Influence of Convective Bursts and Electrification on the Rapid Intensification of Hurricane Earl 2010

The predictability of rapid intensification in tropical cyclones is of growing interest. More important, is which observations are most critical to predict the phenomenon. There are many controversies concerning whether convective bursts are significant indicators in tropical cyclone rapid intensification. Lightning within the eye-wall is also thought to induce changes in intensification during an “eye-wall replacement” as the outer band moves toward the core, large updrafts proliferate the frequency of lightning strikes. Hurricane Earl 2010 is an ideal case study as there were two eye-wall replacement cycles with multiple series of convective bursts present during a rapid intensification period. Furthermore, the storm was very energetic and electrified with lightning in both the eye-wall and outer rain-band regions during strong convective bursts. This poster will demonstrate an observational study using the techniques of spatial correlation, time series analysis, and contour analysis of geophysical variables, in a multi-scale framework. This is an exploratory and descriptive approach, attempting to tease out broad, qualitative correlations between observables such as the relationship between surface pressure fall, cloud top temperatures, and lightning frequency/location/intensity. Probable causal relationships will be represented in a qualitative sense. The available data comes from the Genesis and Rapid Intensification Processes (GRIP) field campaign, providing a rich dataset. The study will focus specifically on the rapid intensification stages of Hurricane Earl, taking place within the Atlantic Basin between 26 August and 4 September 2010. The overarching question is whether a series of convective bursts influenced the juncture of rapid intensification. Is there something unique about the structure of convective bursts that are associated with rapid intensification compared to bursts that are not? Does hurricane electrification reflect intensification and weakening periods? What is the connection between convective bursts, lightning activity, and the eye-wall replacement cycle during rapid intensification? Microwave satellite imagery and ancillary lightning data show strong correlation between lightning and convective burst locations, time, and duration, with respect to the rapid intensification period. During rapid intensification, microwave imagery indicates multiple convective bursts materializing in close proximity to the eye-wall region. Lightning data can be overlaid with bursts to elucidate commensurate electrification. The suggestion that intervals of strong convection, indicated by lightning activity, may be antecedents to storm intensity change is an ongoing investigation. However, an improved understanding of Hurricane Earl's convective structure, lightning activity, and their relationship to intensity change may assist in real-time forecasting applications as well as improving numerical weather models.