How Hurricane Erin exploded in strength and became a major Atlantic hurricane

Erin has strengthened into a powerful Category 5 hurricane in the Caribbean, the National Hurricane Center said Saturday.

The hurricane is not forecast to hit land, but strong winds are affecting nearby islands, prompting forecasters to warn of possible flooding and landslides. The storm will eventually swerve away from the continental United States, the Miami-based hurricane center said.

Erin began as a tropical storm, became a hurricane on Friday and quickly intensified overnight Saturday. Here's how the storm became so powerful.

What is rapid intensification?

On Friday morning, Erin was only a tropical storm. It underwent rapid intensification, which means the storm's wind speeds strengthened by more than 58 miles per hour in a 24-hour window, overnight.

Erin has low wind shear