period of due southerly
winds aloft late-Monday into Tuesday. This will usher monsoonal
moisture up the Colorado River Valley early-to-mid week, with PWATs
exceeding 1.00 inches in southern Nevada, according to the ECMWF
ensemble mean. As the ridge continues to push westward, this
moisture will fail to make additional northward advancement and will
effectively remain stuck beneath the high. As such, PoPs increase
mid-to-late week, primarily over the higher terrain, as orographic
lift and daytime heating will be the main drivers for convection
underneath an otherwise stable ridge. Heading into the weekend, a
trough approaching the region will tap into the existing moisture,
while providing a means for instability and dynamics, thereby
increasing PoPs across the entire forecast area. Stay tuned to the
forecast if you have outdoor plans this weekend.
&&


.AVIATION...For Harry Reid...For the 18Z Forecast Package...Wind
directions will follow typical diurnal patterns today, with east-
southeasterly winds this afternoon between 7 and 10 kts, becoming
southwesterly after sunset. FEW aoa 12 kft expected overnight
through the remainder of the TAF period. Temperatures will be at
or above 100 degrees from 20 to 03Z, peaking around 103.

For the rest of southern Nevada, northwestern Arizona and
southeastern California...For the 18Z Forecast Package...Wind
speeds and directions will follow typical diurnal patterns today,
with speeds between 6 and 10 kts. The exception will be KBIH,
where south- southeasterly wind gusts will peak between 25 and 30
kts before dropping off after sunset. FEW aoa 12 kft across
southern Nevada overnight through the remainder of the TAF period.
&&


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

&&

$$

DISCUSSION/AVIATION...Soulat


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