From TIME · Simmone Shah · · 1m 30s
Early polar vortex breakdown could bring US cold snap
A record-early disruption of the polar vortex is expected to send Arctic air south by late November, but its interaction with a strong El Niño this winter remains uncertain.
In brief
A record-early disruption of the polar vortex is expected to send Arctic air south by late November, but its interaction with a strong El Niño this winter remains uncertain. The earliest recorded polar vortex breakdown is expected to bring cold weather to the US by Thanksgiving, but how it will interact with El Niño…
Quick answers
- What is the polar vortex?
- The polar vortex is a low-pressure band of air centered over the North Pole in the stratosphere, rotating cyclonically around the region.
- What is the key takeaway from Early polar vortex breakdown could bring US cold snap?
- The earliest recorded polar vortex breakdown is expected to bring cold weather to the US by Thanksgiving, but how it will interact with El Niño over the rest of winter is uncharted territory.
What is the polar vortex?
The polar vortex is a low-pressure band of air centered over the North Pole in the stratosphere, rotating cyclonically around the region.
How disruption sends cold south
When the polar vortex weakens, it displaces cold air usually trapped in the Arctic, pushing it toward lower latitudes and triggering cold snaps across the northern hemisphere.
“If the polar vortex gets disrupted and weakens, then that cold air tends to be released southward into the mid-latitudes, and of course, with more cold air, you can also have an increased chance or risk of snowstorms or ice storms.”
Record-early breakdown observed
Meteorologists are observing the earliest recorded polar vortex disruption ever. It typically weakens in January or February, not this early in the season.
“So what's unusual about this event is that it's the earliest recorded sudden warming event.”
Cold expected by Thanksgiving
The polar vortex disruption is expected to bring chilly temperatures to the United States by Thanksgiving week, though its influence may not last much longer.
El Niño interaction uncertain
Experts cannot yet predict how the strong El Niño forecast for this winter will interact with the polar vortex. The two forces could reinforce mild weather or work against each other.
Uncharted territory ahead
This combination of a polar vortex disruption of this magnitude and a super El Niño has never occurred before, leaving the rest of winter's weather genuinely unpredictable.
“We've never had a polar vortex disruption of this magnitude and a super El Nino. So in some ways, this is uncharted territory.”
The main idea
The earliest recorded polar vortex breakdown is expected to bring cold weather to the US by Thanksgiving, but how it will interact with El Niño over the rest of winter is uncharted territory.
