Weather Explainers

Weather Words: Cross-Polar Flow

Cross-polar flow is a phenomenon that describes the movement of air over the North Pole. For U.S. context, this generally describes the movement of air from Siberia into North America.

Cross-polar flow describes a unique meteorological setup most common during the winter. This is often responsible for many of the intense Arctic outbreaks that occur in the U.S. each decade.

For cross-polar flow to occur, a blocking high pressure system or sudden stratospheric warming event must be present to disrupt the polar vortex. For context, the polar vortex is a very high-altitude area of low pressure embedded in arctic air, generally contained near the North Pole by the polar jet stream.

(MORE: What The Polar Vortex Is And What It Means For This Winter)

If the polar vortex is disrupted, either by warm air traveling far north due to a blocking high pressure system or a sudden stratospheric warming event, the polar vortex can become distorted and elongated across the North Pole. This elongated polar vortex can then allow the flow of air from one side of the North Pole to the other.

North Georgia Winter Storm 2025
(Hayden Marshall)

If a disrupted polar vortex is combined with a blocking high pressure system, say over Alaska or the North Pacific, the result can be frigid air getting funneled from Siberia into North America. Once in North America, the air mass can then migrate into the U.S. Because many of these events happen during the winter, the air from Siberia often travels over snowpack and ice, limiting the moderation of the air mass.

The result of this can be frigid, arctic air moving into regions of the U.S. where you typically do not expect it. Examples of this occurring include the 2021 Texas Deep Freeze, the 2023 December Arctic Outbreak, and the 2014 "Polar Vortex" Winter. If you are curious about the role the polar vortex may play in this winter, read this article.

Hayden Marshall is a meteorologist intern and First-Year-Master’s Student at the Georgia Institute of Technology. He has been following weather content over the past three years as a Storm Spotter and weather enthusiast. He can be found on Instagram and Linkedin.