nynjpaweather (@nynjpaweather.bsky.social)

Model Data Supports Weak Polar Vortex We are at the time of year when we can start monitoring the model data for weakening of the Polar Vortex. After a brief period where the Polar Vortex strengthened in early November to support a mild period for the middle of November, the EPS data strongly support a weaker-than-normal Polar Vortex developing by mid-November and continuing through early December. In fact, there are even a fair number of outliers that would suggest a major stratospheric warming event is possible, but I think the model data might be a bit too aggressive; we'll keep an eye on that potential in the coming weeks.The model data, though, does support an atmospheric environment where high latitude blocking and a transport of Polar air masses into the mid-latitudes is far more likely for late November through the first half of December. If the Polar Vortex is weak, the potential for more sustained negative NAO/EPO weather patterns will be even more strongly supported. https://nynjpaweather.com/premium/2025/10/29/model-data-supports-weak-polar-vortex/