On the Use of Indices and Parameters in Forecasting Severe Storms

This paper describes our concept of the proper (and improper) use of diagnostic variables in severestorm forecasting. A framework for classification of diagnostic variables is developed, indicating the limitations of such variables and their suitability for operational diagnosis and forecasting. The utility of diagnostic variables as forecast parameters is discussed, in terms of what we consider to be the relevant issues in designing new diagnostic variables used for making weather forecasts. Finally, criteria required to determine whether a new diagnostic variable represents an effective forecast parameter are proposed. We argue that many diagnostic variables in widespread use in forecasting severe convective storms have not met these criteria for demonstrated utility as forecast parameters. ––––––––––––––––––––––––