Should We Expect More Tornadoes on Cape Cod?

Jul 24, 2019

 

 

The roof over a section of rooms at the Cape Sands Inn in South Yarmouth was ripped off by the tornado on Tuesday.
Credit Sarah Mizes-Tan

The tornado that touched down on Cape Cod on Tuesday was only the third ever reported in the Cape’s history, according to the National Weather Service.

 

So how – and why – did such a rarity occur?   

For one, the weekend’s heatwave contributed.  

Tornadoes require humid, muggy air. That air sometimes meets and mixes a cold front, like the one that stalled over the Cape on Monday. 

 

Then wind on the ground blows from one direction, while wind higher in the sky starts to turn, blowing from a slightly different direction.

 

"It's that turning of the air with height that actually creates the turning at the surface that we see essentially as a tornado or waterspout," said meteorologist Phil Burt.

 

Another part of this story, according to Jennifer Francis, an atmospheric scientist at Woods Hole Research Center, is the jet stream. 

 

Essentially, the jet stream is a fast-moving river of wind that’s responsible for our weather patterns. It looks like a wave, with peaks and valleys. On Tuesday, one of those valleys, or troughs, was over the northeast.  

 

"When we get a sharp trough like that is when you get the extreme upward motions [of air] that can cause severe thunderstorms, or, in this case, even a tornado," said Francis.  

 

It’s that combination of the jet stream, heat and cold front stalling directly over the Cape that created the right conditions for this week's tornado to form.

   

Those conditions, while rare, most likely weren't a one-off, and they have an underlying cause.   

 

"We can’t take one tornado and say, 'yep, climate change did it,' but we can certainly point to factors related to climate change and say unusual weather is happening more often. These kinds of things are gonna happen more often," Francis said. 

 

Because of climate change there's a lot more heat and moisture in the atmosphere, and that moisture is fuel for all sorts of storms, even tornadoes. 

 

So should we expect to see more tornados on the Cape?  

 

"It's possible that we'll see more tornadoes on Cape Cod," Francis said. "But I think that really the question is more general than that. What we should expect on Cape Cod and elsewhere are more unusual weather conditions to occur." 

 

Plus, Phil Burt says, while the tornado wreaked havoc, he has bigger worries. 

 

"By far the greater concern is the Cape getting a hurricane," Burt said. "Imagine what happened in Yarmouth and Harwich in that little stretch that got that storm, but then paint that same picture literally across every single town on the Cape: every road, every home. That's the far greater concern."

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