The Surprising Culprit Behind Highest US Weather Damage Costs

While hurricanes, floods, and tornadoes often grab headlines, it is actually hail that has caused the highest weather damage costs in the US so far this year, according to data from Gallagher Re, a global reinsurance firm.

• Hail is a sneaky hazard that can cause significant damage, as experienced by Barb Berlin, whose car and property were pummeled by fist-sized hailstones.
• Hail accounts for roughly 50 to 80% of insured claims filed from thunderstorm-related losses, according to Steve Bowen, chief science officer for Gallagher Re.
• This year, thunderstorms have been responsible for about $61 billion in economic losses, with hail likely responsible for between $31 billion and $49 billion of that total.

Climate Change and the Threat of Larger Hailstones

Recent research suggests that climate change will cause larger hailstones to become more common, while the likelihood of smaller, less-damaging hailstones will decrease.

• A study published in Nature Climate Change projects that the frequency of hailstones roughly 1½ inches or larger will rise by 15% to 75%, depending on greenhouse gas emissions.
• Higher temperatures provide more energy for stronger updrafts within thunderstorms, allowing hailstones to remain longer in sections favorable for hail formation, leading to larger hailstone sizes.
• Larger hail, which is already one of the costliest weather hazards in the US, will intensify issues related to insurance premiums and risk assessments.

Understanding Hail Formation and Forecasting

Advances in climate and weather modeling now allow scientists to create complex simulations that model thunderstorms and their microphysics, including hail size.

• The study by Northern Illinois University researchers used future climate projections and plugged them into a weather model to predict hail size changes.
• While a warmer atmosphere allows for more melting of smaller hailstones as they fall, larger hailstones with higher terminal velocities are less affected.
• Key questions remain about accurately forecasting hail formation and distribution of hail sizes during storms.

Upcoming Field Study and Continuing Research

Next year, scientists from several institutions plan the first US field study of hail since the 1970s, where they will chase hailstorms and deploy mobile Doppler radars and other instruments to capture the storms' inner physics.

• This field study aims to improve understanding of hail formation and distribution, which could lead to better forecasting and preparedness.
• Despite being a costly weather hazard, hail research has lagged behind other phenomena like tornadoes, but recent advances in radar and modeling have reignited interest.
• Continued research is crucial for mitigating the impacts of hail, which are likely to become more severe with climate change.