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CLIMATEWIRE | Back-to-back disasters rocked Houston last year, when a powerful derecho struck the city in May, followed by Hurricane Beryl in July. Both events brought gale-force winds to the densely built downtown, with gusts exceeding 90 miles per hour.

But after the storms, researchers noticed something strange. The derecho caused more damage than the hurricane to Houston’s tallest buildings.

Now, scientists say there’s a need for more research on the impacts of powerful downbursts in urban centers. That’s especially true for places like Houston, the Gulf Coast’s largest city, where thunderstorms and hurricanes can both wreak havoc.

In a new study, published Friday in the scientific journal Frontiers in Built Environment, researchers from Florida International University demonstrated that different kinds of storms — which produce distinct wind patterns — can pose different threats to tall buildings.

Both hurricanes and derechos can produce high-speed winds. But derechos — long-lasting wind storms often associated with bands of thunderstorms — have unique traits. They’re often characterized by sudden bursts of winds that move in straight lines, often causing damage that radiates outward in a single direction.

The researchers compared the damage caused by last year’s storms on several of Houston’s tall buildings, each at least 600 feet tall. These include the Chevron Building Auditorium, Wells Fargo Plaza, Enterprise Plaza, Wedge International Tower and the Total Energies Tower.

Each of these buildings is designed to withstand gusts up to 150 mph — yet many still sustained significant damage, particularly during the derecho. The researchers noted that an assessment of 18 buildings revealed more than 3,000 broken windows during the storm. Hurricane Beryl, on the other hand, caused significantly less glass damage than the derecho.

The researchers wanted to know why there was such a difference between the two storms. So they conducted a series of experiments in a special wind chamber housed at FIU, altering the airflow to simulate the patterns of derechos versus hurricanes. Model buildings inside the chamber helped them evaluate the impacts of the strong winds on the built environment.

They found that derecho winds can produce unique forces compared with hurricanes, including stronger suction on the walls of city buildings, allowing them to dislodge glass panels and shatter windows. The findings suggest that even buildings designed for strong winds aren’t necessarily resilient for all kinds of storms.

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