Some Interior Observations of Southeastern Montana Hailstorms

Abstract

This study investigates some of the characteristics or the interior regions of several hailstorms penetrated by the armored T-28 aircraft during the 1981 CCOPE field project. The vertical wind data were analyzed to identify updraft and downdraft regions to facilitate the discussion of measurements made within the identified draft regions, such as draft sizes and speeds, cloud liquid water concentrations (LWC), turbulent and hail. Updrafts were more numerous than downdraft regions, tended to have greater horizontal extent and higher speeds, and were somewhat more turbulent. Significant correlations existed between peak vertical wind speeds and peak values of LWC or turbulence, as well as (for updrafts) between peak speed and draft size. Values of the LWC were generally quite low compared to adiabatic values, with the exception of two large severe hailstorms that may have had adiabatic updraft cores. The general characteristics of the hail observations, such as number and mass concentrations, maximum sizes, and locations within specific draft regions are discussed. Reflectivity gradients computed from radar measurements were compared with the had observations from the two largest storms; the analysis shows that the hail tended to be located in high-reflectivity regions rather than in regions of high-reflectivity gradient. The data are discussed in terms of possible implications for numerical modeling or precipitation process in convective storms.