The National Weather Service in State College has issued a flash flood watch for Dauphin, Schuylkill, Lebanon and Lancaster counties.
A flash flood Watch is in effect until 10 p.m. Friday.
Farmlands, country roads and other low-lying spots were also susceptible to excessive runoff and potential flooding.
The area under the flood advisory includes southern Centre County, northeastern Blair County and northern Huntingdon County.
Drivers are advised to turn around when they encounter flooded roads as most flood deaths occur in vehicles, NWS said. "The heavy rains will likely trigger rockslides, mudslides and debris flows in steep terrain, especially in and around these areas".