The outlook says an unstable air mass is over the region and an approaching cold front will cause thunderstorms to form over Middle Tennessee this afternoon.
Those storms are expected to move into Northeast Tennessee and Southwest Virginia this evening.
According to the Weather Service's outlook, the main threat from the storms is large hail, and an isolated tornado is possible.
The cold front will end the spring weather area resident have been enjoying so far this week.
Temperatures should be around the freezing point Wednesday night. Thursday's and Friday's lows are forecast in the mid to low 20s.
Click here for the most current information and weather radar from the Morristown Bureau of the National Weather Service.