Weather Words: Sudden Stratospheric Warming

A Sudden Stratospheric Warming (SSW) event is categorized by a drastic increase in temperatures in the stratosphere over just a few days.

This occurs when large-scale atmosphere waves, known as Rossby Waves, migrate far enough north and high enough in altitude that it affects the stratospheric polar vortex in the process.

Similar to waves in the ocean, these Rossby Waves ‘break’ on top of the polar vortex and cause it to weaken. If the waves are strong enough, the winds of the polar vortex can actually reverse from being westerly to easterly, causing cold air to descend and warm rapidly.

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

The stratospheric polar vortex is a mass of frigid air located aloft in the Arctic. So when it is weaker, split or displaced, the lock of cold air over the polar region is essentially broken, allowing for it to spill further south.

Some notable cold air outbreaks in the U.S. that were tied to SSW events were the 2021 Texas Deep Freeze and the 2024 January Cold Air Outbreak.

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.