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January 3, 2024

Thundersnow – the mystery of thunder and lightning during snow showers

An illustration of a shower of snow with lightning - thundersnow
Thundersnow is a phenomenon that can occur during events of snow showers.

There is a certain lack of knowledge regarding the occurrence of thundersnow, but this article could perhaps lift the understanding somewhat.

Thunderstorms – a phenomenon that some people consider to be terrifying, others consider a cool experience. Regardless of the relationship we have with the phenomenon, thunderstorms are experienced every season of the year.
As widely known, thunderstorms are strongly correlated with the summer months. But they are also common during the spring and autumn, especially over sea (if not as widespread as during the summer). However, under the right atmospheric conditions, it could happen any time of the year. In other words, also during the winter.

The development of a “classic” thunderstorm is favored by the ingredients: very warm sea/surface temperature, and cold air at higher levels. And with a turbulent atmosphere, moist and relatively warm air near the surface is allowed to rise into the cooler part of the atmosphere. Once risen to a certain height, the air condenses, and clouds filled with tiny ice crystals (or supercooled liquid water) and graupel could be formed. The more the mixture of ice crystals and graupel crashes into each other inside the cloud, sooner or later an electrical charge could be created resulting in thunder.

Although winter is not exactly characterized by warm sea temperatures, we do have the colder air at higher altitudes ingredient. But in order to thundersnow during heavy snow showers to be formed, we must also have relatively warm air near the Earth’s surface that can cause the snow showers to be convective and unstable enough.
The air near the surface could be rather cold, even below the freezing point, but it is important that the air above is even colder so that the air near the surface is allowed to rise and produce supercooled liquid water – although not as much supercooled liquid water produced as during a summer thunderstorm.
In matter of fact, it is to this day still unclear how important the content of supercooled liquid water, and likewise the content of graupel, is in the formation of thundersnow.

Satellite image showing showers of snow with lightning
Satellite image from 3rd December 2023 displaying snow showers in the central part of the North Sea. A few of the snow showers generated lightning that day – and thus also thundersnow.

Regardless of the insufficient knowledge about thundersnow, they do occur both over the sea and land. But they are rare. And they could also be somewhat difficult to distinguish with the naked eye, at least from a larger distance. This is because a flash of lightning could be hard to distinguish during snow showers as the sky will be bright white with heavy snowfall, which is harder for a lightning strike to break through than during a summer thunderstorm. Thunder is also harder to hear from a larger distance during snow showers as snow absorbs the sound waves rather efficiently.
So thundersnow is harder to observe both visually and audibly than a summer thunderstorm, making the mystery of thundersnow even more unobtrusive. Then we can be extra grateful for the availability of sensors and satellites to track thundersnow.

For seafarers, heavy snow showers will likely often be enough to stay in port and view the play from there. With the extra ingredient of thunder, the desire to sail out to sea will most likely not increase - but the viewing enjoyment might increase and develop into an amazing acting performance.