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Overnight Tornadoes: How Rare Was Last Night’s In Mississippi

7 Apr 2014, 11:01 am

It’s many people’s worst fear: they go to bed thinking they are safe, and the tornado sirens wake them up (or worse, they don’t).  Until you know what is happening after you wake up, you’re likely to feel terrified at what is happening.

That is what happened to folks in Mississippi overnight last night.  This is a slideshow thanks to WJTV out of Jackson, MS:

 

 

 

Impressive and frightening to think that storm arrived at around 2am. In the next few pararaphs we’ll examine that particular storm, and talk about just how rare overnight tornadoes are.

It turns out that overnight tornadoes are *infrequent* – but calling them rare would be a wrong.  A look at the Southeast Regional Climate Center’s tornado climatology for the Southeast reveals that tornadoes are less frequent overnight, but still happen with regularity.

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Looking at the image above, you can see that between 1954-2010, around the 2am hour, there were close to 200 smaller F/EF-1 tornadoes, or almost four per year.  The red line is F/EF-3 to F/EF-5 and is a smaller scale, so around 2am during that span there were closer to 25 large tornadoes.

That should give you one good piece of news: A strong tornado is less likely during the overnight hours than during the afternoon/evening hours.  That can be easily explained due to excess energy in the atmosphere during the day from daytime heating.

Examining The Overnight Mississippi Tornado

The Mississippi tornado was a scary one to see overnight.  I came in and saw roughly 80+ knots of gate-to-gate shear.  If that last sentence means nothing to you, I’ll explain.  80 knots is nearly 90mph.  “Gate-to-gate shear” is the wind speed from two pixels of radar data added up.

This is what it looked like at around 2am CDT in Mississippi:

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Look in the middle of that picture.  See the bright red pixel of data?  See the bright green one next to it?

I’ve highlighted them in this picture:

 

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That is where the circulation took place.

Frightening.  That is why we STRONGLY recommend that you have a weather radio handy during severe weather season.

WeatherNation Meteorologist Aaron Shaffer @ashafferWNTV

Aaron Out web2

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