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.

Unlike most storms, which have to lug their water hundreds or thousands of miles from the nearest sea, lake effects occur over very short distances and have functionally unlimited moisture sources.

Krein says the arctic air mass that moved down into the U.S. last week creates prime conditions for this sort of event. The air cooled very quickly for this time of year, but bodies of water like Lake Erie hold onto their heat far longer. With some climatologists predicting that arctic events will become much more common as the overall climate warms, lake-adjacent cities like Buffalo might see a lot more of this in the future.