Which currently makes Tampa particularly vulnerable to hurricanes

When the eye of a major storm like Hurricane Milton last hit Tampa Bay in 1921, the city was a sleepy backwater of a few hundred thousand people. A century later, with more than three million residents, it is one of the fastest-growing metropolises in the United States and is particularly vulnerable to flooding due to climate change. As Milton heads toward Florida's Gulf Coast and strengthens into a Category 5 storm on Monday, experts fear a century of good fortune could suddenly come to an end.

Here's what you should know.

Why is Tampa so vulnerable?

The National Hurricane Center is forecasting a storm surge of 8 to 12 feet (2.5 to 3 meters) above normal tidal conditions and rainfall amounts of 4 to 6 inches (10 to 15 centimeters) in Tampa Bay and surrounding waters due to Hurricane Milton.

Florida's entire Gulf Coast is particularly vulnerable to storm surges. Last week, Hurricane Helene, which came ashore about 150 miles (240 kilometers) from Tampa in the Florida Panhandle, still managed to cause drowning deaths in the Tampa area as waves reached about 5 to 8 feet (1.5 to 2 .5 meters) high were normal tide levels.

“If it had made landfall a little further south and east, it could have been much, much worse,” said Philip Klotzbach, a hurricane researcher at Colorado State University.

LIVE MAP: Trace the path of Hurricane Milton

The increased risk is partly due to the topography. The coast of the Gulf of Mexico in Florida is flat with a gently sloping shelf. The higher seafloor acts as a barrier, holding back the storm's water runoff and forcing the ocean to push toward the shore. This is the opposite of Florida's east coast, where the sea floor suddenly drops away a few miles from shore.

“You can have the same storm, the same intensity, the same everything, but very different storm surges,” Klotzbach said.

A 2015 report by Boston-based disaster modeling firm Karen Clark and Co. concluded that Tampa Bay is the most vulnerable place in the U.S. to storm surge from a hurricane, causing $175 billion in damages.

Are the residents ready?

While Florida is no stranger to storms, Tampa has not been in the direct path of a major hurricane in over a century.

During this time the area has grown explosively. Tens of thousands of Americans moved to the region during the COVID-19 pandemic, with many settling on barrier islands like Clearwater and St. Petersburg overlooking the Gulf's normally calm, emerald waters. According to U.S. Census data, more than 51,000 people moved to the area between 2022 and 2023, making it the fifth-largest U.S. metropolitan area.

Long-term residents may be similarly unprepared for a direct hit, having experienced numerous false alarms and near misses like Irma in 2017. A local legend holds that the blessings of the Native Americans who once called the region home and built mounds to keep out invaders largely protected the area from severe storms for centuries.

Kerry Emanuel, a meteorology professor at MIT, said a hurricane in Tampa is the “black swan” worst-case scenario that experts have worried about for years.

“It’s a huge population. It’s very exposed, very inexperienced and it’s a lost cause,” said Emanuel, who has studied hurricanes for 40 years. “I always thought Tampa was the city people would worry about the most.”

What about climate change?

The effects of climate change also lurk in the waves and wind. Rising temperatures due to greenhouse gas emissions have warmed the oceans, caused sea levels to rise and added moisture to the air – all key factors that determine the strength of a hurricane and the potential flooding it can cause.

“Due to global warming, global climate models predict that hurricanes are likely to produce heavier rainfall and bring increased risk of coastal flooding due to higher storm surges caused by rising sea levels,” Angela Colbert, a scientist at NASA's Jet Propulsion Laboratory, wrote in one Report from 2022 report.

On Monday, the National Hurricane Center upgraded Milton to a Category 5 storm after it reached 75 mph (120 km/h) in intensity over the past 24 hours. One reason could be particularly high water temperatures, which act like fuel for the storm.

“Milton’s rapid intensification is incredible,” University of Miami hurricane researcher Brian McNoldy said in an email. “I have been pointing out for months that the Gulf was and is experiencing record or near-record warmth.”

The researcher found that due to sea level rise caused by climate change, Hurricane Andrew's storm surge would be 7 inches (17 centimeters) higher today than when that storm hit South Florida 30 years ago.

Are people being evacuated?

Officials in the region began issuing evacuation orders Monday for residents of six counties surrounding Tampa Bay, home to nearly 4 million people. Particularly at risk are residents of mobile homes, mobile homes and manufactured homes that cannot withstand wind speeds of up to 110 mph (177 km/h).

Kevin Guthrie, director of the Florida Division of Emergency Management, urged people to leave coastal areas, noting that people who died on offshore islands during Hurricane Ian in 2022 would still be alive if they had simply crossed the bridge to the mainland and found shelter.

READ MORE: Emergency officials have this advice for Florida residents preparing for Hurricane Milton

“Please, if you are in the Tampa Bay area, you must evacuate. If they have issued an evacuation order, I ask you, I implore you, to evacuate. Drowning deaths from storm surge are 100% preventable if you leave,” Guthrie said.

When did the last storm hit Tampa?

Almost inexplicably, storms appear to be passing Tampa by, with most of the Gulf disturbances occurring well north of the city. The last time the Tampa area was hit by a major hurricane was October 25, 1921. The hurricane had no official name, but is known locally as the Tarpon Springs storm, after the coastal town where it made landfall came.

The storm surge from this hurricane, estimated to be a Category 3 with winds of up to 129 miles per hour (207 km/h), was estimated at 11 feet (3.3 meters). At least eight people died and damage was estimated at the time at $5 million.

Now the tourist-friendly area, known for its white-sand beaches, has grown by leaps and bounds and has an estimated economic value of nearly $200 billion. Hurricane Milton threatens to wipe out all of these developments.

AP writers Joshua Goodman in Miami and Seth Borenstein in Washington contributed to this report.