MEXICO CITY, Sept 1 (Reuters) - Tropical Storm Henriette brushed past Mexico's Pacific coast on Saturday, threatening to cause mudslides and flash floods before moving out to sea, where it was expected to become a hurricane.

A hurricane watch from the busy port of Manzanillo to Cabo Corrientes, near the beach resort of Puerto Vallarta, was called off although a tropical storm warning remained on some parts of the coast.

After dumping rain and flooding streets in the Acapulco beach resort on Friday, Henriette was beginning to push away from Mexico's Pacific coast and was expected to strengthen, the U.S. National Hurricane Center said.

"Henriette is forecast to become a hurricane in a day or so," the center said.

On Saturday morning, the center of the storm was about 85 miles (135 km) south of the Manzanillo, moving northwest with maximum sustained winds of some 50 mph (85 kmph) with higher gusts, the hurricane center said.

Henriette is expected to pass more than 100 miles (160 km) off the southern coast of the Baja California peninsula on Monday, according to the Miami-based center.

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