Severe Thunderstorm Warning 340, NWS Cheyenne, WY

123 
WWUS55 KCYS 070642
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
1242 AM MDT Mon Sep 7 2026

NEC013-045-070700-
/O.CON.KCYS.SV.W.0340.000000T0000Z-260907T0700Z/
Box Butte NE-Dawes NE-
1242 AM MDT Mon Sep 7 2026

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 100 AM MDT
FOR NORTH CENTRAL BOX BUTTE AND SOUTH CENTRAL DAWES COUNTIES...

At 1242 AM MDT, a severe thunderstorm was located near Box Butte
Campground, or 27 miles southwest of Chadron, moving northeast at 30
mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Box Butte Campground, Roberts Trailhead Campground, Box Butte
Reservoir, Belmont, and Box Butte Dam.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4236 10323 4255 10337 4270 10312 4238 10290
TIME...MOT...LOC 0642Z 243DEG 26KT 4246 10322 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Fuller

874 
WWUS55 KCYS 070654
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
1254 AM MDT Mon Sep 7 2026

NEC013-045-070703-
/O.EXP.KCYS.SV.W.0340.000000T0000Z-260907T0700Z/
Box Butte NE-Dawes NE-
1254 AM MDT Mon Sep 7 2026

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL BOX BUTTE AND
SOUTH CENTRAL DAWES COUNTIES WILL EXPIRE AT 100 AM MDT...

The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However, small
hail, gusty winds and heavy rain are still possible with this
thunderstorm.

&&

LAT...LON 4236 10323 4255 10337 4270 10312 4238 10290
TIME...MOT...LOC 0653Z 241DEG 31KT 4250 10312 

$$

Fuller

Area Forecast Discussion
National Weather Service Cheyenne WY
540 PM MDT Sun Sep 6 2026

.KEY MESSAGES...

- Chances for afternoon and evening thunderstorms continue
  through Monday afternoon. Strong gusty winds and brief heavy
  rainfall are the primary threats.

- A temporary drying trend begins Tuesday and possibly
  continuing through the end of the week.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 250 PM MDT Sun Sep 6 2026

Another warm afternoon today with readings generally in the 80s
to low 90s, warmest across far eastern Wyoming. Western Nebraska
is a little cooler with high dewpoints and breezy south to
southeast upslope winds. Meso Analysis shows quite a bit of BL
CIN across western Nebraska with model soundings showing a
strong temperature inversion just above 800mb. It's likely going
to take a while to weaken this inversion, especially with any
shortwave/vort energy aloft taking its sweet time moving into
the the eastern high plains later this afternoon. Current KCYS
radar loop shows some shower activity starting to get going near
the southern Laramie Range, but nothing too intense noted at
this time. Models have trended higher with 0-6 km bulk shear,
particularly across the far eastern Wyoming plains and near the
NE/WY border. With expected MLCAPE values between 1000 to 1500
j/kg, expect the I-25 corridor eastward to the Nebraska side of
the WY/NE border to be the most favorable region to see strong
to marginally severe thunderstorms today. With the late arrival
of the upper level vort max, expect this activity to be a little
more isolated compared to yesterday. Excessive rainfall is also
less of a concern today due to the faster storm motion. Otherwise,
strong gusty winds and some large hail (0.75 to 1.50 inches in
diameter) possible with the stronger cells. Thunderstorms may
continue to develop and push northeast after midnight across
western Nebraska. Further west, a surface Pacific cold front
will move into Carbon and Albany counties, generally after
midnight. May see some rain shower activity as early as this
evening with gusty winds ahead of, and behind, the cold front
through tonight.

Drier airmass forecast to push into the area on Monday behind
the front with some cooler air. Expect a lower coverage of
thunderstorms, mainly located south along the I-80 corridor and
the mountains as the front briefly stalls before accelerating
eastward Monday night. High temperatures in the mid 70s to mid
80s are expected for most of southeast Wyoming, with highs in
the low 90s for western Nebraska. It will be windy during the
day with southwest winds between 25 to 35 MPH with gusts around
45 MPH likely along and west of Interstate 25. Kept POP around
20 to 40 percent for the morning hours and into the afternoon
hours across far southeast Wyoming and the southern Nebraska
panhandle. High res guidance shows some bands of light rain in
the morning along the cold front, with some shower and thunderstorm
activity for the afternoon and evening hours. A few strong
thunderstorms can't be ruled out Monday evening across western
Nebraska, but confidence is pretty low due to limited coverage.

Models show a drier airmass moving into the area on Tuesday
behind the cold front, with dewpoints lowering into the 30s and
40s along the I-80 corridor and as low as 25 degrees across
central and east central Wyoming. Other than some fire weather
concerns, pleasant weather is expected with temperatures a
little cooler and generally in the mid 70s to mid 80s over most
of the region. It will be windy along and west of Interstate 25
with gusts around 45 MPH possible.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 200 PM MDT Saturday SEPTEMBER 6 2026

Going into Tuesday evening and overnight a few storms may be
possible in the southern most portions of the area. Low temperatures
are progged to be in the mid 40s west of I-25 and in the 50s east.
With mostly clear skies we could see a few high elevation spots get
into the high 30s. A zonal flow west flow aloft on the north edge of
a ridge will keep things mostly dry. Wednesday afternoon humidity
values drop into the teens for our northern and western fire zones.
Thursday looks even drier with single digit humidity values with
poor overnight recoveries. If a shortwave is timed to pass during
any of these day's afternoon hours, enhanced 700 mbar flow could mix
down to the surface increasing wind gust potential. Therefore,
elevated to critical fire weather conditions are likely to manifest
during this time frame through Friday evening. Model ensemble
probabilities for below 25 percent RH and wind gusts above 25 mph
are between 70-100 percent generally along and west of I-25 at this
timeframe, which is rather aggressive from that guidance. There is a
chance that Friday could feature a little more atmospheric moisture
from Hurricane Marie as upper level moisture from it is advected
well east over the intermountain regions. That would be the better
of chances to see showers and storms during this stretch.

Saturday could be the soonest we see improvements to the dry
conditions. An upper level trough is being hinted at in global
models to approach the Pacific Coast. The timing and magnitude of
this trough is largely unknown with high variance in each model and
from run to run. The shutoff of the monsoonal flow thanks to the
placement of the upper level ridge to the south could make getting
moisture north ahead of this possible system a challenge. Being so
far in the future that detail will resolve as we get closer.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 539 PM MDT Sun Sep 6 2026

A few scattered showers and storms are possible early this evening.
Hi-Res guidance shows storms becoming more numerous overnight.
Heavy rain and wind will likely be the main concerns, with heavy
rain reducing visibility down to MVFR or IFR criteria. Showers
will return to much of the area Monday morning.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.

&&

SHORT TERM...TJT
LONG TERM...RV
AVIATION...SF

Special Weather Statement
National Weather Service Cheyenne WY
1115 PM MDT Sun Sep 6 2026

NEZ095-070600-
North Sioux NE-
1115 PM MDT Sun Sep 6 2026

...STRONG THUNDERSTORMS WILL IMPACT NORTHWESTERN SIOUX COUNTY THROUGH
MIDNIGHT MDT...

At 1114 PM MDT, Doppler radar was tracking a cluster of strong
thunderstorms over Harrison, or 30 miles east of Lusk, moving
northeast at 45 mph.

HAZARD...Wind gusts up to 50 mph and half inch 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...
Harrison and Montrose.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4296 10351 4260 10379 4268 10404 4300 10404
      4300 10351
TIME...MOT...LOC 0514Z 203DEG 38KT 4269 10386

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Fuller

Special Weather Statement
National Weather Service Cheyenne WY
1125 PM MDT Sun Sep 6 2026

WYZ117-118-070600-
Central Laramie County WY-South Laramie Range Foothills WY-
1125 PM MDT Sun Sep 6 2026

...STRONG THUNDERSTORMS WILL IMPACT SOUTHWESTERN LARAMIE COUNTY
THROUGH MIDNIGHT MDT...

At 1125 PM MDT, Doppler radar was tracking a cluster of strong
thunderstorms 7 miles southwest of Warren AFB, or 10 miles southwest
of Cheyenne, moving northeast at 25 mph.

HAZARD...Wind gusts up to 50 mph and pea 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...
Cheyenne, Happy Valley, Rocking Star Ranch, Silver Sage Estates, Fox
Farm-College, Cheyenne Regional Airport, Winchester Hills, South
Greeley Highway, Ranchettes, Warren AFB, Frontier Park, North
Cheyenne, South Cheyenne, Bison Crossing, and Cowboy Ranch South.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4130 10498 4126 10460 4100 10479 4100 10513
TIME...MOT...LOC 0525Z 209DEG 22KT 4107 10497

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

Fuller

Special Weather Statement
National Weather Service Cheyenne WY
1128 PM MDT Sun Sep 6 2026

WYZ107-108-070615-
East Platte County WY-Goshen County WY-
1128 PM MDT Sun Sep 6 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN GOSHEN AND EAST CENTRAL
PLATTE COUNTIES THROUGH 1215 AM MDT...

At 1128 PM MDT, Doppler radar was tracking a strong thunderstorm near
Jay Em, or 23 miles northwest of Torrington, moving northeast at 45
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...
Fort Laramie, Pine Ridge Estates, Prairie Center, Jay Em, Fort
Laramie National Historic Site, Grayrocks Reservoir, and Hwy 85 At
Dry Rawhide Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4202 10459 4213 10478 4261 10431 4247 10406
TIME...MOT...LOC 0528Z 218DEG 38KT 4238 10437

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

Fuller

Special Weather Statement
National Weather Service Cheyenne WY
1159 PM MDT Sun Sep 6 2026

NEZ095-096-WYZ102-108-070645-
North Sioux NE-South Sioux NE-Goshen County WY-Niobrara County WY-
1159 PM MDT Sun Sep 6 2026

...STRONG THUNDERSTORMS WILL IMPACT NORTHERN SIOUX...SOUTHEASTERN
NIOBRARA AND NORTHEASTERN GOSHEN COUNTIES THROUGH 1245 AM MDT...

At 1159 PM MDT, Doppler radar was tracking a cluster of strong
thunderstorms 11 miles southeast of Prairie Center, or 24 miles north
of Torrington, moving northeast at 45 mph.

HAZARD...Wind gusts up to 50 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...
Harrison and Fort Robinson State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4228 10399 4238 10419 4288 10399 4269 10352
TIME...MOT...LOC 0559Z 215DEG 41KT 4240 10403

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

Fuller

Special Weather Statement
National Weather Service Cheyenne WY
1205 AM MDT Mon Sep 7 2026

WYZ107-108-118-070630-
East Platte County WY-Goshen County WY-Central Laramie County WY-
1205 AM MDT Mon Sep 7 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN GOSHEN...NORTH
CENTRAL LARAMIE AND SOUTHEASTERN PLATTE COUNTIES THROUGH 1230 AM
MDT...

At 1205 AM MDT, Doppler radar was tracking a strong thunderstorm 12
miles northeast of Whitaker, or 27 miles north of Cheyenne, moving
northeast at 35 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...
Slater.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4142 10460 4149 10482 4184 10471 4173 10434
TIME...MOT...LOC 0605Z 204DEG 32KT 4153 10470

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

Fuller

Special Weather Statement
National Weather Service Cheyenne WY
1210 AM MDT Mon Sep 7 2026

NEZ002-003-095-096-070645-
Box Butte NE-Dawes NE-North Sioux NE-South Sioux NE-
1210 AM MDT Mon Sep 7 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN BOX BUTTE...
SOUTHWESTERN DAWES AND EAST CENTRAL SIOUX COUNTIES THROUGH 1245 AM
MDT...

At 1209 AM MDT, Doppler radar was tracking a strong thunderstorm 8
miles northwest of Flahertys Corner, or 38 miles southwest of
Chadron, moving northeast at 40 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...
Crawford, Soldier Creek Campground, Fort Robinson State Park,
Belmont, and Marsland.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4229 10351 4241 10369 4275 10343 4257 10311
TIME...MOT...LOC 0609Z 218DEG 33KT 4242 10354

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

Fuller