What forecasters said that day
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Cheyenne, WY wrote its last area forecast discussion before the first event at May 21, 1:12 PM MST, 2 hours 36 minutes earlier. Its key messages:
- There is a Marginal Risk (Level 1 of 5) for severe weather this afternoon and evening over portions of the High Plains. Isolated large hail and damaging winds are the primary concerns.
- Friday will be cool and breezy with showers ending in the morning hours. Expect freezing temperatures in Carbon and Albany county Friday morning, with lows in the 30s elsewhere.
- A warming trend will carry through Memorial Day weekend, with near record high temperatures possible by Monday.
- Isolated high-based showers and storms will be possible each day over the long weekend but rainfall will be limited. Rainfall potential will increase on Tuesday and Wednesday.
Area forecast discussion, May 21, 1:12 PM MST, 2 hours 36 minutes before
Area Forecast Discussion
National Weather Service Cheyenne WY
212 PM MDT Thu May 21 2026
.KEY MESSAGES...
- There is a Marginal Risk (Level 1 of 5) for severe weather
this afternoon and evening over portions of the High Plains.
Isolated large hail and damaging winds are the primary
concerns.
- Friday will be cool and breezy with showers ending in the
morning hours. Expect freezing temperatures in Carbon and
Albany county Friday morning, with lows in the 30s elsewhere.
- A warming trend will carry through Memorial Day weekend, with
near record high temperatures possible by Monday.
- Isolated high-based showers and storms will be possible each
day over the long weekend but rainfall will be limited.
Rainfall potential will increase on Tuesday and Wednesday.
&&
.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 210 PM MDT Thu May 21 2026
A potent upper level trough is swinging across Wyoming this
afternoon, which will support active weather through early Friday
morning. ahead of the primary forcing, we have a dryline boundary
setup from roughly Cheyenne to Fort Laramie to the WY/NE/SD triple
point. Southerly winds east of the boundary are advecting in good
low-level moisture, while drier air and westerly flow dominates to
the west. The dryline is providing a focus for some pre-frontal
convection, with several storms already kicking up. The environment
ahead of these storms is favorable for isolated strong to severe
thunderstorms, with SBCAPE around 1000 to 1600 J/kg and 20-40 knots
of effective bulk shear. Vertical wind shear increases further
south, and the most favorable environment for storms is located in
the southern Nebraska panhandle. The overall hazards for today
remain unchanged, with strong, gusty winds and isolated large hail
the primary concerns. An isolated tornado cannot be ruled out,
particularly in the southern panhandle. Expect multiple rounds of
showers and thunderstorms this afternoon and evening. Coverage will
greatly increase over the next few hours as forcing associated with
the approaching trough increases. Current thinking is that the
primary severe threat will be associated with the initial round of
dryline convection, whereas the strongly forced second round about
to move into Carbon county will have lower chances for severe, but
high coverage of rainfall and gusty winds. The window for discrete
storms (and the primary severe threat) should conclude around 8PM to
10PM. The progression of the strong forcing will move eastward
slowly, likely not reaching the edge of the forecast area until
around 10PM to midnight tonight. This will still have the potential
to produce locally heavy rainfall and gusty winds. Showers with
synoptically driven gusty northwest winds will continue behind the
main line, mainly north of the North Platte River Valley. This will
continue into Friday morning. Chadron will be the last area to dry
out, but expect rain to conclude by noon. This lingering shower
activity will be driven by a narrow TROWAL developing in the wake of
the potent upper level low tonight.
As the surface front moves through this evening, expect gusty
northwest winds to spread across the area. The probability for high
winds is low (20% or less), but we can expect to see fairly
widespread wind gusts of 35 to 50 mph, lasting into the day on
Friday. This front will enforce the chilly airmass over the area,
causing much of the area to fall back into the 30s again tonight.
Around Cheyenne, Douglas, and Lusk, look for lows around 32 to 35.
This may stress sensitive vegetation, but confidence in dropping
below freezing not high enough for a Freeze Warning (30 to 50%
probability). In addition, the gusty winds should limit frost
formation. Further west, particularly where snow cover lingers, cold
air advection will support higher probabilities of a freeze (70 to
90%). Winds will also be lighter, mainly in Carbon County, which
should improve radiative cooling. Therefore, confidence was high
enough to issue a Freeze Warning for the valleys of Carbon and
Albany county. Heading into Friday afternoon, high temperatures will
be similar or slightly cooler than today for most of the area.
Another weak vort-max will approach the area from the west Friday
afternoon, which will increase cloud cover over our western areas,
and also lead to a slight chance for a few showers mainly tied to
the higher terrain. This will linger into the evening hours, and
possibly creep eastward along the Colorado state line into the High
Plains overnight.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 210 PM MDT Thu May 21 2026
After this trough pushes through into the Northern
Plains on Friday, A weak upper level ridge starts to build over the
Intermountain West. Southeast Wyoming and the Nebraska Panhandle
will largely be dry this weekend as there will be limited vorticity
and decent lift to play with. However, some diurnal afternoon
showers may be possible, but mostly confined to the southern half of
the forecast area Saturday and Sunday. By Monday the synoptic
pattern starts to shift as a progged Low pressure system starts to
push into Baja California with another northern system to pushes
into the Pacific Northwest. This will push us into a southwest
advecting in some moisture from the Pacific and some dry air from
the downsloping winds off the mountains near the surface. As these
two systems push into United States the southern system almost gets
absorbed by the northern system to form this deep trough to kick
start our wet pattern again on Tuesday most likely in the afternoon.
Thanks to our summer sun, the synoptic set up of this deep trough
will lead to decent destabilization of the atmosphere and produce
scattered thunderstorms for the afternoon and evening. The models
really start to diverge with the synoptic pattern after Wednesday
morning. The GFS has a tilted ridge working its way into the
Intermountain West possibly drying us out or we can go with the
Euro or Canadian that have systems of varying intensities keep
us rainy and stormy throughout the week. It will be interesting
to see how the models trend past our Tuesday trough.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1146 AM MDT Thu May 21 2026
Showers are moving across Southeast Wyoming but should affect
any of the terminals at this point. After 21z the thunderstorm
potential increases for Southeast Wyoming and then expected
around 00z for the Nebraska terminals. There is some severe
potential of temporary wind gusts up to 60 mph and hail sized up
to quarters. Although they dont look to affect any terminals
there is a slight potential for some land spouts and/or a brief
tornado near Kimball county, NE. The severe potential looks to
end around 02z for all areas. With this big upper level trough
moving through showers will probably continue intermittently
throughout the night and ending around 14z for all areas.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Freeze Warning from midnight tonight to 9 AM MDT Friday for
WYZ104-105-109>111-113-115-116.
NE...None.
&&
SHORT TERM...MN
LONG TERM...MM
AVIATION...MMIn the hours before
Local storm report, May 21, 3:09 PM MST, 39 minutes before
Preliminary Local Storm Report
National Weather Service Cheyenne WY
409 PM MDT Thu May 21 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0353 PM Hail 2 NNW Scottsbluff 41.90N 103.68W
05/21/2026 M0.75 Inch Scotts Bluff NE Broadcast Media
Media reported small, accumulating hail
mixed with rain.
&&
NBSpecial weather statement, May 21, 3:14 PM MST, 34 minutes before
Special Weather Statement
National Weather Service Cheyenne WY
414 PM MDT Thu May 21 2026
NEZ002-212300-
Dawes NE-
414 PM MDT Thu May 21 2026
...STRONG THUNDERSTORMS WILL IMPACT CENTRAL DAWES COUNTY THROUGH 500
PM MDT...
At 413 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Chadron to near Roberts Trailhead
Campground to 8 miles east of Crawford. Movement was southeast at 20
mph.
HAZARD...Wind gusts up to 50 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. Accumulating hail is also possible, which may
lead to slick and hazardous road conditions.
Locations impacted include...
Chadron, Whitney, Roberts Trailhead Campground, Chadron Municipal
Airport, Chadron State Park, Red Cloud Campground, Box Butte
Reservoir, Fort Robinson State Park, Dawes County Fairgrounds, and
Chadron State Park Campground.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4265 10282 4246 10311 4263 10345 4281 10322
4300 10310 4300 10279 4279 10279 4278 10277
4275 10277
TIME...MOT...LOC 2213Z 293DEG 16KT 4288 10304 4273 10312 4265 10326
MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH
NatoliLocal storm report, May 21, 3:23 PM MST, 25 minutes before
Preliminary Local Storm Report
National Weather Service Cheyenne WY
423 PM MDT Thu May 21 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0406 PM Landspout 4 NNW Pine Bluffs 41.23N 104.08W
05/21/2026 Laramie WY Broadcast Media
CYS broadcast media shared a picture of a
landspout kicking up dirt/dust.
&&
NBLocal storm report, May 21, 3:24 PM MST, 24 minutes before
Preliminary Local Storm Report
National Weather Service Cheyenne WY
424 PM MDT Thu May 21 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0423 PM Landspout 4 N Pine Bluffs 41.24N 104.07W
05/21/2026 Laramie WY Public
Law enforcement reported a funnel that was
producing a ground circulation for around 45
seconds and kicking up dirt/dust.
&&
NBSpecial weather statement, May 21, 3:24 PM MST, 24 minutes before
Special Weather Statement
National Weather Service Cheyenne WY
424 PM MDT Thu May 21 2026
NEZ019-096-212300-
Scotts Bluff NE-South Sioux NE-
424 PM MDT Thu May 21 2026
...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN SCOTTS BLUFF AND
SOUTHEASTERN SIOUX COUNTIES THROUGH 500 PM MDT...
At 424 PM MDT, Doppler radar was tracking a strong thunderstorm over
Scottsbluff Airport, or near Scottsbluff, moving east at 10 mph.
HAZARD...Wind gusts up to 40 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...
Scottsbluff, Gering, Terrytown, Lake Minatare State Recreation Area,
Lake Alice Number 2, Scottsbluff Airport, and Lake Alice.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4183 10368 4197 10369 4203 10341 4183 10337
TIME...MOT...LOC 2224Z 251DEG 8KT 4190 10359
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH
GoatleyLocal storm report, May 21, 3:33 PM MST, 15 minutes before
Preliminary Local Storm Report
National Weather Service Cheyenne WY
433 PM MDT Thu May 21 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0424 PM Snow Squall 7 NW Elk Mountain 41.76N 106.51W
05/21/2026 Carbon WY Mesonet
Visibility under 1/4 mile, temperature of 30
degrees, and wind gust of 37 mph reported at
mesonet site.
&&
NB