Severe Thunderstorm Watch issued for Cheyenne County, with an isolated gust occurring in Box Butte County.
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The episode as NWS CYS wrote it up.
Severe Thunderstorm Watch issued for Cheyenne County, with an isolated gust occurring in Box Butte County.
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 Aug 18, 4:34 PM MST, 0 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Cheyenne WY 534 PM MDT Mon Aug 18 2025 .KEY MESSAGES... - Scattered thunderstorms with isolated large hail or strong winds possible will taper off through the evening. - Hot temperatures with more limited thunderstorm chances are expected Tuesday through Thursday. - A cold front late in the week will decrease temperatures and increase thunderstorm chances heading into the weekend. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 144 PM MDT Mon Aug 18 2025 Showers and thunderstorms are developing and building across southeastern Wyoming as models aloft indicate some energy clipping eastern portions of the CWA. The threat of storms will expand into portions of the Nebraska panhandle this afternoon into the early evening hours. The best instability and the greatest threat of severe weather will remain across the southern counties of the Nebraska panhandle. This convective weather will be driven by modest instability, but may be limited by poor low level moisture. Forecast soundings indicate that these storms will be capable of producing strong gusty winds along with the possibility of pea to nickel sized hail, primarily along the southern counties of the Nebraska panhandle as indicated by hi-res models. Ridging aloft will strengthen over the next few days as high pressure over the Four-Corners region dominates weather conditions across the CWA. Rain and thunderstorm chances decrease as temperatures increase a few degrees each day through at least mid- week. With the building ridge, temperatures rise but it comes with a decrease in moisture, this may bring an enhanced risk of fire weather concerns for portions of our CWA as well. One thing that may mitigate the fire weather concern is a weak gradient, resulting in weaker winds across the region. We will continue to monitor this evolving pattern over the several days for any areas that may need watches or warnings. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 144 PM MDT Mon Aug 18 2025 The latest heat wave will peak Wednesday and Thursday across the area as the powerful ridge amplifies over the Four Corners region. 700-mb temperatures will crest around +16 to +18C between Wednesday afternoon and Thursday afternoon per the NAEFS average, which is near the 99th percentile of climatology. Record highs are most likely at Laramie and Rawlins, where boundary layer moisture is expected to be considerably lower with deep inverted-v soundings in place. East of the Laramie Range, low-level moisture is expected to be somewhat high, at least relative to typical heat waves of this magnitude. This will be thanks to southeast to south winds on Wednesday, turning northeast on Thursday, but maintaining moisture over the High Plains. With shallower mixed layers, daily record highs are less likely compared to areas further west, but we can still expect widespread 90s with a shot at 100F. For Wednesday, the middle to upper atmosphere will remain quite dry which should suppress afternoon convective activity, but the boundary layer moisture may be enough to get isolated low-topped showers and thunderstorms going, particularly near and adjacent to the higher terrain. By Thursday, a shortwave trough riding over the top of the ridge will pull better moisture out of the monsoon with it, and increase mid to upper level humidity. This should mix down and increase dewpoints west of the Laramie range, while those to the east will see dewpoints similar or slightly lower than Wednesday. Expect to see shower and thunderstorm covering increase for Thursday. A cold front is expected to pass through the High Plains on Thursday, bringing a notable pattern chance for Friday into the weekend. The overall synoptic weather pattern will be characterized by a powerful Four Corners ridge retreating slightly south and westward, and frequent shortwave troughs diving over our area on the northwest flank of the ridge. A persistent surface high pressure over the northern Plains will keep a cooler and wetter airmass in the lower atmosphere pushed up against the mountains, while good to excellent monsoon moisture will continue to pump around the upper level high and into our area. The NAEFS average shows precipitable water around the 90th percentile of climatology beginning late Thursday and continuing through the rest of the forecast period. Expect scattered to numerous showers and thunderstorms beginning Friday afternoon and continuing through at least Monday. It's too early to get into the details of the severe potential and storm mode, but the overall pattern suggests at least a marginal severe potential each afternoon through this period. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 531 PM MDT Mon Aug 18 2025 Thunderstorms near KAIA and KSNY may bring a brief VIS drop and locally gusty winds over the next few hours before departing. A rogue storm cannot be ruled out near KCYS too, but confidence is lower here. Winds may be variable and occasionally gusty near this activity. Winds will be a little messy overnight, but should be generally south to southeast, then southwest to west towards Tuesday morning, before coming back around to southeast Tuesday afternoon. A few isolated thunderstorms will be possible Tuesday PM. KLAR and KCYS will have the highest chance of a storm nearby. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && SHORT TERM...RZ LONG TERM...MN AVIATION...MN
Hazardous Weather Outlook National Weather Service Cheyenne WY 152 PM MDT Mon Aug 18 2025 NEZ002-003-019>021-054-055-095-096-WYZ101>119-192000- Dawes County-Box Butte County-Scotts Bluff County-Banner County- Morrill County-Kimball County-Cheyenne County- Northern Sioux County-Southern Sioux County- Converse County Lower Elevations-Niobrara County- North Laramie Range-Ferris/Seminoe/Shirley Mountains- Shirley Basin-Central Laramie Range and Southwest Platte County- East Platte County-Goshen County-Central Carbon County- North Snowy Range Foothills-Southwest Carbon County- Sierra Madre Range-Upper North Platte River Basin-Snowy Range- Laramie Valley-South Laramie Range-South Laramie Range Foothills- Central Laramie County-East Laramie County- 152 PM MDT Mon Aug 18 2025 This hazardous weather outlook is for portions of panhandle Nebraska...east central Wyoming...south central Wyoming and southeast Wyoming. .DAY ONE...THIS AFTERNOON AND TONIGHT - A slight risk (2 of 5) of severe weather is expected this afternoon and evening, with the most likely area for stronger storms the easternmost counties of the Nebraska Panhandle. - Damaging wind gusts and large hail will be the most likely hazards with storms. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY - Hot temperatures with more limited thunderstorm chances are expected Tuesday through Thursday. - A cold front late in the week will decrease temperatures and increase thunderstorm chances heading into the weekend. .Spotter information statement... Spotter reports are encouraged today for severe weather.
Special Weather Statement
National Weather Service Cheyenne WY
237 PM MDT Mon Aug 18 2025
NEZ054-WYZ117>119-182115-
Kimball NE-Central Laramie County WY-
South Laramie Range Foothills WY-East Laramie County WY-
237 PM MDT Mon Aug 18 2025
...STRONG THUNDERSTORMS WILL IMPACT SOUTHWESTERN KIMBALL AND
SOUTHEASTERN LARAMIE COUNTIES THROUGH 315 PM MDT...
At 236 PM MDT, Doppler radar was tracking a cluster of strong
thunderstorms near Hillsdale, or 20 miles northeast of Cheyenne,
moving east at 35 mph.
HAZARD...Wind gusts of 50 to 55 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...
Cheyenne, Pine Bluffs, Burns, Albin, Egbert, Laramie County
Fairgrounds at Archer, Hillsdale, Pine Bluffs Municipal Airport, Gun
Barrel, Panorama Point, Carpenter, and Ranchettes.
This includes the following highways...
Interstate 80 in Wyoming between mile markers 368 and 402.
Interstate 80 in Nebraska between mile markers 1 and 5.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4100 10469 4145 10471 4144 10416 4137 10401
4101 10390
TIME...MOT...LOC 2036Z 252DEG 32KT 4130 10445
MAX HAIL SIZE...0.50 IN
MAX WIND GUST...55 MPH
TrudelSpecial Weather Statement
National Weather Service Cheyenne WY
316 PM MDT Mon Aug 18 2025
NEZ020-054-WYZ119-182200-
Kimball NE-Banner NE-East Laramie County WY-
316 PM MDT Mon Aug 18 2025
...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN KIMBALL...
SOUTHWESTERN BANNER AND EAST CENTRAL LARAMIE COUNTIES THROUGH 400 PM
MDT...
At 315 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles south of Albin, or 23 miles west of Kimball, moving east at 25
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...
Pine Bluffs, Bushnell, Oliver Reservoir, and Oliver Reservoir
Campground.
This includes Interstate 80 in Nebraska between mile markers 2 and
19.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
&&
LAT...LON 4119 10418 4139 10421 4148 10370 4117 10369
TIME...MOT...LOC 2115Z 260DEG 21KT 4130 10410
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH
TrudelSpecial Weather Statement
National Weather Service Cheyenne WY
510 PM MDT Mon Aug 18 2025
NEZ003-021-190000-
Box Butte NE-Morrill NE-
510 PM MDT Mon Aug 18 2025
...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN BOX BUTTE AND
NORTHEASTERN MORRILL COUNTIES THROUGH 600 PM MDT...
At 509 PM MDT, Doppler radar was tracking a strong thunderstorm over
Alliance, moving east at 15 mph.
HAZARD...Wind gusts of 50 to 55 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...
Alliance and Alliance Municipal Airport.
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 4201 10299 4219 10294 4218 10274 4210 10274
4209 10271 4207 10270 4201 10270 4200 10267
4193 10268
TIME...MOT...LOC 2309Z 281DEG 15KT 4209 10287
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...55 MPH
TrudelThe North Platte radar (KLNX), 184 km away, was scanning. The volume nearest the first event began at 23:34 UTC.
1 thunderstorm wind. Local standard time, as filed.
Isolated thunderstorm gust at the Alliance Airport to 63 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nebraska in 2025Every state in 2025This day in weather historyWarnings in Nebraska, August 2025
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1281344.