A hurricane watch and warnings of storm surges up to 15 feet high were issued Tuesday for almost all of Florida’s western coastline as Tropical Storm Helene formed over the Caribbean Sea, and heads towards the Gulf Coast.

Helene, previously called Potential Tropical Cyclone Nine, officially formed Tuesday, the National Hurricane Center said in an 11 a.m. advisory. The storm is forecast to strengthen into a hurricane Wednesday and authorities are urging people to prepare and exercise caution.