UPDATE: The National Weather Service forecasts 3 to 5 inches of snow in its updated winter weather advisory issued at 10:05 p.m. Thursday.
The weather service forecasts rain will change to light snow late Thursday and the snow intensity will increase Friday afternoon and night.
The National Weather Service has issued a winter weather advisory for snow and blowing snow and warns that travel will be difficult because of slippery roads and reduced visibility.
The advisory is in effect from late Thursday night into Saturday for Allegheny, Butler, Beaver and other counties in the Pittsburgh metropolitan region as well as Ohio and West Virginia.
About 4 to 6 inches of snow is expected to accumulate. Strong winds will cause snow to blow and drift.
Travel will be difficult because of reduced visibility and snow drifting over roads. Winds are expected to gust up to 40 mph and temperatures will fall into the upper 20s.