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Irma Heads North, Downgraded to a Tropical Storm

NASA's GOES-16 satellite shows Hurricane Irma over Florida, in an image captured at 12:30 UTC on September 11, 2017. (Image credit: NASA/NOAA)

Irma, which recently weakened to a tropical storm, is still producing some wind gusts that are close to hurricane strength as it continues to move inland over northern Florida and toward Georgia.

But Irma's maximum sustained winds have dropped to around 70 mph (110 km/h), and the storm is expected to weaken further and become a tropical depression — with maximum sustained winds of 38 mph (62 km/h) or less — by Tuesday afternoon (Sept. 12), the National Hurricane Center (NHC) reported.

Now traveling at 18 mph (30 km/h), Irma is predicted to cross into southern Georgia this afternoon (Sept. 11) and head over Georgia and into Alabama through tomorrow, according to the NHC. [Hurricane Irma: Everything You Need to Know About This Monster Storm]

Irma's size means that hurricane-strength winds can extend up to 60 miles (95 kilometers) from the storm's eye, while winds at tropical-storm strength can reach more than 415 miles (665 km) from Irma's center, the NHC said.

Though Irma's time as a hurricane is done, the storm spent more than 11 days at hurricane strength, more than any other storm since Hurricane Ivan in 2004. Irma also spent the ninth-most days at hurricane strength since satellite observation of storms began in 1966, Philip Klotzbach, a meteorologist with Colorado State University, wrote in a tweet.

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Irma's powerful winds have left more than 6 million people without electricity, representing approximately 62 percent of Florida's population, the Florida Division of Emergency Management reported. More than 800,000 of those people are in the Miami-Dade County area, about 600,000 are in Broward County and more than 500,000 are in Palm Beach County, according to the report.

Bands of rain will continue to drench the region, with up to 3 inches (8 centimeters) of rainfall expected in central Florida, and as much as 6 inches (15 cm) predicted for northern Florida.

Strong winds, storm surges and floods are also still major concerns in Florida today. In Jacksonville, the St. Johns River (which floods at a height of 2 feet (0.6 meters), has already risen to more than 5 feet (1.5 m), exceeding the prior record of 4.1 feet (1.2 m), according to the National Weather Service. Storm surges along the coast could reach up to 6 feet (2 m) if the timing of the surge coincides with high tide, the NHC reported.

Original article on Live Science.

Mindy Weisberger
Mindy Weisberger is a senior writer for Live Science covering general science topics, especially those relating to brains, bodies, and behaviors in humans and other animals — living and extinct. Mindy studied filmmaking at Columbia University; her videos about dinosaurs, biodiversity, human origins, evolution, and astrophysics appear in the American Museum of Natural History, on YouTube, and in museums and science centers worldwide. Follow Mindy on Twitter.