The tornado that ripped through Harrisburg, Ill. overnight Wednesday has been labeled an EF4, among the strongest of five categories with winds in excess of 166 mph.
Jayson Wilson, a meteorologist with the National Weather Service in Paducah, Ky., said weather conditions lined up perfectly to generate a series of tornadoes that touched down in southern Illinois, Missouri and western Kentucky.
The storms killed six people in Harrisburg, and three died in Missouri, where a strong tornado plowed through the music resort city of Branson.
Wilson said the timing and size of the twisters were not ususual. The change in seasons, which usually begins in March, can produce unstable weather conditions, he said.
Overnight, a cold front settled into the area. The front was met with some wind, high humidity and warm weather.
“All the paths lined up perfectly,” Wilson said. And the ensuing storms “created a lot of damage."
The Harrisburg tornado, likely the strongest of the twisters reported, was relatively narrow, about 200 yards wide, and touched down shortly before 5 a.m., he said.
“As the storm beared in, the fall became more compact,” Wilson said. It’s like "an ice skater. She tightens up her body and spins faster.”
The National Weather Service has dispatched several teams to assess the damage.
Another bout of severe weather is predicted for Friday, Wilson said.