Large-Scale Characteristics of Rapidly Intensifying Tropical Cyclones in the North Atlantic Basin

Abstract

The National Hurricane Center (NHC) and Statistical Hurricane Intensity Prediction Scheme (SHIPS) databases are employed to examine the large-scale characteristics of rapidly intensifying Atlantic basin tropical cyclones. In this study, rapid intensification (RI) is defined as approximately the 95th percentile of over-water 24-h intensity changes of Atlantic basin tropical cyclones that developed from 1989 to 2000. This equates to a maximum sustained surface wind speed increase of 15.4 m s 1 (30 kt) over a 24-h period. It is shown that 31% of all tropical cyclones, 60% of all hurricanes, 83% of all major hurricanes, and all category 4 and 5 hurricanes underwent RI at least once during their lifetimes. The mean initial (t 0 h) conditions of cases that undergo RI are compared to those of the non-RI cases. These comparisons show that the RI cases form farther south and west and have a more westward component of motion than the non-RI cases. In addition, the RI cases are typically intensifying at a faster rate during the previous 12 h than the non-RI cases. The statistical analysis also shows that the RI cases are further from their maximum potential intensity and form in regions with warmer SSTs and higher lower-tropospheric relative humidity than the non-RI cases. The RI cases are also embedded in regions where the upper-level flow is more easterly and the vertical shear and upper-level forcing from troughs or cold lows is weaker than is observed for the non-RI cases. Finally, the RI cases tend to move with the flow within a higher layer of the atmosphere than the non-RI cases. A simple technique for estimating the probability of RI is described. Estimates of the probability of RI are determined using the predictors for which statistically significant differences are found between the RI and non-RI cases. Estimates of the probability of RI are also determined by combining the five predictors that had the highest individual probabilities of RI. The probability of RI increases from 1% to 41% when the total number of thresholds satisfied increases from zero to five. This simple technique was used in real time for the first time during the 2001 Atlantic hurricane season as part of the Joint Hurricane Testbed (JHT).

Intense tropical cyclone activities in the northern Indian Ocean

“…To assess the intensification speed of tropical cyclones, DeMaria and Kaplan (1999) for the North Atlantic and Holliday and Thompson (1979) for the western North Pacific used the drop in the central atmospheric pressure measured or estimated in the eye. However, the dropsondes used since 1997 for aerial reconnaissance in the North Atlantic have permitted better wind measurements.…”

An estimation of water origins in the vicinity of a tropical cyclone’s center and associated dynamic processes

“…Kaplan and DeMaria (2003) pointed out the important roles of the ocean, inner-core dynamics, and large-scale environmental interactions in TC intensity change. Many influential factors make it difficult to fully understand the mechanisms of TC development.…”

Modeling Rapid Intensification of Typhoon Saomai (2006) with the Weather Research and Forecasting Model and Sensitivity to Cloud Microphysical Parameterizations

“…Especially, rapid intensification (RI) is one of the most challenging and the least well understood problems in tropical cyclone prediction today. Furthermore, the most intense TCs in the Northern Hemisphere often have a RI period during the peak season, and account for nearly three-quarters of all the RI events (Frederick 2003;Kaplan and DeMaria 2003;Ventham and Wang 2007;Shu et al 2012). RI also poses a significant threat to ships and a growing number of coastal communities.…”