High winds are whipping up wildfires in Texas on Friday as a roiling low pressure system moves east and threatens to land powerful tornadoes in the Plains and beyond.

An estimated 138 million people are at risk of severe storms in the nation’s midsection throughout the weekend. Strong nighttime tornadoes at EF2 on the tornado strength scale, defined by sustained winds of 113 to 157 mph, are possible from southern Iowa to Jackson, Mississippi.

The worst of the system is also threatening damaging winds and hail Friday into Saturday.

The storm on Friday is churning in Oklahoma, Kansas, Nebraska, and beyond, and is expected to produce more forceful winds through at least Saturday morning.

The biggest cities at risk for tornadoes include St. Louis and Memphis, they said. Widespread gusts of 60 to 100 mph and large hail are forecast.

Electricity outages are affecting 96,000 utility customers in Texas, 73,000 in Oklahoma, 23,000 in Kansas, and 21,000 in Missouri on Friday evening, according to utility tracker PowerOutage.us

Strong winds and wildfires in Texas

The southern end of the front is stirring up gusts as strong as 62 mph in parts of northern Texas, according to National Weather Service data.

Winds in Texas and Oklahoma on Friday were the source of multiple vehicle accidents, according to social media images and the National Weather Service office in Norman, Oklahoma.

Potter County Fire-Rescue reported four roads were restricted or closed after separate incidents in which big-rigs had “flipped.” The county in the Texas Panhandle includes the northern half of Amarillo.

“Visibility is poor at best and zero in places,” the agency said on social media. “If you don’t have to be out, please stay where you are.”

The largest of the state’s six active wildfires, the Windmill Fire in Roberts County, grew from 500 to 9,000 acres in the span of a few hours, according to Texas A&M Forest Service. The blaze was 0% contained Friday afternoon.

The Rest Area Fire in Gray County is marching across 1,000 acres so far, with 0% containment reported, according to the service.

Texas A&M Forest Service said on Thursday conditions may be right for a Southern Great Plains Wildfire Outbreak, a dangerous weather formula based in part on low humidity and gusty wind, though such an outbreak was not officially declared by Friday afternoon.

Gov. Greg Abbott said more than 750 emergency responders were at the ready as he ordered the Texas Division of Emergency Management to activate and prepare emergency response resources, according to a statement.

Tornado risk in Missouri, Gulf Coast states, Tennessee Valley

Meanwhile, Missouri Gov. Mike Kehoe declared a state of emergency on Friday as the state prepared for the front’s unstable air overnight, including thunderstorms and possible tornadoes.

In a statement, he warned Missourians the front will move fast and intensify. They should plan to stay off roads, remain indoors, and figure out beforehand where they can go if a tornado touches down.

“I urge all Missourians to stay alert, monitor weather forecasts, and follow official warnings,” he said.

The declaration will allow state resources to reach local governments quicker, Kehoe’s office said. He also said he’s activating Missouri’s Emergency Operations Center on Friday afternoon.

A tornado outbreak across the central Gulf Coast states into the Tennessee Valley was likely late Saturday. Significant tornadoes were possible in eastern Louisiana, in Mississippi, and in Alabama, they said.

Jackson, Mississippi, and Birmingham, Alabama, were also at high risk for tornadoes.

Weather system to shift east

The low pressure system is affecting the southern and northern reaches of the nation’s midsection as it pushes eastward, promising upheaval into the eastern U.S. through the end of the weekend.

As it moves into the Eastern Seaboard on Sunday, the tornado threat will shift to Virginia and Carolinas.

On the northern side of the front, including the upper Midwest and the northern Plains, blizzard conditions were forecast for the weekend, with 8 inches of snow possible in some regions.

The new week was expected to bring even more winter storm action when at least two more low pressure systems march eastward, the National Weather Service Weather Prediction Center said.

The first of the two would likely form a solid, counterclockwise winter storm, a process the weather service calls cyclogenesis, it said. It will likely bring snow to the interior, including the Midwest and Great Lakes, with a second storm likely to bring a fresh wave of snow, rain and thunderstorms to a stretch of the nation from the Rocky Mountains to the Upper Midwest mid- to late-week.

The roiling atmosphere is shaking up the daily routines of millions as the calendar looks forward to the first astronomical day of spring on Thursday.

Thunderstorms and tornadoes are a product of a collision of cold and warm air, so the tumult is on time. Spring will make a move Monday and possibly Tuesday in the Central and Eastern United States as warmer days are expected, if only briefly, federal forecasters said. The week’s winter storms were forecast to fight back on Tuesday and possibly Thursday in the same regions, they said.