(Recasts throughout to reflect dual storms, adds details)
MEXICO CITY, Sept 2 (Reuters) - Two separate tropical storms closed in on Mexico from both the Pacific and Atlantic Oceans on Tuesday, risking a double hit on the country a year after a pair of storms converged to cause major flooding that killed over 100 people.
Tropical Storm Dolly, which formed in the southern Gulf of Mexico early Tuesday, is likely to strengthen slightly in the next 24 hours until it reaches the mainland, the U.S. National Hurricane Center (NHC) said.
The severe weather has already forced the closure of two of the major crude oil export terminals used by Mexican state-run oil company Pemex.
The Cayo Arcas port had been shut since Sunday afternoon while the Dos Bocas hub was closed early on Monday, the Communications and Transport Ministry said.
Mexico’s third major oil export terminal at Coatzacoalcos remained open.
Meanwhile, Tropical Storm Norbert formed on Tuesday off southwestern Mexico, and is about 180 miles (285 km) southwest of the major Pacific port of Manzanillo, the NHC said.
Norbert is churning north-northeast at 14 miles per hour (22 km per hour), but the government has yet to issue any coastal watches or warnings. Norbert is blowing maximum sustained winds of 40 mph, and the NHC expected it to strengthen over the next 48 hours.
Mexico suffered its worst floods on record last September when tropical storms Manuel and Ingrid converged from the Pacific and the Gulf of Mexico, killing more than 150 people and causing damage estimated at around $6 billion.
Dolly, the fourth named storm of the 2014 Atlantic hurricane season, was about 85 miles (140 km) east of La Pesca in northeastern Tamaulipas state.
Dolly was blowing maximum sustained winds of 50 mph (85 km/h) and moving west-northwest at 16 mph (26 km/h). A tropical storm warning is in effect between Cabo Rojo in eastern Veracruz state south to Barra El Mezquital in Tamaulipas.
“The center (of Dolly) will be near the coast of Mexico within the warning area by this evening and move inland by overnight,” the Miami-based agency said.
The storm is expected to produce rainfall of between 5 to 10 inches across much of Tamaulipas, Nuevo Leon, Veracruz and San Luis Potosí states through Wednesday evening.
The rainfall is expected to cause life-threatening flash floods and mudslides in mountainous areas, the NHC said. (Reporting by David Alire Garcia in Mexico City and Debasis Mohapatra in Bangalore)