Impacts of Sea Surface Temperature Gradients on Rapid Weakening in the Eastern North Pacific

Despite steady improvements in tropical cyclone (TC) intensity forecasts over the last decade, predicting rapid intensity change continues to pose a challenge. Decades of research has pinpointed various environmental factors that contribute to a TC’s intensification or weakening; however, previous work has done little to incorporate the magnitude and direction of SST gradients into explaining intensity changes. In this paper, we focus on sea surface temperature (SST) gradients as TCs rapidly weaken (defined as a decrease in maximum sustained winds of at least 30 kt in 24 hours). By exploring SST gradients, we hope to provide further insight into how this environmental factor contributes to large intensity changes. We constrain the study to the eastern North Pacific due to the relative dearth of land in this basin, thus reducing the influence of land during the weakening process. Over the period 2000-2017, we perform empirical orthogonal function (EOF) analyses on TC-centered infrared satellite imagery, using the 4 km NASA MERGIR V1 dataset, to identify dominant spatial patterns during rapid weakening and compare these patterns to the corresponding SST gradients. Variability in the patterns will be informed by environmental variables provided in the Statistical Hurricane Intensity Prediction Scheme's diagnostic archive.