Hurricane Irma: This monster storm is perfect in the most alarming ways
(Note: This post will be updated throughout the day as more forecast information becomes available.)
Hurricane Irma became one of the strongest hurricanes on record in the Atlantic basin on Tuesday, when it reached high-end Category 5 intensity, with maximum sustained winds of 185 miles per hour. Meteorologists are marveling at the storm's presentation on satellite imagery, as it's as close to a textbook definition of an intense hurricane as one could get.
These same forecasters, namely those at the National Hurricane Center in Miami, are raising alarm bells that anywhere from the eastern Gulf Coast to portions of the East Coast, particularly Florida, could see major impacts from Hurricane Irma by this weekend.
According to the Hurricane Center, Irma is the strongest hurricane in the Atlantic basin history to occur outside of the Caribbean Sea or Gulf of Mexico, which is where Category 5 monster hurricanes typically spin up.
The storm is now tied for second on the list of Atlantic hurricanes ranked by wind speed. Hurricane Wilma in 2005 was the most recent Atlantic storm to tie Irma, with maximum sustained winds of 185 miles per hour at its peak. The all-time record for strongest winds in an Atlantic hurricane is 190 miles per hour, measured in Hurricane Allen in 1980. Hurricane Irma could tie or beat that.
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Such an intense storm could cause "catastrophic" impacts wherever it makes landfall, according to the Hurricane Center. On Tuesday, Hurricane Irma is roaring toward a potentially devastating encounter with the northern Lesser Antilles on Tuesday, including popular vacation spots like Antigua, Anguilla, Barbuda, Montserrat, St. John's, and St. Kitts and Nevis. Some of these islands may see their strongest hurricane on record.
Hurricane warnings are also up for the British and U.S. Virgin Islands, as well as Puerto Rico. The U.S. Virgin Islands and Puerto Rico will be the first parts of the U.S. to see direct and damaging impacts from this storm.
Any location that gets into the eye wall of Hurricane Irma, where the strongest winds and heaviest rains are located, will see potentially catastrophic damage from wind gusts greater than 200 miles per hour, as well as storm surge flooding of nearly 20 feet above normal high tide levels in some areas. The southeastern Bahamas and the Turks and Caicos, in particular, are forecast to see potentially devastating amounts of storm surge flooding from this storm.
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However, the storm is so large that its impacts will be felt over a wide area outside the center. For example, its swath of hurricane-force winds extends out to a diameter greater than the width of Florida, according to Weather Channel meteorologist Bryan Norcross, who saw South Florida through Category 5 Hurricane Andrew in 1992 as a television meteorologist in Miami.
The center of Hurricane Irma is forecast to move west-northwest for the next five days. Such a track would take it just north of Puerto Rico and Hispaniola.
From there, though, the track is less certain. The storm may meander into the mountainous island of Cuba, in which case it would weaken some, before slowing down and making a northerly turn. Where that turn takes place is the big question facing forecasters and tens of millions of Americans who might be in harm's way.
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The most likely landfall location in the mainland U.S., if any, appears to be Florida, either on the west coast, southern tip, or east coast of the state. Since the storm is so large, the state could be severely affected regardless of the track of the storm's center.
Other than a track over Cuba and Hispaniola, there are no barriers to Hurricane Irma maintaining Category 3, 4, or 5 intensity for the next five days, according to computer model guidance and other indicators. The storm has already maintained "major" hurricane intensity for more than three days, a remarkable feat in itself.
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Typically, storms encounter environments that no longer support such extreme intensities, such as cooler ocean waters or strong upper level winds that tear their inner cores apart. However, Irma has ample warm water ahead of it, weak upper level winds, and is otherwise in an environment favorable to continued high intensity.
The ocean temperatures across the Caribbean and near Florida in particular are extremely mild, with enough ocean heat content to support a powerful major hurricane like Irma.
The storm's ultimate path depends heavily on weather systems far removed from the tropics, namely a dip in the jet stream across the Northeast and an upper level weather system forecast to dive southeast from the Midwest late this week.
Computer model guidance shows that the upper level system may pick up the storm and turn it to the north, into Florida. However, models disagree on where exactly that northerly turn will take place, and since this will determine the severity and types of impacts that Florida and other parts of the U.S. experience, there remains quite a bit of uncertainty to the long range track and intensity forecast.
The bottom line is that the likelihood of a landfalling major hurricane in the Southeast U.S. during the next week is growing, and residents of Florida and other nearby states should start preparing. The potential damage from Hurricane Irma could be enormously high if it were to strike built-up portions of the Florida coastline as a major hurricane, coming right after Hurricane Harvey, which is likely to be ranked the most expensive hurricane in U.S. history.
Andrew Freedman is Mashable's Senior Editor for Science and Special Projects. Prior to working at Mashable, Freedman was a Senior Science writer for Climate Central. He has also worked as a reporter for Congressional Quarterly and Greenwire/E&E Daily. His writing has also appeared in the Washington Post, online at The Weather Channel, and washingtonpost.com, where he wrote a weekly climate science column for the "Capital Weather Gang" blog. He has provided commentary on climate science and policy for Sky News, CBC Radio, NPR, Al Jazeera, Sirius XM Radio, PBS NewsHour, and other national and international outlets. He holds a Masters in Climate and Society from Columbia University, and a Masters in Law and Diplomacy from The Fletcher School at Tufts University.
