What to know about storm surge as Milton nears Florida

Storm surge is a major threat from Hurricane Milton, which is set to make landfall on Florida's west coast as a Category 3 hurricane Wednesday night.

A dangerous, record-breaking storm surge of up to 12 feet is expected for Tampa Bay and Fort Myers. Storm surge could reach a life-threatening 15 feet near Sarasota.

Here is how storm surge works and why it's so dangerous:

When pressure falls in the center of the hurricane, water levels rise, and the water amasses while the storm is still over the open ocean.

As the hurricane nears the shore, strong winds push that amassed water toward the coast and onto land.

This can build walls of water -- potentially as tall as 20 feet or more -- which can quickly overpower walls and flood homes.

In 2005, during Hurricane Katrina, at least 1,500 people died "directly, or indirectly, as a result of storm surge," according to the National Hurricane Center.

The risks can be even greater if storm surge combines with high tide, which could quickly create a catastrophic rise in water levels.

This article was initially published in 2018.