120
FXUS65 KVEF 022043
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
143 PM PDT Tue Sep 2 2025


.KEY MESSAGES...

* Monsoonal moisture will provide fuel for widespread shower and
  thunderstorm activity today. Flash flooding is the primary concern.

* Moisture remains in place through midweek before slowly scouring
  out of the region, shifting precipitation chances further east
  each day.

&&

.DISCUSSION...

The ridge of high pressure over the Desert Southwest is shifting
slightly eastward, as a result of a shortwave approaching off the
California coast. This is allowing additional moisture into the
area, providing fuel for widespread thunderstorm activity. Dewpoint
rose from the upper 30s to lower-mid 60s across southern portions of
the CWA as storms moved into the area on the heels of a monsoonal
easterly wave propagating from souther Arizona. Storms have produced
strong winds along the periphery of the cloud shield and extended
outflow boundaries, which have provided focus for short-lived storms
as the outflow moved through. There have been brief periods of heavy
rain, but most areas have seen less than .10" of rain with a few
areas of .25" to .35". Clearing this afternoon will allow for a
resurgence of thunderstorm activity, as is being seen in Mohave and
Coconino counties in Arizona. Assuming the clearing continues,
thunderstorms could impact the Las Vegas Valley by the early evening
hours. While storms have been moving fairly quickly, the amount of
available moisture will support high rain rates of over 2" per hour,
meaning stronger storms could cause flooding rapidly. Due to this,
there is a Flash Flood Watch in effect through the 1 AM Wednesday
morning.

A Shortwave moving northward into will linger around the are for the
next several days, keeping an opportunity for showers and
thunderstorms areawide. The area will slowly dry out from west to
east as this shortwave slowly translates eastward and shifts dynamic
support for thunderstorms into Utah and Arizona. Lingering moisture
will keep mountain showers around into the weekend, but coverage
will be much less by then.

&&

.AVIATION...For Harry Reid...For the 18Z Forecast Package...
A very complex and low confidence forecast is in store for much
of the Las Vegas Valley region. With ongoing morning
showers/storms to the south and west of the terminal, uncertainty
is high in how existing cloud cover and outflow will affect
afternoon conditions. Winds will remain south/southwest through
early afternoon, shifting a bit more southeasterly by 20-21z. Wind
speeds should generally remain 10-12 knots or less. This
afternoon, with abundant moisture and the expectation of a few
breaks in the clouds, at least a few thunderstorms are expected to
develop. Heavy rainfall will accompany any storms with reduced
visibilities. However, confidence remains low that the terminal
will be directly impacted. Confidence is high, however, in gusty
outflow winds from any nearby storms, so we have maintained a
TEMPO for this likelihood. From 00z on, confidence is
sufficiently low in storms that the TEMPO has been removed. Storm
activity may linger into the overnight hours with the potential
for additional gusty outflow winds. By 10z-12z, activity should
wane with scattered to overcast mid level ceilings. While
temperatures are forecast to touch the low 100s between 21-23z,
existing cloud cover and rain cooled outflows may make it
difficult to reach.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 18Z Forecast Package...A complex forecast is
in store with scattered showers/storms ongoing and more expected
into the afternoon. Winds to generally remain south/southeast 15
knots or less, except where nearby thunderstorms promote strong
gusty outflow winds, which could affect almost any terminal. A
mostly diurnal wind pattern is expected at KBIH, further removed
from morning showers storms. Ongoing showers/storms to mainly
affect KDAG/KIFP/KEED through late morning. Into the afternoon,
confidence remains low that any individual terminal will be
impacted by a thunderstorm, but if this occurs, very heavy rain
will result in visibilities of 1SM or less, along with gusty
winds. Broken to overcast mid level ceilings can be expected
through most of the period.

&&

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

&&

$$

DISCUSSION...Berc
AVIATION...Austin

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