The other day I watched Thunderball, the fourth James Bond film, which released in 1965 and stars the recently-departed Sean Connery as 007. In the film, Thunderball is a code name; sadly, the flick really has no elements of thunder (or, for that matter, balls). If you’re a fan of the series, youtube currently offers 22 Bond movies free of charge

Taking in Thunderball got me to thinking about storms, specifically, as we move quickly toward winter, thunderstorms that happen when it’s snowing. The phenomenon is officially known to meteorologists as thundersnow. The happening is fairly rare, consigned mostly to a few spots on the planet where the proper ingredients reside.

In short, thunderstorms arise due to instability. When moisture-laden air is warm and meets cold air a thunderstorm is likely to form. The warm air rises and mixes with the higher, colder air, which creates an imbalance of electrical charges. This imbalance results in bolts of lightning and the thunder that accompanies the light splitting air molecules. During the summer, this imbalance is fairly easy to encounter. The ground temperature creates warm air, which can form the updrafts that create thunderstorms. In winter, ground temperatures are obviously far colder. Therefore, an imbalance of air temperatures is much less common.

A simplified image of thunderstorm creation

In certain situations, however, the warm and cold imbalance can be achieved during the winter. Thundersnow most commonly occurs due to lake-effect storms. The temperature of a lake might be significantly higher than its shorelines, which can allow the air above the water to be warmer than air on land. In general, these lake-effect storms are the reason the Great Lakes region of the United States receives so much more snow than other zones. The lakes are, essentially, great engines for storms. In the winter, these storms can produce prodigious amounts of snowfall. They can also create rare thundersnows.

As cited above, the Great Lakes states – Wisconsin, Illinois, Indiana, Michigan, Ohio, and New York experience the bulk of thundersnow. However, other large lakes and oceans can cause the phenomenon, as well. The Great Salt Lake occasionally produces thundersnow and New England states, often the victims of massive blizzards and nor’easters, also encounter it. Though not as frequently, other parts of the world have reported thundersnow, including the British Isles, Japan, spots in the Mediterranean, Brazil, and even Mt. Everest.

Just more than a week ago, residents in Scotland awakened to sounds of explosions, which caused great consternation. Police in the area were flooded with calls about the explosions. These folks have obviously never inhabited the Great Plains! The culprit was thundersnow!

One interesting feature of thundersnow relates to the acoustics of the storms. In a normal thunderstorm, one might hear the rumbles from dozens of miles away. Thanks to snowfall on the ground and the falling particles, the sounds from thundersnow are localized to perhaps a radius of only two to three miles.

In addition, a few notable hazards arrive with a bout of thundersnow. The typical rate of precipitation, usually in the form of snow, obviously, but sometimes also sleet or graupel (soft hail or snow pellets), is higher than traditional snowstorms. Thundersnow can, to mix metaphors, rain down two to four inches of snow per hour! Because the storms tend to be severe, wind speeds are often extremely high, as well. The most intriguing hazard, however, relates to the lightning itself. Most lightning is negatively charged. The bolts from thundersnow are more likely to be positively charged. Positively-charged lightning is far more destructive than its negative cousin, causing the majority of forest fires and power-line damage.

The National Weather Service describes why positively-charged lightning is a bigger issue: “Since it originates in the upper levels of a storm, the amount of air it must burn through to reach the ground is usually much greater. Therefore, electric fields associated with positive Cloud-to-Ground strikes are typically much stronger than those associated with negative strikes. The flash duration is also longer with peak charge and potential up to ten times greater as compared to negative CG strikes; as much as 300,000 amperes and one billion volts!”

A large squall producing heavy snow and frequent lightning over Buffalo - image by Theonlysilentbob

If you rarely click the videos embedded in this newsletter, do yourself a favor and watch the one below. In it Weather Channel superstar Jim Cantore experiences thundersnow firsthand during a blizzard in Massachusetts in 2015. I have been fortunate enough to hear thunder during snowstorms a few times in Ohio and, though it was thrilling, I did not reach the levels of the delirium of Mr. Cantore. Each person has her or his own grails out there! For Jim Cantore, those grails are severe-weather-related. Just check out the rime on his face!

“You can have your $500,000,000 jackpot in Powerball, or whatever the heck it was, but I’ll take this, baby! Four! Four lightning strikes! Four episodes of thundersnow!”

Further Reading and Exploration

How a Blizzard Creates Thundersnow – SciShow

Why don’t snowstorms produce lightning? – The Straight Dope

The Positive and Negative Side of Lightning – National Weather Service

Research on Convective Snows – University of Missouri

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