• The current average lead-time for tornado warnings is 11 minutes. NOAA's National Severe Storm Laboratory is working to increase tornado warning lead times to 20 minutes.
• While it may appear tornadoes target mobile home parks, they do not. But an EF1 tornado might do significant damage to a mobile home but cause minor damage to a regular home, making it look as though the tornado "skipped" the house. Mobile homes are often built with lightweight materials, which do not hold up well in tornado winds. Any wind gust -- including straight-line winds sustained for three seconds over 50 mph -- can damage mobile homes, especially those not anchored.
• On average, about 1,300 tornadoes hit the United States yearly. In April 2011, the National Weather Service documented 875 and in all of 2011 there were 1,894 confirmed tornadoes.
• On average, tornadoes kill about 60 people per year. In 2011, tornadoes killed 550 people; most died on April 27.
Turn to Channel 3 all day today as crews return to every county hit by a tornado on April 27, 2011, to show the recovery one year later.
It wasn't supposed to happen -- not like this.
Swarms of tornadoes threw cars and blasted apart homes and neighborhoods. The violence of wave after wave of storms surprised even the veteran meteorologists who, for days, had been sounding warnings about the weather's potential for disaster.
But who could have fathomed the intensity of the super tornado outbreak one year ago today, April 27, 2011?
Who could have imagined that 316 people would die -- 81 in the Chattanooga region? And who could have predicted the $5.5 billion in damage just in Tennessee, Alabama and Georgia, including the collapse of huge electrical power towers, cutting off electricity to much of the region.
On March 2, Chattanooga had something of a rerun, without the deaths. But hundreds of homes were damaged, and another line of power towers came down.
Now that we know how much is at stake, what's next? What lessons have Tennessee, Alabama and Georgia residents and their government policymakers learned to prepare for the next super outbreak, or even the next March 2?
"I think people at home have a heightened awareness, and I'm hearing the same thing from a lot of people in businesses and health institutions and civic groups. And the home builders association has a new awareness," said Bill Tittle, chief of Hamilton County Emergency Services.
To many, that new awareness means more than just getting a battery-operated weather radio or cellphone alert notification.
Bob Colby, who is just now rebuilding his destroyed home in Apison, is spending an extra $7,000 to $8,000 to have a safe room built into the one-story home that will have no basement.
And Nathan Hollingsworth, the environmental and safety engineer for NA Industries off Amnicola Highway, just conducted the first-ever tornado drill for the company's workforce. In the coming week, two new prefabricated storm shelters also will be installed on NA Industries' grounds.
"Before, we had just one alarm system, and it was for plant evacuation. Obviously if there's a tornado, you don't want to run outdoors," said Hollingsworth, who also is chairman of Hamilton County's Local Emergency Planning Committee.
There are no requirements mandating these precautions -- even for new construction, and that's something that insurance companies find somewhat troubling.
David Colmans, executive director of the Georgia Insurance Information Service, a trade organization of property and casualty insurance companies, said meteorologists have told insurers they are seeing damage from EF1 and EF2 tornadoes that shouldn't have knocked down homes, but did.
"That all has to do with building codes," Colmans said. "And that's a problem when a county doesn't even have a building inspector, much less a building code."
The trend of increasing tornadoes each year also is cause for a closer look, he said, noting that insurance companies apply risk rates to states and geographies based on things such as hurricanes, earthquakes and other natural disasters. But so far tornadoes haven't prompted similar measures in the Southeast.
"Now that the South has been named Dixie Alley for tornadoes, the implication there to me indicates it is considerably more important that the states look at the importance of building codes, because there is reason to consider public safety more so than before," Colmans said.
Even where codes exist, they do not include requirements for safe rooms or shelters in new construction. But the idea is getting some attention.
Plans under construction
In Alabama, where tornadoes killed 242 people in 2011, the Alabama Tornado Recovery Action Council is pushing change. In January, the council presented Alabama Gov. Robert Bentley with a report that said weather disasters there might be less deadly if storm shelters were required in new mobile home parks and apartment complexes, and if tougher building codes were established for homes.
Like many Southern states, Alabama had no statewide building code until last month when it adopted the International Residential and Buildings Code. The same code became law in Tennessee in 2010, and in Georgia in 1991.
But the code does not address safe rooms or storm shelters. What's more, in each state, local governments can choose to enforce the codes or not, and states can change the requirements.
Georgia, too, is looking harder at codes.
The Disaster Resilient Building Code Appendices Task Force was awarded a $160,000 U.S. Department of Housing and Urban Development grant to develop new disaster-resilient building codes for the International Residential and Building Codes -- the general model for most building codes and one often adopted when locales don't want to reinvent the wheel.
"We're supposed to be a model for codes like this in other states," said Ted Miltiades, director of construction programs in Georgia.
The Georgia task force, appointed in February, is to present a final report at the state codes advisory committee meeting on July 26. The codes will be available for adoption on Jan. 1.
Hamilton County enforces the 2003 version of the International Building Code and may upgrade to a newer version later this year. But county officials and local homebuilders indicate there won't be any extra requirements such as safe rooms or shelters added to it -- at least not soon.
"Safe rooms are not part of the code," said builder Karl Sodergren, president of the Chattanooga Builders Association. "But I do believe there will be an increased demand for safe rooms. And if people can afford it, by all means, they should include them. ... And I think probably more builders will begin to market them [in their home plans]."
But Hamilton County Emergency Services planner Greg Smith acknowledged that if the tornado is big enough, not even building codes written to enable a structure to survive hurricanes can keep a home or business together.
"To build a home to withstand EF3 or EF4 tornadoes, the code would have to be much stronger than the Florida [hurricane] code and probably would be exorbitantly expensive," he said.
But building for a 140-mph wind could keep a home standing against an EF1 tornado, Tittle said.
TVA has been a bit quicker to embrace the new realities of the Southeast's increasingly extreme weather as it rebuilt its grid. The utility is spending $7 million to replace nuclear-disaster dedicated sirens with new ones that have battery-backup power to keep them operating for up to seven days.
"The severe weather in this area over the last year is a reminder of the importance of the sirens to the safety of the community," Browns Ferry site Vice President Keith Polson said when the replacement effort began in a 10-mile radius of the Athens, Ala., plant a month ago.
When the Browns Ferry project is finished in late spring, TVA will replace the sirens around Sequoyah in Soddy-Daisy and around Watts Bar near Spring City, Tenn.
The replacement sirens also will be mounted on new steel poles, rather than the wooden poles used with the old sirens.
Adapting to change
One week from today, Greensberg, Kan., will celebrate its rebirth and memorialize the 14 people who died there five years ago when an EF5 tornado leveled all but three buildings in the town.
Mayor Bob Dixson said the town of 1,500 people made a conscious decision to not just build back, but to start over right. With the help of state and federal planners and tremendous community spirit, about 850 residents have rebuilt homes and businesses to be not only safer, but greener than before the May 4, 2007, tornado scoured the earth there.
Surprisingly, he said, the town didn't write in a bunch of requirements and codes for any of that safety and sustainability.
"We kept the same codes. We just made sure that this time we enforced them thoroughly," he said. "We tried to educate everybody to be green and be good stewards. It was just an educational process instead of a mandated one."
Back in Apison, Colby was proud to point to a green outlined square on the ground near the concrete slab that used to be the floor of his garage.
"That will be my safe room," he said with a smile. "We probably would never have considered it before. But now we're believers."