Abstract

Despite being far from the coast, intense rainfall from tropical cyclones is known to cause flash flooding and landslides in Western North Carolina (WNC). A study was conducted to investigate tropical cyclones in WNC during the period 2009-2019 and determine what synoptic and mesoscale features increase the risk of landslides and floods from these events in the Pigeon River Basin (PRB). A case study of two meteorologically similar storms with vastly different surface responses was chosen to begin to answer this question. Both storms tracked west of the Appalachians and reported the same rainfall in the PRB, but Tropical Storm Alberto in May 2018 caused multiple landslides that resulted in two deaths in WNC while Hurricane Nate in October 2017 resulted in no direct effects. To understand why these events had such different consequences, three aspects were analyzed: the preconditioning of the soil from previous precipitation events, the 500 hPa steering flow, and the flow of moisture at 850 hPa. Despite initial analyses indicating otherwise, the difference in moisture flow between Nate and Alberto was not significant enough to suggest that was the reason for their different impacts. Alberto occurred during a prolonged period of anomalous precipitation and was a longer event while Nate was a shorter event that occurred in a relatively dry period.

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