MEXICO CITY (Reuters) - Tropical Storm Ernesto weakened as it neared the coast of Mexico on Thursday, sending wind gusts and showers across the state of Veracruz, home to some of Mexico's busiest ports and oil installations.
The storm's maximum sustained wind strength dropped to 60 mph and it was drifting slowly just off the coast, 5 miles east of Coatzacoalcos, the U.S. National Hurricane Center in Miami said in its 11 a.m. EDT (1500 GMT) advisory.
Mexico's government downgraded a hurricane warning for the coast of Veracruz to a tropical storm warning and the NHC said further weakening was expected as Ernesto moved over mountainous terrain on the mainland.
There were no reports of disruptions to state-run oil company Pemex's facilities in the south of the Gulf of Mexico, which include the Minatitlan refinery, producing 185,000 barrels of crude per day.
The eye of the storm had passed the oilfields of Cantarell and Ku Maloob Zaap, which account for just over half of Mexico's oil production of about 2.5 million bpd.
Coatzacoalcos is home to one of Mexico's key oil exporting ports, which has been closed since Wednesday along with Cayo Arcas and Dos Bocas. Almost all of Mexico's crude oil exports, which totaled 1.425 million bpd in June, are shipped to refineries on the Gulf Coast of the United States from the three ports.
Authorities in Veracruz said they were preparing emergency shelters, if needed, in the flood-prone and densely populated state. The small Mina-Coatza airport, between Minatitlan and Coatzacoalcos, was closed on Thursday and waves of 13-20 feet were reported along the coast.
Ernesto is forecast to plow through Veracruz state and into central Mexico on Friday as a tropical depression.
The storm had made landfall on Mexico's Yucatan coast late Tuesday as a Category 1 hurricane, the lowest on the five-step Saffir-Simpson scale, before being downgraded to a tropical storm Wednesday.
The storm had spared major tourist areas on the peninsula from a direct hit and landed in sparsely populated low-lying jungle, near the port town of Mahahual, 40 miles north of Chetumal, the capital of Quintana Roo state. Ernesto passed well south of the major tourist resort of Cancun, which saw only heavy rains.
About 2,500 people were evacuated from Chetumal up the coast to Tulum in an area known for its scuba diving and eco-tourism attractions.
Rainfall of 5 to 10 inches, and possibly 15 inches in some areas, was expected in the states of Tabasco, Veracruz, Puebla and northern Oaxaca through Friday, the center said.
August and September are usually the most active months of the Atlantic-Caribbean hurricane season, which runs from June 1 to November 30.
(Reporting by Ioan Grillo and Krista Hughes; Editing by Vicki Allen)
