192
FXUS65 KVEF 211153
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
453 AM PDT Wed Oct 21 2026

.KEY MESSAGES...

* Multiple rounds of rain and storms expected northwest of
  Interstate 15 and in northwestern Arizona through Thursday.

* The greatest risk of flash flooding and severe storms exists
  over northwestern Arizona.

* Dry conditions and seasonable temperatures expected this weekend
  and early next week.

&&

.DISCUSSION...through Tuesday.

Latest satellite imagery shows our system spinning off the CA
coast in the form of a closed low. As expected, scattered
showers and storms have developed across our northern/northwestern
zones overnight in the left exit region of an upper-level jet
streak. This activity is forecast to continue through the day
across Inyo, Nye, and Esmeralda counties, though coverage and
intensity will vary over time. A secondary area of convection is
beginning to form across Mohave, Lincoln, and northeastern Clark
counties this morning as the jet streak translates east and robust
moisture advection occurs. PWATs between 1-1.25" should allow for
fairly efficient rainfall within this convective regime, though
quick storm motions mean any flash flooding will likely require
training convection. Best chances of this are in northern Mohave
County, where a Flash Flood Watch is in effect through Thursday
afternoon. In addition to the flood threat, northwestern AZ will
have the risk of severe thunderstorms today, and to a lesser
extent on Thursday. The SPC has given this area a marginal to
slight risk of severe storms, including the potential for a
tornado or two, damaging winds, and hail up to 2" in diameter
today. Anomalous low-level moisture and decent lapse rates will
foster CAPE values between 500-1500 J/kg. Hodograph curvature is
limited, but low-level wind shear is rather impressive for the
area (25-35 knots in the lowest 3km based on forecast soundings).
These long, straight hodographs will favor splitting supercells,
with the left split carrying the greatest hail risk and the right
split having the greatest tornado risk. However, abundant storm
coverage/interactions may complicate or limit the severe threat.
The severe risk may carry over into the overnight hours tonight if
storms manage to stay in our portion of AZ.

The primary vort max of the low/trough swings through on Thursday,
bringing the best chance of widespread precipitation to our
region. PoPs on Thursday are 50% or more in most locations, though
the southern Mojave Desert remains the greatest area of "bust"
potential with PoPs 10-40%. Precipitation chances largely exit the
CWA Thursday night once the shortwave trough axis clears us, but
a secondary shortwave diving south will keep the larger trough
overhead on Friday. This allows shower chances (20-40%) to linger,
primarily in the southern Great Basin. The trough finally pushes
east on Saturday, although guidance has trended slower with this.
The weekend should be much drier, but if the trough continues to
slow, low precipitation chances may linger in our eastern areas on
Saturday.

The hydro/convective concerns are going to be the primary focus
with this system, but there are other aspects worth mentioning
as well. Snow levels bottom out around 8kft, but most of the
precip will fall while they are 9kft+, thus limiting any winter
impacts to the higher elevations of the Sierra. Gusty winds will
be present as well with this storm, with widespread southerly
gusts of 20-40 mph today and Thursday. Friday into Saturday, we
see a shift to gusty north winds as the system pulls away.
Temperatures will be near normal today, dropping to below-normal
values tomorrow through Saturday. Dry and seasonable conditions
expected Sunday through Tuesday as we see a lull in the storm
track.

&&

.AVIATION...For Harry Reid...For the 12Z Forecast Package...Light
winds gradually veer to the east by mid-morning, increasing to
around 8KT. By early to mid-afternoon, winds shift to the
southeast, increasing to 10-15KT with gusts to around 20-25KT
expected thereafter through sunset. Winds become light and
somewhat variable overnight, increasing out of the southwest
toward the end of the forecast period. Clouds will be SCT-BKN
around 8-12kft through the forecast period, with some improvement
expected this afternoon. While thunderstorm activity largely
remains outside of the Las Vegas Valley, impacts to approaches can
be expected due to scattered to numerous thunderstorms across the
Mormon Mesa and Peach Springs Corridors this afternoon onward.


For the rest of southern Nevada, northwest Arizona and southeast
California...For the 12Z Forecast Package...Winds around 5-10KT
this morning will shift to the south and southeast by late
morning into early afternoon and become elevated, with gusts to
20-30KT common through sunset. Isolated showers this morning will
give way to more widespread shower and thunderstorm development by
this afternoon, especially across the southern Great Basin,
northwestern Arizona, and portions of southeastern California.
Convection is largely expected to stay out of the vicinity of area
terminals, with the exception of KBIH, where at least vicinity
showers and thunderstorms are expected through the forecast
period. The best window for thunderstorm impacts at KBIH will be
between around 21/20Z-22/02Z, with erratic gusty winds, lightning
strikes, and ceiling/visibility reductions due to rainfall
expected. Cloud bases will generally be at or above 10kft, but
will be as low as 6-8kft in the vicinity of convection.

&&

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

&&

$$

DISCUSSION...Woods
AVIATION...Phillipson

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NWS Las Vegas (VEF) Office