The watch area, which will be in effect from 8 p.m. tonight until 8 p.m. Friday, includes Sullivan, Hawkins and Washington counties and surrounding areas in Tennessee, and Scott, Lee and Wise counties, among others, in Virginia.
Forecasters said they expect a stationary front to bring “abundant” moisture, including heavy rainfall, to the Southern Appalachian region.
Between three and five inches of rain is expected to fall across the region over the three-day period.
Locally higher amounts of rainfall are also being predicted.The locally heavy rains could cause flash flooding of small creeks and streams, while the prolonged precipitation could impact larger streams and rivers, causing them to rise and flood.
Forecasters are warning area residents to keep an eye out for rising water and water covering roads.
Authorities warn motorists not to drive through standing water.
The showers and thunderstorms are expected to become more frequent tonight, with periods of heavy rainfall possible throughout Thursday and Friday. The rain is expected to subside by late Friday.