Tornado warnings in Oklahoma, including oil hub Cushing

(REUTERS) - Tornado warnings urging residents to seek cover immediately in parts of northern Oklahoma were issued on Thursday, raising concern about another powerful storm after a twister in the area killed 24 people and injured more than 300 last week.

One of the tornado warnings included Cushing, Oklahoma, which is a critical hub for the United States (US) oil markets and home to over 65 million barrels of crude oil storage.

The warnings were put in effect for parts of several counties north of Oklahoma City, according to Mr Corey Mead, a meteorologist at the National Weather Service's Storm Prediction Center.

Oklahoma City and Moore, Oklahoma, which were struck by the fatal EF5 tornado on May 20, were not immediately part of Thursday's warnings but were within a severe weather forecast area extending over a wide area of the Plains states and Midwest.

"It looks like it is going to be an active severe weather day," Mr Mead said. "The Oklahoma City area is definitely at risk of tornadoes."

Severe weather is forecast for a large area of the central US extending from north of Dallas, Texas all the way to near the Canadian border in Wisconsin, according to a National Weather Service map.

Oklahoma City's KFOR television showed video of a dark cloud a few miles from Cushing, which is the delivery point for the US oil futures contract.

Oil traders were closely watching the storm for any sign of damage to infrastructure.

Major centers of population potentially in the path of the storms include St. Louis; Little Rock, Arkansas; and near the Chicago and Milwaukee areas.

The tornado on May 20 that struck Moore, a suburb of Oklahoma City, damaged some 13,000 homes.

Residents of Moore were watching the storms warily.

Ms Kristen Pupek, whose neighborhood was slightly damaged, said she was going about her life on Thursday.

"The way I see it, we can't all just sit around and worry about when the next tornado is going to hit," she said.

Moore has been hit by four damaging tornadoes in the last 15 years, including two rated at the strongest EF5 level.