Though Harvey made landfall as a category 4 hurricane on August 25th, it’s still dangerous despite its downgrade to a tropical storm. The worry isn’t the winds — which are how hurricanes are categorized — but the rain. The storm is expected to continue dumping rain across southeast Texas, and its heaviest rains haven’t yet hit the state.
“We think the heaviest rainfall will be today and tomorrow,” says Dan Petersen, a forecaster with the Weather Prediction Center. Another 15 to 25 inches of rain will fall across coastal areas of southeast Texas, including over Houston, and southwestern Louisiana, Petersen tells The Verge. Some areas could see as much as 50 inches of rain — or about four feet.
Rivers in the area will reach “major to record flooding,” Petersen says. “Some of these rivers will reach the highest levels they’ve ever been observed to reach.” That means that it will take at least a week or two for the flood water to subside and the rivers to go down, Petersen says.
Harvey has stalled over land for the last two days, dropping heavy rain on Texas. But the storm is expected to move over the Gulf of Mexico later tonight and tomorrow, Petersen says. Warm waters fuel hurricanes, so there’s a “remote possibility” that the tropical storm will regain some strength and turn into a hurricane again, he says. “It’s something we’ll be watching.”
By midweek, Harvey is expected to reach southwest Louisiana, dumping several inches of rain over New Orleans. Because the city’s pumping and drainage system has recently failed, cutting its pump capacity by half, there could be flooding there, and that’s something that the Weather Prediction Center is going to be monitoring closely, Petersen says. The storm will then move northeast and reach Arkansas by Friday, where it will wind down over the weekend.
Harvey has been called “unprecedented” by the National Weather Service, and it may match 2005’s Hurricane Katrina as the costliest natural disaster in US history.