Observed and forecasted (NOAA GEFSv12) wind speed (top) and temperature (bottom) in the polar vortex compared to the natural range of variability (faint shading). For the GEFSv12 forecast issued on February 12, ~90% of the individual model runs predict a reversal of the vortex winds (top, thin magenta lines), accompanied by a sharp increase in stratospheric temperature (thick pink line). While the average of the individual forecasts just crosses the 0 m/s threshold, other forecast models are indicating a larger wind reversal (not shown). If a major warming does occur, it’s currently forecast to last no more than a few days, but the vortex could still remain weaker than normal for the next few weeks. NOAA Climate.gov image, adapted from original by Laura Ciasto.