Extreme weather battered parts of the Midwest over the weekend, providing another tragic reminder that catastrophic weather events uniquely impact rural America.
At least five people, including an infant, were confirmed dead as of Sunday in Oklahoma and Iowa after 78 tornadoes were reported Friday, and a separate weather system brought 35 tornado reports from northern Texas and Oklahoma to Missouri on Saturday.
Oklahoma Governor Kevin Stitt, speaking Sunday from the hard-hit small town of Sulphur, confirmed four people died across the state.
Watch: Oklahoma Governor Kevin Stitt responds to the deadly tornadoes
A late-night tornado rolled through Sulphur, killing one woman. Governor Stitt said it was the worst he had witnessed in his six years in office.
“It seems like every business in downtown has been destroyed now,” he said, adding, “thank goodness… there wasn’t a lot of people here at 10:30 at night.”
The Oklahoma Department of Emergency Management (OEM) reported that at least two individuals lost their lives in the town of Holdenville, and another person died on a highway in Marietta, where videos broadcast by local media showed several battered cars along the side of the road, with two semi-trucks overturned and a nearby warehouse ripped open.
The National Weather Service said a preliminary investigation had confirmed tornadoes in Sulphur and Marietta were at least EF-3 on the five-level Enhanced Fujita Scale, meaning gusts above 136 miles per hour.
On Monday, the tornado that initially struck Marietta, Oklahoma, was upgraded to an EF4 rating on the 1-5 scale. This designation signifies that the tornado sustained winds of at least 166 mph, potentially reaching as high as 200 mph.
It is the first EF-4 tornado in the U.S. since March 31, 2023, when a twister with winds of 170 mph struck Keota, Iowa, during a dayslong tornado outbreak that killed 31 people across six states.
According to a tweet by the NWS office in Norman, the tornado in Marietta marks Oklahoma’s first EF-4 tornado since a twister near Katie, Oklahoma, on May 9, 2016. That twister also killed a person before dissipating near Interstate 35.
In response to the devastation in Oklahoma, Governor Stitt proclaimed a 30-day state of emergency to aid the twelve most affected counties swiftly. White House officials said President Joe Biden spoke to Gov. Stitt on Sunday and offered the federal government’s full support.
While the region is known for its frequent and powerful tornadoes during the spring, meteorologists said it is extremely rare to have two significant outbreaks on consecutive days.
Tornado trends are changing as cold weather storms increase and move eastward.
Federal data show that warmer-than-average temperatures, which are driven by climate change, are making tornado outbreaks fiercer, more frequent, and shifting more definitively to the east.
“It looks as if we may be having fewer days in the U.S. with just one tornado and more days when there are multiple tornadoes,” says Naresh Devineni, an associate professor at City University of New York, who co-led a 2021 geographical analysis of large tornado outbreaks.
Tornado Statistics for the Contiguous U.S.
From the 1950s through the 1990s, tornadoes mostly struck in Tornado Alley, a region centered in northeastern Texas and south-central Oklahoma. However, research published in 2018 found outbreaks have shifted eastward by 400 to 500 in the past decade. This shift has made tornadoes more prevalent in eastern Missouri, Arkansas, western Tennessee and Kentucky, and northern Mississippi and Alabama, creating a new region with a higher concentration of these storms often referred to as “Dixie Alley.”
In the United States, tornadoes can occur any month, but recent research suggests climate warming may increase the number of tornadoes striking during cooler months. A study published in 2021 found that due to the warming atmosphere, tornado-favorable environments during the winter months have increased across the southern United States.
Manufactured homes can be deadly during a tornado.
Tornadoes can be extremely dangerous, but with proper shelter, survival is possible. Experts emphasize the significance of taking refuge in structures that are firmly anchored to the ground during a tornado. However, mobile homes are often more vulnerable, even to less intense tornadoes, as they lack central tornado shelters.
According to an Associated Press analysis of National Oceanic and Atmospheric Administration tornado death data, 815 people living in mobile or manufactured homes have been killed by tornadoes since 1996. This number accounts for 53% of all home-related tornado fatalities even though just 5.6% of the American population lives in mobile or manufactured homes.
Following the adoption of a 1976 Housing and Urban Development code, mobile houses are now better constructed, but a recent study found that the likelihood of a tornado-related fatality is 15 to 20 times greater in a mobile home than in traditional housing.
“Why we see such a disparity in fatalities and serious injuries between mobile homes and permanent homes is the way they fail,” said David Roueche, assistant professor of civil engineering at Auburn University.
According to Roueche’s research, permanent homes typically fail from the roof down in a tornado. The roof sheathing often comes off first, followed by the roof structure, trusses, and rafters before the walls collapse. Manufactured and mobile homes usually start to fail underneath when the metal straps and screws anchoring the house to the ground break.
Tornado-safe housing requires expensive concrete or tie-down systems that experts say will save lives, but the manufactured housing industry has been criticized for prioritizing cost over safety. This issue is particularly prevalent in the South, where the geographic shift of tornadoes from the Great Plains has exposed scattered mobile homes to increased risks.
Federal wind safety regulations for manufactured homes were created for hurricanes, not tornadoes.
The Department of Housing and Urban Development established the federal safety standards for mobile homes in 1976. In the 1990s, HUD updated these requirements for wind safety, establishing three distinct Wind Zones across the country, each corresponding to areas with varying degrees of susceptibility to windstorms in terms of intensity and occurrence.
However, the HUD wind zones are built around the threat of coastal hurricanes and do not consider tornado risk.
HUD Wind Zone Map For Manufactured Housing
Wind Zone One covers most of the United States, but it is most common in the interior, where hurricanes are less impactful. Mobile homes in this zone are designed to withstand wind speeds of up to 70 miles per hour. The zone covers nearly all the “Tornado Alley” states of Texas, Oklahoma, Kansas, and Nebraska.
However, mobile homes on the coast built in Wind Zone Three must withstand winds of up to 110 miles per hour.\
As of April 30, 2024, the National Centers for Environmental Information (NCEI) database has tracked 343 tornadoes this year, two-thirds of which had wind gusts of over 85 miles per hour.
“People are dying in new and old Zone 1 manufactured homes,” according to Roueche. Manufactured homes throughout the country would be much safer if the coastal federal requirements applied everywhere, he said.
Experts recommend alternative sheltering options for mobile home residents in case of severe weather, such as friends’ permanent houses, designated shelters, or community safe rooms. Authorities need to provide clear communication about where shelters are located, as access to information during chaotic situations is crucial.
Manufactured homes are more common in the newly defined “Dixie Alley.”
Nearly 22 million people live in manufactured housing, representing 7 percent of US households. The highest share of mobile homes are in the rural South and Southwest. About 3 percent of housing in urban areas is mobile homes, compared to 15 percent in rural areas.
In “Dixie Alley,” tornadoes often lead to higher fatality rates due to the vulnerability of mobile homeowners. Four of the top ten states for manufactured home purchases in 2017 were in Dixie Alley states.
Manufactured Homes as Share of County’s Housing as of 2017
For example, in 2021, a tornado outbreak occurred on December 10 and 11, producing 66 tornadoes. One of the most notable tornadoes from this outbreak was an EF4 tornado that hit Mayfield, Kentucky. This tornado had winds estimated at 190 mph and traveled a path of 165.7 miles. The tornado, nicknamed the “quad-state storm,” crossed four states: Arkansas, Missouri, Tennessee, and Kentucky. It remained on the ground continuously across three of these states.
Another tornado outbreak on Dec. 15 produced more than 60 tornadoes.
In December 2022, a series of tornadoes swept through Louisiana from December 13 to December 15, marking a significant weather event. Over 50 tornadoes were confirmed during this outbreak, including an EF2 tornado that caused substantial damage in New Orleans on December 14. Notably, the strongest tornado of the outbreak was an EF3, which struck Union Parish near Farmerville.
A few months later, on March 24, 2024, a violent tornado packing wind speeds of 170 miles per hour struck Rolling Fork, Mississippi, resulting in the tragic loss of at least 26 lives. Within a week, a series of storms claimed the lives of more than 30 people.
All of these outbreaks occurred during the colder months of the year within the boundaries of “Dixie Alley.”