Scientists at The University of Alabama in Huntsville are organizing a research program to better understand the April 27 tornadoes that killed more than 240 people in Alabama and other Southeastern states.
Supported by a one-year, $150,000 grant from the National Science Foundation, the UAH team plans to analyze radar data each day and merge information with detailed storm surveys and other data. They want to learn more about how the storms formed, what made that day’s storms so unusually powerful and what might be done to make tornado warnings more effective.
Phillip Gentry, a member of the UAH research team, said it was a bit too early to tell if they had made any discoveries and that studies like these take time.
“Basically, everything we can learn about tornadoes is going to be helpful on some level, even if it’s reducing the number of false alarms,” he said.
The NSF is funding this project through a Rapid Response Research grant, which enables support for fast-response research tied to events such as tornadoes.
In addition to studying the physics of the storm, the team will also look at the psychology and sociology of storm warnings. UAH student volunteers and faculty will also be interviewing tornado survivors to learn more about how and when people reacted to that day’s repeated tornado warnings.
“One thing we’re after is whether people are desensitized because the false alarm rate is so high, especially in counties where there are only countywide alerts,” said Kevin Knupp, head of the UAH weather research team.
In their analysis of the storm data, the UAH team will use data from the NWS NEXRAD between Huntsville and Chattanooga, a dual polarimetric Doppler radar at the Huntsville International Airport, and UAH’s own mobile dual-polarimetric Doppler, which on April 27 was stationed between the two stationary radars.
Years since NEXRAD was first installed, the number of small tornadoes such as EF-0 and EF-1 tornados documented by the National Weather Service in Alabama has increased almost threefold, while the number of larger tornadoes has stayed roughly the same.
“Since we have three radars, we can reconstruct the wind field in detail for each of the cells and squall lines that moved through that day,” Knupp said. “We had a full spectrum of storms that day, and it seemed that almost every storm was forming a tornado.”
The increase in tornado warnings is due in large part to the NEXRAD radar’s ability to spot “rotation” inside a storm system. Installed between 1993 and 1997, the five NEXRAD radar units in Alabama are also better at detecting small tornadoes than the previous system, according to the website.
“Before NEXRAD, we didn’t know these rotational elements along squall lines were so prevalent,” Knupp said. “If a small tornado didn’t cause property damage or wasn’t reported, we might never know about it. Now we can see the rotation, pinpoint the location, then go out afterward and look for damage to confirm that there was or was not a tornado on the ground.”
The UAH survey team is also trying to determine how the public judges the threat of dangerous weather.
According to the team of scientists, the detailed radar and surface data will also be helping them to determine whether other factors, such as surface roughness, topography or gravity waves, played a role in forming or strengthening tornadoes.
“We will look at Google Earth to see what was in those areas before the storms hit,” Knupp said. “We can use that information to relate what we saw in the radar with what was being churned up by the tornado.”
