An Objective Aid for Forecasting September Thunderstorms at Denver , Colo

The climatology of September thunderstorms a t Denver, Colo., is discussed. Data as near as possible to the time of occurrence of thunderstorms are studied to determine variables related to the occurrence of thunderstorms. The same variables from earlier data are investigated to determine their forecasting value. Three variables taken from the 2000 MST raobs and 700-mb. charts are ultimately used to obtain an objective aid for forecasting thunderstorms between midnight and midnight following the 2000 MST upper air chart. It is pointed out that for practical purposes this constitutes a forecast of afternoon and evening thunderstorms, or a forecast for 12-20 hours in advance. , The conclusion is drawn that the objective aid developed should prove of value in forecasting September thunderstorms at Denver.