Friday evening‘s storm brought an unusual weather combination to metro Detroit — thundersnow. The rare phenomenon happens when thunder and lightning accompany snowfall. Let’s take a closer look at thundersnow and how it occurs.

Weather conditions

A unique combination of weather factors causes thundersnow to develop, said National Weather Service Meteorologist Andrew Arnold at the agency’s White Lake office. A mix of moisture, instability, a warm front, and snow create the necessary conditions for thundersnow.

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“It’s very similar to an actual thunderstorm itself, where you’ve got a highly dynamic system, where you’ve got a lot of moisture, a lot of instability going on with the storm,” Arnold said.

Frequency

While not unprecedented, thundersnow is a rare occurrence in Michigan, Arnold said. This weather form is highly dependent on the above-mentioned conditions coming together in the right mix.

This article originally appeared on Detroit Free Press: Thundersnow heard in Michigan: Here’s how it happens