A severe winter storm is threatening states from Texas to New England with crippling freezing rain, sleet and snow, prompting several governors to issue states of emergency as of late January 2026. Forecasters warn of hazardous travel conditions, dangerous wind chills and widespread power outages that are expected to last for days.
The sudden cold snap might be a shock after a mostly mild start to winter, but that earlier warmth may actually be contributing to the storm’s intensity.
Understanding this extreme weather requires looking more than 20 miles above Earth’s surface, to the stratospheric polar vortex. As atmospheric and climate scientists, we study what makes these events happen and how climate change might play a role.
Mathew Barlow, CC BY
What Fuels These Severe Winter Storms?
Several weather factors must align to create a storm of this magnitude. Winter storms typically form where there are sharp temperature differences near the ground and a southward dip in the jet stream – the fast-moving air current that steers weather systems. A substantial source of moisture is also needed to produce heavy precipitation.
In late January, a strong Arctic air mass moving south clashed with warmer air. Multiple disturbances within the jet stream created favorable conditions for precipitation, and the storm drew moisture from the very warm Gulf of Mexico.
National Weather Service
The Polar Vortex: What’s Its Role?
The jet stream’s fastest winds occur just below the top of the troposphere, the lowest atmospheric layer extending about seven miles above Earth. Weather systems are capped by the stable atmosphere above the troposphere.
The stratosphere, the layer above, stretches from roughly seven to 30 miles. While high above weather systems, it can still interact through atmospheric waves moving up and down. These waves are similar to those in the jet stream, but they move vertically instead of horizontally.
NOAA
You’ve likely heard the term “polar vortex” during cold snaps. It describes air circulating around the pole, but refers to two circulations: one in the troposphere and one in the stratosphere. The stratospheric polar vortex is a belt of fast-moving air circling the North Pole, a second jet stream higher above the familiar one, and usually less wavy.
When the stratospheric polar vortex stretches southward over the U.S., it creates conditions for waves to move up and down, connecting the stratosphere with severe surface weather.
Mathew Barlow and Judah Cohen, CC BY
Warming Climate, Winter Storms: What’s the Connection?
Earth is unequivocally warming due to greenhouse gas emissions, and snowfall is decreasing overall. However, severe winter weather isn’t disappearing.
Research suggests that even in a warmer climate, cold events, while less frequent, may remain relatively severe in some locations.
Increasing disruptions to the stratospheric polar vortex, potentially linked to the rapid warming of the Arctic, may be a factor.
NOAA
A warmer ocean also increases evaporation, and a warmer atmosphere can hold more moisture, providing more fuel for storms. However, warming can also reduce storm intensity by lessening temperature contrasts. The interplay of these factors makes predicting changes in storm strength complex. But, the most intense winter storms may be becoming more intense.
A warmer environment also increases the chance that precipitation will fall as sleet or freezing rain instead of snow.
Ongoing Research and the Importance of Funding
Scientists are continually working to improve our ability to predict and respond to these events, but many questions remain. Much of this work relies on data and research from federal employees and labs like the National Center for Atmospheric Research, which has faced funding challenges.
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