During the late afternoon of May 22, 2026, low-topped supercell thunderstorms developed along a cold front advancing across eastern Nebraska and northwest Iowa. At 4:42 PM CST, one of these discrete cells produced a brief tornado in Cass County, Nebraska.
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The episode as NWS OAX wrote it up.
During the late afternoon of May 22, 2026, low-topped supercell thunderstorms developed along a cold front advancing across eastern Nebraska and northwest Iowa. At 4:42 PM CST, one of these discrete cells produced a brief tornado in Cass County, Nebraska. The tornado was visually confirmed and photographed by multiple trained spotters. No damage was reported.
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 Omaha, NE wrote its last area forecast discussion before the first event at May 22, 11:41 AM CST, 5 hours 1 minute earlier. Its key messages:
Area Forecast Discussion National Weather Service Omaha/Valley NE 1241 PM CDT Fri May 22 2026 .KEY MESSAGES... - A broken line of storms is forecast to move through this afternoon with a strong to severe storm or two possible. Hail is the primary hazard. - A warming trend begins this weekend with above normal temperatures expected to hold into next week. - Low chance (20-30%) for a few storms possible Sunday afternoon/evening, with our next better chance for showers and storms starting Wednesday through the end of next week. && .DISCUSSION... Issued at 1241 PM CDT Fri May 22 2026 Remnant showers from this morning's storms are exiting to the east this afternoon. We're seeing clouds breaking up in the warm sector of the Low over norht-central Nebraska out ahead of the cold front which is just now moving into Knox, Antelope, and Boone Counties. This front will be a focus for a line of thunderstorms this afternoon, and any clearing ahead of storm development will only aid in increasing instability and potential storm strength. While shear is modest ~30kt 0-6km bulk shear, instability has the potential to reach 1500 J/kg. Hodographs show decent 0-1km shear leading to some potential for a low- topped supercell or two. This could lead do a few quarter-size hail reports, or damaging winds up to 60 mph, but it's a very marginal threat (level 1 out of 5). Once storms clear this evening, we'll see skies gradually clear with winds shifting to the northwest. A surface High building in from the southwest will bring warmer temperatures for the weekend, starting with highs in the 70s on Saturday. Sunday we see enhanced warm-air advection as weak ridging builds in aloft which will lead to afternoon highs warming into the upper 70s to mid 80s. We do see a weak shortwave trough move through during the afternoon and evening, developing a surface low over north-central Nebraska/south-central South Dakota. This pulls in a belt of moisture from the Gulf, potentially leading to a few isolated to scattered showers or storms through the afternoon and evening hours. Rain chances remain low, around 20-30%. SPC does highlight, again, a marginal risk for severe storms, mainly due to the ample amount of instability and decent shear profile; however, moisture may be limited depending greatly on how much we can advect in ahead of this system. A deep upper-level trough digging on to the West Coast out of the Gulf of Alaska will enhance southerly flow across the Central CONUS early next week, maintaining above-normal temperatures into midweek. This trough as it shifts closer will lead to a more active weather pattern toward the latter half of the week as we start to bring in more moisture up from the Gulf. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1210 PM CDT Fri May 22 2026 A mix of MVFR/IFR cigs around this morning with showers exiting to the east. We may see some breaks in the clouds or brief clearing between 18Z and 21Z before a line of thunderstorms develops along the cold front moving across our area. By the time storms develop, the line should already be east of KOFK, so not expecting impacts at this terminal. KLNK and KOMA may see storms (70% chance) move through around 20-22Z. It likely won't be a solid line of storms so there is potential that KLNK and/or KOMA may be missed. Storms should clear within an hour as the line moves fairly quickly from west to east. Expect winds to shift toward westerly behind the front with cigs improving to VFR. Winds will be shifting toward northwesterly as cigs clear through the evening. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && DISCUSSION...McCoy AVIATION...McCoy
Hazardous Weather Outlook National Weather Service Omaha/Valley NE 1243 PM CDT Fri May 22 2026 IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034- 042>045-050>053-065>068-078-088>093-231745- Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont-Page- Knox-Cedar-Thurston-Antelope-Pierce-Wayne-Boone-Madison-Stanton- Cuming-Burt-Platte-Colfax-Dodge-Washington-Butler-Saunders-Douglas- Sarpy-Seward-Lancaster-Cass-Otoe-Saline-Jefferson-Gage-Johnson- Nemaha-Pawnee-Richardson- 1243 PM CDT Fri May 22 2026 This Hazardous Weather Outlook is for southwest Iowa, west central Iowa, east central Nebraska, northeast Nebraska and southeast Nebraska. .DAY ONE...This afternoon and tonight. A broken line of thunderstorms is expected to develop in eastern Nebraska by the late afternoon, pushing eastward into western Iowa during the evening. A strong to severe storm or two remain possible, with hail (up to ping pong ball sized) and strong wind gusts up to 60 mph the primary hazards under any stronger storms. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed.
The Omaha radar (KOAX), 59 km away, was scanning. The volume nearest the first event began at 22:44 UTC.
1 tornado. Local standard time, as filed.
Multiple trained spotters reported a brief, weak tornado, supported by photographic evidence. No damage was reported.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nebraska in 2026Every state in 2026This day in weather historyThe tornado archive for Nebraska, 2026Warnings in Nebraska, May 2026
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: 1339547.