Hurricane Harvey is spinning into potentially the biggest storm to hit the US mainland in more than a decade, with life-threatening floods expected along the Gulf Coast.
Harvey has grown into a category 2 storm with winds of 169 kph as it moved northwest about 355 km off Corpus Christi, Texas, the National Hurricane Centre said in an advisory. It's forecast to make landfall late on Friday or early Saturday.
Up to 97 cm of rain is expected over parts of Texas, with winds up to 125 mph, and sea levels could surge as high as 3.7 metres. Flood warnings are in effect for Louisiana and northern Mexico.
"Life-threatening and devastating flooding" was expected near the coast due to heavy rainfall and storm surge, the hurricane centre said.
The storm's approach triggered evacuations and cancelled the first day of school in communities along the south Texas coast, which is home to 5.8 million people from Corpus Christi to Galveston.
Energy companies shut coastal refineries, pulled workers from offshore oil platforms in the Gulf of Mexico and halted onshore drilling in south Texas on Thursday. By midday, just under 10 per cent of offshore US Gulf of Mexico crude output capacity and nearly 15 per cent of natural gas production had been halted, government data showed.
Louisiana and Texas have declared states of disaster, authorising the use of state resources to prepare for the storm.
Harvey is forecast to come ashore as a Category 3 hurricane, the US National Hurricane Centre said, the third most powerful on the Saffir-Simpson scale.
That would make it the first major hurricane to hit the mainland United States since Hurricane Wilma struck Florida in 2005.
