Image caption
Atmospheric conditions in the troposphere in late December 2023 (left globe) did not match either of the two patterns (center and right) that usually precede major disruptions of the polar vortex. When planetary waves in the troposphere adopt either of the configurations shown in the middle and right-hand globes, their energy is amplified, enabling them to push upward and break into the stratosphere. The configuration in late December had low pressure over the North Pacific (gray), which is part of the "wave-1" pattern that often precedes the polar vortex getting displaced off the pole. But the pattern lacked the high pressure (red areas) across Greenland and the eastern Arctic. NOAA Climate.gov image, adapted from original by Amy Butler.