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Severe thunderstorms in Nebraska and Iowa

By Scott Bachmeier •

1-minute GOES-19 “Red” Visible (0.64 µm) images with time-matched (+/- 3 minutes) SPC Storm Reports plotted in red, from 2200 UTC on 17 April to 0056 UTC on 18 April [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-19 (GOES-East) “Red” Visible (0.64 µm) images (above) showed 2 supercell thunderstorms that produced numerous tornadoes, hail to 4.00? in diameter and wind gusts to 86 mph (SPC Storm Reports) across parts of eastern Nebraska and western Iowa on 17 April 2025. Pronounced overshooting tops and Above-Anvil Cirrus Plumes were apparent with these thunderstorms.

The corresponding 1-minute GOES-19 “Clean” Infrared Window (10.3 µm) images are shown below. The coldest cloud-top infrared brightness temperatures associated with some of the pulsing overshooting tops were -75 to -78ºC.

1-minute GOES-19 “Clean” Infrared Window (10.3 µm) images with time-matched (+/- 3 minutes) SPC Storm Reports plotted in white, from 2200 UTC on 17 April to 0211 UTC on 18 April [click to play animated GIF | MP4]

In a toggle between GOES-19 Visible and Infrared images at 2322 UTC (below), there was a pronounced “warm trench” immediately downwind (east) of the cold overshooting top associated with the northernmost supercell thunderstorm. Hail of 2.75″ in diameter and a wind gust of 82 mph were reported near the overshooting top/warm trench around the time of these two GOES-19 images.

GOES-19 Visible and Infrared images at 2322 UTC on 17 April [click to enlarge]

According to a plot of 2000 UTC rawinsonde data from Omaha, Nebraska (below), the coldest cloud-top infrared brightness temperature of -78ºC represented a ~2 km overshoot of the Most Unstable air parcel Equilibrium Level.

Plot of Omaha, Nebraska rawinsonde data at 2000 UTC on 17 April [click to enlarge]

Categories: GOES-19, Severe convection