A viewer snapped a picture of a gustnado in Pinal County in 2013.
A gustnado may look like a tornado, but it forms differently.
A tornado forms in the updraft of a supercell thunderstorm and is attached to the base of the cloud.
Plus the vortex that creates a tornado drops down from the cloud.
This vortex is first called a funnel cloud and then a tornado when it makes contact with the ground.
A gustnado is formed from the gusty outflow of a powerful thunderstorm.
The outflow can kick up air ahead of the storm and some of that air can then start rotating to form a small vortex.
Notice that the gustnado in the picture below is not attached to the base of the cloud but out ahead of the storm.
A gustnado is independent of the storm cloud and forms from the surface of the Earth, stretching upward, which is similar to dust devil formation.
Gustnadoes are generally weak but can match the strength of an EF 0 or EF 1 tornado with 60 to 80 MPH winds.
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