Weather Like the Deadly Houston Windstorm Is Being Fueled in Part by Climate Change

(Bloomberg) -- The winds that roared out of a supercell thunderstorm Thursday night leaving a deadly trail across Houston are on the rise in a warming climate, though researchers are still teasing out the exact relationship between a rapidly heating planet and relatively small-scale weather patterns.

Power remains out for almost 700,000 customers in the Houston area after an intense storm swept through the area with winds in excess of 75 mph (120 kmh), downing trees, blowing out windows and leaving at least four dead. Economic losses and damages could be between $5 billion and $7 billion, according to an initial AccuWeather estimate.

The trail of destruction is the result of what’s known as straight-line winds, fierce gusts that can rival their more familiar siblings, tornadoes. The atmosphere has been primed to unleash all types of violent weather this spring across the central and southern US owing to several factors.

“It seems like we cannot go a day without there being some sort of severe weather,” said John Feerick, a meteorologist at AccuWeather. “It has been active, and it looks like it will stay fairly active.”

The fast-flowing river of air in the atmosphere known as the jet stream has helped send a steady stream of unsettled weather across the region. It’s a little farther south than usual for this time of year, and it has been ejecting systems out of the Rocky Mountains and into the Southern Plains. A lingering El Niño may be helping contribute to this pattern.

The second key driver of the severe weather is the Gulf of Mexico, which has been warmer than normal. That allows ample moisture to mix with these systems giving them more power, Feerick said. The world’s oceans and the Atlantic in particular — of which the Gulf of Mexico is part — have been setting heat records for the last 13 consecutive months, Karin Gleason, monitoring section chief with the US National Centers for Environmental Information, said in a briefing Thursday.

That’s created a “powder keg” in the atmosphere, according to Bill Bunting, deputy director of the US Storm Prediction Center. The conditions have helped fuel tornadoes across the Southern Plains this spring. But the storm that rolled into Houston on Thursday was different. The supercell that struck Houston formed in a derecho that swept from Texas to Florida, said Bunting. Derechos are rapidly moving lines of thunderstorms that can travel long distances and cause billions of dollars in damages owing to their strong winds that blow in a straight line as opposed to rotating like tornadoes. 

Straight-line winds form when down drafts of cool air three to four kilometers (about two miles) above the surface rush toward the ground, said Andreas Prein, a project scientist at the National Center for Atmospheric Research. The faster they come down, the stronger the winds will be at the surface.

The atmosphere over Texas on Thursday was the perfect setup for straight-line winds, he said. A thin layer of warm, moist air sat at the surface with dry, cooler air above it. Temperatures dropped by 10F (5.5C) in places as the storms came through, an indicator of how much power the system had. What made the situation worse in Houston was a small-scale circulation set up over the area, which gave the winds a boost.

Research has shown that clusters of tornadoes are becoming more common as the planet warms. (So, too, are heavy rainstorms.) Climate change’s impact on straight-line winds is less studied than tornadoes, but the growing body of research indicates it is playing a role. Since 1980 there has been an increase in the number and intensity of straight-line wind storms due to climate change, said Prein, who published a paper on the phenomenon in  last year. 

What’s more, model data suggested there would be an increase, but actual observations have shown even more storms than what the computers predicted. Prein’s study found that straight-line winds’ intensity increased 13% for every 1C (1.8F) warming, nearly double what models predicted. The Gulf Coast has already warmed by 1.2C since the late 1970s and early 1980s.

“There is a clear increase in straight-line wind storms, significant changes,” Prein said.

As the climate warms, it heats air lower in the atmosphere, which leads to more evaporation as the cold air drops from on high. The evaporation actually cools the falling air further, leading to a greater differential between the surface air and the cold from upper altitudes. That creates conditions for fiercer, more damaging winds.

In 2020, a powerful derecho sweeping across the Midwest caused about $11 billion in damage. Tree-toppling gusts also damaged buildings and power lines in 2022, and earlier this year, hurricane-strength winds knocked out power in Oklahoma. 

The exact influence of climate change on Thursday’s weather, though, will require more research. The smaller the weather phenomenon, the harder it is for climate scientists to study it, as a general matter. And compared to a hurricane or heat wave, the Houston storm was relatively tiny.  

Climate change can create conditions that are “more conducive” for tornadoes, said Andrew Dessler, a professor of atmospheric sciences at Texas A&M University, but the more localized the event, the more uncertainty there is about making a clear connection. “Climate change is going to enhance these severe rain events, and that’s going to make flooding worse.”

Regardless, the Southern Plains aren’t out of the danger zone yet. There’s a good chance another round of severe storms will race across the southern Plains through the middle of next week. 

(Updates with AccuWeather economic loss estimate in second paragraph.)

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