After the the Northeast was hammered by frigid rain or snow on Thanksgiving, a bitter blast of Arctic air is set to envelop much of the country by the time travelers head home this weekend. In New York City,

The National Weather Service warned that severe winter conditions—triggered by an Arctic blast—could persist over the weekend into Monday.

Lake-effect snow happens when cold air passes over unfrozen and relatively warm waters - in this case in the Great Lakes - causing the air to rise and form clouds that produce snow. Up to 8in (20cm) could fall in some places, the NWS says.

The coldest air of the season so far is set to arrive later this week for the Northern Plains-Midwest and into parts of the South and East. The threat for heavy lake effect snow across the Great Lakes continues to increase as well.

As if heavy snow and rain from potent storm systems sweeping across the U.S. wasn’t enough to cause travel delays and dampen the holiday spirit, the coldest air of the season will start to infiltrate the country starting on Thanksgiving and could last into at least the start of December.

While the Northeast gets hammered by frigid rain or snow this Thanksgiving, much of the US can be thankful for calm, dry weather. But a bitter blast of Arctic air will envelop much of the country by the time travelers head home this weekend.

Rain is falling across the northeast on Thursday morning, setting up what's bound to be a soggy Thanksgiving for dozens of states. The forecast for both the New York and Philadelphia's Thanksgiving parades are on track for periods of rain and drizzle with temperatures in the 40s and a chilly breeze at 10-25 mph.