The National Weather Service is wrapping up their survey of the tornado outbreak that hit the Miami Valley on Memorial Day. They now say 15 tornadoes struck the region with a total of 20 across all of Ohio.
The tornado that affected northern Montgomery County was upgraded to an EF4 with estimated winds maxing out at 170 mph, the strongest observed tornado in the county since the National Weather Wervice began keeping official data in the 1950s.
"There was an apartment complex that was pretty much destroyed up there with the roof and walls taken off," asys National Weather Service meteorologist Jim Lott. "And that was indicative of EF4 damage so once they saw, that they did go ahead and increase the rating on the tornado to an EF4."
Lott says that Monday’s conditions were ideal for tornadoes because winds were converging over Southwest Ohio from different directions.
"The winds at the surface down at the ground were more out of the east, and then as you go up in the atmosphere, the winds switched around more to the south and the southwest."
This combination is known as wind shear and according to Lott, "It causes the rising air to go up and then start to spin as the air goes up through the atmosphere, and that’s what eventually causes the storms to rotate and then eventually could lead to tornadoes."
The National Weather Service says because tornadoes originate from above, tall buildings or residing in a valley won't prevent the storm from affecting highly populated areas.
