April 7, 2006 Morgan County Storm Survey

Danville (F1) [ Back to Top | Back to April 7 Home ]

This particular tornado was spawned by a supercell thunderstorm that initially produced extensive damage in the Haleyville area around 1005 CDT. In addition, this same supercell would eventually move across the Huntsville metro area producing a brief F0 tornado near the Greenbrier exit of Interstate 565, measured wind gusts to near 60 MPH on Redstone Arsenal, and drop huge amounts of damaging hail across the southern part of the city.

One of the interesting things about the Danville tornado is that it formed not in the classic hook echo region of the storm, but in what is commonly referred to as the cyclonic bookend vortex or “comma head” portion of the storm. This tornado initially produced maximum estimated wind speeds of 90 miles an hour and demolished a large barn. The width of the tornado at this point was at 100 yards. The tornado weakened to F0 intensity with maximum estimated winds at 70 miles an hour as it approached Danville. The tornado moved east and northeast through Danville, producing slight damage to the Danville High School gymnasium roof, the roof of the press box at the football field, and to the back stop and outfield walls at the high school baseball field.

The intensity of the tornado increased to F1 just east of Danville High School as it uprooted a few large trees and lightly damaged some roofs and awnings of around five homes. Maximum estimated winds of the tornado at this point were 80 miles an hour. The tornado continued east to Craze Road, about a mile east of Danville, where estimated maximum winds increased to 90 miles an hour. At least four homes suffered minor roof and awning damage, and a barn was destroyed on Craze Road. The width of the tornado at this point increased to 150 yards before it rapidly dissipated 300 yards east northeast of Craze Road. The path length of the tornado was at least five miles.

A tornado warning had been issued for Lawrence County at 1001 PM CDT. A tornado warning was issued for Morgan County at 1026 PM CDT.


Radar reflectivity image of the storm that produced the F1 tornado near Danville. The tornado actually occurred in the “comma head” region of the storm.	The Storm Relative Motion (SRM) image from KHTX radar showing the velocity couplet near the time of the tornado touchdown in Danville. Note: the bright orange and pink colors are bad velocity values known as “dealiased data”.

Barn destroyed 2 miles northeast of Danville.	Damage near Danville.

Decatur (F0) [ Back to Top | Back to April 7 Home ]

A separate tornado that occurred earlier Friday evening, east of Decatur, Alabama, was determined to have F0 intensity. This tornado touched down along highway 20, about two miles east of Decatur and sporadically produced very light tree damage until it reached the Madison-Morgan county line. A large billboard along Interstate 65 also suffered damage as the tornado approached Madison County. The maximum estimated winds with this tornado were 70 miles an hour. The path width of the tornado was 50 yards.