Severe thunderstorms, heavy rain, and flooding are possible in the region starting Monday evening and continuing through Tuesday night, according to the National Weather Service in Morristown.
Isolated tornadoes are possible, mainly across the Cumberland Plateau and southern half of the Tennessee Valley, the Weather Service said. A tornado watch remains in effect until 8 p.m. Monday for southwestern Virginia and East Tennessee. The watch includes Anderson, Blount, Campbell, Knox, Loudon, Morgan, Roane, and Scott counties, among others.
The flood watch is in effect from 8 p.m. today until 8 a.m. Tuesday.
The National Weather Service said its main concerns are the isolated tornadoes, widespread damaging winds that could cause power outages due to fallen trees and power lines, and heavy rainfall producing flash flooding. Large hail is also possible.
The forecast near Oak Ridge calls for a 60 percent chance of heavy rain this afternoon, with a 100 percent chance of severe thunderstorms tonight.
The chance of severe thunderstorms falls to 60 percent on Tuesday, and there is a 90 percent chance of heavy rain on Tuesday night.
Wind gusts this afternoon and tonight could be as high as 25 mph, forecasters said.
Forecasters said a slow-moving low-pressure system will affect the region through Wednesday, meaning there is a continued chance of severe thunderstorms again on Tuesday afternoon and evening, and heavy rainfall could linger until well into Wednesday.
Across a wider region, the National Weather Service said severe thunderstorms are expected over parts of the lower Mississippi and Tennessee Valleys this afternoon and tonight. Affected locations include northern and central Mississippi, northwest Alabama, western and middle Tennessee, and extreme northeast Louisiana.
The hazards include several tornadoes; a few intense widespread large hail, some baseball size; and scattered damaging winds, forecasters said.
“A severe weather outbreak is forecast today into tonight from parts of the lower Mississippi Valley into the Tennessee Valley and central Gulf Coast states,” the NWS said. “Numerous tornadoes are expected, some of which could be intense. Very large hail and damaging straight line winds are also likely.”
More information will be added as it becomes available.