Looking Back, July 13th 2013

On July 13th, we had strong to some severe thunderstorms move through the area causing several damaging wind reports as well as several large hail reports including a tornado warning that was issued for parts of northern Laurel, Rockcastle, and Jackson Counties. Although no tornado touched down, but straight line wind damage was confirmed. With this post I want to look back and describe some of the events that happened and what indeed could have happened that day.

On the evening of July 13th, thunderstorms popped up and moved mostly due north out of Tennessee into southern and southeastern Kentucky. These storms became strong and severe especially the one that moved into southwestern Laurel County. By time that particular storm reached west central parts of Laurel County, calls started pouring into the NWS in Jackson reporting a "funnel cloud" being spotted over I-75 near exit 38 and moving over St. Joes hospital between the two London exits on I-75. Because of all of these calls, the NWS in Jackson issued a TORNADO WARNING for northern Laurel, Rockcastle, and Jackson Counties although radar did not indicate anything up to tornado parameters.

Several images poured onto social media sites and this is where I learnt of the "odd" cloud formation that everyone though was a funnel cloud. Here's an image of the cloud formation sent into me by Stacy Calhoun of London.

 

This is a great shot of the cloud formation although I do not recommend doing this while driving. I also had several other shots of this from different angles.

 

The cloud structure in the picture above is called a Wall Cloud. A wall cloud is a lower hanging cloud that often spins and can sometimes spin very fast. Notice the clouds leading into the wall cloud coming from the left? That is what we like to call a "Feeder Band". A feeder band is clouds that move into the right side of the wall cloud causing it to spin. In the northern hemisphere, 98% of all tornadoes, but all hurricanes spin counter-clockwise. While nearly all tornadoes, but all hurricanes in the southern hemisphere spin clockwise. Why do they do this? It's the Coriolis Effect of course. Now when the feeder band pushes clouds into the wall cloud like in the picture above it makes the wall cloud spin, and the more clouds that push into it, the tighter the wall cloud becomes and it increases the likelihood of a Funnel Cloud being produced and we all know what comes after a funnel cloud, Tornado!

 

By looking at the structure of this wall cloud and how well defined it was, I do believe it could have produced a tornado eventually, but it didn't. Why you ask? Because storms were Training that day. When storms "train" they follow storms ahead of them over the same area producing a lot of rain and flooding conditions. A storm had already moved over the area before this one rolled into town and on the back side of that first storm it left behind rain-cooled air. The storm with the wall cloud ran into this rain-cooled air and the outflow the first storm left and made the second storm die out to where it lost the wall cloud. Looking back I can seriously say we got lucky a tornado didn't develop on last week.

 

Thanks for reading everyone, have a great night and take care! :)