Hailstorms are analyzed across the United States using explicit hailstone size calculations from convection-permitting regional climate simulations for historical, mid-century, and end of twenty-first-century epochs. Near-surface hailstones <4 cm are found to decrease in frequency by an average of 25%, whereas the largest stones are found to increase by 15–75% depending on the greenhouse gas emissions pathway. Decreases in the frequency of near-surface severe hail days are expected across the U.S. High Plains, with 2–4 fewer days projected—primarily in summer. Column-maximum severe hail days are projected to increase robustly in most locations outside of the southern Plains, a distribution that closely mimics projections of thunderstorm days. Primary mechanisms for the changes in hailstone size are linked to future environments supportive of greater instability opposed by thicker melting layers. This results in a future hailstone size dichotomy, whereby stronger updrafts promote more of the largest hailstones, but significant decreases occur for a majority of smaller diameters due to increased melting.

通过对历史、本世纪中叶和二十一世纪末允许对流的区域气候模拟进行明确的冰雹尺寸计算，对美国各地的冰雹进行了分析。研究发现，近地表 <4 厘米的冰雹发生频率平均降低了 25%，而最大的冰雹则增加了 15-75%，具体取决于温室气体排放途径。预计美国高平原近地表严重冰雹发生的频率将减少，预计减少 2 至 4 天（主要是在夏季）。在南部平原以外的大多数地区，最大的严重冰雹日数预计将大幅增加，其分布与雷暴日数的预测非常相似。冰雹尺寸变化的主要机制与未来的环境有关，该环境支持更大的不稳定性，而更厚的融化层则相反。这导致了未来冰雹尺寸的二分法，即更强的上升气流促进了更多最大的冰雹的出现，但由于融化的增加，大多数较小直径的冰雹会显着减少。