Sheets said the hurricane's sustained winds would "certainly increase to 130, 140 miles per hour."
In the coastal resort of South Padre Island, about 25 miles southeast of Brownsville, the mayor ordered its 1000 residents to evacuate.
"We can't force them to leave, but it doesn't make any sense to stay," said Mayor Bob Pinkerton Jr., adding that water and electricity would be turned off yesterday afternoon.
Tropical storm force winds, at least 39 mph, extended outward up to 250 miles to the north and 200 miles to the south of the center.
The storm's first landfall earlier this week left at least 19 people dead in Jamaica, five in the Dominican Republic, 10 in Haiti and two in Mexico. It also left a half-million people homeless in Jamaica and caused widespread damage to the Cayman Islands.
The storm barreled into the Yucatan coast at dawn Wednesday, thrashing beaches with 23-foot waves, uprooting trees, knocking out electricity and water supplies and severing telephone lines.