Hurricane Helene: Catastrophic Rainfall and Flooding in 2024

Hurricane Helene made landfall as a Category 4 storm in fall 2024, resulting in extreme rainfall and flooding across southern Appalachia and surrounding areas, particularly affecting North Carolina and eastern Tennessee. The storm’s anomalously heavy rainfall distribution prompted emergency responses from agencies like FEMA, as significant impacts were observed across various regions, including Florida’s Gulf Coast.

In the fall of 2024, Hurricane Helene escalated as it neared Florida’s Big Bend, achieving Category 4 status upon landfall at 11:10 p.m. Eastern Time on September 27. Prior to making landfall, the hurricane initiated catastrophic impacts across various land regions while still over the Gulf of Mexico, resulting in significant rainfall in southern Appalachia beginning September 25, owing to preceding rain events and the storm itself. This led to severe flooding across eastern Tennessee, western Virginia, North Carolina, and several other areas. According to estimates derived from remote sensing technology via IMERG (the Integrated Multi-Satellite Retrievals for GPM), the rainfall accumulation during the three days leading up to September 27 reached alarming levels. While these estimates are informed by satellite data, significant discrepancies can occur between these figures and on-the-ground measurements, as IMERG averages rainfall across each pixel, potentially overshadowing local extremes. In Asheville, North Carolina, rainfall amounted to a staggering 13.98 inches (35.52 centimeters) throughout the event, subsequently confirmed by the National Weather Service. The overwhelming precipitation resulted in flooded neighborhoods, impaired infrastructure, landslides, outages of electricity and telecommunications, and necessitated the evacuation of residents to temporary shelters. The state witnessed record-high flood crests on numerous rivers, with preliminary rainfall totals nearing or surpassing 10 inches (25 centimeters) across parts of Georgia, North Carolina, South Carolina, Tennessee, and Virginia. On Florida’s coast, the most substantial rainfall was paradoxically concentrated west of the hurricane’s center, particularly in Apalachicola. Typically, during Gulf storms, the heaviest rain affects the eastern regions due to counterclockwise rotation, which brings moisture from the ocean. However, as mentioned by Steve Lang, a research meteorologist at NASA’s Goddard Space Flight Center, a frontal boundary over the Florida Panhandle interacted with the hurricane’s circulation, redirecting the heaviest rain westward. Moreover, coastal areas in Florida that received less rainfall were not immune to flooding, as several Gulf Coast cities, including Cedar Key and Tampa, experienced the adverse effects of the storm surge. The NASA Disasters Response Coordination System has been activated to assist organizations responding to the storm, including FEMA and the Florida Division of Emergency Management. The team is committed to disseminating maps and data products through its open-access mapping portal as updates on flooding, power outages, rainfall totals, and other relevant matters become available. The information provided is based on NASA Earth Observatory imagery by Lauren Dauphin and utilizes IMERG data from the Global Precipitation Mission (GPM) at NASA’s Goddard Space Flight Center, within the context of the accompanying story authored by Lindsey Doermann.

Hurricane Helene emerged as a significant weather event, showcasing the devastating effects of tropical storms on the eastern United States, particularly in 2024. Understanding hurricanes, including their formation, trajectory, and impact, underlines the importance of monitoring rainfall accumulation and its subsequent effects, such as flooding and infrastructure damage. Analysis of storm patterns highlights both expected behaviors and anomalies, as seen in Helene’s rainfall distribution. This context is crucial for developing responses to natural disasters and coordinating relief efforts adequately.

In summary, Hurricane Helene’s landfall resulted in unprecedented rainfall and flooding across southern Appalachia and the Florida coast, leading to widespread destruction and necessitating emergency responses from federal and state agencies. The heavy rains recorded in Asheville and other regions underscore the need for effective disaster preparedness and response strategies. Furthermore, the peculiar distribution of rainfall associated with Helene illustrates the complexities of hurricane behavior, necessitating continuous monitoring and understanding of storm dynamics.

Original Source: earthobservatory.nasa.gov