Josiah Destin

The Republic | azcentral.com

The strong monsoon storms that downed trees and power poles and flooded streets in the Valley late Thursday afternoon brought one more surprise — a tornado.

The tornado formed in the skies just south of downtown Phoenix by gusts of wind going 40 miles per hour about 5 p.m., said Andrew Deemer, a meteorologist with the National Weather Service in Phoenix.

Deemer described it as a landspout tornado, which is caused when the boundaries of converging winds start spinning near the land's surface.

The Weather Channel, on its website, explained it this way:

"A tornado is spawned from a parent thunderstorm with a rotating updraft, but a landspout isn't. A landspout requires a towering cumulus cloud to be present over a boundary of converging winds near the surface. As that cumulus cloud grows and passes over the boundary, the rotating air is stretched vertically and eventually grows into a landspout. If you've ever seen a waterspout develop, it's very similar, except landspouts occur over land."

The NWS tweeted images of the tornado shared with the agency via social media along with a radar screenshot confirming what it described as a "brief'' landspout tornado over an area southwest of the Interstate 17 and 10 freeway split south of downtown Phoenix.

It was the first reported tornado in the Phoenix area since Oct. 6, 2015, when one was cited over Goodyear, according to NWS.

The tornado did not cause any damage or injury.

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