Update: As of 1400 hours CDT, Hurricane Harvey is now a Category 3 hurricane with 193 kph (120 mph) winds.
By: Robin Andrews/IFL Science Hurricane Harvey will make landfall in Texas later this Friday or early Saturday morning, and it’s set to be the most destructive in the last eleven years. Like all hurricanes, this one threatens both powerful winds, a storm surge, and intense rainfall – but Harvey is set to stand out from the crowd in the worst possible way.
Currently barreling towards the Lone Star State through the Gulf of Mexico, this beast is registering as a Category 2 (out of 5) hurricane right now, but it’s expected to build strength and become a Category 3 by the time it makes landfall, between Port O’Connor and Matagorda Bay.
To put this in perspective, the highly-damaging Hurricane Sandy that hit the eastern seaboard back in 2012 – and caused $75 billion in damages – was just a Category 1 when it made landfall in the US. This makes Harvey the first “major” hurricane to hit America since Hurricane Katrina back in 2005. For awhile, it looked as if it was going to be merely a tropical storm, but as it tracked across the gulf, it suddenly regenerated into something far more ominous.
— NWS Corpus Christi (@NWSCorpus) August 25, 2017
Tens of thousands of people have been evacuated, and over 30 Texas counties have been issued with disaster proclamations. Texan Governor Greg Abbot, in a statement, has announced that he is calling up 700 members of the National Guard, and that helicopters are being called in to fly people out of the most at-risk zones.
“I… do hereby certify that Tropical Depression Harvey poses a threat of imminent disaster,” he said.
Let’s take a look at the threats posed by Hurricane Harvey. First, its sustained peak wind strength is expected to be in the range of 178–208 kilometers per hour (111–129 miles per hour) when it makes landfall. Although these will clearly threaten the general public, particularly from flying debris, it’s a common misconception that the wind is the most dangerous component to a hurricane.
As we explain here, for the average hurricane, 400 times more energy goes into the cloud and rain formation than goes into producing those monstrous winds. By far, the precipitation and flooding are far more threatening.
— NWS Eastern Region (@NWSEastern) August 24, 2017
According to the National Hurricane Center (NHC), Harvey is expected to dump between 51 to 89 centimeters (20-35 inches) of rain on parts of Texas’ middle and upper coast. To compare, the normal annual precipitation in Houston is around 126 centimeters (50 inches), which means this hurricane could dump 71 percent of it over the next 24-36 hours.
The storm surge, however, is by far the worst threat here, as it almost always is when it comes to hurricanes. Created when the low atmospheric pressure allows the ocean to rise upwards and encouraged further by the strong winds, Harvey’s will be around 3.7 meters (12 feet) high – and it’s almost certain to claim some lives. All in all, the NHC says that some areas will “be uninhabitable for weeks or months.”
Kerry Emanuel, a professor of atmospheric science at the Massachusetts Institute of Technology, told BuzzFeed News that this storm surge will be like “having a tsunami arrive in the middle of a hurricane.”
As the storm continues to intensify, people are rushing to stores to purchase last-minute supplies before they hit the road; offshore oil platforms are being evacuated, and immigrants stuck in detention centers in the path of the hurricane are being moved.
— Eric Holthaus (@EricHolthaus) August 25, 2017
Although it can’t be directly attributed to the phenomena, it’s more than likely climate change has exacerbated Hurricane Harvey. The waters in the Gulf of Mexico are up to 4°C (7.2°F) higher than normal, and warm oceanic water is where hurricanes draw their strength. At the same time, sea level rise along the southeastern US is rising up to six times faster than average thanks to human activity. Ultimately, this will make storm surges far worse than they should be.
Although this hurricane is largely a natural event, we’re making it needlessly more dangerous. Whatever Harvey brings to the shores of Texas, then, should be seen as not an anomaly, but a harbinger of times to come.