Thunderstorm Wind in Monroe County, Indiana

Tree downed by thunderstorm wind gusts near State Road 45.

On the afternoon of March 15, 2026, a strong and deepening upper-level trough strengthened an already potent 990 mb surface low as it crossed the northwestern Midwest into the southern Great Lakes. The resultant surface gradient over central Indiana produced non-thunderstorm wind gusts that caused tree, powerline, and/or power pole damage in 10 local counties. Some structural damage was also reported and a 59 mph non-thunderstorm gust was measured at the Shelbyville Airport ASOS.

A few hours later, during the 15th evening, a fast-moving quasi-linear convective system (QLCS) then swept across central Indiana ahead of a cold front, fueled by a potent 55-knot low-level jet and strong synoptic forcing. Despite modest instability, a high-shear environment allowed the line to maintain intensity as it tracked from Knox County at o Henry County. The Storm Prediction Center had placed the region under a Slight Risk, citing the potential for damaging straight-line winds. This was realized as a peak gust of 71 mph (62 knots) was measured in Marion County, while the Indianapolis International Airport (KIND) recorded a 58 mph gust.

The resulting damage was widespread, primarily affecting timber and utility infrastructure. A significant swath of downed trees and power lines stretched from Manilla to Arlington in Rush County. Structural impacts were also noted, including shingle damage in Madison County and a fence destroyed in Johnson County. Throughout the event, multiple state roads'including SR 32 and SR 45'were obstructed by fallen trees, and large pine trees up to 1.5 feet in diameter were snapped in Bartholomew County, reflecting the intensity of the straight-line winds.