NEW ORLEANS — A few strong to severe storms moved across Southeast Louisiana on Sunday. I'm sure some of them interrupted your Mardi Gras afternoon parade plans, but they were nothing compared to what happened in Alabama, Georgia and Florida. So why were the storms so much worse there?
Let’s take a look at the science.
A strong cold front moved across the Southeast U.S. with an area of low pressure along it.
On the north side of the cold front it was cold and dry. On the south side of the cold front it was warm and extremely humid, thanks to southerly winds from the Gulf of Mexico.
This extra humidity caused the environment to become very unstable right on top of Alabama, the Florida Panhandle and Central Georgia.
When the cold front moved into this very unstable atmosphere it popped up thunderstorms that quickly became severe. The thunderstorms started rotating thanks to the strong winds around them. A rotating thunderstorm is called a supercell, and these type of thunderstorms develop tornadoes. This was the case on Sunday.
The strongest supercell thunderstorm of the day was in Lee County, Alabama. This supercell produced a very large tornado that caused incredible estimated EF-4 (winds of 170+ mph) damage. It also took a number of lives.
The higher humidity levels and winds were much farther to the east of Southeast Louisiana, so we missed out on the most unstable air. This is why our storms were weaker, and we were not going to have any tornadoes.
The Sunday tornado outbreak killed 23 people, but some people are still missing. The total killed by tornadoes in all of 2018 was 10.
Late Winter and early Spring is the severe weather season across the Southeast U.S., including here in Southeast Louisiana. Historically, large and violent tornadoes have occurred this time of year across Dixie Alley, an area from North Louisiana and Arkansas, east across Mississippi, Alabama and into Georgia.
The worst tornado outbreak on record in Dixie Alley was on April 25-28, 2011. This is known as the Super Outbreak of 2011 where 362 tornadoes occurred across 15 states. There were 321 people killed during this time period with 316 of those deaths coming just on April 27.