Best views, weather, etc. How to test them 👓 SC, Ala. sites look back Betty Ford honored
NEWS

It's thunder. It's snow. It's thundersnow!

Thomas M. Kostigen
Special for USA TODAY

Thundersnow. It sounds like something out of a James Bond movie, and the rare weather phenomenon that occurs when thunder and lightning combine with a snowstorm can be a dangerous adversary.

Batches of lake-effect snow — including many reports of thundersnow — dumped more than 7 feet of snow on doorsteps outside Buffalo this week, trapping hundreds in their cars and homes and leaving at least 12 dead in western New York.

Tami Normile and Richard Brooks attempt to remove some of the 5 feet of snow from a rooftop Nov. 20 in the Lakeview neighborhood of Buffalo.

That wasn't the phenomenon's first appearance of the season: This month, thundersnow rumbled through Mentor, Ohio, flashing and crackling as if to warn residents a ferocious storm had arrived.

That storm dumped more than a foot of snow during an unseasonal first blast of cold air, turning the region into a pre-winter wonderland — and a dangerous one at that.

Thundersnow can be an indicator of a heavy snowfall. At least one study found that when lightning strikes during a snowstorm, it's likely at least 6 inches of snow will fall.

Thundersnow forms when temperature and moisture conditions are just right — a mass of cold on top of warm air, plus moist air closer to the ground. Such conditions usually occur in late winter or early spring, but the autumn season can produce similar results.

Lakes promote the phenomenon. Lake-effect snow occurs when moisture from a lake evaporates into cold air, forming clouds and snow, which often develops quickly and in large, concentrated amounts.

A bicycle messenger chains his bike to a snow-covered parking meter in downtown Cleveland on Nov. 14.

In addition to heavy snowfall and lightning, thundersnow brings other hazards — such as ice pellets larger than hail.

"It's important to remember that when you hear thunder when it's snowing, the storm is producing lightning," says Jack Williams, the founding editor for USA TODAY's weather page in 1982. "Probably the last thing you'd think of are lightning safety rules — those are for summer ... but thunder always means there's lightning, and winter lightning is as dangerous as summer lightning."

To stay safe, Williams advises people to mind the basic rule: "If you hear it, fear it." Whenever lightning threatens, seek shelter inside a sturdy building or structure.

"If you hear thunder when it's snowing, don't go outside to look at it, no more than you'd go outside to watch a summer thunderstorm," says Williams, who was recently honored as an American Meteorological Society fellow for 2015. "You could become a rare victim of lightning that hit while snow was falling."

Going outdoors in a snowstorm to watch for lightning can result in injury or death. Two men were struck by lightning during snowstorms in 1996 — one in Minnesota and the other in Colorado. In 2002, four teenagers in Maine were struck on a hill while sledding, according to the National Lightning Safety Institute.

As fascinating as thundersnow may be, don't try to get a glimpse or capture video of lightning during a snowstorm.

You Only Live Twice is the title of a Bond film, not a feat for real life.

Thomas M. Kostigen is the founder of The Climate Survivalist.com and a New York Times bestselling author and journalist. He is the National Geographic author of "The Extreme Weather Survival Guide: Understand, Prepare, Survive, Recover" and the NG Kids book "Extreme Weather: Surviving Tornadoes, Tsunamis, Hailstorms, Thundersnow, Hurricanes and More!" Follow him @weathersurvival, or e-mailkostigen@theclimatesurvivalist.com

MORE FROM THOMAS M. KOSTIGEN:

Featured Weekly Ad