437
FXUS65 KVEF 181852
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
1152 AM PDT Tue Aug 18 2026

.KEY MESSAGES...

* Temperatures peak on midweek with above- normal afternoon highs
  and near-record morning lows.

* Monsoon moisture increases late this week into the weekend,
  accompanied by increased shower and thunderstorm chances.

&&

.DISCUSSION...Through The Weekend.

Mostly sunny skies prevailed across the region today. With high
pressure overhead and minimal change to the atmosphere over the past
24 hours, afternoon temperatures are on track to be similar to
yesterday- running 5-8 degrees above normal in most locations. In
addition, there are several climate sites that are currently tied or
broke a record warm low temperatures this morning, which may hold if
temperatures are slow to cool off tonight. These two factors
combined result in a heightened risk for heat related impacts, and
an Extreme Heat Warning is in effect for desert valley areas. This
heat warning continues through Friday as continued above normal high
temperatures and abnormally warm overnights will result in Moderate
to Major HeatRisk. By the weekend, upper level heights will begin to
fall with an incoming West Coast trough and  increasing monsoon
moistures, so moderating temperatures and decreasing HeatRisk is
expected.

As the area of high pressure repositions itself over the Four
Corners region the second half of the week, monsoon moisture will
push back north on southerly flow. This will result in a return of
afternoon shower and thunderstorms chances, starting in Mohave
County on Thursday then spreading further north and west on Friday.
Highest chances for thunderstorms and impacts should be in the
terrain as there will be minimal upper level support Thursday and
Friday, but will need to watch how this weekend sets up as moisture
lingers as the trough moves inland. Any storm will have the
capability of producing locally heavy rain, flash flooding,
lightning, and sudden gusty winds. How long the monsoon moisture
remains over the area as a drier southwesterly flow sets up with the
trough is uncertain as models struggle with how far inland the
trough is able to overcome the area of high pressure. Cluster
analysis shows general agreement that the trough will run into the
area of high pressure this weekend then slowly weaken, but varying
ideas of where high pressure will be centered early next week. Low
confidence in forecast details in the long range forecast given the
uncertainty of the synoptic setup.
&&

.AVIATION...For Harry Reid...For the 18Z Forecast Package...Winds
will remain southerly to southwesterly though sunset this
evening, increasing to around 10KT with intermittent thermally-
induced gusts to 15-20KT this afternoon and early evening. Winds
become lighter overnight, with elevated southerly winds returning
by early Wednesday afternoon. VFR conditions prevail with FEW-SCT
clouds with bases between 10-25kft. Temperatures will exceed 100
degrees through 03Z this evening, reaching a high of 109 degrees
this afternoon. Temperatures rise above 100 degrees again by 18Z
Wednesday.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 18Z Forecast Package...Winds will settle out
of the south and southwest early in the period, with sustained
speeds around 10-12KT with intermittent higher gusts to around
20KT expected this afternoon through sunset. Thereafter, winds
become lighter, following typical daily directional patterns.
Exceptions include KDAG/the western Mojave Desert where winds
generally remain westerly through the period, with gusts expected
late afternoon and overnight, and KBIH in the northern Owens
Valley where gusty south-southeasterly up-valley winds are
expected. VFR conditions otherwise prevail, with passing bands of
clouds with bases at or above 10kft.

&&

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

&&

$$

DISCUSSION...Nickerson
AVIATION...Phillipson

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