A sprawling, late-season winter storm was forecast to dump a mixed bag of precipitation across a wide stretch of the United States through Saturday, raising concerns about hazardous driving conditions and scattered power failures, meteorologists said on Friday.About 70 million people from Arizona to Tennessee and up through Maine were under some sort of winter weather alert, according to the National Weather Service. The interior Northeast was expected to get the worst of the storm.“It’s a pretty impressive storm system,” Matthew Clay, a meteorologist with the Weather Service in Burlington, Vt., said on Friday. “For interior New England, we’re expecting pretty much a widespread seven to 14 inches of snow.”Light snow will fall from the Southern Plains to Wisconsin on Friday on the backside of a cold front crossing the central United States, the Weather Service said. That front will strengthen, leading to the development of a significant winter storm across the Tennessee and Ohio Valleys through the eastern part of the country this weekend.“Snow rates of greater than one inch per hour combined with gusty winds will produce blowing and drifting snow,” the Weather Prediction Center said on Friday. “This will severely reduce visibility and make for difficult to hazardous driving conditions.”The National Weather Service in Flagstaff, Ariz., also warned people that gusty northeast winds would continue to midday on Friday. “Some roads may be snow-covered and icy this morning, especially east of Flagstaff,” the service cautioned. “Be careful out there.” Four to six inches had fallen in the area as of Friday morning.Areas across North Texas and southern Oklahoma were expected to receive a few inches of snow through Friday morning. Similar snow totals were expected for areas around eastern Tennessee through Saturday evening, and as much as five inches of snow could fall across portions of Kentucky.Parts of Kansas received as much as five inches of snow, the Weather Service said. Warnings about the weather prompted Kansas City, Mo., to close its public schools on Friday.Jim Stefkovich, a meteorologist with Alabama Emergency Management Agency, said that a winter storm warning was issued for northern Alabama from Friday at 9 p.m. to 9 a.m. Saturday.High winds would “produce dangerous wind chill readings in the single digits overnight and into Saturday morning,” he said.“You don’t want to be outside in these conditions,” he said, adding, “it is best to avoid all travel from tonight into Saturday.”The Northeast was most likely to see the brunt of snow accumulations, forecasters said. Areas around Albany, N.Y., could see up to four inches of snow. Towns farther north could see as much as 12 inches. In Vermont, between seven and 14 inches was forecast for much of the state.“We’re expecting very difficult travel conditions during the day on Saturday and into Saturday night,” Mr. Clay said of the upper Northeast. “We discourage travel, unless you need to do it, and also be prepared for isolated power outages as some of the snow we’re experiencing will be wet.”One meteorologist said that it was not unusual to see a late winter storm system in March.“March is one of those months where there are some years that we see plenty of snow and there are some years, we see next to nothing,” Torry Gaucher, a meteorologist with the National Weather Service in Norton, Mass., said on Friday.“Technically, we’re in meteorological spring,” he added. “Calender-wise, we have another month before spring really arrives.”Cities closer to the coast, including New York City and Boston, were expected to see a mix of rain and snow, with significantly less accumulation. The Boston area could see at least an inch of snow Saturday and Sunday morning.This weekend’s storm follows a pattern of active winter weather throughout much of the South and East Coast this year.In early January, back-to-back storms created perilous driving conditions in the Mid-Atlantic and Northeast, including one weather system that stranded hundreds of drivers on Interstate 95 in Virginia for more than 24 hours. The storm trapped truckers, students, families and every stripe of commuter, including Senator Tim Kaine.In mid-January, another storm slammed the South, killing at least two people and leaving thousands without power before moving north and dropping heavy snow over parts of the Northeast and Canada. Another January storm swept through the East Coast, prompting thousands of flight cancellations and pushing the governors of New York and New Jersey to declare states of emergency. That storm dropped more than 30 inches of snow in parts of Massachusetts.In early February, another storm slammed parts of Texas with snow and sleet, disrupting travel and power. Gov. Greg Abbott called it “one of the most significant icing events that we’ve had in the state of Texas in at least several decades.” Yet another storm followed in late February, lashing the Northeast with a mix of snow, sleet and rain.Johnny Diaz contributed reporting.