Comment on nhess-2023-16

Abstract

<strong class="journal-contentHeaderColor">Abstract.</strong> Hail and tornadoes are hazardous weather events that are responsible for significant property damage and economic loss world-wide. The most devastating hail and tornado events are commonly produced by supercells in the United States. However, some hazard-producing supercells may grow upscale into mesoscale convective systems (MCSs) or may be embedded in MCSs. Quantifying the relationship of hail and tornado occurrences with MCSs on the long-term climatology is lacking. In this work, the radar features associated with MCSs are extracted from a 14-year MCS tracking database over the contiguous United States, and the hazard reports are matched to the extracted MCS features. We analyze the characteristics of hail and tornadoes associated with MCS characteristics and consider the seasonal and regional variabilities. On average, about 8&ndash;17 % of hail and 17&ndash;32 % of tornado events are associated with MCSs depending on various criteria used to define MCSs. The maximum total and MCS-associated hazard events occur in March&ndash;May, but the highest MCS-associated portion (23 % for hail and 45 % for tornado) occurs in winter (December&ndash;February) because MCS is the dominant type of convection due to strong synoptic forcing. In contrast to the decreasing trend in the relationship of MCS-associated fraction with hailstone size, the more severe the tornado event is, the more likely it is associated with an MCS. The different trends indicate the distinct mechanisms for the MCS-associated production of the two types of hazards.