Sunday, March 23, 2008
News, In this Issue...

Urban twisters

As Atlanta recovers from the March 14 tornado, it can learn from Nashville and Fort Worth

 

CREDIT: Sandy Hooper

Top 10 deadliest tornados

Shortly after 8 a.m. on April 6, 1936, Gainesville, Ga. was virtually destroyed by a tornado that left 203 people dead and 1600 injured. To this day, it ranks among the worst tornados in American history. In 1903 an early summer tornado had hit the same town and killed 98 people—ranking in the top 25 deadliest tornados. Here are the top ten, ranked in order of deaths and injuries, as reported by The Tornado Project, a private tornado information company formerly funded by the National Science Foundation. Death tolls reported prior to the mid-1900s may be low estimates since record keeping was not uniform and in some cases deaths among blacks were not reported. In more recent years, tornado-related death tolls have dramatically dropped thanks to warning systems and better emergency response. –By Stephanie Ramage

By Mark Woolsey

A tornado swoops down on a major city, leaving windows blown from skyscrapers, office furniture sucked out of tall buildings and significantly damaged cars, power lines, and residences. Dozens of people are injured and victims wander the streets in a faze.
  
Though it’s an accurate snapshot of Atlanta on March 14, 2008, the same words could describe Fort Worth, Texas on March 28, 2000, or downtown Nashville on April 16, 1998.

On August 12, 2004, a tornado spun off by Hurricane Bonnie hit Jacksonville, Fla., damaging a Norfolk Southern rail yard. Almost exactly five years prior to that, on August 11, 1999, a tornado hit downtown Salt Lake City, Utah, destroying 34 homes, knocking over construction cranes and tearing windows from 500-foot-tall buildings. St. Louis, Mo., has survived multiple tornados, stretching back at least as early as 1896, when 137 people were killed, and more recently over a period of three days in March 2006, when 200 tornado warnings were issued for the St. Louis area.

So much for the conventional wisdom that tornados are somehow warded off by tall buildings or urban heat islands.
  
“I don’t know where that myth originated,” says Greg Carbin, a warning co-ordination meteorologist with the National Weather Service’s Storm Prediction Center in Norman, Okla. No research supports that notion, he says. Carbin was on duty both the night before and the night after Atlanta’s March 14 storm and says it was a “freak event”—a tornado resulting from a relatively weak-looking departing weather system—that kicked in even as meteorologists focused on what appeared to be the heightened risk of another storm system arriving in the Southeast early Saturday morning.
  
Not only do tornadoes not somehow “take a pass” on downtown areas, says Carbin, damage and injuries have shown a marked increase in recent years due to sprawl and growth in and around major cities. As cities spread out, they provide a bigger target for tornados, making it much more likely that humans and their property will lie in a twister’s path.

Georgia Tech meteorology research scientist Jim St. John, who has done extensive research on tornado damage paths, also pooh-poohs the notion of the tornado-proof city.
  
“It’s rare that a tornado hits a downtown, but it’s rare that a tornado hits any spot,” he says. “A tornado damage path is typically on the order of several miles long and several hundred yards wide. Calculate that area and compare it to all of Georgia, and that’s a very small number.”
 
One impact that downtown areas do seem to have on twisters, he says, is that significantly large structures tend to somehow lessen or dissipate the winds of a tornado—but it comes at the expense of those buildings being heavily damaged. St. John theorizes that as the tornado ripped across Atlanta’s heart, the city’s big buildings took the brunt of the storm and lessened the damage east of the downtown area. But, he says, the channeling of winds through the canyons of a downtown can also increase a tornado’s destructive power, much as forcing a river into a narrower channel increases the speed of the current.

What Atlanta can learn from Nashville and Fort Worth

 
Whatever the myths and mechanics that come into play, at least two other southern cities have learned from their experiences to improve their tornado-readiness.

Ironically, the very day a late-afternoon twister ravaged Nashville’s center on April 16, 1998, county officials had been meeting with a potential tornado siren provider, recalls Amanda Sluss, spokeswoman for the Nashville Mayor’s Office of Emergency Management. Then came the storm, causing one fatality, at least 100 injuries and damage to some 300 buildings.
  
Nashville’s response to the experience was a 70-siren-strong outdoor warning system that was operational by 2002. And it’s worked, Sluss says: When an April 2006 tornado outbreak smacked Goodlettsville in northern Davidson County and shot a twister into neighboring Sumner County, all the fatalities were in Sumner—Davidson County residents said Nashville’s legion of sirens gave them as much as 15 minutes of warning time.
   
Contrast that with an estimated eight minutes of pre-warning here, with no sirens in place in downtown Atlanta or across Fulton County.

Jessica Corbitt, spokeswoman for Fulton County government, says the Atlanta Fulton County Emergency Management Agency isn’t considering a warning system yet, because the agency’s focus is on securing disaster recovery funds from the federal government, but such a system is a future consideration.

“Right now they are still assessing damage from the tornado,” says Corbitt. “But I know that as a long-term goal, they will be looking at having a warning system in open public areas where people may not have access to a radio or something of that nature.”
   
Nashville’s Sluss says one of her city’s sirens sits atop the Sommet Center, a large arena similar to Atlanta’s Georgia Dome, in the center of the city. A hockey game was underway the night a pack of early February twisters threatened, and Emergency Management Officials kept the center’s officials abreast, leading them to have fans “sheltering in place” as a tornadic thunderstorm skipped over the city. Other sirens, Sluss says, cover the downtown area, sports facilities, parks, public schools and other outdoor gathering spots.   

The National Weather Service’s Carbin says that, on a broader scale, recent fierce storms hitting city cores has led to closer cooperation between weather and emergency management officials on one end, and large venue operators on the other. In St. Louis, he says, the Weather Service certified Busch Stadium as a “storm-ready” facility. The certification program recognizes businesses and agencies that have laid plans and prepared facilities in a way that will move people to safety quickly or provide them with safe shelter on-site. Busch Stadium’s certification worked out nicely, he says, when a fierce windstorm struck it in July 2006. With ample warning and advance plans, the field and stands were evacuated, limiting injuries to about 30.
     
Atlanta’s March 14 twister hit while an SEC basketball game was in overtime in the Georgia Dome, which was packed with fans, but well after most of the city’s workforce had departed downtown for the evening. 

Fort Worth’s March 28, 2000 downtown twister played out much like Atlanta’s, says Lt. Kent Worley, spokesman for the Fort Worth Fire Department, even down to lucky timing: The Fort Worth storm struck around 6:15 pm, after the bulk of office workers had left downtown streets and skyscrapers. That storm, like Atlanta’s, also forced the closure of much of downtown for several days of cleanup.
   
And the twister, which tore a four-mile path, killing two and injuring 80, led to some changes in emergency response. Reported delays in contacting building managers, property owners and major downtown employees led to the establishment of the so-called “OPEN” pager network. Weather bulletins and other emergency messages originating from the city’s emergency communications center go out to “anything that receives a text message,” as Worley puts it. So anyone with a cell phone, BlackBerry or laptop is notified.
  
“In the wake of that storm, we were needing to meet with building managers and others to talk about cleanup plans and letting them get to their buildings, and we didn’t want to do it one business at a time” in the future, says Worley. A plethora of building managers, property owners and major employers have signed onto the system, which he says has worked well, warning the core area of everything from weather to construction-related street closures.

The Weather Service’s Carbin, who partly attributes better local emergency management to lessons learned in the Sept. 11 terrorist attack, says that “the scariest” scenario would involve a tornado hitting a large outdoor venue like the Atlanta Motor Speedway, with tens of thousands of people in attendance and little immediate shelter. He says proper coordinating and lead time is critical, but “the science is not as advanced as we’d like it to be in terms of giving people advance warning.” SP