Meteorologists warn that “an outbreak of severe thunderstorms and tornadoes” could imminently impact the Ohio, Tennessee and Mississippi valleys.

The National Weather Service issued a severe weather outlook on Wednesday afternoon, warning that a dangerous storm system capable of producing hurricane-force winds, several tornadoes and sizeable hail was trending across the central United States.

The National Weather Service issued tornado watches for parts of ten states: Louisiana, Iowa, Mississippi, Illinois, Arkansas, Tennessee, Missouri, Kentucky, Alabama and Indiana.

Meteorologists said the outbreak is expected to occur this afternoon and last into tonight. The areas most at risk for “long-tracked tornadoes” are western Tennessee, northern Mississippi and eastern Arkansas.

The news comes on one of the busiest travel days of the year. AAA projects a record 100.5 million Americans would be traveling in the 12-day period that began this morning, more than 90 percent of them driving.

The Weather Channel uses its own index, called TOR:CON, to calculate the risk of a tornado occurring at any given time in a specified area. Initially, meteorologists said the areas most at risk only had a 50 percent chance of seeing a tornado, but that rose significantly Wednesday.

Meteorologists now warn northern Mississippi, northern Alabama and western Tennessee have an 80 percent chance of a tornado occurring within 50 miles. The channel said there was also a 70 percent chance of a tornado within 50 miles of eastern Arkansas, and at least a 50 percent chance of a tornado in a widespread region from the Florida panhandle to Kentucky, North Carolina and Missouri.

High winds were already being blamed for at least one death.

Arkansas television station KTHV reported an 18-year-old girl was killed after high winds uprooted a tree and sent it crashing through a home in Pope County.