Flash Flood Warning 81, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
101 PM PDT Fri Sep 5 2025

.KEY MESSAGES...

* Monsoon moisture will remain in place through Sunday, promoting
  scattered afternoon showers and thunderstorms each day. Activity
  will gradually shift eastward as drier air moves into the
  region early next week.

* A drying trend is expected the first half of the week as flow
  becomes more westerly. Relatively cooler temperatures will also
  overspread the region by mid week.

&&

.DISCUSSION...
Anomalously high moisture remains across the Desert Southwest,
trapped beneath a flattening area of high pressure situated over
northern Mexico. This coupled with daytime heating and orographic
and mesoscale influences will continue to promote scattered
showers and thunderstorms through tonight. Areas of central and
southern Nevada, and adjacent western Arizona look to hold the
greatest potential for showers and storms. Hi-res ensembles have
recently struggled with convective evolution into the evening and
overnight hours, often underestimating the longevity and intensity
of showers and storms. Recent examples include Tuesday earlier
this week and last night, when large storm complexes developed and
lasted well past sunrise. The gradual invasion of drier air makes
for lesser confidence in something similar happening overnight,
but there remains at least a 10-20 percent chance of some kind of
convective complex developing across central/southern Nevada and
shifting south and east overnight. Regardless, any stronger storm
cells will be capable of producing rainfall rates of 3-4 inches
per hour, localized flooding and gusty winds. The focus for
Sunday's storms will shift eastward into mostly western Arizona
and Utah as upper flow becomes more westerly in nature. However,
an isolated terrain induced storm or two may occur further west.

Medium to long range ensembles display rather high confidence in
the development of a large upper trough off the California coast.
This will push remnant moisture east of the region, resulting in
drier conditions. With lower heights, we can also expect to see
temperatures around 5-10 degrees below seasonal normals. The drier
air will also bring more relief overnight with pleasant morning
conditions from midweek on.

&&

.AVIATION...For Harry Reid...For the 18Z Forecast Package...
East to northeast winds to persist into the afternoon hours with
speeds generally 15 kt or less. Low confidence in isolated
shra/tsra from 21z through 02z. While these may not directly
impact the terminal, gusty outflows may. Winds to eventually
become southwesterly after 00z, then gradually shift to the
northwest/north overnight. Outside of thunderstorm outflows, winds
should generally remain 10 kt or less. Temperatures to remain
below 100 degrees through the period.

For the rest of southern Nevada, northwest Arizona and southeast
California...For the 18Z Forecast Package...Another day of
isolated showers/storms is expected, which could result in gusty
outflows at all terminals aside from KBIH, where drier conditions
persist. Winds to generally remain east/southeast initially,
shifting to a more southerly direction late this afternoon into
the evening. Winds will eventually take on a more diurnal pattern
overnight except where any showers or storms linger. KBIH will be
the one exception to this, where gusty up-valley breezes can be
expected through 00z to 03z before shifting back to the northwest.

&&

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

&&

DISCUSSION/AVIATION...Austin

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Preliminary Local Storm Report
National Weather Service Las Vegas NV
149 PM PDT Fri Sep 5 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1153 PM     Flash Flood      20 WNW Needles          34.92N 114.96W
09/04/2025                   San Bernardino     CA   Law Enforcement

            Goffs Road was closed due to flooding from
            US 95 to Interstate 40.

&&

ASG