Hurricane Michael: What if it had hit Tampa Bay?

Hurricane Michael barely grazed the edge of the Tampa Bay area on its way to flattening the small towns of the Florida Panhandle.

But what if Tampa Bay had been its target? What if the strong Category 4 storm had slammed into Belleair Shore instead of Mexico Beach? What if the Air Force base that it leveled was MacDill, not Tyndall?

The death toll would have been catastrophic, and the damage far greater than what occurred in the Panhandle, according to experts.

"We are in a very vulnerable area," said Sean Sullivan, executive director of the Southwest Florida Regional Planning Council.

The last major hurricane to score a direct hit on the Tampa Bay region was an unnamed storm that made landfall at Tarpon Springs on Oct. 25, 1921. The storm surge was 11 feet, and the winds were what we would now classify as a Category 3 strength, from 111 to 129 mph. Homes and businesses throughout the region were obliterated and eight people died.

The Tampa Bay region has packed in a lot more buildings and a lot more people since then.

The area Michael hit was sparsely populated by comparison: The Panama City metro area, the most densely populated area struck near the shore, has just under 200,000 residents. By contrast, St. Petersburg and Tampa are Florida's third- and fourth-largest cities, part of the state's second-most-populous region.

AccuWeather ranked the Tampa Bay region among the top five places in the U.S. most vulnerable to a hurricane (Miami and Key West were the top two). Last year the Washington Post named the Tampa Bay area as "the most vulnerable in the United States to flooding and damage if a major hurricane ever scores a direct hit." The story noted that a World Bank study "called Tampa Bay one of the 10 most at-risk areas on the globe."

Eight years ago, the planning council ran a simulation of what would happen if a Category 5 hurricane hit Tampa Bay. Dubbed "Hurricane Phoenix," the council's simulation showed the storm making landfall at Indian Rocks Beach just before noon.

Over the next six hours, it roared across four counties with maximum sustained winds ranging from 160 to 105 mph, causing $233 billion in economic losses and leaving behind 41 million tons of wreckage.

"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," a report on the exercise concluded.

Michael's winds were only 2 mph under the ranking for a Category 5. Only three actual 5s rank higher. They are the Labor Day hurricane that hit the Keys in 1935, Camille, which hit the Mississippi coast in 1969, and Andrew, which clobbered South Florida in 1992.

If such a Michael-like hurricane did hit, the Phoenix exercise found that Pinellas County would be cut in half by storm surge. The water would wash all the way across barrier islands from Longboat Key to Clearwater Beach. St. Petersburg would suffer a 23-foot surge, while downtown Tampa would see a 26-foot surge with water flooding the lower stories of some downtown office towers.

Inland areas would wind up underwater as well because the surge would push Tampa Bay inland. The Howard Frankland and Gandy bridges and the Courtney Campbell Causeway would all suffer structural damage and their approaches would possibly wash away.

"Because of the storm surge, a lot of stuff on the coast is toast," said Marshall Flynn, a planning council employee who worked on the study.

The scouring winds and waves would destroy 470,000 homes and 10,000 businesses, the study found. About 2 million people would require medical care, and the estimated death toll would be about 2,000 people -- slightly more than the 1,817 who were killed by Hurricane Katrina.

Most of those killed would become casualties because they were unable or unwilling to evacuate, the report states.

When the planning council set up the Phoenix scenario, it used 2000 census data that showed 2.4 million people living in the Tampa Bay area -- a far larger number of people to evacuate than the population of the mostly rural Panhandle.

Now that number has grown to 3.5 million, Sullivan said. As a result, he said, if a Michael-like hurricane hit here "I know the numbers (for casualties) would be higher." (The council has applied for a grant to update the Phoenix plan with current numbers.)

The larger population also makes evacuation considerably more difficult.

Big storm surges are especially dangerous in the low-lying Tampa Bay region because of the relatively shallow offshore shelf in the Gulf of Mexico, experts say. Because of the shelf, a storm surge has nowhere to go but up on land. Meanwhile, as the sea level rises due to climate change, storm surges will go farther and farther inland.

Then there's the speed of the hurricane.

Under the Phoenix scenario, Tampa Bay officials had six days to get ready for landfall. The tropical depression strengthened into a named tropical storm on Oct. 9, became a hurricane on Oct. 10 and made landfall on Oct. 15.

"Ideally we would get five to seven days, in a perfect world, to evacuate," Sullivan said. "That would give us enough time to secure all the structures."

But Michael zoomed through the Gulf of Mexico in just 73 hours -- a little more than three days to go from being named a tropical storm with 40 mph winds to crashing into Florida as one of the most powerful hurricanes in U.S. history.

"That doesn't give us much time to prepare," said Michael Ryan, Hillsborough County's deputy emergency manager. "It takes a lot of resources to get a lot more people out of the area a lot faster."

That means if Michael had hit here, there would not be nearly enough time to evacuate everyone -- not all the elderly and others with serious medical problems, the people living in mobile homes, the folks whose houses were built in flood zones. Some would not get out at all. Others would be caught in the open, trying to leave.

One of the biggest facilities that would need to evacuate is MacDill. The home to U.S. Central Command, U.S. Special Operations Command sits in one of the region's riskiest flood-prone areas. To evacuate would mean dispatching 18,000 military and civilian personnel, not to mention all the jets, refueling tankers and helicopters based there.

They did it last year when Hurricane Irma seemed to be taking aim at the Tampa Bay area, but it wasn't easy.

"Irma gave us an opportunity to strengthen relationships with our community partners when it comes to evacuation guidance and local resources," said Air Force Capt. Samantha Morrison, spokeswoman for the 6th Air Mobility Wing.

The base puts on "hurricane preparedness briefings" each month, she said, "and commanders encourage personnel to keep extra food and water at home in case the need arises to evacuate."

Another potential problem is the time of year that Michael occurred, Ryan pointed out.

"It's October, the end of the hurricane season, when people start to let their guards down," he said.

October can produce deadly hurricanes just like June, July, August and September. For instance, in 2005, Hurricane Wilma came ashore near Naples as a Category 3 storm. It killed 23 people in the United States and caused $19 billion in damage.

Avoiding a direct hit for 97 years might make some Tampa Bay residents complacent about getting ready for a hurricane. Fortunately, Ryan said, all the news coverage about Harvey and Irma last year "got a lot of people to sit up and take notice."

Now, he said, Michael can serve as a similar reminder to get ready now for the disaster that's sure to come someday.

"It serves as another wakeup call," he said, "because this is two years in a row that Florida has been hit by a major hurricane."

Times staff writer Howard Altman and researcher Caryn Baird contributed to this story. Contact Craig Pittman at craig@tampabay.com. Follow @craigtimes.