File:Accuracy of western North Pacific tropical cyclone intensity guidance (IA accuracyofwester109452317).pdf

Consensus methods require that the techniques have no bias and have skill. The accuracy of six statistical and dynamical model tropical cyclone intensity guidance techniques was examined for western North Pacific tropical cyclones during the 2003 and 2004 seasons using the climatology and persistence technique called ST5D as a measure of skill. A framework of three phases: (i) initial intensification; (ii) maximum intensity with possible decay/reintensification cycles; and (iii) decay was used to examine the skill. During both the formation and intensification stages, only about 60% of the 24-36 h forecasts were within +/- 10 kt, and the predominant tendency was to under-forecast the intensity. None of the guidance techniques predicted rapid intensification well. All of the techniques tended to under-forecast maximum intensity and miss decay/reintensification cycles. A few of the techniques provided useful guidance on the magnitude of the decay, although the timing of the decay was often missed. Whereas about 60-70% of the 12-h to 72-h forecasts by the various techniques during the decay phase were within +/- 10 kt, the strong bias was to not decay the cyclone rapidly enough. In general the techniques predict too narrow a range of intensity changes for both intensification and decay.

Subjects: Tropical meteorology; North Pacific Ocean; Cyclones; Tropics; Cyclone forecasting; Meteorology; Tropical cyclone intensity; Tropical cyclone intensity change forecast techniques; Numerical and statistical intensity change guidance.