Why Do Some Tropical Cyclones Fail to Intensify Rapidly Despite the Existence of All Necessary Environmental Conditions?

Monday, 15 December 2014: 8:00 AM
Edward J Zipser, University of Utah, Salt Lake City, UT, United States
There has been a long-standing uncertainty about the requirements for rapid intensification of tropical cyclones, once formed. While there is general agreement on the necessary environmental conditions for many years, there is no such consensus on the role of deep, intense convection, sometimes referred to as convective bursts. One school of thought, stimulated by the original “hot tower” hypothesis from the Riehl-Malkus era, can be characterized as “the more intense the convection, the better”. This talk examines the evidence from 16 years of data from the Tropical Rain Measuring Mission (TRMM) satellite, as well as other passive microwave sensors, by a number of investigators, which suggests a different conclusion. While there is still some consensus that intense convection in the eyewall (or inside the radius of maximum winds) can contribute to deepening, evidence is accumulating to suggest that strengthening of the tropical cyclone is favored by symmetric inner core rainfall from convection of only moderate intensity, while intense convective bursts may delay or even hamper intensification.