EF1 Tornado — Marion, Indiana

2019-06-15 · near Beech Grove, Marion, Indiana

Event narrative

The EF-1 rated tornado, with max wind speeds of 100 mph, began southwest of Beech Grove causing roof damage before crossing Emerson Avenue and causing additional roof damage to a school, apartment complex, and house. Alro Steel Company also sustained damage to the roof and wall of a warehouse-like structure. Numerous power poles were also downed near the Alro structure. In addition to the roof damage at Beech Grove High School, they also had more than 20 classrooms damaged or destroyed. The scoreboard on the football field was significantly damaged as well. The tornado continued for several hundred feet before dissipating.

Wider weather episode

A warm front brought severe storms, tornadoes, and heavy rain on June 15th. A significant tornado outbreak that was the largest since November 17, 2013 occurred during the evening of Saturday, June 15th. Seven tornadoes occurred in central Indiana with 3 additional tornadoes across portions of eastern Indiana.

This is what the environment showed. A weak shortwave trough was moving through central Indiana during the time of the severe weather. This was a high shear, low CAPE environment initially which kept convection to a minimum until around 5 PM when just enough CAPE was there to rapidly increase storm coverage and severity. LCL heights were around 750m at the time. The shear profile was ideal for creating numerous rotating thunderstorms. With 0-1km Shear over 30 knots and Storm Relative Helicity in excess of 300 m^2/s^2, the low level environment was primed for tornadoes. The 0-6km shear of 40-50 knots was sufficient for rotating supercells. The significant tornado parameter was not quite as impressive and was kept fairly low due to the low CAPE environment. Had CAPE values been closer to 2000-3000 J/kg, a much more intense outbreak would have occurred. In addition to the tornado threat, Precipitable Water values were in excess of 1.5 inches which also lead to significant flash flooding as the evening progressed.

View location on OpenStreetMap → (39.7071, -86.0971)

Source: NOAA Storm Events Database, event_id 837748. Narrative written by the NWS forecast office that issued the report.