From the US National Weather Service
A Flood Watch has been issued through 10 PM for much of southwest Pennsylvania. Heavy rainfall from thunderstorms may create flash flooding of small streams, roads, and poor drainage areas through this evening. Be ready to take action if Flash Flood Warnings are issued!
Rain could begin as early as 4 pm in Indiana County, but the greatest chance for rain is 9 pm (81%). Rain is also forecasted for the early Tuesday morning hours.