GUSTNADO

A gustnado is a colloquial expression for a type of short-lived, shallow, cyclonic circulation that can form in a severe thunderstorm. While it derives its name from the tornado, it has little in common with tornadoes structurally in terms of vertical development, or in regard to intensity, longevity, and formative process (classic tornadoes are associated with mesocyclones).
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[Slang], gust front tornado. A small tornado , usually weak and short-lived, that occurs along the gust front of a thunderstorm. Often it is visible only as a debris cloud 
or dust whirl near the ground. Gustnadoes are not associated with storm-scale rotation (i.e. mesocyclones ); they are more likely to be associated visually with a shelf cloud than with a wall cloud .