Central and eastern areas of the United States face multiple rounds of severe thunderstorms on Tuesday and Wednesday that are capable of producing strong tornadoes, damaging winds and hail as big as tennis balls, forecasters say.

On Monday tornadoes were reported in Nebraska and Oklahoma, and some residents in Arkansas, Illinois, Kansas, Missouri and Texas were under tornado warnings overnight, according to the National Weather Service. The extent of the damage was not immediately clear early Tuesday.

Bryan Smith, a lead forecaster at the Storm Prediction Center, said on Monday that tornadoes would still be a notable threat on Tuesday and Wednesday. “There’s the potential for a couple of strong tornadoes, centered on parts of southern Kentucky, western and middle Tennessee and into portions of northern Mississippi and Alabama,” he said.

The Storm Prediction Center has highlighted a Level 3 risk, on a scale of 1 to 5, for severe weather in those areas on Tuesday. A broader area from northeastern Louisiana to Illinois, the west of the Carolinas and into northern portions of Georgia, Alabama and Mississippi are under a Level 2 risk.

Storms already active on Tuesday morning in parts of Kentucky, northern Mississippi and portions of Arkansas and Louisiana were expected to continue and grow stronger as the day goes on.

Later on Tuesday, new thunderstorms are anticipated to form ahead of a cold front pushing through the region. Some of these will likely become supercells — powerful rotating storms that can produce tornadoes, large hail and damaging winds and can last for several hours. These may develop in parts of western and southern Kentucky, Tennessee, northern Mississippi and northern Alabama, according to the Storm Prediction Center.

Farther north, a separate area of storms is expected to form in parts of Missouri, Illinois and Indiana by Tuesday afternoon. These storms could also bring hail, strong winds and possibly a few tornadoes. Some areas could see clusters of storms forming and merging, which would increase the chances of severe weather.

The Weather Prediction Center has also warned that flash floods are likely, especially over portions of Indiana, Ohio, Kentucky, West Virginia and Tennessee, where the ground is already saturated from recent storms.

The severe weather threat has been in effect since last week, as a storm system brings warm, humid air from the Gulf of Mexico northward into the central United States and cooler, drier air moves in from the west. This clash of air masses, combined with strong winds higher up in the atmosphere, has created an unstable environment — perfect for severe thunderstorms to form.

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In Oklahoma, storms downed power lines, damaged at least 10 homes and destroyed a firehouse, the state’s Department of Emergency Management said on Monday. There was also flash flooding in parts of Oklahoma and Missouri late Monday.The threat of severe weather is expected to lessen on Wednesday as the storm moves toward the Atlantic. Still, a swath from eastern Virginia and eastern North Carolina, along the East Coast to the Florida and Georgia border, may still experience damaging wind gusts and possibly a tornado, before the storm system eventually clears.

Beyond the middle of the week, forecasters expect a calmer period of weather.

“A little bit of a more benign weather pattern will ensue across the lower 48,” Mr. Smith said.