Analysis of Hailstone Temporal and Spatial Variability over the Central United States

Hailstones pose a significant threat to property and economy. Therefore, a detailed knowledge of their occurrence and characteristics is essential. Further understanding the dynamic and physical factors affecting hail formation and hailstone size is of a great importance to the weather and climate prediction. In this study we analyze the temporal and spatial variabilities for hailstones over the Southern Great Plains (SGP) and Northern Great Plains (NGP) with the data in the recent decade over 2004-2016, when the report biases may not be a significant problem (we also only analyze hail with a size larger than 1 inch). We find that in spring, the occurrence of the large hail (>2 inches) has a trend of moving toward southern Texas. However, in summer, the hail zone has a northwest expansion over NGP. As a result, the hail occurrence increases significantly over NGP from the first 6-year period to the second 6-year period. The hail occurrence frequency has a large year-to-year variability. The dynamic and physical factors are examined to quantify their contributions to the magnitudes of the annual variability.