U.S. forecasters say Hurricane John has strengthened into a Category 3 storm as it churns off Mexico's Pacific coast, with wind speeds of 185 kilometers per hour.

The storm is on a track that parallels the Mexican coast. Forecasters warned Tuesday that the system could strengthen within 24 hours, triggering dangerous flash floods and mudslides over areas of mountainous terrain. At mid afternoon local time, the storm was centered 280 kilometers south of the tourist resort of Acapulco.

A tropical storm warning is in effect from Lagunas de Chacahua westward to Lazaro Cardenas. A tropical storm watch is posted from west of Lazaro Cardenas to Cabo Corrientes.

John is the sixth hurricane of this year's Pacific season.

Some information for this report was provided by AP and Reuters.