Lack of rain in the Ohio River Valley and along the Upper Mississippi meant the Mississippi River (pictured) was nearing record low levels. Photo: Scott Olson / Getty Images via AFP
Powerful tornadoes and large hail may batter a large swath of the southern United States on Tuesday (US time), according to the National Weather Service (NWS) forecast.
The NWS warned the violent storms would hit parts of Mississippi, Louisiana, Arkansas and Tennessee, with heavy wind damage expected.
The NWS said the storms could produce powerful "long-track" tornadoes - twisters that stay on the ground far longer than normal tornadoes.
NWS meteorologist Andrew Orrison said the severe storms were being triggered by the collision of a cold front barrelling down from the Rocky Mountains and pushing across the central plains, with warmer, moist air pushing north from the Gulf of Mexico.
Tornadoes with gusts of 111 miles per hour (179km/h) and above could break out from the lower and middle Mississippi valley area into portions of the southeast, Orrison said.
There was even a chance for the most powerful twisters - with winds over 200 miles per hour (322km/h)- hitting the area, he said.
-Reuters