MIAMI (AP) — Tropical Storm Odile is slowly strengthening as it swirls in the Pacific off Mexico’s southern coast.

The storm’s maximum sustained winds early Thursday increased to near 50 mph (85 kph). The U.S. National Hurricane Center says Odile is expected to get stronger and become a hurricane on Friday.

A tropical storm watch is in effect for Mexico’s coast from Lazaro Cardenas to Manzanillo.

Odile is centered about 210 miles (335 kilometers) southwest of Lazaro Cardenas and is drifting west near 2 mph (4 kph).

Swells from the storm are expected to begin affecting parts of Mexico’s southwestern coast in a day or so. The swells are likely to cause life-threatening surf and rip current conditions.

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