Helene was upgraded to a hurricane after rapidly strengthening in the Caribbean on Wednesday. Forecasters warned that the storm would intensify as it crosses the Gulf of Mexico on a path to Florida. The storm's center was near Mexico's Yucatan Peninsula on Wednesday, the U.S. National Hurricane Center said, and it was expected to intensify and grow in size as it crosses the Gulf of Mexico. The storm is so large that rural areas roughly 90 miles (145 kilometers) north of the Georgia-Florida line are under a hurricane warning. Helene, which formed Tuesday in the Caribbean, is expected to move over deep, warm waters, fueling its intensification. The hurricane was about 500 miles (810 kilometers) southwest of Tampa, Florida, and had sustained winds of 80 mph (130 kph), according to the U.S. National Hurricane Center. Forecasters said it is expected to become a major hurricane with its center making landfall in the Big Bend area of Florida’s northwestern coast as soon as late Thursday. Mara Lezama, the governor of the coastal state of Quintana Roo in Mexico, declared red alert for the northern part of the state and asked residents in those areas to stay indoors. Hurricane watches, which are a step down from warnings, were also in effect for parts of western Cuba and Florida, including the Tampa Bay area, the hurricane center said. In western Cuba, authorities moved cattle to higher ground and seven medical brigades were dispatched to communities usually cut off by storms. Helene was expected to dump heavy rain on the western part of an island struggling with severe water shortages and chronic power outages. In the Pacific, former Hurricane John re-formed as a tropical storm Wednesday and threatened areas of Mexico's western coast anew. John had hit the country's southern Pacific coast late Monday, killing two people, blowing tin roofs off houses, triggering mudslides and toppling scores of trees, officials said Tuesday. AP video by Dan Christian