Tornado in Cass County, Nebraska

At approximately 6:20 PM CST on Thursday, April 17, video evidence supports the development of a tornado near 286th St and McKelvie Road that lasted for approximately 2 minutes. No damage was reported as it passed through open fields, supporting an EF-U rating.

On April 17, 2025, two powerful and long-lived supercells swept across eastern Nebraska and southwest Iowa during the afternoon and evening hours, bringing significant severe weather impacts. The event was driven by a dynamic upper-level pattern, including a compact shortwave trough that helped spin up a surface low near the Nebraska-Kansas border. This low tracked eastward through the day, accompanied by a surface cold front advancing from the northwest and a dryline bulging into southeast Nebraska.

Ahead of these features, strong southerly flow transported warm, moist air into the region. Temperatures rose into the 80s, with dewpoints climbing into the mid-50s to low 60s. These conditions yielded moderate instability, with MUCAPE values ranging from 1000 to 2000 J/kg. Vertical wind shear was notably favorable for organized convection, with deep-layer shear in the 50'60 kt range and strong low-level hodograph curvature supporting supercell development.

Two discrete supercells initiated in eastern Nebraska during the late afternoon and tracked eastward into western Iowa during the evening. The northern supercell initially developed near Columbus, Nebraska, and tracked east through Colfax, Dodge, Washington, and Douglas counties before entering Pottawattamie County, Iowa. It produced large hail, with reports of stones up to 4 inches in diameter, and caused widespread wind-driven hail damage. The storm also spawned an EF-3 tornado that impacted portions of Douglas and Washington counties.

The second and southern-most storm formed north of Seward, Nebraska, and moved eastward across Seward, Lancaster, and Cass counties before crossing into Fremont and Page counties in Iowa later in the evening. Along its path, the storm produced baseball-sized hail (up to 2.75 inches) and several tornadoes. In Cass County, Nebraska, three tornadoes were reported'two rated EF-0 and one rated EF-U. After crossing into Iowa, the storm produced an EF-0 tornado in Fremont County, followed shortly by a stronger EF-1 tornado in Page County. This tornado grew to a maximum width of 1,971 yards before dissipating. Additionally, damaging winds associated with the storm's rear-flank downdraft reached up to 86 mph in Page County. Both storms continued into southwest Iowa during the evening before gradually weakening.