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In Rolla, Judy Welch, 57, said she called her husband after the storm passed to tell him their home was gone but that she was able account for their 13 dogs, including nine German shepherds. A number of cats that had scurried away hadn’t returned.

“I kept praying to God. The house shook so bad, the windows were bowing and then going back to normal,” Ms. Welch said.

Overnight storms damaged buildings and boat docks around Table Rock Lake in southern Missouri, leaving several boats adrift after wrenching them from their moorings. Several homes and businesses were damaged in the St. Louis County town of Sunset Hills, and a church was damaged in nearby Fenton.

In Illinois, a tornado at Petersburg, northwest of Springfield, knocked a tree onto a car, injuring one person. The injury wasn’t considered life-threatening.

Several flights to and from the Northwest Arkansas Regional Airport at Highfill were delayed or canceled Friday morning until crews could clear debris littering the runway.

The region has been bracing for severe weather for much of the week. Gulf moisture riding southerly winds pushed temperatures into the upper 60s and 70s on Thursday — ahead of a cold front expected to drop temperatures into the teens by Saturday morning.

“This storm system has been showing significant signs that it could develop,” said Chris Buonanno, a meteorologist at the National Weather Service in North Little Rock who was monitoring the storms as they moved deeper into Arkansas. “Conditions are favorable for seeing a severe outbreak.

“In the winter you don’t always have the instability” that would allow tornadoes to develop, Mr. Buonanno said. “This time, we have the instability.”

While the spring brings most of the region’s tornadoes, violent weather at this time of year isn’t unheard of. A February 2008 outbreak killed 31 in Tennessee and 14 in Arkansas, and in January 1999 two separate outbreaks across the South killed 18, including seven in Arkansas.

A year ago, there were no tornado deaths nationwide between Oct. 9, 2009, and March 10, 2010.

Buonanno said there appears to be some association between changes in South Pacific Ocean temperatures and changes in the flow of the jet stream in the central part of the United States, causing an uptick in violent weather.

Friday’s tornado fatalities are the first in the nation since Sept. 16, when a woman hit a falling tree while driving in Queens, N.Y., and a man was killed in his home at Belleville, W.Va. The deaths push this year’s count to 42 nationally, and to 5 in Arkansas. The deaths in Missouri were its first of the year.

Associated Press writers Margaret Stafford in Kansas City, Mo., and Kelly P. Kissel in Little Rock; and AP photo stringer April Brown in Cincinnati, Ark., contributed to this report.