(Video courtesy Anthony Andrew)
Residents near Unionville received some excitement Tuesday evening about 7 p.m. when a landspout tornado was reported to the 911 call center.
KTTN received numerous Facebook messages asking why no watches or warnings were issued.
The National Weather Service in Kansas City tells us that the reason no watches or warnings were issued, is that they simply couldn’t see any rotation in the clouds on radar. KTTN did observe a cell of heavy precipitation moving through the Unionville area last evening, and indeed, there was no familiar “hook” normally seen on a radar image.
The weather service tells KTTN that these types of landspout tornadoes normally form on an outflow boundary, during the growth stage of clouds, by stretching upward and into the updraft. They generally are smaller and weaker than a supercell tornado and do not contain pre-existing rotation in the cloud. Because of this, landspouts are rarely detected by Doppler weather radar.
Landspouts have a strong resemblance and development process to that of waterspouts, usually taking the form of a translucent tube, as you can see in the video above, provided by the National Weather Service. Landspouts are considered tornadoes since a rotating column of air is in contact with both the surface and a cumuliform cloud. Not all landspouts are visible, and many are first sighted as debris swirling at the surface before eventually filling in with condensation and dust.
A few landspouts can persist in excess of 15 minutes and have produced F3 damage however, most of them rarely produce damage given their abbreviated duration, typical slow forward motion, and compact wind field. The potential for damage is further minimized over sparsely populated regions