Overview
- Scientists recorded a sudden weakening and brief reversal of upper‑level Arctic winds around Nov. 10–11, a timing that is earlier than past documented events.
- Observations show winds about 30 km above the pole fell from roughly 28 m/s eastward to near 2 m/s reversed and stratospheric temperatures rose about 10°C above normal on Nov. 11.
- Changes high in the stratosphere usually take two to six weeks to influence weather at ground level, so forecasters say any major winter impacts are most likely to appear in late November or December.
- A record‑strong El Niño is also driving large‑scale circulation toward warmer patterns, which makes it uncertain whether a stratospheric disruption will cause widespread or only localized cold outbreaks.
- A short cold pulse and first frosts have already hit parts of North America and northern Europe, and national agencies and researchers are closely watching models and will update seasonal guidance in the coming weeks.