Spatial characteristics of storm‐total rainfall swaths associated with tropical cyclones over the Eastern United States

Abstract

The eastern United States is extremely vulnerable to Atlantic basin tropical cyclones (TCs) and their associated precipitation. While many studies have focused on the magnitude or contribution of tropical cyclone precipitation (TCP) to overall rainfall, there is a need for a detailed climatology of spatial characteristics of inland TCP extent for this region. In this study, we develop a Geographic Information System method to delineate rainfall swaths for 257 US landfalling TCs during 1948 to 2014 using a daily gridded dataset. We then describe spatial patterns of TCP using three methods. First, we measure the rainfall swath areas and average widths over land, and find that TCs that spend longer periods over land have wider average widths so that rainfall swaths cover larger areas. Second, trends in the change of left extent of TCP swaths are analysed and TC attributes related to these trends are explored. Seventy of 85 TCs have rain swaths that expand on the left side at some points as they move inland. The TCs exhibiting expansion were hurricanes at landfall, re‐intensifying over land, undergoing extratropical transition, and/or moving near the coastline. Last, we construct a series of maps with return intervals and frequency distributions for inland TCP and tropical storm‐force winds. The results show that 94% of 2435 counties over the eastern United States are more frequently exposed to rainfall than wind from TCs. While cumulative rainfall shows a gradual decrease from southeastern coast inland, many inland regions have received five to six TCP events in a single season, which confirms that TCP should be a concern for people living inland as well as near the coast. This study's analysis of the spatial characteristics of TCP inland extent from a climatological perspective should benefit forecasting, hazard mitigation, and risk analysis of TC hazards.

Comparing the Spatial Patterns of Rainfall and Atmospheric Moisture among Tropical Cyclones Having a Track Similar to Hurricane Irene (2011)

“…Storm-total rainfall for the 11 TCs was calculated utilizing the cell statistics tool in ArcGIS. When considering the top 10% of rainfall totals produced by each TC, the outermost regions of rainfall belonging to each TC were defined using the method outlined in [45] where 12.5 mm values of daily rainfall were contoured and converted to polygons. Polygons whose centroids were located within 550 km of the storm track were retained and used to define the grid cells containing rainfall that was produced by a TC.…”

“…The next step was to measure the distance between the storm track and location of the center of each grid cell to better gauge the extent of areas that were affected by this storm. According to [45] the average TC making landfall along the East Coast produces rainfall totaling 12.5 mm or more out to 222 km on the left side of the storm track. The current study finds that Irene produced 12.5 mm or more of rainfall over regions 250 km left of the storm track near the point of landfall, expanding up to 330 km as the storm tracked north.…”

“…TCs that are transitioning into extratropical cyclones are expected to exhibit an expansion in or dispersion of their rain fields [6,13,45], although the increase in translational speed during the process may lower the rainfall totals received as the storm moves inland. Significant positive coefficients indicate expansion for Floyd, Bertha, Gloria, Unnamed, and Carol.…”

Variations in the Intensity and Spatial Extent of Tropical Cyclone Precipitation

“…Geophysical Research Letters, 46, 13,992-14,002. https://doi. org/10.1029/2019GL083452 Atlantic region (e.g., Chen et al (2006), Daloz et al (2010), , Jiang et al (2008), Konrad and Perry (2009), Lau and Zhou (2012), Prat and Nelson (2016), Zhou and Matyas (2017) and Zick and Matyas (2016)). Using radar, satellite, or station observations, these studies conclude that TCs that make landfall as major or minor hurricanes (as opposed to tropical storms) deliver the highest TCP rates and accumulations of TCP as they weaken over land.…”

A Nowcasting Model for Tropical Cyclone Precipitation Regions Based on the TREC Motion Vector Retrieval with a Semi-Lagrangian Scheme for Doppler Weather Radar

“…The previous studies employing TREC or its derivatives mostly focused on either convective or stratiform cases, not the mixed scenario that occurs with a TC. Furthermore, although the average extent of a TC's rainfall is 220-240 km on either side of its circulation center [30,31], it is generally considered that rainfall within a 500-km radius from a TC's eye is produced by the TC rather than another type of weather system [32]. This 500-km distance obviously exceeds the detection range of one radar station.…”