Severe Thunderstorm Warning 20, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
1210 PM MDT Sat May 30 2026

.KEY MESSAGES...

- An unsettled weather pattern will continue into the weekend
  with daily chances for afternoon/evening showers and
  thunderstorms.

- Strong to severe thunderstorms will develop this afternoon for
  areas east of the I-25 corridor. If severe thunderstorms
  develop all hazards are possible; large hail, damaging winds,
  and tornadoes are possible.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 600 AM MDT Sat May 30 2026

A negatively tilted trough will push into the Southeastern corner of
Wyoming this afternoon. A 45 knot 500 mb speed maximum is
expected to pivot around the base of the wave located over SE
Wyoming and Western Nebraska, providing a source for deep-layer
vertical wind shear and the potential for organized deep
convection. SPC issued a slight risk with a 2 percent chance for
Tornadoes over the Nebraska Panhandle. The upstream shortwave
trough is expected to initiate showers and thunderstorms over
the higher terrain around 18-20Z before moving NE over lower
elevations. With an effective bulk wind difference of 25-30
knots combined with 1500-2000 J/Kg MLCAPE in the warm sector,
supercells remain possible across the Nebraska Panhandle late
afternoon into the evening hours. The main failure mode for
tornadoes tomorrow will be the lack of low-level shear, as 850
mb flow remains weak around 10-15 knots before gradually ramping
up to 20 knots after 03Z with the onset of a weak low-level
jet, however storms look to be elevated at this time, therefore
limiting the tornado threat. The main threats tomorrow will be
large hail and damaging winds, especially with any sustained
rotating updrafts where hail has a longer residence time within
the cloud (to allow for maximum accretion and growth). Storms
should begin to exit the Nebraska Panhandle after 06Z Sunday. As
the low pressure begins to lift and head north, winds will turn
westerly and high winds will be possible as the 700mb jet
develops and wind speeds begin to ramp up to around 60 knots.
Strong downward omegas develop over the wind prone areas
allowing for those faster winds to mix down to the surface. In-
house guidance continues to show Arlington with 65%
probabilities of exceeding high wind criteria into Sunday
morning, with Bordeaux at about 40% adding confidence in the
high wind scenario. The strong 700mb jet doesn't last very long
at the wind speeds needed to produce high winds so a High wind
watch was issued for the usual wind prone areas along with the
Summit and Foothills area between Laramie and Cheyenne along
I-80. The winds will gradually decrease in the afternoon and
evening hours on Sunday. THe high wind watch goes from 9pm
tonight to 3 pm Sunday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 231 PM MDT Fri May 29 2026

The long term will remain as unsettled as the short term with near
daily chances of precipitation through at least mid-week. With
the upper-level trough responsible for Saturday's storm expected
to eject northeastward out if the area Sunday, precipitation
chances on Sunday will be rather slim. Lingering showers could
be possible for the northern Wyoming and Nebraska zones of the
forecast area as the system ejects into the Dakotas, but even
these chances look rather slim.

Precipitation chances will increase for the start of the work week
as the upper-level trough/low begins to retrograde back towards the
northwest. The rough location of the low over the Montana/Canada
border, will allow the CWA to once again tap into moisture from the
Gulf. Moisture-rich mid-level southerly flow will usher in the
necessary humidity to fuel storm develop during the afternoon and
evening. Lift will come in the form of vorticity maxes streaming
through the area from the trough to the north, as well as another
trough the enters the picture during the middle of next week. At
this point, global models seem fairly consistent on showing daily
storm chances east of the Laramie Range Monday through Thursday. A
quick look at model soundings for areas east of the Laramie Range
show moderate amounts of CAPE each afternoon as well as decent shear
most days. As a result, severe weather cannot be ruled out each
afternoon.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1210 PM MDT Sat May 30 2026

Potent upper level low/trough will lift northeast across the area
today and tonight. Numerous showers and scattered thunderstorms will
develop across the mountains and move east into the high plains this
evening. Thunderstorms will likely become strong to severe for the
western Nebraska terminals and contain strong gusty winds, hail, and
brief very heavy rainfall.

HAZARDS/WEATHER TRENDS: VFR conditions should prevail at KRWL and
KLAR, although some periods of MVFR CIGS can't be ruled out tonight
with some rain shower activity. Further east, showers and
thunderstorms are expected to develop over the next few hours and
track northeast. There is a chance of IFR conditions with these
thunderstorms (15% to 25%), but impacts should be less than 2 hours.
Also, the terminals that see heavy rainfall amounts may see some fog
and/or low CIGS later this evening and into tonight. However
confidence is low (prob and coverage), so will keep out of the TAF
for now.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Watch from this evening through Sunday afternoon for
     WYZ106-110-116-117.
NE...None.

&&

SHORT TERM...MM
LONG TERM...SF
AVIATION...TJT

Special Weather Statement
National Weather Service Cheyenne WY
157 PM MDT Sat May 30 2026

NEZ095-302030-
North Sioux NE-
157 PM MDT Sat May 30 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL SIOUX COUNTY
THROUGH 230 PM MDT...

At 157 PM MDT, Doppler radar was tracking a strong thunderstorm near
Montrose, or 24 miles south of Edgemont, moving north at 25 mph.

HAZARD...Wind gusts up to 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Montrose.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4289 10369 4285 10393 4300 10398 4300 10370
TIME...MOT...LOC 1957Z 168DEG 21KT 4295 10383

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

Trudel

Preliminary Local Storm Report
National Weather Service Cheyenne WY
220 PM MDT Sat May 30 2026

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

0220 PM     Hail             12 E Jay Em             42.48N 104.13W
05/30/2026  E0.50 Inch       Goshen             WY   Public

            Also indicated via radar imagery.

&&

NSB

Special Weather Statement
National Weather Service Cheyenne WY
225 PM MDT Sat May 30 2026

NEZ002-302100-
Dawes NE-
225 PM MDT Sat May 30 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN DAWES COUNTY
THROUGH 300 PM MDT...

At 225 PM MDT, Doppler radar was tracking a strong thunderstorm over
Red Cloud Campground, or 8 miles south of Chadron, moving north at 25
mph.

HAZARD...Wind gusts up to 40 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Chadron, Chadron Municipal Airport, Red Cloud Campground, Chadron
State Park, Dawes County Fairgrounds, and Chadron State Park
Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Severe Thunderstorm Watch remains in effect until 900 PM MDT for
the Panhandle of Nebraska.

&&

LAT...LON 4263 10283 4259 10306 4290 10324 4297 10288
TIME...MOT...LOC 2025Z 168DEG 21KT 4270 10297

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

Vasquez

Special Weather Statement
National Weather Service Cheyenne WY
237 PM MDT Sat May 30 2026

WYZ102-108-302115-
Goshen County WY-Niobrara County WY-
237 PM MDT Sat May 30 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN NIOBRARA AND
NORTHWESTERN GOSHEN COUNTIES THROUGH 315 PM MDT...

At 237 PM MDT, Doppler radar was tracking a strong thunderstorm over
Rawhide Buttes, or 12 miles south of Lusk, moving northwest at 25
mph.

HAZARD...Wind gusts up to 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Lusk, Manville, Keeline, Rawhide Buttes, and Niobrara County
Fairgrounds.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Severe Thunderstorm Watch remains in effect until 900 PM MDT for
southeastern and east central Wyoming.

&&

LAT...LON 4250 10437 4247 10455 4277 10477 4284 10441
      4274 10440
TIME...MOT...LOC 2037Z 151DEG 24KT 4258 10450

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

Trudel

Special Weather Statement
National Weather Service Cheyenne WY
308 PM MDT Sat May 30 2026

NEZ095-WYZ102-302145-
North Sioux NE-Niobrara County WY-
308 PM MDT Sat May 30 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN SIOUX AND EAST
CENTRAL NIOBRARA COUNTIES THROUGH 345 PM MDT...

At 308 PM MDT, Doppler radar was tracking a strong thunderstorm 15
miles north of Van Tassell, or 19 miles northeast of Lusk, moving
northeast at 25 mph.

HAZARD...Wind gusts of 50 to 55 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

This storm will remain over mainly rural areas of northwestern Sioux
and east central Niobrara Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 900 PM MDT for
the Panhandle of Nebraska...and east central Wyoming.

&&

LAT...LON 4311 10405 4300 10405 4300 10374 4279 10406
      4280 10421 4288 10427 4313 10410
TIME...MOT...LOC 2108Z 214DEG 21KT 4289 10411

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...55 MPH

Mose

Preliminary Local Storm Report
National Weather Service Cheyenne WY
310 PM MDT Sat May 30 2026

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

0310 PM     Hail             2 NNW Chadron           42.85N 103.02W
05/30/2026  E0.75 Inch       Dawes              NE   Public

&&

NSB