Whether you’ve lived in the Tennessee Valley one year or ten years, there’s one thing we all know for certain. We’re all aware of what seems to be the “Sand Mountain Affect”. It basically says that any storm marching across the Tennessee Valley seems to intensify once it hits NE Alabama and more specifically Sand Mountain. Most will agree that there seems to be an increased number of tornadoes in that section of the Tennessee Valley. It turns out that this activity has been noticed by researchers as well.
The Sand Mountain area has been studied for a few years now, and the folks at UAH have released part of their findings. That is the topic of today’s weather blog. It is worth noting that from here on a good chunk of this blog is quoted from the released findings.
The VORTEX – SE program is comprised of researchers from several different universities and folks at NOAA that come to the Tennessee Valley during peak severe weather season to study severe storms. The program is funded federally and supported by representatives that understand the need for this type of research.
One of the main studies was Sand Mountain. “The Alabama portion of Sand Mountain sees the formation of an above average number of tornados, and the new research explores the possibility that topography has an influence on tornado formation in the Sand Mountain region. Researchers don’t know yet exactly how the environmental changes impact the storms, but they have gained insights into the environments surrounding tornadic storms in northeast Alabama.
“The first paper that we published on the subject shows a statistically significant ‘hot spot’ of tornado formation centered on the Sand Mountain plateau when analyzed against a region within 250 kilometers of either Sand or Lookout Mountains,” says author Anthony Lyza, who started the research as a UAH masters student and continues it as a doctoral candidate. Much of the work in the paper he completed as a doctoral student.”
“When comparing surface observations prior to tornado events on Sand and Lookout Mountains, we found that cloud base heights tend to be lower at Albertville, atop Sand Mountain, than at Scottsboro in the adjacent Tennessee Valley, and that surface winds tend to be stronger and more backed, or counter-clockwise oriented, over the plateau,” Lyza says. “Lower cloud base heights and more backed flow both tend to be generally more supportive of tornadoes.”
The program recognizes that one of the problems is that surface observations are tougher to come by in this section of the state.
“Thus, our goal in the fall 2016-spring 2017 VORTEX-SE experiment period was to gather information about deeper layers of the atmosphere over northeastern Alabama to address a fuller extent of how the atmosphere evolves in the terrain and how that may potentially affect the possibility of tornado formation in northeast Alabama,” he says.
“The initial analysis of data gathered in northeast Alabama since 2016 indicates that the atmospheric changes associated with lowered cloud base heights are typically present atop Sand Mountain,” Lyza says. “These observations also show that the vertical wind shear changes that were hypothesized based off the long-term surface observations can occur, but are not consistent under all environmental conditions.”
An ongoing analysis aims to identify the conditions under which vertical wind shear may be favorably enhanced atop Sand Mountain. While there are some encouraging signs being noted in the data, Lyza says, the results are too preliminary to discuss at this time.