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HOW THE POLAR VORTEX AND WARM OCEAN ARE INTENSIFYING A MAJOR US
WINTER STORM  
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Mathew Barlow, Judah Cohen
January 24, 2026
The Conversation
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_ Multiple weather factors have to come together to produce such a
large and severe storm. How climate change might or might not play a
role. _

, Mathew Barlow

 

A severe winter storm sweeping across the central and eastern U.S. in
late January 2026 is threatening states from Texas to New England with
crippling freezing rain, sleet and snow
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Several governors issued states of emergency
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as forecasters warned of hazardous travel conditions, dangerous wind
chills and power outages amid bitter cold expected to linger for days.

The sudden blast may come as a shock to many Americans after a mostly
mild start to winter
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but that warmth may be partly contributing to the ferocity of this
storm.

As atmospheric
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climate scientists
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conduct research that aims to improve understanding of extreme
weather, including what makes it more or less likely to occur and how
climate change might or might not play a role.

To understand what Americans are experiencing with this winter blast,
we need to look more than 20 miles above the surface of Earth, to the
stratospheric polar vortex.

[[link removed]]A
forecast for Jan. 26, 2026, shows the freezing line in white reaching
far into Texas. The light band with arrows indicates the jet stream,
and the dark band indicates the stratospheric polar vortex. The jet
stream is shown at about 3.5 miles above the surface, a typical height
for tracking storm systems. The polar vortex is approximately 20 miles
above the surface. Mathew Barlow, CC BY
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What creates a severe winter storm like this?

Multiple weather factors have to come together to produce such a large
and severe storm.

Winter storms typically develop where there are sharp temperature
contrasts near the surface and a southward dip in the jet stream
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fast-moving air that steers weather systems. If there is a substantial
source of moisture, the storms can produce heavy rain or snow.

In late January, a strong Arctic air mass from the north was creating
the temperature contrast with warmer air from the south. Multiple
disturbances within the jet stream were acting together to create
favorable conditions for precipitation, and the storm system was able
to pull moisture from the very warm Gulf of Mexico
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[A map of storm warnings on Jan. 24, 2026.]
[[link removed]]The
National Weather Service issued severe storm warnings (pink) on Jan.
24, 2026, for a large swath of the U.S. that could see sleet and heavy
snow over the following days, along with ice storm warnings (dark
purple) in several states and extreme cold warnings (dark blue).
National Weather Service [[link removed]]

Where does the polar vortex come in?

The fastest winds of the jet stream occur just below the top of the
troposphere, which is the lowest level of the atmosphere and ends
about seven miles above Earth’s surface. Weather systems are capped
at the top of the troposphere, because the atmosphere above it becomes
very stable.

The stratosphere is the next layer up, from about seven miles to about
30 miles. While the stratosphere extends high above weather systems,
it can still interact with them through atmospheric waves that move up
and down in the atmosphere. These waves are similar to the waves in
the jet stream that cause it to dip southward, but they move
vertically instead of horizontally.

[[link removed]]A
chart shows how temperatures in the lower layers of the atmosphere
change between the troposphere and stratosphere. Miles are on the
right, kilometers on the left. NOAA
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You’ve probably heard the term “polar vortex” used when an area
of cold Arctic air moves far enough southward to influence the United
States. That term describes air circulating around the pole, but it
can refer to two different circulations
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one in the troposphere and one in the stratosphere.

The Northern Hemisphere stratospheric polar vortex
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is a belt of fast-moving air circulating around the North Pole. It is
like a second jet stream, high above the one you may be familiar with
from weather graphics, and usually less wavy and closer to the pole.

Sometimes the stratospheric polar vortex can stretch southward over
the United States. When that happens, it creates ideal conditions for
the up-and-down movement of waves that connect the stratosphere with
severe winter weather [[link removed]] at the
surface.

A stretched stratospheric polar vortex reflects upward waves back
down, left, which affects the jet stream and surface weather, right.
Mathew Barlow and Judah Cohen, CC BY
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The forecast for the January storm showed a close overlap between the
southward stretch of the stratospheric polar vortex and the jet stream
over the U.S., indicating perfect conditions for cold and snow.

The biggest swings in the jet stream [[link removed]]
are associated with the most energy. Under the right conditions, that
energy can bounce off the polar vortex back down into the troposphere
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north-south swings of the jet stream across North America and making
severe winter weather more likely.

This is what was happening in late January 2026 in the central and
eastern U.S.

If the climate is warming, why are we still getting severe winter
storms?

Earth is unequivocally warming [[link removed]]
as human activities release greenhouse gas emissions that trap heat in
the atmosphere, and snow amounts are decreasing overall
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not mean severe winter weather will never happen again.

Some research suggests that even in a warming environment, cold
events, while occurring less frequently, may still remain relatively
severe in some locations [[link removed]].

One factor may be increasing disruptions to the stratospheric polar
vortex [[link removed]], which appear to
be linked to the rapid warming of the Arctic
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[Two globes, one showing a stable polar vortex and the other a
disrupted version that brings brutal cold to the South.]
[[link removed]]The
polar vortex is a strong band of winds in the stratosphere, normally
ringing the North Pole. When it weakens, it can split. The polar jet
stream can mirror this upheaval, becoming weaker or wavy. At the
surface, cold air is pushed southward in some locations. NOAA
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Additionally, a warmer ocean leads to more evaporation, and because a
warmer atmosphere can hold more moisture, that means more moisture is
available for storms. The process of moisture condensing into rain or
snow produces energy for storms as well. However, warming can also
reduce the strength of storms by reducing temperature contrasts.

The opposing effects make it complicated to assess the potential
change to average storm strength
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not necessarily change in the same way
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events. On balance, it appears that the most intense winter storms may
be becoming more intense [[link removed]].

A warmer environment also increases the likelihood that precipitation
that would have fallen as snow in previous winters may now be more
likely to fall as sleet and freezing rain.

There are still many questions

Scientists are constantly improving the ability to predict and respond
to these severe weather events, but there are many questions still to
answer.

Much of the data and research in the field relies on a foundation of
work by federal employees, including government labs like the National
Center for Atmospheric Research
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known as NCAR, which has been targeted by the Trump administration for
funding cuts. These scientists help develop the crucial models,
measuring instruments and data that scientists and forecasters
everywhere depend on.[The Conversation]

Mathew Barlow
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Professor of Climate Science, _UMass Lowell_
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Cohen [[link removed]],
Climate scientist, _Massachusetts Institute of Technology (MIT)_
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This article is republished from The Conversation
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the original article
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* Science
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* weather
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* polar vortex
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* warm ocean
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* Climate Change
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