'A lot of broken windows.' Hail is one of the costliest severe weather elements

AUSTIN (KXAN) -- It was a day to remember for a long time for Colin Hald and his team in Wimberly, Texas: a severe thunderstorm struck the Austin area and softball-sized hailstones generated over $600 million in damages, according to the National Centers for Environmental Information.

"What we witnessed with that was a lot of broken skylights, a lot of broken windows, siding damage. Of course, roof damage," Hald said, remembering the scene after the storm on Sept. 24, 2023.

Hald works at Elite Roofing and Restoration, and he and his team used storm-detection software to identify tens of thousands of their clients who were impacted by significant hail damage. The software displays hail reports submitted by National Weather Service trained volunteers known as "SKYWARN Spotters," as well as photos of hail damage. They worked for weeks to repair the damage done by these strong thunderstorms.

These severe thunderstorms produced $600 million in losses, which will go down in the books as the costliest hailstorm in Austin-area history, far outdistancing the following hailstorms.

Hail Growth in a Warming Climate

Researchers, such as Meteorology Associate Professor Victor Gensini of Northern Illinois University, are now looking at whether hailstones have been increasing in size over the years and if large hailstorms will become more frequent.

Gensini and his team used advanced climate modeling to conduct their research. These simulations covered three distinct time periods: a historical baseline (late 20th century), mid-century (2044-2055) and late 21st century (2085-2100).

"We conducted this research to basically try to better understand, if we see these changes in global weather patterns and warmer temperatures, how does that actually feed back to the thunderstorm scale," Gensini explained.

Warmer global mean temperatures lead to an increase in atmospheric instability, also known as thunderstorm fuel. Higher instability creates stronger updraft speeds, which produce larger hailstones in the clouds. Warmer temperatures also raise the melting level height in a thunderstorm, which limits the melting as the stone falls from the cloud to the surface.

"One of the things that we really look for in these simulations are very strong updrafts. And that will give us an indication of where there might be very large hail in these simulations," Gensini said.

To factor in a warming climate, Gensini looked at two types of greenhouse gas emission levels to see how warming might influence hailstone dichotomy. He found that hailstones that are the size of a golf ball or smaller will become less frequent in the future.

"What ends up happening is, as you warm the atmosphere and you create these hailstones, a warmer atmosphere leads to a lot more melting on the way down, and these smaller hailstones don't fall fast enough to penetrate through that warming layer," Gensini said.

Stronger updrafts, driven by greater instability, allow hailstones to grow larger before falling. Therefore, larger hailstones, "end up way more frequent because we get stronger updrafts. And of course, they fall to the surface of the Earth much, much faster, and they don't experience as much melting."

Hail can quickly become destructive, a reminder of nature's raw power and complexity. Stay up to date with the First Warning Weather Team as we begin to enter the severe weather season.