What is Cold Air Damming?

Icy, damp, cloudy, and cold weather. These are frequent scenes of winter… and they’re often the result of “cold air damming.” It’s a meteorological phenomenon that can last for several days, and even lead to dangerous ice storms!

Cold air damming is typically seen from October to April in numerous parts of the country, but it’s more commonly found east of the Appalachian Mountains.

Here’s how it works. During the winter months, cold high pressure systems swing in from Canada. This cold, dense air tends to dam, or get trapped, by the Appalachian Mountains. Meanwhile, a storm system nears and brings warmer, less dense air over the stagnant low-level cold layer. Once precipitation begins, if can fall as snow, sleet, or freezing rain…depending on the depth of the cold layer.

This kind of weather set-up can lead to thick ice, resulting in downed trees and loss of electricity, or just enough of an icy glaze to make travel slippery and hazardous. In stronger events, cold air damming can cause an icy mess as far south as Georgia and Alabama.