HRD seminar – John Kaplan, AOML/HRD – 25 April 2014

John presented a seminar on two topics: (1) “Enhancements to the SHIPS Rapid Intensification Index”;


Predicting episodes of tropical cyclone rapid intensification (RI) remains one of the highest operational forecasting priorities of the National Hurricane Center (NHC). In recent years, a statistically based rapid intensification index (RII) that employs predictors from the SHIPS model has been developed utilizing linear discriminant analysis. The SHIPS-RII provides estimates of the likelihood of RI over the succeeding 24-h for both the Atlantic and eastern North Pacific basins and is currently utilized as an operational forecasting tool by the NHC.  Although the current version of the SHIPS-RII has generally exhibited some skill, its utility is somewhat limited since it was developed exclusively for the 24-h lead-time and its skill has tended to be limited particularly in the Atlantic basin.

Thus, in an effort to improve the overall forecasting utility of the current operational SHIPS-RII, a number of model enhancements have been developed. First, ensemble-based versions of the RII that employ both the current SHIPS-discrimant RII as well as the newly developed Bayesian and Logistic versions have been derived for the current operational 24-h forecast lead-time as well as the added lead times of 12-h, 36-h and 48-h to provide additional guidance during the critical watch and warning period that has recently been extended to 48-h by the NHC. In addition, revised versions of the recently developed deterministic rapid intensity aid guidance have been developed utilizing the new multiple lead-time ensemble-based RII models. The results of independent tests of the aforementioned RII model guidance that were conducted utilizing real-time forecast model data for Atlantic and E. Pacific systems that developed during the period from 2004-2013 will be presented at the upcoming seminar.

 (2) “Assessing the relationship between the large-scale and inner-core estimates of vertical shear”


Numerous previous studies have examined the impact of vertical shear on both tropical cyclone structure and intensity. However, the results of those earlier studies were typically obtained based solely upon estimates of shear deduced from either large-scale global analyses or to a lesser extent wind data obtained from within a tropical cyclone’s inner-core region with few if any seeking to examine the relationship between the large-scale and inner-core shear estimates themselves.

Thus, comparisons between inner-core NOAA WP-3D airborne Doppler and GFS re-analysis deduced wind flow and vertical shear have been conducted for approximately 40 cases for which adequate inner-core airborne Doppler data coverage was found to exist. In our presentation, the preliminary results of the comparisons between the large-scale and inner-core kinematic flow fields as well as the potential modulating impact that tropical cyclone intensity and structure might have on these relationships will be discussed.

A video recording of the combined presentations is available on the anonymous ftp site:

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