What’s an Alberta Clipper?

DEM Blogger

January 25, 2014

The term “Alberta Clipper” has featured in some news coverage of our recent weather. We were curious about the term’s precise meaning and origin, so we went looking for answers – and found them on the National Weather Service’s site (also the source of the illustration to the right).

According to the NWS, the name comes from the phenomenon’s point of origin and its speed. These weather systems begin in or near the Canadian province of Alberta. They move quickly, like the 19th-century clipper sailing ships. Technically, we suppose an identical weather system that began in Montana could be called a “Big Sky Clipper,” though Alberta seems to get all the credit for this type of weather!

A clipper is a low-pressure system that develops on the lee (downwind) side of the Rocky Mountains, where it gets caught up in the jet stream. The jet stream carries it southeast through the northern Great Plains and Great Lakes to the Mid-Atlantic coast – though, as you can see from the path in the NWS image, it’s not unknown for one to swing south toward Kentucky. A clipper’s high speed and lack of moisture usually limit its snow delivery to one to three inches, as it doesn’t hang around long enough to drop a lot precipitation. Other clipper-driven weather conditions are colder temperatures and strong, gusty winds.