Some Criteria for Distinguishing Large Scale Weather Processes

The concept of a large scale weather process covering a hemisphere or perhaps the whole earth and lasting for periods of twenty to thirty days presents some possible value as an aid in extending weather forecast periods beyond those now used with any degree of confidence, In defining and studying such processes various factors must be considered such as tl1e general atmospheric circulation trends and flow patterns, centers of high pressure and low pressure action, and zones of convergence of airflow; and the movement of these zones. Comprehensive charts, flow pattern charts, or any other chart giving a broadscale weather picture over an extended period of time are of much use in making a subjective study. Statistical studies by computation of correlation coefficients or better yet by use of contingency tables furnish a more objective view of the problem. It is the purpose of this study to make preliminary investigations of these factors using some of these techniques. From a study of these processes it is hoped a procedure will be developed for forecasting the general atmospheric flow pattern and from this a reasonable weather forecast for several weeks.