This is the dramatic moment a shelf cloud looms above a gas station in Michigan.

Footage captured by James shows the creepy dark formation stretching across the horizon against a fading orange sunset in South Haven on October 6.

Authorities said the phenomenon was part of a series of severe thunderstorms that prompted tornado warnings across West Michigan that same day.

Shelf clouds are large, horizontal cloud formations that develop along the leading edge of a storm. They occur when cold, dense air from the storm pushes outwards and undercuts warm air, forcing it to rise and condense into a wide arc of cloud.

They differ from wall clouds, which are smaller, more compact, and form when the base of a supercell or rotating storm lowers closer to the ground.