Severe thunderstorms across the Northern Plains
1-minute Mesoscale Domain Sector GOES-19 (GOES-East) Visible images (above) and Infrared Window images (below) included time-matched plots of SPC Storm Reports — which showed thunderstorms that produced wind gusts as high as 98 mph, hail as large as 3.75 inches in diameter and isolated tornadoes across parts of Montana, Wyoming, North Dakota and South Dakota from the late afternoon until a few hours after after sunset on 07 June 2026. Widespread overshooting tops were very apparent in the Visible imagery — and initial discrete storms exhibited enhanced-V signatures in the Infrared imagery, before upscale growth resulted in a large Mesoscale Convective System centered over western North Dakota.
Plots of rawinsonde data in the pre-convective environment at Bismarck ND (KBIS) and Rapid City SD (KUNR) are shown below. Of particular significance were the large Downdraft CAPE (DCAPE) values of 1730 J/kg at 0000 UTC and 1569 J/kg at 1800 UTC at Rapid City and Bismarck, respectively — which highlighted the potential for a strong downward transport of air to surface, producing the widespread damaging winds that were seen across the region.
The coldest cloud-top infrared brightness temperatures in the 1-minute GOES-19 Infrared Window images were around -70C — which represented a significant overshoot of the Most Unstable (MU) air parcel’s Equilibrium Level (EL) as depicted in the plots of rawinsonde data.