Big Weekend Storm Coming, But Path of Heavy Snow Uncertain

(Dec. 7) -- With a deep snowpack already in place in the Northwest and northern Rockies, snow accumulating by the foot near the Great Lakes and cold air as far south as Florida, winter has started quickly this year. A potent storm this weekend will add to winter's early fury.

The path of the storm's heavy snowfall is far from certain, but the extent of the cold to follow will match or exceed the current cold snap in the eastern half of the country.

Heavy snow -- potentially more than a foot -- is more likely along a corridor from the Midwest to interior parts of the East than along the Eastern Seaboard, but uncertainty related to the storm track means the potential for a disruptive snowstorm exists from the Plains to the East Coast.

The storm will strengthen in the middle of the country by Saturday night and then move northeastward Sunday and Monday, and it will have all the ingredients needed for a heavy snowfall on its northern and western sides, including a strong low-pressure system, plenty of moisture and access to cold air.

But where will the storm track?

A more western track, from Missouri northeastward into Ontario and Quebec, would produce heavy snow in the central Plains and upper Midwest, including Chicago, while rain and a blast of unseasonable warmth streams into areas farther to the east. Temperatures could soar into the 50s in the major cities along the East Coast, temporarily erasing the early winter cold.

The easternmost possible track would result in a more classic nor'easter, with an intensifying storm riding northward from the mid-Atlantic region to the Northeast. With that track, heavy snow or a mixture of rain and snow would fall from Washington, D.C., to Boston, with the most intense snowfall occurring from interior parts of the mid-Atlantic to interior New England.

Neither the western or eastern extreme is as likely a path as somewhere in between, with heavy snow from the central Plains and Ohio Valley to western New York and interior New England. Mainly rain would fall along the Eastern Seaboard, and Chicago would be on the boundary between light snow and more intense snow not far to the east.

While the snow forecast is uncertain, the arrival of a new blast of unseasonably cold air from Canada isn't.

A northwesterly wind following the storm will result in a new blast of bitter cold from the latter part of the weekend into next week. The cold will be as intense -- or perhaps more intense -- than the current cold spell and would extend from the Plains eastward to the Atlantic coast and southward to the Gulf Coast.

The combination of snow and wind will result in wind-chill temperatures in the single digits in much of the East, snow will accumulate by the foot in the favored locations downwind of the Great Lakes, and snow showers might occur as far south as the mountains of eastern Tennessee and northern Georgia.