Brief Landspout Tornado South of Pueblo

At around 446 PM MDT, a brief non-mesocylone tornado touched down around 6 miles South or South Southwest of Pueblo and lasted for about 5 minutes. Several reports were relayed to the office from Law Enforcement, and from weather spotters, and it was visible from the National Weather Service Pueblo Office. This weak tornado, or landspout, resembled a tall dust devil with connection to a growing cloud base above.  Spotter reports indicated it formed along I-25 near mile marker 91 south of Pueblo in an open field.  No damage was reported.

Landspouts typically form when thunderstorms develop overtop of low level boundaries where winds from different directions converge and create eddies.  When a growing thunderstorm updraft intersects with these converging winds, small tight circulations can form, which get stretched into the cloud base, forming these often brief and weak tornadoes. 

At 430 PM, this boundary was evident in Visible satellite imagery as the line of clouds extending from Northwest to Southeast across Pueblo County. 

 

At 442 PM, Pueblo doppler radar showed this boundary as well, with a growing cell just south of the city of Pueblo.

 

This cell grew in strength by 446 PM, which was the time at which the landspout was reported in a field just east of I-25 around mile marker 91 south of Pueblo.   

It lasted for only 5 minutes before dissipating quickly.  No circulation was evident in doppler radar velocity imagery because the feature was too small in scale to be resolved by the radar beam width.

Cold air aloft associated with the trailing edge of a low pressure system departing into the central plains helped destabilize the atmosphere this afternoon.  Although temperatures only warmed into the 50s across southeast Colorado today, this cold air in the mid levels of the atmosphere resulted in enough instability for small scale briefly strong updrafts to form.   Other thunderstorms in the area produced some small hail, pea to 1/2 inch in diameter near Holly and Two Buttes, while showers and thunderstorms across the mountain areas produced some brief heavy snowfall and snow pellet showers.   However this storm was able to interact with the boundary to produce the brief landspout tornado.  In the image below, the shaded colors represent the mid level temperatures (around 20,000 feet MSL) with cooler blue colors over Southeast Colorado representing temperatures of around -27 Celsius.   The solid lines which dip southward through the central portion of the country represent the 500 MB heights and denote the location of the departing Low pressure system.

 



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