Thunderstorm Wind in Monroe County, Indiana

The Monroe County Airport ASOS gusted to 61KT as the EF2 tornado vortex center tracked 700 yards to the north-northwest.

A strengthening storm system lifted through the Middle Mississippi Valley on the 19th, dragging its warm frontal zone northward through the Midwest, and bringing near-record high temperatures and anomalous dewpoints into central Indiana. Multiple rounds of severe weather occurred over the region, from early morning large hail in two far-northern zones, covering roads in Warren County, to more organized evening severe weather from rotating supercell thunderstorms. Through the evening of the 19th, the destabilized atmosphere combined with a stregthening low-level jet stream that progressed eastward into the region, boosting 0-1 km wind shear as high as 300 m2/s2. A resultant cluster of discrete late-day to evening supercells were focused along the frontal zone, near or south of the Interstate 70 corridor, and produced scattered large hail over 6 counties and isolated wind damage to trees and/or power poles in 4 counties.

A stronger supercell with a history of producing two weak tornadoes in Crawford County, Illinois, continued into central Indiana, spawning an EF-0 tornado in Sullivan County, an intense EF-2 just west of Bloomington that caused extensive structural damage to homes, apartments, and airport facilities, and a brief EF-U in Decatur County; this cell also produced ping-pong ball (1.50-inch diameter) sized hail in Greene and Monroe Counties.