Freakish weather rumbled across the Southern Plains and Midwest yesterday as roughly 6 million people dodged tornadoes, floods, pounding hail and 70-mph wind gusts in Texas, Oklahoma, Kansas and Missouri.

An extraordinarily late May snowstorm dumped more than a foot in parts of Colorado’s Front Range after a rock-slide Tuesday closed Interstate 70 in both directions near Glenwood Springs with truck-sized boulders that crashed down from steep canyon walls.

Scientists say such rock slides are usually caused by saturated soils and a freeze-thaw cycle expanding fissures in rock and causing boulders to break and fall.

Since Monday, more than 30 tornadoes had touched down, mostly in the Southern Plains, while up to 8 inches of rain swamped parts of eastern Oklahoma and southern Kansas, pushing the Arkansas River to what could be its second-highest flood crest on record and prompting evacuation orders from Tulsa to Muskogee, Okla.

Remarkably, only one death was attributed to tornado damage as of last night, but at least three people had died from causes related to heavy rains and flooding.

Tulsa Mayor G.T. Bynum expressed concern about the Army Corps of Engineers’ decision to release 215,000 cubic feet of water per second from Keystone Dam on the Arkansas River west of his city after its 40-square-mile reservoir rose 8 feet in 48 hours.

“That’s a number we were hoping we wouldn’t hear, so it’s a concern,” Bynum said yesterday. “I think there will be parts of our city that will be adversely impacted by a release of this rate.”

Several homes were extended precariously over the Cimarron River in Crescent, Okla., due to high flows and severe erosion of the river’s banks. One unoccupied home collapsed into the river, according to the Associated Press.

Kansas City, Mo., saw between 3 and 5 inches of rain, and severe storms were beginning to hit St. Louis and the flood-swollen Mississippi River, with more rain forecast in the coming days. Much of southwest Missouri remained under a flood warning yesterday.

As if that weren’t enough, the National Weather Service issued a critical fire weather alert for portions of southern New Mexico and westernmost Texas. And temperatures in the Southeast were climbing into the mid-90s, with forecasts saying they could hit 100 degrees Fahrenheit by early next week.

Experts attribute the wild weather to a “wavy” pattern in the mid- to high-level atmosphere combined with an atmospheric trough in the West and a high ridge in the East.

Between the coasts, moist Gulf of Mexico air is being carried into the country’s midsection, where it is colliding with much colder air from Canada, triggering violent spring storms.

“I don’t have enough data to say exactly how rare this is, but we are definitely getting into the rarer, more extreme side of things,” said Marc Chenard, a meteorologist with the National Weather Service’s Weather Prediction Center in College Park, Md.

Climate scientists have been careful not to draw direct links between specific weather events and a warming atmosphere, but it is clear the climate has been more variable in recent years and that warmer, wetter conditions are becoming the norm.

Jeff Basara, an associate professor of meteorology at the University of Oklahoma and an expert on extreme weather, said recent research suggests climactic changes in the eastern Pacific Ocean could be a driver of the nation’s recent extreme weather.

“We’ve seen this broad pattern since last October when the precipitation really picked up in the Plains,” Basara said. “Now we’re getting into the warm season, and it’s exacerbating everything. The pattern hasn’t changed, but we’re seeing much heavier precipitation with convection and spinning thunderstorms. It’s really a recipe for some of these higher-impact events.”

NOAA said last month was the second-hottest April on record, exceeded only by April 2016, which also saw major flooding and severe tornado outbreaks in the Plains and Ohio Valley.

This year’s dramatic flooding in the Missouri and Mississippi river basins follows the wettest meteorological winter on record, with 25% more precipitation falling between December and February than in an average year (Climatewire, March 7).

The United States has experienced 412 consecutive months with temperatures, at least nominally, above the 20th-century average, according to NOAA. Climate disasters have also been on the rise, with three of the four most active disaster years coming in 2016, 2017 and 2018.