A winter weather system moving through the U.S. is expected to wallop the East Coast this weekend with a mix of snow and freezing rain from the southern Appalachians to the Northeast — although it’s too early to say exactly which areas will get what kind of precipitation and how much.

Details on the storm’s path should firm up this week as the Pacific system moves through Colorado and New Mexico Thursday and into Texas and the Southeast before moving up the East Coast, said Tony Fracasso, a meteorologist with the National Weather Service’s Weather Prediction Center in College Park, Maryland.

“It’s still a few days away, so we’ll have to hash out the storm track — where the precipitation falls, and how long the cold air can stay,” he said Wednesday.