A ROLL CLOUD is a low-level, horizontal, tube-shaped cloud completely detached from the base of the parent thunderstorm. It is located along the gust front and most frequently on the leading edge of a squall line of thunderstorms.

A ROLL CLOUD is similar to a shelf cloud, except, unlike a shelf cloud, a roll cloud is detached from the base of a thunderstorm. They are produced when very strong, damaging downdraft winds hit the ground and then roll back skyward. Moist air at ground level is pulled skyward as well. The moisture in the air condenses into the tube-shaped cloud.

A roll cloud is not a tornado. They do not produce tornadoes. Roll clouds usually appear to be "rolling" about a horizontal axis. They should not be confused with funnel clouds or tornadoes.

They are more often associated with microbursts and other damaging straight-line winds.