5th UF Water Institute Symposium Abstract

Submitter's Name Stephanie Zick
Session Name Poster Session - Coastal Waters
Poster Number 18
Author(s) Stephanie Zick,  University of Florida (Presenting Author)
  Evolving Geometries in the Water Budgets and Precipitation Patterns of US Gulf Coast Landfalling Hurricanes
  According to a 2014 publication by former National Hurricane Center director Dr. Edward Rappaport, water-related deaths from inland flooding and storm surge are the leading causes of hurricane-related fatalities in the United States. Observations reveal that TCs of a given intensity vary significantly in size and structure, and there is mounting modeling and observational evidence that supports large-scale moisture as one controlling factor. Thus, the influence of environmental moisture on hurricane morphology is a critical research question, especially during the period around landfall, which has been less studied. In this analysis, we quantify the spatial distribution of TC moisture by formulating three shape metrics that encompass characteristic geometries of TCs moving into the mid-latitudes: asymmetry (A), fragmentation (F), and dispersiveness (D). Using reanalysis-derived water budget terms, the geometric patterns are measured every 3 hours, and a moving Mann Whitney U test is applied to determine significant break points in the evolution of moisture. As TCs moves into the eastern and central Gulf of Mexico, these shape statistics reveal organization into a highly symmetric, central, and circular. Furthermore, in major hurricanes (maximum wind speeds greater than 111 mph) during the 2004-2012 period (n = 11 storms), a distinct pattern emerges with a significant (p < 0.05) number of storms displaying a redistribution to the moisture budget during a window beginning 12-24 hours before landfall. As the TCs approach land and move inland, precipitation becomes more dispersed from the TC center but the overall structure maintains a cohesive, although asymmetric, pattern. Based on these findings, TC structural evolution needs to be closely monitored in conjunction with large-scale moisture availability in order to more accurately forecast the scale and spatial distribution of TC wind and water impacts.