Tropical Storm Dolly, the fourth named storm of the 2014 Atlantic Hurricane Season, has formed off Mexico's coast over the Bay of Campeche.

The storm's maximum sustained winds early Tuesday were near 45 mph with additional strengthening forecast until it makes landfall. The U.S. National Hurricane Center says Dolly will approach Mexico's coast by Tuesday night and move inland by Wednesday morning.

A tropical storm warning is in effect for Mexico's coast from Tuxpan to La Pesca.

Dolly was centered about 220 miles east of Tampico, Mexico, and was moving northwest near 10 mph.

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