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Thundersnow, also known as a winter thunderstorm or a thundersnow storm, is a thunderstorm in which snow falls as the primary precipitation instead of rain. It is considered a rare phenomenon. [1] It typically falls in regions of strong upward motion within the cold sector of an extratropical cyclone.
Dec 22, 2022 · Meteorologists say Toronto could see what they call a “weather bomb” storm accompanied by wind gusts up to 100 kilometres per hour, blowing snow and freezing rain. Here are some of the winter...
Nov 18, 2022 · Thundersnow is a rare phenomenon seen only in the strongest winter storms, such as nor’easters, intense blizzards and bomb cyclones. But the underlying mechanisms of thundersnow are the...
- Overview
- What causes thundersnow?
- How rare is thundersnow?
- Where does thundersnow occur?
Until recent decades, we didn’t know if the phenomenon was even real. Now scientists are peeling back why thunder and lightning can happen in a snowstorm.
When Patrick Market began researching thundersnow more than two decades ago, he received two very different kinds of responses.
“One type was, ‘Thank you for doing this, I knew that I’d seen this and nobody believed me,’” recalls Market, who is now the director of the University of Missouri’s School of Natural Resources. “And then the other type was, ‘There’s no such thing as thundersnow, this never happens in wintertime storms, and you’re wasting our money.”
But as he and other scientists have shown, thundersnow—which is when thunder and lightning occur during a snowstorm—is a very real winter weather phenomenon with serious implications.
(What are winter storm watches, advisories, and warnings?)
If you witness those phenomena at the same time, “somebody nearby you is getting at least a half a foot of snow,” Market says. In fact, his 2006 study showed that 86 percent of thundersnow events were associated with storms causing more than six inches of snowfall in a 24-hour period—more than enough to cause havoc on our roads and to our homes.
Scientists believe that thundersnow is caused by the same conditions as a summer thunderstorm: Turbulence in the atmosphere causes moist and relatively warm air near Earth’s surface to rise, where it condenses to form clouds filled with supercooled liquid water, tiny ice crystals, and a form of soft hail called graupel. The more that mixture crashes around inside the cloud, it can create an electrical charge and result in lightning and thunder.
But Sebastian Harkema, a Ph.D. candidate at the University of Alabama in Huntsville who studies thundersnow, says we don’t really know for sure how or why this process occurs in the wintertime.
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During a winter storm, the “warm” air near the ground is still very cold, or below freezing. When that air rises into the even cooler atmosphere, it produces less of the supercooled liquid water that is believed to be important for producing summer thunderstorms.
Thundersnow has been a challenge for researchers to truly understand in part because it’s a relatively rare phenomenon. In the decades before Market began researching thundersnow, we mostly only knew about it through occasional accounts from people who saw lightning or heard thunder during a snowstorm.
But those telltale signs tend to be masked during a snowstorm. Although you can hear thunder rumbling well into the distance during the summer, snow is very good at absorbing sound waves—meaning you’ll only hear thunder if you’re within a few miles of it. (And Market points out the muffled sound can also easily be mistaken for a snowplow). It’s also harder to distinguish a flash of lightning against the backdrop of a bright white flurry-filled sky.
(Here's what you need to know about lightning.)
Yet reports of thundersnow have increased in the decades since Market began his research. “It seems like every two weeks in the wintertime somebody posts a video to their Instagram,” he says. “Is it really happening more or are we observing it more?”
Both things might be true. Harkema’s work has shown that tall radio towers that conduct electricity may be responsible for generating more thundersnow in urban areas. Additionally, the ubiquity of everyday technology like doorbell cameras has also made it easier to capture images of a storm from the safety of your own home.
Most importantly, scientists have now found ways to detect thundersnow without hearing a sound. Not only have our sensors for detecting lightning improved over the years, but satellite imagery has also now made it possible to see where lightning is occurring from space.
These new technologies are helping scientists pinpoint exactly where thundersnow is happening at any given time. The satellite-borne geostationary lightning mapper can detect lightning flashes across an entire hemisphere. Wherever those flashes overlap with snowfall, that’s thundersnow, Harkema says.
He adds that thundersnow is particularly common in the Colorado Front Range, upper Great Plains, and the Great Lakes where wind turbines generate electricity. But thundersnow can happen anywhere—even in the relatively warm Huntsville, Alabama. “When we do get snow, there’s a pretty good chance there’s thundersnow.”
More than just identifying where thundersnow is taking place, the GLM has given researchers a glimpse into what these lightning flashes look like from some 22,000 miles above Earth. Even though there seem to be fewer lightning flashes in thundersnow events than in summer storms, Harkema says the evidence is mounting that thundersnow flashes are also larger than those of summer thunderstorms—and could pose more of a threat to people on the ground.
(How to stay safe in a lightning storm.)
- Amy Mckeever
- 3 min
Mar 4, 2023 · Heavy snow across southern Ontario was punctuated by the rumble of thunder and flashes of lightning on Friday night as a winter storm rolled through. The storm, dubbed thundersnow by many,...
- Isaac Callan
Mar 3, 2023 · “Thundersnow” rolled into the GTA Friday night with a winter storm that was expected to dump up to 30 centimetres of heavy, wet snow on the city by Saturday morning. Thundersnow is a rare...
Mar 4, 2023 · ‘Thundersnow,’ simply put, is when lightning and thunder accompany a snowstorm, and although it doesn’t happen often, CP24 meteorologist Chris Potter said it’s not completely uncommon.
