MIAMI (AP) — Tropical Storm Erick formed early Tuesday near southern Mexico in the Pacific Ocean and is expected to become a hurricane on Wednesday, the U.S. National Hurricane Center said.

The storm was about 430 miles (692 kilometers) southeast of Punta Maldonado, Mexico, with maximum sustained winds of 40 mph (64 kph), the Miami-based center said. It was forecast to approach the coast by late Wednesday.

Erick was moving west-northwest at 12 mph (19 kph).

A hurricane watch was posted for a stretch of the Pacific coast from Bahia De Huatulco in Oaxaca state to Punta Maldonado. A hurricane watch means hurricane conditions with winds exceeding 74 mph (119 kph) are possible in the area within two days.

A tropical storm watch was in effect further south from Salina Cruz to Bahia De Huatulco.

Heavy rainfall was forecast for parts of Oaxaca and Guerrero with lighter amounts in Chiapas, Tabasco and Veracruz states as well as parts of El Salvador and Guatemala.

The rainfall may produce flooding and mudslides, the center said, and storm surge could produce coastal flooding.