‘Lucky’ Weather Keeping Worst of Chemical Plume Out of Houston

(Bloomberg) -- Houston has been lucky so far.

Every night since a petrochemical storage site erupted in flames on Sunday, a lid of warm air 400 feet to 600 feet (120-180 meters) over the city hasn't been stout enough to halt the ascent of a super-heated torrent of inky smoke rumbling out of the destroyed tanks. That means residents and wildlife at ground level have been spared the worst of the choking, toxic cloud.

“The heat is creating enough warmth to rise rather vigorously to push through'' the warm layer, said Charles Roeseler, a meteorologist with the National Weather Service in Houston. “All things considered, we have been lucky.”

Normally temperatures get cooler the higher into the sky you go. With nightly inversions such as those in place since the weekend, though, there is a layer of warmer air that “creates a lid,” Roeseler said. He likened it to a covered pot of boiling water: The steam stays trapped under the lid. If Houston were the pot, its lid is too flimsy to hold back the steam.

Houston is also catching a break because the inversion has been between 400 to 600 feet, which means even if the smoke did get trapped it would still be off the sidewalks. If the nights had been foggy, typical of this time of year, the inversion would have been closer to the ground.

“In spring, in southeast Texas and in the Houston area that hasn't happened,” Roeseler said. “We have been fairly fortunate.”

To contact the reporter on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net

To contact the editors responsible for this story: James Attwood at jattwood3@bloomberg.net, Joe Carroll, Christine Buurma

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