Tuesday, May 27, 2014

Sunday Afternoon Landspout

Sunday afternoon around 3:00PM a tornado spun up in Dunklin county just west of the intersection of HWY 102 and HWY 25 north of Malden. 

Tornadoes usually form with rotation severe thunderstorms and usually have a few minutes warning time before they develop.  But there is one type of tornado that usually develops quickly and without warning.  That type of tornado is called the landspout.  A landspout tornado forms much in the same way its cousin the waterspout develops over the water.  Instead of a rotating severe thunderstorm in which rotation form the mid levels is brought down to the surface, these tornadoes start as a swirl on the ground that is stretched under a storm’s updraft. 
Two dust swirls on the ground.  Photo Leslie Asher.

Sunday afternoon there was a thundershower located over Dunklin County that collapsed around 2:40PM sending a boundary of rain cooled air across the Bootheel.  Along and immediately behind this boundary little eddies or swirls form.  Picture your arm moving along the top of the water in a swimming pool.  Right behind your arm you will see little swirls form.  This same action occurs in the atmosphere as boundaries move through.  

Video above from Brandon Shelton.

As the boundary approached Malden a thundershower was rapidly developing.  This thundershower’s updraft encountered the swirls on the ground stretching them making the rotation stronger.  The stretched rotation is pulled into the thundershower’s updraft and a tornado forms.  

Dust Swirl stretched into the storm. Photo Leslie Asher.

Now landspouts are usually very weak, EF0, but in some cases have reached EF3 strength depending on the storm’s updraft strength.  Looking at the video seen these were very weak, maybe technically not reaching the 65MPH wind speed needed to be classified as an EF0 tornado.  But with that said anytime there is a rotating column of air in contact with a storms updraft by definition, it’s a tornado.  Not sure if this will go down as an official tornado but to all who sent video and photos to help me investigate, thanks.  You can tell all your family and friends you saw a tornado. 

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