Design of a Hall Suppression Project for Illinois

Abstract

A description is given of a broad program to Design and Experiment to Suppress Hail (DESH) in Illinois. This program draws on results acquired during 17 years of extensive hail research in Illinois. There are two principal tasks to DESH: the determination of the desirability and the feasibility of hail suppression experimentation in Illinois and the Midwest. Socio-economic studies have led to an affirmative conclusion on the desirability issues. The feasibility decision appears affirmative and rests on certain key results. Airborne cloud base seeding in the humid midwestern environment is possible but will be more difficult and expensive than in less humid areas. Radar will be needed for short-term forecasting, aircraft operations, identification of potential hailstorms, and in the evaluation of seeding effectiveness. Weather forecasting by objective techniques will be valuable in both operations and evaluation, and adequate objective techniques have been largely developed. The overall shape of the proposed experiment is now clear. It will consist of an impact monitoring effort, which will make assessments of societal, environmental and economic impacts and communicate with the public; an operational effort to execute the experiment according to the final detailed design; and an evaluation effort combining a variety of surface, synoptic and radar data to assess the efficacy of the chosen seeding technique.