By 6 a.m. ET Tuesday, Irma was about 65 miles southwest of Atlanta. Its top winds were down to 25 mph, and it was charging across the Southeast toward Tennessee and the Ohio Valley as a nasty thunderstorm system. The National Hurricane Center reclassified it as a tropical depression and canceled all tropical storm warnings late Monday.
Still, Irma was producing heavy rain across the Southeast, leading to flash floods and rapid rises in creeks, streams and rivers. The hurricane center said that significant river flooding would persist over the Florida peninsula for several days and that parts of Georgia, South Carolina and north-central Alabama remained vulnerable to flash floods.
In Irma's wake, meanwhile, lay a trail of devastation from the Cape Verde Islands to Georgia.
Irma was a full-fledged hurricane in less than 24 hours. It was so strong and so robust that it seemingly set a record for the number of records it set.
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According to Phil Klotzbach, a noted atmospheric research scientist at Colorado State University:
When Irma reached Category 5 — the strongest there is — it stayed there for more than three days, the longest run since forecasters began using satellites to monitor tropical storms more than a half-century ago.
Irma blew 185-mph maximum sustained winds for 37 hours — the longest at that intensity anywhere on Earth since records started being kept.
Irma generated the most accumulated energy of any tropical cyclone in the Atlantic tropics on record.
But if there's one statistic that sums Irma up, it's this one: It generated enough accumulated cyclone energy — the total wind energy generated over a storm's lifetime — to meet the National Oceanic and Atmospheric Administration's definition of an average full Atlantic hurricane season. By itself, it was more powerful than 18 of the 51 full hurricane seasons since 1966, according to Klotzbach's calculations (PDF).
After 12.75 days as a named storm, #Irma has weakened to a tropical depression - the longest-lived Atlantic named storm since Nicole (2016). pic.twitter.com/8rlvFJinAw
"The next couple of days and couple of weeks — probably months, in a lot of spots — are going to be very busy for a lot of people rebuilding," Ari Sarsalari, a meteorologist for The Weather Channel, said Monday night.
Irma is confirmed to have killed 10 people in the United States so far: four in the U.S. Virgin Islands, three in Puerto Rico, two in Georgia and one in Florida.
About 7.5 million customers remained without power in Florida late Monday. Almost 1½ million had no power in Georgia, which experienced the oddity of tropical storm warnings over Atlanta, more than 800 miles from where Irma made its first U.S. landfall.
"This will be the largest-ever mobilization of [electric] line restoration workers in this country, period, end of story," Tom Bossert, President Donald Trump's homeland security adviser, told reporters Monday.
Irma killed 10 people in Cuba, eight on the French-Dutch island of St. Martin and St. Maarten, five in the French Caribbean territories, four in the British Virgin Islands and one each on Anguilla and Barbuda.
Nine out of 10 government and business structures on Anguilla were estimated to have been damaged or destroyed. The French government estimated damage at almost $1.5 billion just on St. Bart’s and St. Martin. The prime minister of Antigua and Barbuda, Gaston Browne, described his country as "barely habitable," saying 90 percent of all vehicles and buildings had been damaged.
The U.S. military spread far and wide in what Bossert called "the largest-ever mobilization of our military in a naval and marine operation."
"We have the largest flotilla operation in our nation's history to help not only the people of Puerto Rico, the people of the U.S. Virgin Islands, but also St. Martin and other non-U.S. islands affected," he said.
Moody's Analytics, the research arm of the financial services giant Moody's Corp., estimated Monday that Irma would end up having caused $64 billion to $92 billion of damage in the United States. It stressed that that was just a preliminary estimate.