Thursday, June 16, 2011

Dumas Landspout and Thursday Severe

KATV picture of landspout from Martin Henry
10 AM Friday Update... The landspout below has now been officially classified as the 69th tornado of the year in Arkansas.  Here's a portion of the email I received from John Robinson with the National Weather Service office in North Little Rock.

"Landspouts are counted as tornadoes for record-keeping purposes, but
they do not form like typical springtime tornadoes do.  In fact, the
mechanism that causes landspouts is very similar to that which causes
waterspouts in the Gulf of Mexico off the Florida and Texas coasts.  As
a cloud begins to tower upward rapidly, the landspout forms.  Then, when
cloud growth tapers off, the landspout dies.

In Arkansas, we get a report of a landspout once every two or three
years.  Almost invariably, they occur in June, July, or August on hot,
humid afternoons.  They normally occur without thunder, as did the one
yesterday.  Every recorded Arkansas landspout in recent years has
occurred in the flat, eastern part of the state.  Usually, they just
occur over open farmland and cause no damage.  However, they can
occasionally be strong enough to cause structural damage if they do
encounter a structure."

John Robinson



 What will more than likely turn out to be tornado #69 for the state occurred near Dumas around 1:50 PM Thursday.  A KATV viewer sent in a picture which clearly shows a landspout over soybean fields just to the northeast of town.

While technically classified as a tornado, the process by which they form is much different.  They are not associated with mesocyclones in a supercell thunderstorm.  They are usually very weak and only last a few seconds and maybe a few minutes at the most.

Here's the official definition by the National Weather Service...

"a tornado that does not arise from organized storm-scale rotation and therefore is not associated with a wall cloud (visually) or a mesocyclone (on radar). Landspouts typically are observed beneath towering cumulus clouds (often as no more than a dust whirl), and essentially are the land-based equivalents of waterspouts."

Other thunderstorms across the state produced large hail.  Check out these pictures from KATV viewers.  You can always send your pictures and video to photo@katv.com

Large hail 4 miles west of Stuttgart
Hail damage near Humnoke
Hail covering the ground near Brinkley

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