A rare blue supermoon could play a role in an unfolding disaster as Hurricane Idalia takes aim at Florida's west coast. That’s because a supermoon that can increase normal tides is expected Wednesday night. That's just as Idalia is expected to make landfall as a major hurricane. A supermoon is the closest full moon to Earth. That makes it appear larger and provides a spectacular backdrop in photos around the world. Experts say it's expected to make tidal flooding worse not only in Florida, but in states such as Georgia and South Carolina.