Another huge tornado today, pretty gnarly video above.
It’s not your imagination, they seem to be coming in bigger bunches.
Tornadoes are tricky.
They are too small and short lived to be properly resolved in Climate models – and we still don’t have a long enough record of the best quality Doppler Radar observations to make a clear connection to climate change.
But something is going on.
And even as the number of tornadoes has stayed relatively consistent in the last few years, experts say there have been key changes in their behavior over time that could have major consequences.
More tornadoes are now concentrated in fewer days, meaning they are less spread out and there’s a higher number occurring on the same day, according to a 2019 study published in Theoretical and Applied Climatology. A growing number of tornadoes are also occurring in the southeastern part of the US in addition to the Great Plains, where they have been historically most common.
There’s still a lot experts don’t know about why both these trends are occurring and it’s not clear if climate change is playing a role. What is more certain is that these shifts mean people will have to prepare for these natural disasters in new ways, with some communities enduring more severe storms in rapid succession and others being forced to build infrastructure for tornadoes they had rarely experienced before.
Scientists have some information about why there are more concentrated tornadoes, or clustering, and why the locations of tornadoes have shifted slightly. With clustering, it’s tied to the presence of atmospheric and wind conditions that fuel dozens of tornadoes at once. And with changes in geography, it’s related to parts of the country drying out while other areas are seeing more rain.
The increase in tornado clustering has been observed since the 1980s and continues into present day, says Tyler Fricker, an author of the 2019 study on the subject. According to that study, while 11 percent of tornadoes occurred on days when there were 20 or more tornadoes from 1950 to 1970, now 29 percent of them do. The prevalence of low-pressure systems, warm moist environments, and high wind shear (changes in speed and direction of wind combined with height) all come together to fuel these clusters.
“We are seeing a reduction in the total number of days where there are tornadoes, but those that do occur are almost ‘supercharged,’ producing substantially more tornadoes than what we would otherwise expect,” says Jana Houser, an atmospheric scientist at Ohio State University.
What’s still unknown is whether such shifts are related to climate change as the Earth has gotten warmer due to human-generated greenhouse gases.
“It’s hard to pull out the different trends — maybe the natural variations are impacting tornadoes, maybe the broader climate change, maybe it’s a combination of both,” says Jase Bernhardt, a climatologist at Hofstra University. “We want more research done to understand why it’s happening.”