The eastbound lanes between Reading and Morgantown were also closed for a time to allow cars to get out of the massive traffic backup on the other side and head back to the Morgantown exit, LancasterOnline reported.
Renee Colborn, a spokeswoman for the Pennsylvania Turnpike Commission, said the problems began when several vehicles rear-ended a snowplow shortly after 9 a.m. A state trooper said there were as many as 10 multi-vehicle crashes.
The turnpike did not reopen completely until after 5 p.m.
Police reported numerous injuries from the crashes.
Eric Horst, head of the weather center at Millersville University, said an unexpectedly heavy snowfall, 1 to 2 inches, hit the area starting at around 2 a.m. Storms usually weaken as they move eastward into Lancaster County but this one became stronger, he told LancasterOnline.