Do Tornadoes Traveling Uphill Do More Damage? New Study Contradicts Past Research

By: weather.com

Published: August 27, 2013

 

 

 

 

 

1 / 9

Joplin, Mo.

The EF-5 tornado was powerful enough to wrap this heavy-duty hauling vehicle around a tree. (Image: weather.com/Tornado Hunt)

• 
• 
• 
• 
• 
• 
• 
• 
• 

FAYETTEVILLE, Ark. -- New research from the University of Arkansas finds that tornadoes cause greater damage when traveling uphill -- and that the twisters tend to climb toward higher elevations rather than going downhill.
Engineering researchers studied images of the 2011 deadly tornadoes in Tuscaloosa, Ala., and Joplin, Mo.
The research team found similarities between the two tornadoes and say the findings likely apply to all tornadoes.
Researchers also found that when a region is surrounded by hills, tornadoes skip or hop over the valleys below.
Damage is noticed only on the top of the hills.

Past Studies Disagree

The Weather Channel's tornado expert Dr. Greg Forbes, who worked with Dr. Ted Fujita who created the original F-scale by which tornadoes are rated, says his research has given him different results than the University of Arkansas study.
"The results of this study do not seem to be 'universal' in that they disagree with most previous studies, including some of those by Fujita and some of my own," said Dr. Greg Forbes. "Of course, every tornado can have its own behavior."
Dr. Forbes also points out that tornadoes are not nearly as common in mountainous areas as they are in the Plains.
"Most studies have shown that tornadoes get somewhat more diffuse, but sometimes wider, as they climb mountain slopes. Sometimes multiple inflow swaths of damage emerge in the process," said Dr. Forbes. "The tornado sometimes then re-intensifies if it reaches an elongated plateau at higher elevations. It has more commonly been observed that tornadoes intensify and get more narrow (i.e., become more concentrated) as they descend mountain slopes  - somewhat in the same sense as a bathtub vortex intensifies as water is pulled down the drain."
The EF4 tornado in Tuscaloosa that researchers studied killed 64 people, while the EF5 Joplin twister killed 158 people.
The research was conducted by civil engineering professor Panneer Selvam and civil engineering graduate student Nawfal Ahmed.