A major winter storm is slated to wallop a large swath of the U.S., dumping heavy snow from Kansas to Maryland and bringing some regions what could be the heaviest snowfall in more than a decade.

An updated winter storm watch was issued by the National Weather Service on Saturday at 3:40 a.m. valid for Sunday between 7 a.m. and 10 p.m. for Western Chester, Eastern Chester, Western Montgomery,

The Lehigh Valley is now under a winter storm watch for up to 8 inches of snow Sunday, according to the National Weather Service.

While Northeastern Illinois was under a winter weather advisory with lake effect snow expected Monday, Washington County in downstate Illinois was under a shelter-in-place order after a major winter storm brought "life-threatening weather conditions" with snow,