September 22, 2022 By Vaseline

Hail experts highlight advances in understanding damage storms

Scientists brief reporters at a North American hail workshop

September 22, 2022 – by David Hosansky

Scientists are making significant strides in better understanding hailstorms, an important step in improving forecasts of the multibillion-dollar hazard, leading hail experts said at a briefing on Thursday.

The briefing took place at the Second North American Workshop on Hail & Hailstorms, an event hosted by the National Center for Atmospheric Research (NCAR) for US and international hail scientists to share important advances in hail research. Hailstorms are one of the most costly types of weather disasters, causing $16 billion in damage across North America last year alone.

Speaking at the briefing, senior NCAR scientist Andrew Heymsfield emphasized the importance of using radar to better detect hail and thereby reduce storm-related damage. He highlighted key questions scientists are trying to answer, including the impact of changing climate on hailstorms and the processes within a storm that affect hail intensity and size – specifically why some storms produce particularly large and destructive hailstones.

“In a hailstorm, just a select few hailstones become the largest,” he said. “What are the underlying physical processes that select these ‘preferred’ hailstones?”

Computer simulation of hailstones falling through a storm
Scientists use machine learning and computer simulations to study the many trajectories of hailstones through a storm. (Image by Becky Adams-Selin, Verisk Atmospheric and Environmental Research.)

Becky Adams-Selin, senior scientist at Verisk Atmospheric and Environmental Research, discussed using machine learning techniques and advanced computer modeling to determine why it is so difficult to predict which storms will produce large hailstones. Her research shows that the processes that lead to large hail may have more to do with the structure of the storm than atmospheric conditions like wind or temperature.

“Predicting large hailstones is difficult from a forecasting perspective because every storm is really different and the same atmospheric environment can produce multiple types of storms,” ​​she said. “We use machine learning to identify patterns in the tens of thousands of different hail trajectories in a storm, with the goal of identifying the conditions that produce the most damaging hailstones.”

Ian Giammanco, senior director for standards and data analytics and chief research meteorologist at the Insurance Institute for Business & Home Safety, found that hail accounts for about 70% of damage from severe thunderstorms, which is far more than the financial losses caused by tornadoes or lightning . He stressed that society needs to focus on greater hailstorm resilience, especially as more development takes place in hail-prone regions.

“Our homes are getting bigger, they’re being built closer together and our communities are more dispersed, so a lot of material gets hit by hail and needs to be replaced,” he said. “We have a big challenge ahead of us because a lot of the things we have — our homes, our businesses, our cars, etc. — aren’t well suited to dealing with hailstorms.”

Panellists stressed the importance of collecting more data on hailstorms. They noted that there had not been a major US field project to study hail in more than 40 years. Instead, scientists must rely on anecdotal reports of hail falling to the ground and try to deduce general characteristics of the storm that created them. Adams-Selin, Heymsfield and their colleagues have proposed a new field project, ICECHIP (In-situ Collaborative Experiment for Collection of Hail in the Plains), that would use aircraft, radar and other instruments to make detailed observations of hailstorms over the Great Plains and Front Range of the Rocky Mountains.

“We need better observations so we can understand the complex processes that go on in a hailstorm, which will lead to better predictions,” Heymsfield said.

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