Despite overall warming, severe winter storms in the United States are becoming more intense. The paradoxical explanation lies thousands of miles north in the rapidly warming Arctic.
The Polar Vortex Connection
The polar vortex — a band of cold air circling the Arctic — is weakening as the Arctic warms 2-4 times faster than the global average. When it weakens, it "wobbles," sending blasts of Arctic air deep into the United States.
More Moisture, Heavier Snow
- Warmer atmosphere holds 7% more moisture per degree Celsius of warming
- When Arctic blasts meet this moisture-rich air, the result is heavier snowfall
- The contrast between warm and cold air masses creates more intense storms
- Lake-effect snow belts are seeing record accumulations as lake ice decreases
The Data
The number of "extreme" winter storms (dropping 12+ inches in 24 hours) has increased 35% since 1980 in the northeastern United States. Meanwhile, mild winters have also become more common — the extremes on both ends are amplifying.
Climate scientists call this "weather whiplash" — the increasing tendency for weather to swing between extremes rather than settling into stable patterns.
