Heavy rains threaten river flooding in central U.S

(Reuters) - A swath of heavy rainfall and possible severe weather moving across the central United States on Thursday is threatening to flood several areas where rivers are already swollen from previous rains, the National Weather Service said.

The storms, which may include high winds and possibly hail and tornadoes, could overflow many rivers, including parts of the Ohio and the Mississippi, that are already running higher than average, the weather service said.

"It won't take much added rain to cause flooding," said Bob Oravec, a meteorologist at the National Weather Service's Weather Prediction Center in College Park, Maryland.

Flood watches have been issued in Northern Texas, eastern Oklahoma, northern Arkansas and through the lower Ohio River Valley, which includes parts of Missouri, Illinois, Indiana and Kentucky, Oravec said.

Rainfall in those areas in the past two weeks has been running two to three times above average, he said.

On Wednesday, six tornadoes touched down in areas straddling northern Texas and southern Oklahoma, he added.

The Oklahoma tornadoes killed two people, one in Tulsa and the other in Bokchito, about 150 miles southeast of Oklahoma City, the state's Office of the Chief Medical Examiner said. Another 22 people were injured, authorities said.

The severe weather, which included up to 6 inches (15 cm) of rain in some parts of Oklahoma, prompted Governor Kevin Stitt on Wednesday to declare a state of emergency for 52 counties.

"The storm system has delivered tornadoes, high winds, and widespread rain since early Tuesday, with damage reported to homes, businesses, outbuildings, trees and power poles," the state's Department of Emergency Management reported.

(Reporting by Peter Szekely in New York; Editing by James Dalgleish)