MIAMI, Florida. The irresistible onslaught of Hurricane Irma is threatening one of the most vulnerable areas of the country to flooding from a tropical cyclone - Tampa Bay, home to four million people.
A combination of factors puts Tampa at higher risk than other coastal cities, in large part because the area has not suffered the direct impact of a major hurricane for almost a century and few buildings are constructed to withstand such megastorms.
The beautiful, funnel-shaped bay can become a deadly trap as Irma's massive force pushes the sea ahead of it, potentially flooding Tampa and St. Petersburg, experts warn.
The hurricane is expected to hit Tampa Bay on Sunday evening after wreaking havoc on communities on the southwest Gulf coast of Florida such as Naples, Fort Myers and Cape Coral, where storm surge could rise to 15 feet, meteorologists say.
Tampa could still escape a worst-case scenario if the angle of the hurricane struck directly from the west, generating an even greater tidal surge. Irma's forecast track indicates that Irma will reach the bay from the south, limiting the spiral effect of the winds that push the sea towards the coast. As a result, the storm surge in Tampa Bay is expected not to exceed eight feet.
"If this came straight from the west it would cause a surge of up to 20 feet," says meteorologist Jeff Masters with the private forecaster Weather Underground, noting that storm surge is the principal cause of death during a hurricane.
The Tampa Bay region has not suffered a direct impact from a major Category 3 or greater hurricane in nearly a century. That's because the city faces the Gulf of Mexico to the west and hurricanes usually advance from east to west as a result of the prevailing trade winds.
The last time it was hit came in 1921; a Category 3 hurricane with winds of 115 miles per hour (185 kms/h) that caused severe damage. Then, only 160,000 people lived in the four counties of the Tampa metropolitan area, mostly in highland areas.
Another risk factor for Tampa is the Continental Shelf, a submarine geological formation sticking out from the Florida peninsula resulting in shallow water less than 300 feet (90 meters) deep that extends 90 miles (140 kilometers) offshore. "Because of this, the effects of sea level rise are more severe on the west coast of Florida than in the east," says meteorologist Albert Martinez, likening it to an infinity pool. "There is simply nowhere for the water to go," he said.
Tampa is the U.S. city with the highest risk of flooding from a hurricane, according to a report by the consulting firm Karen Clark and Company, and the seventh most at risk city in the world, according to the World Bank.
In photos: Irma's anxious wait in Naples on Florida's
Despite this risk, the region has not taken sufficient steps to mitigate the impact of rising sea levels, environmental activists say. Few buildings in the Tampa Bay area were built with modern hurricane safety codes.
Part of the blame is political. State officials, including Florida's current Governor Rick Scott, a Republican, have tended to play down environmental threats, including manmade climate change. In 2015 Scott notoriously instructed state employees to refrain from using the words "climate change" or "global warming" in official communications.
In June, the Republican-controlled legislature passed laws allowing any citizen to question textbooks and codes that deal with the science of evolution and global warming.
Only recently, Tampa Bay authorities began to study the effects of flooding. They quickly identified several key facilities at risk, including Tampa General Hospital and 30 parks overlooking the bay, according to a " Peril of Flood" workshop held in March by the Hillsborough County Planning Commission, where Tampa is located.
One of the few hurricane-protected sites is the Salvador Dalí Museum in downtown St. Petersburg, a popular tourist attraction which has 18-inch thick concrete walls and pressured glass supported by steel frames that could withstand powerful storms.
Hurricane Irma meets downtown Miami
To find out what would happen in the worst-case scenario a Category 5 hurricane with winds exceeding 156 mph was simulated by the Tampa Bay Regional Planning Council back in 2010. The fictitious Phoenix Hurricane projected that wind damage would destroy half a million homes and businesses. About two million residents would need medical treatment and more than 2,000 people would be killed, more than died from Hurricane Katrina in Louisiana and Mississippi.
Activists point to strides taken by Miami since Hurricane Andrew in 1992 destroyed 127,000 homes and caused $26.5 billion in damages. The massive destruction exposed poor construction codes, and even weaker enforcement, resulting in a major overhaul and a push for greater regional cooperation. Today Miami is widely credited as having some of the most stringent building codes in the nation.
"Most places in Florida are far behind Miami in efforts to mitigate the impact of extreme weather conditions such as a hurricane and sea level rise," Susan Glickman, an environmental activist living in Tampa.
"We have a lot of catching up to do," adds Glickman.