I've seen yellow skies, I just never figured out the correlation to hail before. Thanks. We lived in Omaha in 1985, when we got 7 feet of snow in January (the big pile in the empty lot at the end of our street didn't completely melt til the end of April) and then a big tornado in May. Once you've seen a "tornado sky" and the damage that a big tornado can do you take those things seriously! Lots of damage and two deaths.
Later we moved back to Denver, and one day we looked out and saw green-black and headed for the basement, flipping radio stations to find out what was up. It was a tornado all right, but the only radio station that was talking about it was on the other side of town from the actual track and almost no one paid any attention to the Civil Defense sirens. Not a lot of damage, (four houses) but a lot more injuries than in Omaha from flying debris.
Boston doesn't get tornadoes much -- Western Massachusetts does. But we get "microbursts", sudden downdrafts of wind that can flatten a tree or a house and leave all the neighbors alone.