urricane Helene made a powerful impact in the fall of 2024, intensifying to a Category 4 storm as it approached Florida's Big Bend region. The hurricane made landfall at 11:10 p.m. Eastern Time on September 27, unleashing a torrent of destruction both along the coast and far inland. While still over the Gulf of Mexico, the storm's effects began to manifest on land, triggering severe flooding in southern Appalachia well before its actual arrival.
As Hurricane Helene moved toward Florida, it caused heavy rainfall starting on September 25, significantly affecting areas in eastern Tennessee, western Virginia, and North Carolina. The initial downpour, known as a "predecessor rain event," compounded with the hurricane's main rain bands, resulting in catastrophic flooding across the region.
Data from the Integrated Multi-Satellite Retrievals for GPM (IMERG), a product of the Global Precipitation Measurement (GPM) mission, revealed the extent of rainfall accumulation over a three-day period ending at 7:59 p.m. Eastern Time on September 27. These satellite-based estimates help provide a broader picture of the rainfall distribution, although they may differ from localized ground measurements. IMERG data averages rainfall across each pixel, which can mean actual rainfall in specific areas could be higher or lower than what the data suggests.
The hurricane's impact was particularly severe in Asheville, North Carolina, where a staggering 13.98 inches (35.52 centimeters) of rain fell between September 25 and 27, as recorded by the National Weather Service. This intense rainfall swamped neighborhoods, damaged roads, caused landslides, disrupted power and cell services, and forced numerous residents to evacuate to temporary shelters. Several rivers in the region experienced record-breaking flood crests, compounding the devastation.
Flooding extended beyond Asheville, with rainfall totals nearing or exceeding 10 inches (25 centimeters) across parts of Georgia, North Carolina, South Carolina, Tennessee, and Virginia. The widespread nature of the flooding emphasized the storm's far-reaching impacts beyond its initial landfall in Florida.
On Florida’s coast, the heaviest rainfall was concentrated west of the hurricane's center, particularly around the town of Apalachicola. Interestingly, hurricanes in the Gulf typically bring the most rainfall to the east of their center due to the counterclockwise rotation that draws moisture from the Gulf of Mexico. However, in Helene's case, a frontal boundary over the Florida Panhandle interacted with the storm's circulation, concentrating the heaviest rainfall to the west.
Despite receiving less rain, other parts of Florida's coast were not spared from the storm's wrath. Storm surges caused significant flooding in Gulf Coast cities and towns, including Cedar Key and Tampa, illustrating the multifaceted dangers posed by hurricanes.
In response to Hurricane Helene, NASA's Disasters Response Coordination System was activated to support the storm response efforts by agencies such as FEMA and the Florida Division of Emergency Management. NASA's team is actively providing maps and data products through its open-access mapping portal, which includes updated information on flooding, power outages, and precipitation totals. These resources are critical for coordinating relief efforts and mitigating the impact of the storm's aftermath.
Hurricane Helene's landfall in fall 2024 serves as a stark reminder of the potential devastation caused by intense storms. The hurricane not only battered Florida's Big Bend with severe winds and storm surges but also brought heavy rainfall and flooding to areas far from its center. The widespread destruction in the southern Appalachians and along the Gulf Coast underscores the importance of advanced forecasting, coordinated emergency responses, and continued research to better understand and manage the impacts of such natural disasters in the future.
Data: https://earthobservatory.nasa.gov/images/153387/devastating-rainfall-from-hurricane-helene, 02/10/2024
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