A strong, slow-moving storm system will move across Tennessee beginning tonight and lasting through Saturday, bringing periods of heavy rain, flooding, and a low but notable risk for strong thunderstorms. According to the National Weather Service, rain will begin Friday morning and continue for much of the next 36 hours, with the heaviest rainfall expected late Friday night through midday Saturday.

Forecasters say flooding is the primary concern with this system. The Weather Service offices in both Morristown and Nashville report that widespread totals of two to four inches of rain are possible, especially across southern Middle Tennessee and areas south of Interstate 40.

Flooding is most likely in low-lying locations, urban areas with poor drainage, and along small creeks and streams. While recent drought conditions may help reduce the likelihood of major river flooding, the National Weather Service cautions that rising water levels cannot be ruled out.

The severe weather threat remains limited, but not zero. The National Weather Service in Nashville places Middle Tennessee under a marginal risk—level one on a five-tier scale—for severe storms beginning as early as 4 a.m. Friday.

Forecasters note that a few storms could produce strong wind gusts capable of causing damage, and while tornadoes are not expected, they cannot be completely ruled out. In East Tennessee, the highest chance for stronger storms arrives late Friday night into early Saturday, where gusts up to 60 miles per hour are possible.

Wind will also be an issue outside of thunderstorms. A Wind Advisory is in effect for the East Tennessee mountains beginning at 7 p.m. Thursday and lasting through 1 p.m. Friday, with sustained south winds of 15 to 30 miles per hour and gusts up to 55 miles per hour. The Weather Service warns that unsecured outdoor objects may be blown around and that high-profile vehicles could experience difficult driving conditions.

Overall confidence is high that widespread rain and at least some flooding will occur across the region. However, meteorologists say confidence is lower regarding exactly where the heaviest rainfall axis will set up and whether severe storms will fully develop or stay farther south and west of the area. Even so, the National Weather Service urges residents across Middle and East Tennessee to remain alert, avoid flooded roadways, and have multiple ways to receive weather warnings throughout Friday and Saturday.