- 10-15 day forecast trend - The tropospheric polar vortex breaks down, as massive high-pressure systems crawl into the North Pole and the North Atlantic. The pattern breakdown will release waves of colder weather down into the United States and North Europe. https://www.severe-weather.eu/global-weather/10-15-day-forecast-europe-united-states-october-polar-vortex-fa/ 14 comments worldnews