Bracing for Round 3: 53 million under severe weather threat

(CNN) -- It's already killed scores of people in a massive tornado that devastated the town of Moore, Oklahoma. And it's not over yet.

The storm system behind Monday's twister and several on Sunday was threatening a large swath of the United States on Tuesday, putting 73 million people at risk of severe weather.

"We could have a Round 3," CNN Meteorologist Ivan Cabrera said. "Hopefully, it won't be as bad."

Further tornadoes were not expected in devastated Moore, Oklahoma. But a severe thunderstorm watch was issued in central and southeastern Oklahoma until 7 p.m. (8 p.m. ET), including Oklahoma City and Moore. Large hail and wind damage are possible, HLN Meteorologist Bob Van Dillen said.

A flash-flood warning was in effect Tuesday afternoon in McAlester, Oklahoma, and surrounding areas.

A tornado watch was in effect for north-central and northeastern Texas, including Dallas-Fort Worth, and southern Oklahoma until 7 pm as well (8 p.m. ET), CNN Meteorologist Sean Morris said.

"Tornadoes, some of them strong, will also be possible into southwestern Arkansas and northeastern Louisiana later today. Storms will also be capable of producing large, destructive hail, heavy rain, flash flooding and gusty winds," Morris said. "They will also be accompanied by dangerous cloud-to-ground lightning."

Rainstorms pushed through the Dallas area on Tuesday afternoon. A ground stop at Dallas-Fort Worth International Airport was later lifted.

Will Rogers International Airport in Oklahoma City said bad weather continued to affect flights midday Tuesday.

About 10.5 million people live in the area under moderate risk of severe weather, according to the National Weather Service.

A large swath of the country, stretching from part of Texas into bits of the Great Lakes and Northeast, is under slight risk of severe weather as well. The weather service says 62.3 million people live in the region.

The storms weren't restricted to the Great Plains and Midwest.

The National Weather Service said weather spotters on Tuesday afternoon reported a tornado near Copake, New York, near the Massachusetts border.