Accuracy of Atlantic and Eastern North Pacific Tropical Cyclone Intensity Guidance

Book excerpt: Five statistical and dynamical tropical cyclone intensity guidance techniques available at the National Hurricane Center during the 2003 and 2004 Atlantic and Eastern North Pacific seasons were evaluated within three intensity phases: (I) formation; (II early intensification; and (III) decay. During the formation phase, the Decay Statistical Hurricane Intensity Prediction (DSHIPS) technique was the best technique in both basins. When the forecast errors during formation exceed +/- 10 kt, the statistical techniques tend to over-forecast and the dynamical models tend to under-forecast. Whereas DSHIPS was also the best technique in the Atlantic during the early intensification stage, the Geophysical Fluid Dynamics Laboratory model was the best in the Eastern North Pacific. All techniques under-forecast periods of rapid intensification and the peak intensity, and have an overall poor performance during decay-reintensification cycles in both basins. Whereas the DSHIPS was the best technique in the Atlantic during decay, none of the techniques excelled during the decay phase in the eastern North Pacific. All techniques tend to decay the tropical cyclones in both basins too slowly, except that the DSHIPS performed well (13 of 15) during rapid decay events in the Atlantic. Similar error characteristics had been found in the western North Pacific.