An Operational Evaluation of the Navy Operational Global Atmospheric Prediction System (NOGAPS): 48-Hour Surface Pressure Forecasts

Abstract

The second in a series of studies designed to identify systematic pressure, displacement, and directional errors in the 48-hour surface pressure forecast of extratropical cyclones by the Navy Operational Global Atmospheric Prediction System (NOGAPS) has been completed for the 1983 Northern Hemisphere winter season (5 January?31 March). All available NOGAPS 0000 and 1200 GMT forecast cycles are verified for the Western Pacific, Eastern Pacific, and Atlantic Oceans north of the equator. NOGAPS generally underforecasts the intensity of cyclones during their early stages, but overforecasts them during their mature and decaying phase. NOGAPS was slow in forward movement but showed improvement over the previous Navy forecast model. Case studies are presented which illustrate typical pressure and speed error patterns and the possible consequences of an inferior analysis on forecast quality. The results of this study correspond closely with the conclusions derived from the preliminary evaluation.