Waterspouts are common over Lake Erie. They form when cold air passes over warm water, so there are more of them in the fall, although I've seen them in summer. You have nothing to fear on land, they dissipate as soon as they make landfall. On the water they're pretty powerful - I've seen one pick up and toss an 18' fishing boat with a man and a dog in it about 50'. Fortunately, other boaters in the area got to them quickly and saved them and the boat.