Severe thunderstorms in Iowa and Minnesota

September 20th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed thunderstorms that developed in the vicinity of a surface low and associated cold front (surface analyses) that was moving northeastward across the Upper Midwest during the afternoon and evening hours of 20 September 2018. These storms produced damaging winds and several tornadoes across northern Iowa and southern Minnesota (SPC storm reports | NWS FSD summary | NWS MPX summary). An animation of Visible images with hourly plots of surface reports is available here.

GOES-16 “Clean” Infrared Window (10.3 µm) images (below) showed cloud-top infrared brightness temperatures as cold as -70 to -75ºC (black to light gray enhancement) with the more vigorous overshooting tops. These thunderstorms continued moving eastward as a squall line, causing additional damaging winds across northern Wisconsin.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play MP4 animation]

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