Hurricane Florence made landfall in North Carolina early on September 14 with Category 1 winds, but its biggest impact has been the flooding left in its wake [1]. From September 13 to 18, Florence stalled over the state, unleashing record-breaking rainfall on the Coastal Plain from New Bern, North Carolina to Florence, South Carolina [2]. Inland flooding has been extensive in both states, affecting towns more than 100 miles from the coast and resulting in closed roads, loss of life, damages in the billions, and the prolonged displacement of people evacuated ahead of the storm.
AER’s FloodScan system has been mapping the flooding daily since September 17 when rain bands began to clear, allowing observations of surface conditions [3]. FloodScan uses data from passive microwave satellite sensors to penetrate clouds and vegetation and measure large-area flooded fraction in close to real time. A relative floodability database transforms flooded fraction into a depiction of flood extent at 90-meter resolution, accounting for topography, streamlines, and land cover.
The images below show FloodScan’s maximum flood extent maps from satellite observations spanning September 17, 18, and 19. The larger map shows the entire affected area, revealing how widespread the flooding has been. The other two maps focus on the heavily affected areas around Wilmington, Fayetteville, and Lumberton, North Carolina. The entire area is crisscrossed by woody wetlands – under normal conditions capable of absorbing and carrying away excess rainfall but now overwhelmed by the volume of water from Florence. Roads are indicated by thin red lines. Zooming in on the Wilmington area makes it clear how difficult it has been to find an unflooded route in or out of the city all week.
Image 1, AER maxFlood Florence, large area: 
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Image 2, AER maxFlood Florence, Fayettville-Lumberton focus area: 
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Image 3, AER maxFlood Florence, Wilmington focus area: 
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