Tropical Storm Dolly intensified over the warm waters of the western Gulf of Mexico as it bore down on southern Texas on Tuesday, but forecasters don't expect it to reach catastrophic strength before hitting land near the Mexican border on Wednesday.
The storm, with sustained winds of nearly 70 miles per hour (110 km per hour), emerged from the Yucatan Peninsula over the warm waters of the Gulf of Mexico. A hurricane watch was issued for the southern Texas coast, the US National Hurricane Center said.
At 11 am EDT (1500 GMT), Dolly was 230 miles (370 km) south-east of the border town of Brownsville, Texas, where it is due to come ashore on Wednesday as a low-grade hurricane. The storm's predicted landfall and strength are unlikely to jeopardise sensitive offshore drilling rigs and production platforms in the US and Mexican waters of the Gulf of Mexico. US crude oil prices on Tuesday fell over $4 a barrel.
The United States has largely escaped the past two Atlantic hurricane seasons, with just one hurricane - Humberto in November 2007 - making landfall on its coasts. But it was pummelled in 2004 and 2005, when a series of powerful hurricanes, including the catastrophic Katrina, ravaged Florida and the US Gulf Coast.
The National Hurricane Center said Dolly is unlikely to become a major hurricane prior to landfall, but could dump as much as 15 inches (38 cm) of rain on South Texas and north-eastern Mexico in coming days. The 2008 Atlantic hurricane season is already a month ahead of schedule, but is unluntil August 29. Dolly, this year's fourth, formed on July 20. In Texas, Governor Rick Perry put 1,200 National Guard troops on alert, and told citizens to take precautions, although no mandatory evacuations were ordered.
In Mexico, Dolly had dumped rain in the popular resort of Cancun in the Yucatan Peninsula, but no major damage was reported. The north-eastern state of Tamaulipas on Mexico's Gulf Coast issued a hurricane warning and began preparing dozens of buildings to receive possible evacuees.