How big winter storms create snow, sleet and freezing rain

When big winter storms move in, they can bring nasty weather that shows up as different things in different places — maybe it’s snow, or sleet, or freezing rain. Or maybe just extreme and dangerous cold. Slight differences can lead to one or another. For snow, it takes consistent cold air from the clouds where flakes form all the way to the ground. Sometimes there's a sandwich with a warm layer of air between cold layers. When that happens, a flake can melt as it passes through the warm layer and then refreeze into sleet as it passes back into cool air. If that last cool-air layer isn't big and cold enough, it can mean the worst thing — freezing rain.