How Do Hailstorms Respond to a Warmer Future?
The impact of climate change on severe convective storms, like hailstorms, is a pressing issue since those storms result in large property and economic losses. Scientific understanding of how these storms evolve in a warming climate is low because the coarse resolution of global climate models cannot simulate them. Here researchers performed a fine-resolution (1.2 km grid spacing) modeling study to explore how typical hailstorms in the Great Plains respond to future warming under the business-as-usual (high-end) anthropogenic emission scenario. They found that large hail (diameter > 2.5 cm) in two types of hailstorms had contrasting responses to the warming. Large hail occurrences for the hailstorms under the frontal systems exhibited a large increase, compared to very small response for the Great Plains low-level jet (GPLLJ) systems.
Hailstones generate substantial economic losses across the United States and the globe. Their small-scale convective features pose a great challenge to predicting future changes. With fine-resolution simulations and the pseudo-global warming (PGW) approach, this study showed that large, or synoptic, scale features regulate the response of storms to anthropogenic warming. By linking the impacts of climate change on hailstorms to the easier-to-model synoptic-scale feature, this study advances our knowledge of hailstorm predictability with important implications for risk management. In addition, this study presents an important concept to study and understand climate change impacts on hail based on generally well-understood and predictable regional synoptic scale features.
Researchers conducted model simulations at 1.2 km grid spacing of severe convective storms with large hail and heavy precipitation over the central United States in the spring season. The storms, which occurred in two typical types of large-scale weather systems, were selected and simulated under both current and future climate conditions. The future climate simulations were conducted using the PGW approach. The researchers found that the responses of large hail (diameters > 2.5 cm) to anthropogenic warming are markedly different between the two types of synoptic-scale environments. Frontal systems showed an over 110% increase in large hail occurrences, whereas GPLLJ systems had a less than 30% increase. This is due to the frontal storms having a larger increase in convective intensity and updraft width as well as a smaller increase in warm cloud depth than the GPLLJ storms. Interestingly, the occurrences and intensity of heavy precipitation (rain rate > 20 mm h-1) in both types of systems are similarly sensitive to anthropogenic warming. This study presents the important concept of connecting hail predictability with predictable synoptic-scale systems, which can be used to facilitate studies of climate change impacts on hail in other hail-prone regions.