Winchester, Nevada Weather Forecast Discussion

009
FXUS65 KVEF 160753
AFDVEF
Area Forecast Discussion
National Weather Service Las Vegas NV
1253 AM PDT Tue Sep 16 2025
.KEY MESSAGES...
* Warm and dry weather will continue through Wednesday.
* Chances for showers and thunderstorms will spread over the region
  from south to north Wednesday night through Friday, with slight
  chances lingering through the weekend. Thursday and Friday will be
  the most likely period for widespread rainfall and impacts.
&&
.DISCUSSION...through Monday. Clear skies and light winds again
early this morning. The main concern for this forecast is still the
remnants of Mario and how much rain could fall. Satellite imagery
from Monday evening showed the tropical storm looking very poor,
although a new burst of convection overnight suggests Mario is not
quite dead yet. Regardless of whether it is a TS, TD, or remnant
low, tropical moisture will be surging north across our area from
Wednesday evening through Thursday night. Precipitable water should
reach one inch over nearly all of our CWA, with up to an inch and a
half in the lower elevations of the Colorado River Valley and
possibly Death Valley. Models have honed in a little on rainfall
timing since yesterday, and amounts have generally risen. The best
chances for heavy rain seem to be focused on Thursday and Friday.
25th percentile rain amounts now show about one tenth of an inch
over most of the Mojave Desert and two to four tenths in the
mountains (these numbers were nearly zero yesterday), and 75th
percentile amounts show half an inch to one inch for most of the
Mojave Desert and up to two and a half inches in the mountains, both
of which are up roughly 30 percent since yesterday. Not enough
confidence in the details to issue a Flash Flood Watch yet, although
if model trends continue, one may be needed later today or early
tomorrow morning. The most likely "failure mode" for flash flood
potential will be overcast skies inhibiting instability and causing
rain to be more stratiform than convective. Once we get past Friday,
there is a lot of model disagreement on how much instability and
forcing will be available, so low confidence in PoPs over the
weekend and into early next week. The forecast will reflect slight
chances for showers and thunderstorms, mainly in the afternoons,
which is a good middle ground assuming moisture does not get scoured
out (moderate to high confidence) and there is no synoptic forcing
(low to moderate confidence).
&&
.AVIATION...For Harry Reid...For the 06Z Forecast Package...Winds
will continue to follow diurnal directional patterns through the
forecast period. After winds shift to the east-southeast Tuesday
afternoon, intermittent thermally-induced gusts to around 15KT
will once again be possible, particularly from late afternoon into
early evening. Winds diminish, shifting to the southwest after
sunset. High clouds look to begin increasing near or just beyond
the end of the forecast period with VFR conditions prevailing.
Temperatures are expected to remain under 100 degrees.
For the rest of southern Nevada, northwest Arizona and southeast
California...For the 06Z Forecast Package...Across the region,
winds will follow typical diurnal directional patterns the next
24 hours. Wind speeds will generally remain around 10KT or less,
with gusty up-valley winds expected through portions of the Owens
Valley on Tuesday afternoon. VFR conditions prevail, with high
clouds starting to overspread the region from south to north late
in the forecast period.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
DISCUSSION...Morgan
AVIATION...Phillipson
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NWS VEF Office Area Forecast Discussion