Abstract
A statistical theory developed previously is applied to graphical predictions of the 500-mb surface, using a barotropic model. Synoptic observations are regarded as samplings of the initial state. Probabilities of initial and forecast height values to occur in specified height intervals, are computed with graphical aids. These are limiting probabilities, determined by network density and initial synoptic analysis. They decrease with time.
The forecast procedure is described. Examples of probability forecasts and verifications are presented and discussed. The predictability of the graphical technique is examined quantitatively.
