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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  • Storm downs power lines in Phoenix

    Storm downs power lines in Phoenix

  • Rains blow manhole covers at Sky Harbor

    Rains blow manhole covers at Sky Harbor

  • Monsoon storm in north Phoenix

    Monsoon storm in north Phoenix

  • Storm drops rain on Chandler

    Storm drops rain on Chandler

  • Rain falls in Tempe

    Rain falls in Tempe

  • Rain pours at Desert Botanical Garden

    Rain pours at Desert Botanical Garden

  • Toppled tree after monsoon storm

    Toppled tree after monsoon storm

  • Heavy rain in downtown Phoenix

    Heavy rain in downtown Phoenix

  • Double rainbow after storm moves through

    Double rainbow after storm moves through

  • Driving in rainstorm in north Phoenix

    Driving in rainstorm in north Phoenix

  • Light rain in Chandler

    Light rain in Chandler

  • Manhole cover blown at Phoenix airport

    Manhole cover blown at Phoenix airport

  • Driver gets stuck on flooded street

    Driver gets stuck on flooded street

  • Mesa Fire and Medical rescue in Apache Junction

    Mesa Fire and Medical rescue in Apache Junction

  • Apache Junction flooding

    Apache Junction flooding

  • Monsoon weather in downtown phoenix

    Monsoon weather in downtown phoenix

  • Rain in Phoenix

    Rain in Phoenix

  • Flooded street in Apache Junction

    Flooded street in Apache Junction

  • San Tan Heights flooding

    San Tan Heights flooding

  • Wash floods in San Tan Valley

    Wash floods in San Tan Valley

  • Water rescue Mesa

    Water rescue Mesa

  • Rain and rushing water in east Mesa

    Rain and rushing water in east Mesa

  • Ensenada Park in east Mesa

    Ensenada Park in east Mesa

  • Rain soaks Mesa neighborhood

    Rain soaks Mesa neighborhood

  • Dust storm moves toward the Phoenix area

    Dust storm moves toward the Phoenix area

  • Monsoon storm in Phoenix

    Monsoon storm in Phoenix

  • Pouring rain at Power and Brown roads in east Mesa July 20, 2017

    Pouring rain at Power and Brown roads in east Mesa July 20, 2017

  • Riding out a monsoon windstorm in Phoenix

    Riding out a monsoon windstorm in Phoenix

  • Images from Friday's Phoenix-area storm

    Images from Friday’s Phoenix-area storm

  • Monsoon storm approaches in far West Valley

    Monsoon storm approaches in far West Valley

  • Time-lapse of monsoon storm thunderhead building over Carefree

    Time-lapse of monsoon storm thunderhead building over Carefree

  • Time-lapse view of monsoon storm from Broadway curve in Phoenix

    Time-lapse view of monsoon storm from Broadway curve in Phoenix

  • Storm downs tree in Gold Canyon

    Storm downs tree in Gold Canyon

  • Watch a dust storm move across the East Valley

    Watch a dust storm move across the East Valley

  • Monsoon rains hit far West Valley

    Monsoon rains hit far West Valley

  • Clouds form over Mount Lemmon

    Clouds form over Mount Lemmon

  • Downtown Phoenix, July 15, 2017

    Downtown Phoenix, July 15, 2017

  • Surprise/Waddell monsoon storm

    Surprise/Waddell monsoon storm

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