As monster storms like Helene approach the U.S., meteorologists use five categories to help signal the life-or-death consequences for residents in the path. This scale – officially known as the Saffir-Simpson Hurricane Wind Scale – is a rating based on maximum sustained wind speed,

Helene is forecast to intensify rapidly over the Gulf of Mexico before making landfall in Florida on Thursday. Residents are urged to make preparations — and in many counties, evacuate — before then.