A massive lake effect snowstorm rolled over northwest New York state from Lake Erie Tuesday, dumping more than five feet of snow in some places and leaving at least four people dead. Buffalo Youtuber Alfonzo Cutalia made this amazing timelapse illustrating the process behind the frigid barrage.
National Weather Service meteorologist Andrew Krein tells Popular Science that lake effect storms result when cold winds slide over warmer bodies of water. The water heats the air close to the ground in discrete parcels, destabilizing the entire mass. Those parcels of warmer, less dense air rise into the atmosphere. "The idea is like a hot air balloon," he says.
Only instead of thrill seekers, that rising air carries moisture. And the longer the wind moves over the lake, the more moisture rises. You can watch this happen in the above video.