VERACRUZ, Mexico - Tropical Storm Helene formed just offshore in the southwestern Gulf of Mexico on Friday, threatening coastal areas of eastern Mexico where thousands of people are still recovering from flooding spawned by Hurricane Ernesto.

The National Hurricane Center said aircraft found the tropical storm about 90 miles (145 kilometers) east-southeast of Tuxpan. It had maximum sustained winds of 45 mph and was moving northwest at 7 mph (11 kph).

The storm's center was expected to make landfall Saturday in the northern part of Veracruz, a lush coastal state with hundreds of towns and villages sitting along streams and rivers that can swell dangerously in heavy rain. Many were evacuated during Ernesto, which hit last week.

Mexico's government declared a state of emergency in more than 100 population centers in Veracruz and was providing them with emergency aid. The hurricane center said Mexico had issued a tropical storm warning along the Gulf coast from Barra de Nautla to La Cruz.

Helene was predicted to bring 5 to 10 inches of rain, with as many as 15 inches across northeastern portions of Mexico. A storm surge could raise water levels by as much as 1 to 2 feet above normal along the immediate coast and to the north of where landfall is made. Heavy rain was expected in the city of Tampico, an oil-refining center and important port in the southernmost part of Tamaulipas state.

Meanwhile, Portugal issued a tropical storm watch for the central and eastern Azores islands as Tropical Storm Gordon moved eastward.