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Rapid intensification (RI) of hurricanes is notoriously difficult to predict and can contribute to severe destruction and loss of life. While past studies examined the frequency of RI occurrence, changes in RI magnitude were not considered. Here we explore changes in RI magnitude over the 30-year satellite period of 1986-2015. In the central and eastern tropical Atlantic, which includes much of the main development region, the 95th percentile of 24-hr intensity changes increased at 3.8 knots per decade. In the western tropical Atlantic, encompassing the Caribbean Sea and the Gulf of Mexico, trends are insignificant. Our analysis reveals that warming of the upper ocean coinciding with the positive phase of Atlantic Multidecadal Oscillation, and associated changes in the large-scale environment, has predominantly favored RI magnitude increases in the central and eastern tropical Atlantic. These results have substantial implications for the eastern Caribbean Islands, some of which were devastated during the 2017 hurricane season.

Plain Language Summary In this study, using an analysis of observations and climate model output, we demonstrate that the magnitude of rapid intensification (RI), defined as an event where a hurricane increases in intensity by 25 knots or higher in 24hr, increased in the central and eastern tropical Atlantic during the 30-year satellite period of 1986-2015. On the other hand, in the western tropical Atlantic, changes in RI magnitude are insignificant. Conspiring changes in the large-scale hurricane environment brought about by a positive shift in the phase of the Atlantic Multidecadal Oscillation, the dominant mode of decadal climate variability in the Atlantic, are primarily responsible for these changes in RI. While previous studies examined the frequency of RI, our study is the first to understand potential changes in RI magnitude. The results from our study have substantial implications for the eastern Caribbean Islands, some of which were ravaged by several major hurricanes undergoing RI during the recently concluded 2017 Atlantic hurricane season.