How High Does a Tornado Go?
Posted by JAC on 4/26/2010, 12:36 pm
Dr. Greg Forbes, Severe Weather Expert

You have no doubt heard about the terrible outbreak of tornadoes that hit parts of the South on Saturday April 24.

One of them devastated Yazoo City, Mississippi, rated an EF4 with winds estimated to have been at least 170 mph.

You can read more about the tornado and see great video at Weather.Com.

I was covering it live on The Weather Channel as the tornado approached Yazoo City. I hope I saved some lives.

I got a very sad, sick feeling when I saw the radar image below (radar graphics using GRLevelX), however.

Do you see that purple circle/oval just on the south side of Yazoo City?

That intense return is from debris tossed into the air by the tornado in progress!

It's a tornado debris signature.

As soon as I saw the radar I knew a devastating tornado was in progress.

The EF5 tornado that hit Greensburg, KS on May 4, 2007 had one of these debris signatures, and it was even in the shape of a donut.






The storm-relative velocity -- computed from the storm moving northeastward at 56 mph, is shown below.

That red-green couplet is the tornado vortex signature (TVS), with greens being winds from the northwest and reds being winds from the southeast.






People sometimes ask how high does a tornado extend up into the cloud?

Here was a good chance to hunt for an answer.

So I looked to see how far up could I track that TVS.

The answer is at least 29,500 feet above ground in this case!

The figure below shows that rotation signature, displaced 10 miles to the northeast of where its cloud base location.





How far aloft was the debris being carried?

Let's estimate that from how high the purple debris signature went.

I took a cross-section to see that, shown below, with the slice heading northeastward toward that 29,500 foot rotation center.





And the answer is at least 8,000 feet in this case.

There is a scale on the right.

Scary stuff!








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A Strong Jet and High Theta-E Air is a Deadly Combo when a Cold-Front Approaches. - JAC, 4/26/2010, 12:04 pm
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