Riverside, Nevada Weather Forecast Discussion

926
FXUS65 KVEF 231112
AFDVEF
Area Forecast Discussion
National Weather Service Las Vegas NV
412 AM PDT Tue Sep 23 2025
.KEY MESSAGES...
* Low impact weather with dry conditions and near normal
  temperatures likely through Wednesday.
* Precipitation chances increase the second half of the week as
  anomalous moisture interacts with an upper level disturbance,
  however details and weather impacts remain low confidence at this
  time.
&&
.DISCUSSION...
Weak ridging is expected to build over the region today and
Wednesday. Under mostly sunny skies, temperatures will sit near
normal for this time of the year. Breezy north winds will develop
each afternoon but no impacts are expected as gusts remain under 25
MPH.
An unsettled weather pattern is expected to set up after Wednesday
as an upper level low off the California Coast shift east into the
Desert Southwest. Meanwhile, PWATs will increase, climbing to 150%-
200% of normal Thursday onward (though it`s worth mentioning: PWAT
normals are starting to decrease as we exit our typical monsoon
season). None the less- with anomalous moisture and increasing
forcing, chances for precipitation are expected at times Thursday
through at least the weekend. Details beyond that are uncertain
though as models show differing solutions with how the upper level
system moves through the region. Cluster analysis all generally show
the disturbance moving inland on Thursday then moving overhead
Friday and Saturday, center over southern Nevada-ish, before
shifting into Arizona on Sunday. Precipitation chances, coverage,
amounts, and potential impacts will depend on the exact track and
strength of the low. NBM 50th percentile 24-hr rainfall amounts are
not overly impactful, however there is a large spread between the
50th and 90th percentile and some 90th percentile 24-hr rainfall
amounts suggest at least minor rainfall impacts. The Weather
Prediction Center paints the Southern Great Basin and northern
Mohave County with a Marginal Excessive Rainfall Risk on Thursday,
then expands the Marginal Risk across the entire region for Friday
and Saturday. At the moment, this is a fair assessment as any
rainfall that develops could be heavy at times given the anomalous
moisture and upper level support which could lead to localized flash
flooding in flash flood prone areas. Expect fine tuning of impacts
and forecast details as we get closer to later in the week, stay
tuned.
After Saturday, models consensus diverges even further with what the
upper level disturbance does as it moves into Arizona. Ensembles do
show PWATs remaining above normal through early next week though- so
the continued presence of moisture should keep rain chances in the
forecast, especially in the afternoons with any diurnal heating.
Temperatures after Wednesday will cool with high temperatures
dropping to below normal levels Thursday through early next week.
&&
.AVIATION...For Harry Reid...For the 12Z Forecast Package...Light
winds early this morning will shift to the northeast and increase by
mid-morning.  Sustained speeds around 10 knots are still expected,
but model guidance now indicates a higher probability of gusts to
near 20 knots and these have been included in the latest TAFs from
late morning through mid-afternoon.  Winds will become light and
variable once again this evening before turning northerly overnight.
VFR conditions will prevail through the TAF period under mainly
clear skies.
For the rest of southern Nevada, northwest Arizona and southeast
California...For the 12Z Forecast Package...Conditions at the Las
Vegas area TAF sites will be similar to what is described above for
Harry Reid, except no gusts are expected at KVGT.  Elsewhere, up-
valley gusts to around 20 knots are expected at KBIH this afternoon
before the typical light northerly winds return by late evening.
Gusty northerly winds are likely in the Colorado River valley, with
the strongest winds expected in the vicinity of KIFP.  A few gusts
are also expected at KEED, but these should diminish by evening.
Across the western Mojave Desert, typical diurnal wind variations
are expected.  VFR conditions will prevail at all sites with mainly
clear skies expected.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Nickerson
AVIATION...Planz
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NWS VEF Office Area Forecast Discussion