The early-season polar vortex breakdown is expected to bring a sudden and significant drop in temperatures across the United States, particularly during Thanksgiving weekend. Regions such as the Northern Rockies, Montana, the Dakotas, the Midwest, and the Great Lakes may experience the season's first snowfall. While the cold snap may not be as severe as those occurring later in winter, the abrupt shift from the above-average temperatures seen earlier this fall could feel particularly jarring. The clash with El Niño's typically warmer and drier conditions may also lead to unpredictable weather patterns, including increased precipitation that could result in localized snowfall.