April 11, 2007 Severe Weather

Four Tornadoes, Hail, and Damaging Winds Strike Central Indiana on April 11

A strong spring storm system brought tornadoes, hail, and damaging winds to central Indiana on April 11. National Weather Service Assessment teams determined that 4 tornadoes struck central Indiana during the afternoon. A map of the tornado paths is below. Details about each tornado follows below the pictures of the event.

Tornado track map. Click for full size version.

The initial tornado touchdown was reported by a storm spotter at 4:20 P.M. EDT in Harmony, about 22 miles east of Terre Haute .  Minor tree damage resulted from this storm.  This tornado was rated EF0 on the Enhanced Fujita intensity scale with winds estimated around 70 mph.  The term ‘EF’ stands for “Enhanced Fujita,” a more accurate method of rating tornado intensity recently introduced by the National Weather Service.  

 The same mini supercell storm produced a second tornado at 5:35 P.M. EDT near North Salem or about 12 miles west of Brownsburg. This tornado, first reported by the Hendricks County Sheriff Department, touched down over open fields causing no damage and was rated an EF0 on the Enhanced Fujita Intensity scale with winds estimated near 70 mph.

A new mini supercell, which prompted a tornado warning but caused no damage in Putnam County , produced the third tornado of the evening in Hendricks County .  This tornado, also reported by the Sheriff Department, began at 6:37 P.M. EDT about two miles southwest of Lizton, or about 8 miles northwest of Brownsburg.  This tornado passed southeast of Lizton and lifted about one mile west of Pittsboro around 6:50 P.M. EDT.  Several garages and barns were destroyed, several homes suffered lighter damage.  This tornado was rated an EF1 on the Enhanced Fujita scale with winds estimated around 90 mph.

Below are pictures of the tornado near Lizton (Click on a picture for larger version). Photos courtesy of Rebecca Saylor:

Below are pictures of damage from the tornado that moved near Lizton (click on a picture for a larger version):

The original mini supercell that produced the first two tornadoes recycled one last time to produce its third tornado, the fourth tornado overall for the evening, in northeast Hamilton County .  This tornado touched down at 7:25 P.M. EDT, as reported by trained spotters, about 3 miles east of Arcadia .  The tornado continued a path to the northeast, lifting around 7:30 P.M. EDT as it damaged a barn just across the Hamilton county line in extreme southeast Tipton County .  An EF2 rating was assigned to this tornado given the significant destruction of a barn, and the tornado moving a dual wheel pickup truck/trailer rig nearly fifteen feet. Winds were estimated near 120 mph.  Several other outbuildings suffered major damage while several homes exhibited moderate to minor damage.

Below is a picture of the tornado near Arcadia (Click for a larger version). Photo courtesy of David Gorman:

Below are pictures of damage from the Hamilton and Tipton counties tornado (Click for a larger version):

Mini supercell storms are a cool season, smaller size version, of summer-time rotating thunderstorms that produce tornadoes.  The supercells during this event reached to around 25,000 feet tall compared to summer-time supercell storms which often reach heights of 40,00 to  50,000 feet tall.