Thundersnow is a rare and electrifying experience
A ripping snowstorm is a force to behold. Boisterous snowfall rates with whipping winds reveal nature’s raw power on even the coldest day. But sometimes it’s a flash high above the surface that really steals the show.
Vivid bouts of thundersnow are a rare but beautiful phenomenon that some folks are lucky to experience during the winter months. It takes a special storm to unleash this fleeting spectacle. Here’s a look at how it happens.
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Thundersnow is just a thunderstorm that produces snow instead of rain. This relatively uncommon phenomenon is usually found in mountainous areas, near the Great Lakes, and across communities affected by powerful winter storms.
I managed to catch some of the awesome thundersnow here in Toronto. Here’s the best one that I captured. The thunder rumbled on for a very long time.#thunder #lightning #snowstorm #toronto pic.twitter.com/BPAlnzNr5d
— George Kourounis (@georgekourounis) March 4, 2023
Even though it’s freezing outside and the sound of thunder is muffled by the blanket of snow, the lightning that creates thundersnow is still dangerous. If you ever see lightning or hear thunder when it’s snowing, make sure you head for safety indoors.

An average thunderstorm forms when warm air near the surface rises through cooler air aloft. Ice crystals high in the developing clouds separate positive and negative electrical charges in the atmosphere, creating the conditions needed for a tremendous discharge of lightning.
We don’t see many thunderstorms in the winter, though, because that sharp temperature contrast is usually missing. Lacking the buoyant lift we’d see during the warmer months, thundersnow requires an outside force to shove air from the surface skyward.
Intense bands of lake-effect snow are the most common way we experience thundersnow in Canada.
With towering clouds and very heavy snowfall rates, these convective bands of lake-effect snow can closely mimic the structure and intensity of a strong summertime thunderstorm—just with much colder temperatures.
It’s possible for dozens, or even hundreds, of lightning strikes to accompany a particularly strong snow squall snaking off the Great Lakes.
A powerful winter storm can also produce the dynamics needed for thundersnow to flourish. A strong low-pressure system often resembles a comma on satellite imagery. The ‘comma head’ on the northwestern side of the storm features some of the system’s most intense motion.
Winds within the storm are colliding with air outside of the storm, forcing the air aloft to stretch out into that comma head shape. This process leaves a void high in the atmosphere that air from the surface has to rush upward to fill—providing the lift needed to produce thundersnow.
Thundersnow can also occur over and around mountains as a result of orographic lift. Winds blowing up the side of mountainous terrain can provide the oomph necessary for cumulonimbus clouds robust enough to generate lightning.