State College, Pa. — AccuWeather.com — Heavy snow will spread across the Lower Midwest and into the Northeast and mid-Atlantic this week in a two-part system that could give Philadelphia its first significant snowfall.

The first and weaker system will spread lighter snow from the central Plains to the Ohio River Valley tonight. Some snow will also streak east reaching the mid-Atlantic coast, including in the Philadelphia area, by daybreak. A bit of snow will continue into Tuesday along this corridor.

A heavier round of snow will spread from the Ohio River Valley into the Northeast and mid-Atlantic on Tuesday night into Wednesday.

A swath of 3 to 6 inches of snow will be delivered to central Illinois, central Indiana and a large part of Ohio.

As the snow ramps up and pushes into the mid-Atlantic on Tuesday night into Wednesday, 3 to 6 inches of snow will fall over a large part of Pennsylvania, upstate New York and much of New England. Six to twelve inches is expected to fall from northeastern Pennsylvania to western and central Massachusetts and southern New Hampshire.

Philadelphia will have 1 to 3 inches of snow before mixing in with or changing over to sleet and freezing rain. The heaviest snow will fall on Tuesday night before sleet and freezing rain start mixing into the evening. The northwestern suburbs will likely have more snow before changing over to a mix, which will cause messy road conditions for the Wednesday morning commute.

Only 1.1 inches of snow has fallen there since Dec. 1, 2008, which will make the upcoming system the first significant snow in the city for the year.

Roads in New York City will also be a mess on Wednesday morning as heavy snow will fall on Tuesday night, without any mixing. Two to four inches of snow is expected to fall, as some sleet and freezing rain will start to mix in during the day on Wednesday.

Boston will have 4 to 8 inches of snow on Tuesday night through Wednesday without any mixing expected as enough cold air will remain in place. The heaviest snow will fall on Wednesday.

Blast is Boston's Online Magazine