OKLAHOMA CITY (AP) — A sprawling storm system crossing the U.S. on Friday overturned semitrucks on highways and fanned wildfires in Texas, Oklahoma, Missouri and Kansas, prompting evacuation warnings in some communities. Tornado threats loomed for the Mississippi Valley into the night and the Deep South on Saturday. The National Weather Service predicted extreme weather across a vast swath of the country that is home to more than 100 million people. Powerful winds gusting up to 80 mph (130 kph) were forecast from the Canadian border to Texas. An approaching wildfire fueled by dry grasses and spread by strong winds prompted emergency officials to urge residents to evacuate Leedey, Oklahoma, a town of about 400 people. Meanwhile the Oklahoma State Patrol said on the social platform X that dusty winds toppled several tractor-trailers. “This is terrible out here,” Charles Daniel, a truck driver hauling a 48-foot trailer along Interstate 40 in western Oklahoma, said of the high winds whipping up dust. “There’s a lot of sand and dirt in the air. I’m not pushing it over 55 mph. I’m scared it will blow over if I do.” Forecasters said the severe storm threat would continue into the weekend with a high chance of tornadoes and damaging winds Saturday in Mississippi and Alabama. Heavy rain could bring flash flooding to some parts of the East Coast on Sunday. Experts say it's not unusual to see such weather extremes in March. “What’s unique about this one is its large size and intensity,” said Bill Bunting of the weather service's Storm Prediction Center in Norman, Oklahoma. “And so what that is doing is producing really substantial impacts over a very large area.” Tornadoes likely amid storm outbreak The Storm Prediction Center said fast-moving storms could spawn tornadoes and hail as large as baseballs Friday. But the greatest threat would come from straight-line winds near or exceeding hurricane force, with some gusts possibly reaching 100 mph (160 kph). A tornado watch was issued until 11 p.m. for central and eastern Missouri, including St. Louis, as well as parts of Illinois and Arkansas. Forecasters said areas also at risk included parts of Iowa, Kentucky, Tennessee and Mississippi. About 47 million people faced an enhanced to moderate severe storm threat from Madison, Wisconsin, to Birmingham, Alabama. Forecasters grew increasingly worried that intense thunderstorms farther south will likely bring an even greater tornado threat Saturday. The Storm Prediction Center said parts of Mississippi including Jackson and Hattiesburg and areas of Alabama including Birmingham and Tuscaloosa will be at a high risk of damaging winds and tornadoes. Severe storms and tornadoes are also possible across eastern Louisiana, western Georgia, central Tennessee and the western Florida Panhandle. “We have a lot of confidence that we most likely will have a tornado outbreak tomorrow,” Storm Prediction Center meteorologist Evan Bentley said in an online briefing Friday. Wildfires break out amid dry, gusty conditions Wildfires in the Southern Plains threatened to spread rapidly amid warm, dry weather and strong winds. A blaze in Roberts County, Texas, northeast of Amarillo, quickly blew up from less than a square mile (about 2 square kilometers) to an estimated 17.1 square miles (44 square kilometers), the Texas A&M University Forest Service said on X. About 60 miles (90 kilometers) to the south, another fire grew to about 3.9 square miles (10 square kilometers), but crews stopped its advance by the afternoon. The Oklahoma Department of Emergency Management activated its emergency operations center after several fast-moving fires that prompted evacuations of the town of Leedey in the western part of the state and in a rural area east of Norman. Police ordered mandatory evacuations for Mannford, a town of about 3,300 west of Tulsa. Jennifer Thompson, a National Weather Service meteorologist in Norman, described the fire conditions in the central and northern parts of the state as historic and highly anomalous. Evacuation notices were issued for an area that is home to about 30 people in Cowley County in southeastern Kansas as a wildfire neared homes. There were no reported injuries directly caused by fires, County Administrator Lucas Goff said, but low visibility due to smoky conditions led to car accidents. Roughly 120 miles (190 kilometers) of Interstate 70 in western Kansas shut down due to blowing dust and limited visibility, and roads in the state's east were closed amid wildfires and smoke. Officials urged people in some areas of central Missouri’s Camden County to evacuate due to wildfires, and the State Highway Patrol warned via social media that they were nearing homes and businesses. High winds also knocked out power to more than 220,000 homes and businesses in Texas, Oklahoma, Kansas and Missouri, according the website poweroutage.us. Blizzard warnings in Northern Plains The National Weather Service issued blizzard warnings for parts of far western Minnesota and far eastern South Dakota starting early Saturday. Snow accumulations of 3 to 6 inches (7.6 to 15.2 centimeters) were expected, with up to a foot (30 centimeters) possible. Winds gusting to 60 mph into Saturday afternoon were expected to cause whiteout conditions. Combined with a light glaze of ice that could fall in some places before the temperature drops, travel conditions in the area could be treacherous that day, the weather service said. The winter blast continued after snowfall of up to 3 feet (90 centimeters) blanketed the Sierra Nevada earlier in the week. ___ Bynum reported from Savannah, Georgia. AP journalists Susan Montoya Bryan in Albuquerque, New Mexico; Jim Vertuno in Austin, Texas; Steve Karnowski in Minneapolis; Kim Chandler in Montgomery, Alabama; Mike Hempen in Washington; Summer Ballentine in Columbia, Missouri; Jaimie Ding in Los Angeles; and Lisa Baumann in Bellingham, Washington, contributed. ...read more read less