Florida is headed for a 'near worst-case scenario' with Hurricane Ian. Here's what a Category 5 storm could look like.

• Hurricane Ian increased to a Category 3 storm on Tuesday with 125 mph winds.
• Forecasters expect the storm to strengthen in the Gulf of Mexico as it heads toward Florida.

As Hurricane Ian intensifies and heads toward the Florida Gulf Coast, forecasters are sounding the alarm for what could be a devastating Category 3 storm with 125 mph winds.

"This is a near worst-case approach angle coming in from the south and west and stalling," Jamie Rhome, the National Hurricane Center acting director, told CNN. "With it slowing down, this would be a near-worst case approach angle."

The last time a storm that strong hit Florida was a century ago, when a Category 3 came to Tampa Bay, knocking out the region's power and killing eight people. But that was when the population was only about 200,000, according to the Tampa Bay Times.

Tampa Bay, which includes the cities of Tampa, St. Petersburg, and Clearwater, is now home to about 3.2 million people, according to the 2020 US Census.

In a worst-case scenario — a Category 5 with winds of 157 mph or higher — the impacts could be devastating and take years to recover from.

A major storm like that could flood the downtown Tampa Bay area with up to 26 feet of water, which is more than twice the depth of the 1921 hurricane, according to Vox.

The National Hurricane Center forecasted on Tuesday morning that Tampa Bay and Charlotte Harbor could expect 5 to 10 feet of storm surge flooding if Hurricane Ian hits at high tide.

In the Tampa Bay Regional Planning Council's catastrophic plan, which lays out this worst-case scenario through a simulation called Hurricane Phoenix, flooding from a Category 5 storm could turn various parts of Pinellas County, including St. Petersburg, into islands.

Winds of up 157 mph could tear through homes, smash windows, and destroy stoplights. About half a million buildings could be destroyed and 843,000 households displaced, the catastrophic plan predicts.

The death toll could reach similar figures to that of Hurricane Katrina in 2005, when that Category 5 storm killed over 1,800 people. The region's planning council estimated that — even considering Tampa Bay's developed infrastructure — a storm that strong could kill about 2,000 people, along with another 200 more after the storm.

Economic losses also could be unprecedented. The report estimates about $250 billion in "expected economic losses" due to structural damages and loss of business.

"As one might expect, a storm of the size and strength of Hurricane Phoenix would create almost unthinkable damage to the area's homes, businesses, infrastructure, overall economy, and social systems that are currently in place," the report stated.