As it gears up its fund-raising and spreads the work out among other local agencies such as the North Texas Food Bank, the Salvation Army and the Volunteer Center, the nonprofit is putting together a "what if" video, using Marshall's storm footage to dramatize its point. It likely won't include the running husband-wife commentary, like Kay's remark after they fled the overpass with no time to spare: "Do that again, and I'll divorce your ass."

With one local institution planning for the prospect of an EF5 tornado hitting the region's most densely populated areas, the Dallas Observer looked around to find others in the city who are thinking about the unthinkable. What are the probabilities of it happening? What would it look like? What are some of the area's vulnerabilities should the big one blow into town?

It's a subject that gets little attention, says Martin Lisius, a veteran storm chaser from Arlington and chairman of the Texas Severe Storms Association, a nonprofit dedicated to severe weather education. "When it happens, and it will in our lifetime, people will be completely stunned."

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For this theoretical scenario, a North Texas Council of Governments researcher traced the path of an actual tornado—the one that hit near Oklahoma City on May 3, 1999— over a land-use map of the Dallas-Fort Worth area. Its path through Arlington grows to a mile wide, but narrows as it cuts through Irving, Dallas and Richardson. The numbers along the track indicate the F-scale damage levels of the Oklahoma twister.
For this theoretical scenario, a North Texas Council of Governments researcher traced the path of an actual tornado—the one that hit near Oklahoma City on May 3, 1999— over a land-use map of the Dallas-Fort Worth area. Its path through Arlington grows to a mile wide, but narrows as it cuts through Irving, Dallas and Richardson. The numbers along the track indicate the F-scale damage levels of the Oklahoma twister.
A large, violent tornado approaches a crowded Highway 183 in Irving. Not really! It’s a photo composition presented at the 2006 Texas
Severe Storms Association’s national conference to demonstrate the risk the Dallas-Fort Worth area faces from a major tornado strike.
Martin Lisius/TESSA
A large, violent tornado approaches a crowded Highway 183 in Irving. Not really! It’s a photo composition presented at the 2006 Texas Severe Storms Association’s national conference to demonstrate the risk the Dallas-Fort Worth area faces from a major tornado strike.

My house in East Dallas stands to be hit by a twister rated EF4 or greater only once every 5,000 years, according to Harold Brooks, a federal research meteorologist who has analyzed tornado data going back to 1921 and arrived at the "return rate" of tornadoes for points around the country. Those odds hardly inspire me to get to work digging a concrete-reinforced hidey-hole in the backyard.

But extend the threat out to an EF4 or better hitting within 25 miles of my house—or 25 miles from downtown Dallas for that matter—and the "return rate" shrinks to about 33 years, or three times per century, says Brooks, who works at the National Severe Storms Laboratory in Norman, Oklahoma.

Hence his conclusion: Dallas is "overdue." Since 1950, only one 4-rated twister has touched down in either Dallas, Tarrant, Denton or Collin counties: the April 25, 1994, Lancaster tornado that struck just after 9:30 at night and killed three people along a six-mile path of destruction that included the suburb's historic downtown square. In the past 59 years, only one other tornado has caused fatalities in Dallas County. On April 2, 1957, an Oak Cliff tornado killed 10 and injured 200 after it touched down just east of what is now Executive Airport and moved almost straight north into West Dallas and the Love Field area. Appearing in the late afternoon in relatively bright light, the F3-rated twister was heavily documented by TV and still photographers who captured it transforming from a rope-like wisp to a relatively stout funnel about 100 yards wide. At one point along its 17-mile path, it formed multiple funnels before dissipating around Bachman Lake. The tornado that ambled into downtown Fort Worth on March 28, 2000, was classified as a weak F3, but was likely losing intensity when it began hurling roof gravel downtown and damaging 17 high-rise buildings. Two people were killed in the strike.

"The spot with the peak frequency for big tornadoes is in Oklahoma, right between Dallas and Oklahoma City," Brooks says. "Dallas certainly gets a decided threat."

What would be a long shot for my house alone is a much more likely prospect for some unlucky subset of the Dallas-Fort Worth metro area's 6.3 million people spread across 9,200 square miles. "The target's just getting bigger all the time," says Scott Rae, data application manager for the North Central Texas Council of Governments. "We've been adding 100,000 people a year. What a decade ago would have been a tornado missing in a field is now a tornado hitting a neighborhood."

At the urging of forecasters at the National Weather Service's Fort Worth office, Rae in 2000 constructed a computerized model of the damage path of the Moore twister. He layered the storm's southwest-to-northeast footprint on detailed land-use maps of the D-FW area and chose some 55 different points for the initial touchdown. While the Moore tornado was rated F5, detailed damage-path maps show that it produced F5-level destruction for only a small portion of its 80 minutes on the ground. Most of the way it produced F4- and F3-level damage, meaning, at a minimum, roofs and walls were torn off well-constructed houses.

On those 55 points and "countless other" paths through the Dallas area, the Moore cyclone would cause at least $2 billion in damage. It would hit 30,000 structures, threaten 50,000 people in homes or apartments and trap over 2,000 people on any one backed-up freeway, Rae concluded in his report aptly titled, "The Tornado Damage Risk Assessment: Predicting the Impact of a Big Outbreak in Dallas-Fort Worth, TX." There are many paths in which it would destroy far more, he estimated. If it struck during the workday, buildings containing at least 50,000 people would be in its way.

Marty Nerren, the Dallas Red Cross chapter's emergency planning director, says he used Rae's study, as well as a 2002 threat assessment prepared by Dallas city officials, to arrive at the conclusion that the chapter should plan for 40,000 survivors needing immediate shelter. From the standpoint of planning a response, he says, something Rae's study identified as Scenario 5 provides the most headaches.

In this worst-case scenario, the twister touches down in central Arlington, crosses UT-Arlington, Six Flags Over Texas and Texas Stadium, churns through Irving, across North Dallas and up Central Expressway in Richardson. It finally lifts around East Parker Road on the eastern side of Plano. There aren't many cow pastures on this heavily-populated route. A full 70 percent of the footprint is developed, meaning a whopping 18 square miles of houses, offices, apartments and retail shops would be reduced to bombed-out rubble. Three mobile home parks covering 49 acres also would be pulverized.

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