Statistical Analysis of the SHIPS Hurricane Model Rapid Intensification Index

Using statistical analysis, the SHIPS hurricane intensity model's rapid intensification (RI) Index was analyzed to determine its skill relative to climatology in different regions of the East Pacific and Atlantic oceans. The SHIPS RI Index was developed to give guidance as to when large scale and inner-core parameters are favorable for rapid intensification (30 kts increase in 24 hours). All tropical cyclone forecast cases since 1995 in the Atlantic and 1997 in the East Pacific were included in this study. These cases were broken down by forecast time and region in each basin and were further stratified into initial and non-initial periods of RI as well as RI and non-RI time periods. T-testing concluded that significant differences in RI parameters were present between the different times tested, between the regions in each basin, and for the initial onset of RI compared to non-initial RI. The most statistically significant differences were found for the standard deviation of infrared brightness temperature and dry air flux predictors within the storm's inner-core region. Brier skill scores comparing model predictions to climatology were significantly better in the East Pacific compared to the Atlantic; however different regions of the Atlantic showed comparable or higher RI index skill than the East Pacific.