Large tornadoes ravage the Ohio Valley

The weather news of the week was certainly the tornado outbreak that proved catastrophic to a large tract of the country. Below is the image of all the reports. It was decidedly a storm with a wide impact, though note the red triangles clustered around the Ohio River.

The strongest individual cell was one that tracked just north of Louisville, in southern Indiana. An EF4 tornado that touched down near New Pekin, devastating the towns of Henryville and Marysville on it’s way to Chelsea, Indiana 13 people have been confirmed to have died because of this storm, most in Henryville, and the largest segment of fatalities of the 39 confirmed killed in the outbreak. 8 people were also killed in a tornado that swept through West Liberty, Kentucky, a town in the eastern portion of the state.
This outbreak, while terrible, could have been significantly worse. Consider the EF-4 twister that hit Tuscaloosa, and the EF-5 that leveled Joplin, Missouri last year. Both individual storms killed more people than the entire outbreak did in the past two days. Granted, full tallies have not been confirmed yet, but it shows that, though this is a terrible tragedy, there was a great deal of luck. The luck was that the tornadoes didn’t hit more densely populated areas as they did on two occasions last year.
The past weekend’s storm was thanks to a strong ball of energy that drove through the southern Great Lakes. Because there was so much energy flowing into such a deep area of low pressure, the helicity (essentially the localized spin in the atmosphere, a good indicator for a tornado threat) was very high, and higher closest to the center of low pressure. This is why there were tornadoes along the entire front but the largest, longest lived twisters were closest to the low, where the energy and turning motion was the greatest.
It was certainly a devastating tragedy, but it was well forecast, and thankfully, there was a great stroke of luck, that all of these tornadoes strafing the country didn’t end up hitting larger cities, otherwise, the potential was there for the system to be oh so much worse.