Impact of Hurricane Helene: Rainfall and Flooding across the Southeast

Hurricane Helene made landfall as a Category 4 storm on September 27, 2024, causing catastrophic rainfall and flooding primarily in eastern Tennessee, western Virginia, and North Carolina. Asheville received 13.98 inches of rain, leading to evacuations and significant damage. The storm’s unusual rainfall patterns resulted in flooding even in areas receiving less precipitation. Emergency response efforts are being coordinated by NASA and FEMA to address the disaster’s impacts.

Hurricane Helene made a significant impact as it approached Florida’s Big Bend in late September 2024, ultimately making landfall as a Category 4 storm at 11:10 p.m. Eastern Time on September 27. Prior to landfall, the hurricane had already begun to produce severe consequences on land due to a preceding rain event that began affecting southern Appalachia on September 25. The resultant severe flooding was particularly damaging in eastern Tennessee, western Virginia, and North Carolina, among other affected regions. Data reflecting rainfall accumulation over a three-day period, which concluded at 7:59 p.m. Eastern Time on September 27, 2024, illustrates the extent of rainfall due to this hurricane. Such data, obtained from the Integrated Multi-Satellite Retrievals for GPM (IMERG), represent remotely-sensed estimates which may vary from measurements taken on the ground. Notably, rainfall averages across pixels may obscure areas where rain gauge measurements could be significantly higher or lower. In Asheville, North Carolina, the National Weather Service recorded an extraordinary total of 13.98 inches (35.52 centimeters) of rain from September 25 to September 27. The storm led to devastating floods that inundated neighborhoods, caused substantial road damage, triggered landslides, disrupted electricity and cell services, and necessitated the evacuation of numerous residents to temporary shelters. Moreover, several rivers within the state registered record flood crests, with preliminary rainfall totals approaching or exceeding 10 inches (25 centimeters) across parts of Georgia, North Carolina, South Carolina, Tennessee, and Virginia. On the Florida coast, the greatest rainfall occurred west of the hurricane’s center, particularly near the town of Apalachicola. This phenomenon diverges from the typical occurrence of heavy rainfall east of a storm center in Gulf hurricanes, which generally benefits from the counterclockwise motion drawing moisture from the Gulf. In Hurricane Helene’s case, the interaction between a frontal boundary in the Florida Panhandle and the storm’s circulation led to higher rainfall totals being reported to the west of its center, as noted by Steve Lang, a research meteorologist at NASA’s Goddard Space Flight Center. Despite receiving less rain, various coastal towns in Florida, including Cedar Key and Tampa, experienced flooding due to storm surge. The NASA Disasters Response Coordination System has been activated to assist agencies involved in the storm response, including FEMA and the Florida Division of Emergency Management. This team is expected to disseminate maps and data products through its open-access mapping portal, providing updated information concerning flooding, power outages, precipitation totals, and other pertinent topics.

Hurricane Helene represents a significant meteorological event, occurring as a result of complex interactions between tropical storm systems and frontal boundaries. The devastating rainfall produced by such hurricanes can lead to widespread flooding and infrastructural damage, particularly in coastal and mountainous regions where terrain may exacerbate flooding conditions. Understanding how these storms operate—especially in relation to rainfall patterns—allows meteorologists and responders to better predict and manage their impact. The collaboration of agencies like NASA, FEMA, and local emergency management is crucial in response and recovery efforts during such natural disasters.

In conclusion, Hurricane Helene’s landfall in Florida in September 2024 resulted in substantial rainfall and severe flooding across multiple states, particularly in the southern Appalachians. Asheville, North Carolina, recorded a staggering 13.98 inches of rain, leading to extensive damage and requiring evacuation measures. The unusual precipitation patterns observed with Helene underscored the importance of understanding storm dynamics in forecasting and mitigating disaster impacts. The ongoing collaboration among agencies and the use of advanced data collection methods will be integral in managing the aftermath of this significant weather event.

Original Source: earthobservatory.nasa.gov