Overview
- Multiple forecast models show a sudden stratospheric warming developing over the Arctic in late November, with temperatures aloft rising about 40–50°C and winds weakening.
- NOAA experts note that such events can disrupt the polar vortex and often lead to persistent surface impacts that emerge days to weeks later.
- NWS and other outlooks indicate below-normal temperatures could begin in the Upper Midwest and Plains around November 25 and expand east into early December.
- Risk is highest for the northern U.S. and southern Canada, including greater potential for Great Lakes lake-effect snow, but specific storms and local totals remain unclear.
- November SSWs are uncommon in records since the 1950s, making this an unusually early event, and concurrent La Niña conditions may influence how the pattern evolves.