Have you ever heard thunder during a big snowstorm? If so, you've experienced an extremely rare weather occurrence.
The ingredients necessary for thundersnow are so uncommon that it's estimated that only .07 percent of snowstorms are associated with thunder.
Thundersnow — when thunder and lightning occur during a snowstorm — is most likely to happen during late winter or early spring when a mass of cold air meets warm, most air near the ground.
University of Missouri atmospheric scientist Patrick Market says that heavy snowfall is common during thundersnow.
In a 30-year study of snowstorms involving lightning, Market found that there's an 86 percent chance that at least 6 inches of snow will accumulate within a 70-mile radius of the lightning.
He says witnessing thundersnow is a matter of being in the right place at the right time, but even then, you likely won't see much.
"In a really nice thundersnow event, the sky gets bright," he told National Geographic. "You don't see a lightning bolt. There's nothing for a second or two, and then you hear a rumble of thunder."
Thundersnow is most common in the Midwest, the Great Lakes and along coasts where moisture from warm water can easily evaporate into the colder, drier air above.
Some of the places that most frequently report the rare weather event are Wolf Creek Pass, Colo.; Bozeman, Mont.; and the shores of Lake Ontario.