In the early nineties, I was driving to work early one March morning. I lived out in the country and had about a 15 mile commute to work. However, this particular morning I was driving slowly due to the fact of falling snow, lots of falling snow. The snow storm was unremarkable for Central Ohio, especially in March. The only thing that seemed unusual, about the storm, was the sheer size of the snowflakes themselves. They seemed to be about the diameter of a quarter, maybe this is a bit of an exaggeration and were the purest white in my car headlights.
I was nearing town when I saw something I had never seen before and have never seen since. A bolt of lightning cut through the sky and made its crooked path down to the waiting earth below. In that moment, the flash seemed so incredibly bright, magnified by the early morning darkness and the pure white of the snow. Each individual snowflake seemed to glow with the illumination of that solitary lightning bolt. I will never forget that moment as long as I live. It was in that moment that I experienced thundersnow.
I can almost hear you asking: “what in the world is thundersnow?” Thundersnow, or a thunder snowstorm, is simply a thunderstorm where the precipitation comes down in the form of snow instead of rain. A thunder snowstorm is an incredibly rare event. Thunderstorms are often associated with warmer temperatures that are found in spring and summer. Thunderstorms are caused when cooler air gets mixed with warmer air that creates turbulence and eventually produces the storm. However, I know it can be hard to believe but these same kinds of conditions can occur with a snowstorm.
How is thundersnow caused? Wikipedia identifies three major contributors to thundersnow: lake or ocean effect snowstorms, synoptic forcing and upslope flow. The most common factor is lake or ocean effect snowstorms. Lake or ocean effect snowstorms occur when cold air passes over a warmer body of water. In Central Ohio, the late winter months allow cold air to blow over Lake Erie’s warming waters. These factors begin to produce a thunder snowstorm.
When the warmer air from the water begins to mix with the cooler air moving across the water, a process of turbulence is activated. As turbulence, starts to effect the atmosphere, it churns the clouds within the building storm. The churning mixes both the snow crystals with the droplets of water within the clouds. This mixture allows electrons to move from the droplets of water. Soon there is a build up of energy in negative and positive charges. As the turbulence continues these charges start to separate within the cloud. We understand of energy tells us that opposites attract. Negative charged particles gather together in the cloud base and are draw to the positive charges particles on the ground or in other clouds.
Thundersnow has been recorded in a variety of places around the world, including China and Japan. Closer to home, thunder snowstorms are most likely to appear in the Great Lakes region and the midwest United States.