OKLAHOMA CITY (Reuters) - The death toll rose to six from a tornado that ripped through an Oklahoma town during a weekend outbreak of dozens of twisters across the Great Plains, officials said on Monday.
While storms were still breaking out from the Midwest into the Appalachian Mountains region, the threat of more tornadoes had declined, meteorologists said.
The sixth Oklahoma victim died after being flown to a Texas hospital for treatment, following injuries received when the tornado struck the northwestern Oklahoma town of Woodward early on Sunday, said Amy Elliott, spokeswoman for the Oklahoma Medical Examiner's Office.
Three young girls and two other adults were also killed in the Woodward tornado, Elliott said.
More than 120 tornadoes were reported in the outbreak on Saturday and Sunday, which mainly hit less-populated areas of Kansas and Oklahoma, said Henry Margusity, an AccuWeather.com senior meteorologist.
The storms skipped through what is often called "Tornado Alley" in the U.S. Central and Southern Plains, but mostly struck rural areas, sparing the region from worse damage.
Twisters just missed the most densely populated areas of Wichita, Kansas, Margusity said.
Greg Carbin, warning coordination meteorologist for the National Storm Prediction Center in Norman, Oklahoma, said that, after duplicate reports are eliminated, 75 tornadoes "is probably a reasonable estimate" for the total.
On Monday, the front was moving east and north toward Canada, stretching from Texas to the Upper Peninsula of Michigan with a much-diminished threat from tornadoes, Carbin said.
"There is still a chance along this line of storms that you might see some increase in thunderstorm activity as the system moves through the Appalachians, but overall the potential is much reduced from what it was over the weekend," Carbin said.
The twister caught many unaware in Woodward, a town of 12,000 people, when storm sirens failed to sound after lightning apparently disabled the warning system, Mayor Roscoe Hill said on Sunday.
Twenty-nine people were treated at Woodward Regional Hospital, Chief Executive Officer Dave Wallace said.
The Woodward tornado was given an EF-3 preliminary rating on Monday, said John Pike, a meteorologist with the National Weather Service forecast office in Norman, Oklahoma. EF-3 tornadoes generate speeds of 136 to 165 miles per hour.
A tornado that struck Woodward in April 1947 still ranks as the deadliest in Oklahoma history, with 116 people killed, according to the National Weather Service.
The storms left Great Plains states residents cleaning up from damage that left thousands without power in Kansas, hit an aircraft fuselage production facility, and damaged up to 90 percent of homes and buildings in tiny Thurman, Iowa, population 250. Only minor injuries were reported in Thurman.
The storm damaged a hangar at McConnell Air Force Base in Wichita and destroyed several nearby homes, leaving thousands without power, but it missed downtown and heavily populated neighborhoods, authorities said.
The Wichita tornado, part of a "super cell" storm that produced tornadoes in Kansas for about two hours on Saturday night, has received a preliminary EF-3 rating, said Robb Lawson, a National Weather Service meteorologist in Wichita.
The tornado damaged the roof and knocked out power to a Spirit Aerosystems production facility in Wichita that manufactures fuselages for Boeing's 7-series airplanes, forcing it to suspend operations at least through Tuesday.
The company said it expects production to be disrupted in the short term, affecting delivery, though production equipment appeared to be largely unaffected.
The strongest tornado in Kansas from the outbreak was an EF-4 near Kanopolis Lake about 70 miles north of Wichita that demolished a house and caused extensive tree damage, Lawson said. A family had fled the house and were not injured, he said.
The U.S. tornado season started early this year, with twisters already blamed for 63 deaths in 2012 in the Midwest and South, raising concerns that this year would be a repeat of 2011, the deadliest tornado year in nearly a century.
Some 550 people died in tornadoes last year, including 316 killed in an April outbreak in five Southern states, and 161 people in Joplin, Missouri, the following month.
Reporting by Steve Olafson, Mary Wisniewski, Corrie MacLaggan, Kevin Murphy and David Bailey; Editing by Greg McCune and Eric Walsh