First Alert Weather Investigation: Terrain and tornadoes studying Sand Mountain

First Alert Weather Investigation: Terrain and tornadoes studying Sand Mountain

HUNTSVILLE, Ala. (WAFF) - The Tennessee Valley is no stranger to severe storms and tornadoes.

Local researchers continue to focus on portions of northeast Alabama where tornadoes have left a path of destruction.

Sand Mountain in northeast Alabama has seen numerous tornadoes over the past decade, several of them violent and fatal.

Portions of Sand Mountain sit several hundred feet higher than surrounding areas and it is topography that has sparked atmospheric researcher’s interests.

Topography, like the mountainous terrain over northeast Alabama has a major influence on thunderstorms and their intensification.

“I think the toughest part of forecasting with the terrain of north Alabama and southern Tennessee is we don’t really have a full understanding of the scope of how these terrain changes impact things,” said Brian Carcione, NWS Huntsville Science and Operations Officer.

The University of Alabama at Huntsville’s PHD candidate Tony Lyza has been studying severe storms entering Sand Mountain over the past several years.

“We noticed in a statistical pattern of tornado formation across northeast Alabama, and indeed the Sand Mountain plateau and especially the northwestern part of the plateau did serve as a statistical hot spot in tornado formation,” said Tony Lyza, PHD Candidate, Dept. of Atmospheric Sciences.

Using long term observational weather data in thunderstorm environments, Lyza was able to start piecing together some of his findings.

His main focus was on tornado-genesis, or points where tornadoes form. He did notice two main components in his research, the first being a lower cloud base.

“The data set we have strongly supports the assertion we came in with that the cloud bases are lower, quite a bit lower, 300 or 400 feet lower to the ground across the sand mountain plateau than in the Tennessee Valley. That is a substantial amount of height change for the cloud base. What that allows is basically for the storms to be warmer relative to the environment and that is behavior that is conducive to tornadoes,” Lyza.

The second observation was for stronger winds over the plateau, which leads to increased wind shear and tornadic development.

“The atmosphere is favorable for winds to be accelerated over the obstacle, over the plateaus. In that acceleration we see in our observations in tornado supported environments tends to allow for more low-level wind shear, that generation of spin that allows storms to spin and then go on to become tornadic,” said Lyza.

While Lyza’s tornadic research does indicate a potential connection between storms and their surrounding environments over Sand Mountain, he says he needs a lot more data to work with and that may take years to accomplish.

"We are a long way away from saying this is a fact that this happens but we are starting to hone in more on what we suspect happens and in what environments it happens. More particularly in environments that are more broadly supportive of tornadoes on a larger scale,” said Lyza.

In the meantime, operational forecasters at the national weather service will continue to monitor the research being done in sand mountain. Terrain forecasting is always a challenge, no matter what the season.

“The terrain all of the time, it’s just a function of what are you trying to forecast and what is the biggest impact of the day,” said Lyza.

Copyright 2019 WAFF. All rights reserved.