This NOAA-NASA GOES Project satellite image shows storm activity off the south-east coast of the US.
This NOAA-NASA GOES Project satellite image shows storm activity off the south-east coast of the US.
Harvey intensified into a hurricane today and steered for the Texas coast with the potential for up to nearly one metre of rain, 200km/h winds and four-metre storm surges in what could be the fiercest hurricane to hit the United States in almost a dozen years.
Forecasters labelled Harvey a"life-threatening storm" that posed a "grave risk".
Millions of people braced for a prolonged battering that could swamp dozens of counties more than 160km inland.
Landfall was predicted for late Friday or early Saturday local time between Port O'Connor and Matagorda Bay, a 48km stretch of coastline about 70km north-east of Corpus Christi.
The region is mostly farm or ranchland dotted with waterfront holiday homes and has absorbed numerous Gulf of Mexico storms for generations.
Harvey grew unexpectedly quickly Thursday from a tropical depression into a Category 1 hurricane. Fuelled by warm Gulf waters, it was projected to become a major Category 3 hurricane. The last storm of that category to hit the US was Hurricane Wilma in October 2005 in Florida.
Superstorm Sandy, which pummelled New York and New Jersey in 2012, never had the high winds and had lost tropical status by the time it struck. But it was devastating without formally being called a major hurricane.
"We're forecasting continuing intensification right up until landfall," National Hurricane Centre spokesman Dennis Feltgen said.
Typical Category 3 storms damage small homes, topple large trees and destroy mobile homes. As in all hurricanes, the wall of water called a storm surge poses the greatest risk.
As of late Thursday afternoon, Harvey was about 490 kilometres south-east of Corpus Christi, moving to the north-northwest at about 17km/h. Sustained winds were clocked at 137km/h.
Harvey's effect would be broad. The hurricane centre said storm surges as much as one metre could be expected as far north as Morgan City, Louisiana, some 640km away from the anticipated landfall.
And once it comes ashore, the storm is expected to stall, dumping copious amounts of rain for days in areas like flood-prone Houston, the nation's fourth most-populous city, and San Antonio.
Raymond Durant, left, passes a sandbags to Delarentae Evans as Hurricane Harvey approaches the area on , in Corpus Christi, Texas. Photo / AP
National Weather Service Director Louis Uccellini said scientists were "looking at a potentially impactful storm over a two-, three-, four-day period."
Harvey grew unexpectedly quickly Thursday from a tropical depression into a Category 1 hurricane. Fuelled by warm Gulf waters, it was projected to become a major Category 3 hurricane. The last storm of that category to hit the US was Hurricane Wilma in October 2005 in Florida.
Superstorm Sandy, which pummelled New York and New Jersey in 2012, never had the high winds and had lost tropical status by the time it struck. But it was devastating without formally being called a major hurricane.
"We're forecasting continuing intensification right up until landfall," National Hurricane Centre spokesman Dennis Feltgen said.
Typical Category 3 storms damage small homes, topple large trees and destroy mobile homes. As in all hurricanes, the wall of water called a storm surge poses the greatest risk.
As of late Thursday afternoon, Harvey was about 490 kilometres south-east of Corpus Christi, moving to the north-northwest at about 17km/h. Sustained winds were clocked at 137km/h.
Harvey's effect would be broad. The hurricane centre said storm surges as much as one metre could be expected as far north as Morgan City, Louisiana, some 640km away from the anticipated landfall.
And once it comes ashore, the storm is expected to stall, dumping copious amounts of rain for days in areas like flood-prone Houston, the nation's fourth most-populous city, and San Antonio.
National Weather Service Director Louis Uccellini said scientists were "looking at a potentially impactful storm over a two-, three-, four-day period."
Aaron Berg fills up a gas can and his portable generator Thursday in Houston, as Hurricane Harvey intensifies in the Gulf of Mexico. Photo / AP
In Houston, one of the nation's most flood-prone cities, Bill Pennington was philosophical as he prepared his one-story home for what he expected would be its third invasion of floodwaters in as many years and the fifth since 1983.
"We know how to handle it. We'll handle it again," Pennington said he told his nervous nine-year-old son.
Dozens were in lines early Thursday at a Corpus Christi Sam's Club, at home improvement stores and supermarkets. The city also was passing out sandbags. Alex Garcia bought bottled water, bread and other basics in the Houston suburb of Sugar Land after dropping his daughter off at college. He said grocery items were likely more available in Houston than back home in Corpus Christi, where Garcia, a beer distributor salesman, said stores were "crazy."
A man uses a dolly help carry sandbags on the parking lot of the Brownsville Public Library Main Branch as residents of Brownsville, Texas, prepare for Hurricane Harvey. Photo / AP
Kim Fraleigh, of Sugar Land, stocked up with five cases of water, three bags of ice and other supplies at a supermarket.
"We've got chips, tuna, dry salami, anything that does not require refrigeration," she said.
Joey Garcia, director of the HEB store, said more than a semi-trailer load of water was sold Wednesday, and he expected to two more trailers on Thursday. In Galveston, where a 1900 hurricane went down as the worst in US history, City Manager Brian Maxwell said he was anticipating street flooding and higher than normal tides.
"Obviously being on an island, everybody around here is kind of used to it."
- Associated Press writers Frank Bajak in Houston; Seth Borenstein and Catherine Lucey in Washington; Diana Heidgerd, Jamie Stengle and David Warren in Dallas; and videographer John Mone in Sugar Land contributed to this story.
