AN EVALUATION OF A LEE WAVE FORECASTING NOMOGRAM

Abstract

A re-evaluation of Harrison's (1957) lee wave prediction nomogram has resulted in the design of a diagram for wave soaring forecasts. The diagram is slmple to use and may be adapted to any lee wave area. It takes into account both occurrence and strength of lee waves in such a manner that the wave soaring prospects can be assigned a rough confidence level (e.g., greater or less than 50% probability). Further refinenent and modification of the diagram is recommended. The lack of sufficient data has not allowed the diagram to be verified statistically and therefore, this should be done as data become available. The accuracy of the diagram is strongly dependent on accurate forecasts of sealevel pressure gradlents and winds aloft in the area of anticipated waves. Thus, one should not be misled by the hlgh levels of accuracy stated in the last section; as with most meteorological forecasts, the accuracy of the device will decrease as the length of the forecast period lncreases.