MIAMI (AP) — Tropical Storm Joaquin is strengthening in the Atlantic and is expected to become a hurricane.

The U.S. National Hurricane Center in Miami said the storm was centered about 360 miles (580 kilometers) east of the northwestern Bahamas Tuesday night and was moving west-southwest at 5 mph (7 kph). Its maximum sustained winds were 70 mph (110 kph).

Forecasters say further strengthening is expected and Joaquin could be upgraded late Tuesday night or Wednesday. A hurricane watch is in effect for the Central Bahamas.

Meanwhile, in the Pacific, Tropical Storm Marty was nearly stationary off Mexico’s Pacific coast.

Marty was centered about 100 miles (160 kilometers) south-southeast of Zihuatanejo, Mexico, with maximum sustained winds of 50 mph (85 kph). A turn to the west or west-northwest was expected later Tuesday. A tropical storm warning is in effect for Mexico’s coast from Acapulco to Lazaro Cardenas.

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