Early Polar Vortex Weakening Puzzles UK Forecasters
Scientists have recorded an unusually early weakening of the polar vortex, a large pool of cold air high above the Arctic. Experts are unsure how much it will affect UK weather, and whether it could bring snow. The explainer looks at what the change could mean for winter conditions in Britain.
Context
The polar vortex is a ring of strong winds and cold air circling the North Pole in winter, which usually keeps the coldest air near the Arctic. When it weakens, it can let cold air drift south, sometimes bringing cold snaps to Europe and North America.