Choose an unoccupied 15-foot cube of air that you can see within range. An elemental force of swirling winds appears in the cube and lasts for the spell's duration. The cloud heavily obscures its area.   Any creature that enters the storm for the first time on a turn or starts its turn there must make a Strength saving throw. On a failed save, the creature takes 3d4 slashing damage. As a bonus action, you can move the storm up to 30 feet in any direction. If the storm's area contains leaf litter, flowers, bushes, or trees, it sucks up extra material and the damage the spell deals increases by 2d4 .