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 toward the Gulf Coast.

Helene is expected to rapidly intensify into a major and massive hurricane with 115-mph winds by the time it makes landfall Thursday.

Tampa Bay residents should prepare for potential hurricane conditions within 48 hours, officials say, with Tropical Storm Helene expected to become a hurricane in the Gulf of Mexico Wednesday. A stretch of Florida’s west coast including Pinellas and Pasco counties is under a hurricane watch.