By Kevin Murphy
April 3 (Reuters) - The central United States braced for strong thunderstorms, heavy rain and possible tornadoes on Thursday from an unstable weather system that has already produced a twister and flooding in Missouri.
"There is certainly the potential for some violent storms," said Jayson Gosselin, a meteorologist for the National Weather Service in St. Louis.
Some homes were damaged and large trees uprooted in the St. Louis suburb of University City when an EF-1 tornado, packing winds of about 100 miles (160 km) per hour, struck shortly before 6 a.m., Gosselin said. The EF-1 rating is the weakest on the five-step scale of tornado strength.
No injuries were reported. The storm also produced heavy rain, causing streams to overflow, flooding some streets, Gosselin said.
In Johnson County, Missouri, about 50 miles (80 km) east of Kansas City, up to 5 inches (13 cm) of rain on Wednesday and early Thursday morning flooded railroad tracks and suspended Amtrak rail service through the area, officials said.
"I have been here 13 years and never has Amtrak been shut down because of flooding," said Gloria Michalski, director of Johnson County emergency services.
One major state highway, along with many other roads, was closed because of flooding for part of Thursday morning, Michalski said. At least two motorists required water rescues, she said.
Severe thunderstorms were expected to return in Missouri as well as in Arkansas and western Tennessee by Thursday evening, said Andy Bailey, meteorologist for the National Weather Service for the Kansas City, Missouri, region.
Moisture ahead of a cold front will produce super cells and upper air rotation, leading to strong storms, he said.
"It could have all the classic severe weather impacts - hail, high winds and a potential tornado," Bailey said. Central Missouri faces the highest likelihood of tornadoes, he said.
Parts of Louisiana, Kentucky, Illinois, Indiana and Ohio were also at risk of thunderstorms on Thursday, according to the National Weather Service. (Reporting By Kevin Murphy; Editing by Scott Malone and Gunna Dickson)