As Tropical Storm Harvey strengthened in the Gulf of Mexico, the National Hurricane Center has issued a hurricane warning for a 280-mile stretch of the Texas coast Thursday and forecast up to 25 inches of rain over the next week.

The warning covers an area from Port Mansfield in the central coastal area to Matagorda at the tip near the Mexican border.

The forecast track shows Harvey strengthening to a hurricane — meaning sustained winds of 74 mph or higher — late Thursday as it treks across the Gulf, making landfall along the southern Texas coast Friday evening or Friday night.

As of 5 a.m. EDT, the storm was centered about 370 miles southeast of Port Mansfield and was moving north near 10 mph.

The storm’s maximum sustained winds had increased to near 45 mph (70 kph). The U.S. National Hurricane Center said additional strengthening was expected and Harvey could become a hurricane by Friday, when it’s expected to approach the southern Texas coast.

A hurricane watch was in effect for Texas from Port Mansfield to San Luis Pass. A storm surge watch was in effect from Port Mansfield to High Island. Forecasters said the storm surge could be from 5 to 7 feet from Port Mansfield to San Luis Pass.

Texas Gov. Greg Abbott has ordered the State Operations Center to raise its readiness level, making state resources available for possible rescue and recovery actions. The governor also pre-emptively declared a state of disaster for 30 counties on or near the coast to speed deployment of state resources to any affected areas.

Emergency officials have urged residents along the upper Texas coastline to move or prepare to move inland. Those in low-lying areas should seek higher ground, officials said.

On South Padre Island, people filled sandbags and loaded them into cars and vans Wednesday to take to protect exposed homes and businesses. Others in the forecast path of the storm sought out generators, plywood and other goods from hardware stores. Meanwhile, rice farmers in coastal Matagorda County moved quickly to harvest their crops.

Contributing: Associated Press