The northern edge of the Appalachian Plateau begins in the Catskills, runs through western New York, crosses the northwest tip of Pennsylvania and then turns southwestward just east of Metro Cleveland. The counties that sit atop this highland are known for their prodigious lake-effect snowfalls, which generally occur in the fall and early winter.
As cold, north winds blow across Lakes Erie and Ontario, they become humidified. Forced to rise by the Appalachian front, this moisture-laden air cools below its dewpoint, dropping heavy amounts of snow on the border zone; snowfalls of 2 to 3 feet are not uncommon. This snow machine generally shuts down by mid December as the Great Lakes freeze over. However, a mild early winter across the Northeast and Upper Midwest have kept the Lakes open and, as an Arctic Front passed through yesterday, heavy, lake-effect snows followed. As our climate warms, this pattern will likely continue and the Snowbelt will earn its name from October through March.
