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International Journal of Mass Emergencies and Disasters March 2007, Vol. 25, No. 1, pp. 1–36
Call-to-Action Statements in Tornado Warnings: Do They Reflect Recent Developments in Tornado-Safety Research?
John E. Farley Professor Emeritus Department of Sociology and Criminal Justice Studies Southern Illinois University Edwardsville [email protected]
Call-to-action statements in tornado warnings are content analyzed to determine to what extent their wording has been influenced by recent research calling into question official safety guidelines and traditional advice regarding vehicles and mobile homes. While the statements do not directly contradict official guidelines and advice, there is significant variation among NWS offices regarding what advice is given and what guidelines are emphasized in call-to-action statements in tornado warnings. Some of this variation is regional, and interviews with NWS meteorologists reveal a frequent opinion that what is best to do if in a vehicle during a tornado warning may vary by region, time of day, and terrain. The interviews also reveal widespread awareness among NWS meteorologists of debates over tornado safety in vehicles and mobile homes, and strong support for local office autonomy in decisions about the wording of call-to-action statements.
Key Words: tornado, warning, advice, safety, recommendations.
Introduction The research reported in this paper examines “call to action” (CTA) statements in tornado warnings issued by the National Weather Service (NWS) in light of scientific controversies associated with
1 2 International Journal of Mass Emergencies and Disasters recent research by Thomas W. Schmidlin and others regarding the safety of vehicles relative to mobile homes and ditches. This research presents a dilemma to the NWS and other emergency management agencies because it calls into question the validity of safety guidelines that have been used for a number of years. It also presents a challenge because the recent research suggests that the safest action to take is highly conditional upon the specifics of the situation (Schmidlin, 2002), while research on risk communication indicates that repeated provision of clear and understandable messages about the nature of the risk and what to do about it is the means of communication most likely to lead to adoption of appropriate preparedness and response measures (Mileti et al., 1993; Mileti, 1997). For example, research has confirmed that in tornadoes and other emergencies, knowledge of safety rules does lead people to take actions that can prevent death and injury (Aguirre, et al., 1987; Burby and Wagner, 1996; Perry, Lindell, and Green, 1980; Rogers, 1985). Relatedly, people are more likely to respond to a warning message if it contains information about what to do to protect themselves (DiGiovanni et al., 2002; Mileti and Darlington, 1997). Warning messages are most effective when they are not only clear but also repeated (Drabek, 1969; Mikami and Ikeda, 1985; Mileti and Fitzpatrick, 1993) and consistent (Christiansen and Ruch, 1980; DiGiovanni et al., 2002; Nigg, 1987). For example, Mileti and Fitzpatrick (1993) have shown that when the same information is received multiple times from multiple different sources, its impact on risk perception and on people’s efforts to obtain further information is maximized (see also Pfister, 2002). Unfortunately, it can be difficult to give repeated and consistent recommendations when the best course of action is highly situation- dependent. Moreover, research has shown that a clear and simple message is more likely to evoke action than one that is complicated or contains multiple response options (DiGiovanni et al., 2002; Rogers and Sorensen, 1989). Hence, the research shows that the advice given in warnings for tornadoes and other hazards has real impacts on what people do, but also that giving good safety advice that will be heeded represents a significant challenge when the best response is situation-dependent. The purpose of this paper Farley: Tornado Warnings 3 is to determine the extent to which actions recommended in CTA statements are consistent or inconsistent with the recommendations of Schmidlin and his colleagues based on their research findings, and how these CTA statements, if at all, have been influenced by debates surrounding those findings. This represents an important issue, because as Golden and Adams (2000) have pointed out, considerably more research has focused on the physical sciences and technology portion of the warning process than upon the warning communication process, the behavioral response to warnings, and the epidemiology of tornadoes and their consequences. Schmidlin’s Research on Vehicles, Mobile Homes, and Tornado Safety Research findings by Schmidlin and his colleagues (Schmidlin 1997; Schmidlin et al. 2002) suggest that, while vehicles are far from the safest place to be in a tornado, they may in many instances be safer than mobile homes (so that a person in a mobile home with no sturdy shelter nearby would be safer in a vehicle than in the mobile home). Nonetheless, there are no tornado safety guidelines currently in use by the National Weather Service or American Red Cross that convey the idea that a vehicle may be safer than a mobile home. Schmidlin’s research and that of others also suggests that vehicles may be safer than outdoor locations such as ditches, and Schmidlin notes there is no research supporting the idea that a ditch is safer than a vehicle . Yet, it is often recommended in safety guidelines that people abandon mobile homes and vehicles for a ditch, if no sturdy shelter is available. Schmidlin and his colleagues conducted site surveys of mobile home parks and vehicles that had been hit by tornadoes of various strength. They found that in a large number of instances, mobile homes were severely damaged or destroyed, while vehicles parked next to them or nearby suffered no major damage. In these cases, a person remaining in the mobile home would have been killed or severely injured, while a person in the nearby vehicle would have been unharmed. In general, Schmidlin found that winds of about 80 miles per hour were required to tip a mobile home, while much stronger winds of 120 miles per hour were required to tip a car. 4 International Journal of Mass Emergencies and Disasters
Specifically, he found that in tornadoes rated F1 or F2 on the Fujita Scale 1, just 4 percent of the vehicles he observed were tipped over and just 28 percent were moved. The upper end of the F2 range is estimated wind of 157 mph at a height of 10 meters, which translates to a speed of about 120 mph at door-handle height. At this wind speed, most mobile homes are tipped or blown apart, even if tied down, in contrast to the overwhelming majority of cars that survive and are not tipped, or in most cases even moved or significantly damaged. At higher Fujitia Scale ratings, cars suffer greater, sometimes devastating, damage, but the great majority of tornadoes are F2 or weaker. For example, between 1985 and 1996, more than 85 percent of tornadoes were F0 or F1, and fewer than 4 percent were F3 or stronger (Thompson and Vescio, 1998). In addition to the site survey research, Schmidlin and his colleagues also performed wind tunnel tests on one-sixth scale models of a midsize sedan and a minivan (Schmidlin et al., 2002). The tests indicated that it would take winds around 115-130 mph to tip the sedan (depending on wind direction) and a little stronger to tip the minivan. These findings are very consistent with those of the site-survey research, indicating that it takes much stronger winds to tip an automobile than to tip or blow apart a mobile home. It has also been pointed out by Schmidlin (2002) and by Bernner and Noji (1993) that there is no research evidence establishing that outdoor locations such as ditches are safer than vehicles, and multiple studies of tornadoes in which it was found that people who stayed in their vehicles fared better than those who tried to take shelter outside. In the Marion, IL tornado of 1982, DuClos and Ing (1989) found that people who tried to drive to safety were less likely to be injured than people who took shelter outside, and that nobody was injured in a vehicle even in a few instances in which the vehicle was overturned by the tornado. Carter, Millson, and Allen (1989) also found in the Barrie, Ontario tornado of 1985 that people who remained in vehicles were less likely to be injured than people who took shelter outdoors. Two studies of the devastating tornadoes in Oklahoma on May 3, 1999 also produced similar findings. Daley et al. (2005) found that people in vehicles were less likely to be injured or killed than persons who were either outdoors or in mobile homes. Additionally, Hammer Farley: Tornado Warnings 5 and Schmidlin (2002) found that people who left their homes to drive out of the path of the tornado fared better than even people who remained in their homes. This finding may be tied to 1) the lack of basements in most homes in that area and 2) the long lead time (30 minutes) between the warning and the time the tornado struck. Additionally, there are multiple documented cases in recent years in which people have followed the recommendation to abandon their vehicles and get in the ditch and have been killed as a result, either by their own vehicle or other objects. On February 16, 2001, a woman saw a tornado near Goodman, Mississippi and abandoned her car. The tornado, which was rated F2, rolled her car over onto her, causing her death (National Weather Service Storm Prediction Center, 2004). In 1999, a woman and a fifteen year old girl were killed near Logan, Iowa when they took shelter in a ditch, and their abandoned car and a 3-ton soybean head from a combine were blown on top of them by an F3 tornado (National Climatic Data Center, 2000, p. 109). On the other hand, there are also multiple documented cases in which people died in vehicles, not necessarily because the vehicle was tipped, but because it was hit by flying projectiles or falling tree branches. For example, on June 7, 2001, a man died when a tree fell on the pickup truck he was driving near Zachary, LA (Storm Prediction Center, 2002). The tornado was only rated F1. Hence, because of falling trees or flying projectiles, vehicles may be a dangerous place to be, even if they are not moved or tipped by the wind. It is also true that a handful of deaths and injuries in the May 3, 1999 Oklahoma City tornado occurred outdoors when people were attempting to reach their vehicles to drive out of the path or to shelter, or when they abandoned vehicles to get under an overpass (it is unknown whether these individuals had initially gotten into a vehicle to flee the tornado). While getting under an overpass is not recommended, either by the NWS and other emergency management agencies or by Schmidlin and his supporters, it is possible that some of the individuals in both groups might have survived had they remained in shelter rather than trying to flee. Nonetheless, the overall death and injury rates were far lower for those who drove away than for those who remained in mobile homes or were outdoors, and even somewhat lower than for those who remained in houses or apartments. 6 International Journal of Mass Emergencies and Disasters
Advice Given to the Public Concerning Vehicles, Mobile Homes, and Tornadoes There are a number of ways in which the NWS communicates with the public regarding what actions should be taken when a tornado threatens. First, the NWS and other public-safety and emergency- response agencies publish safety guidelines advising people what actions should be taken when a tornado threatens. Second, information on tornado safety is given to the public by NWS personnel at severe weather safety talks and storm spotter trainings . Finally, information on actions to take to protect oneself is included with tornado warnings in the form of CTA statements. The research reported here focuses primarily on CTA statements, although the NWS personnel who were interviewed also gave useful information on their practices in safety talks and spotter trainings. However, a brief review of the content of safety guidelines is in order, because these are these publicly- promulgated guidelines give a sense of the “official” NWS position. Of course, the degree to which this “official” position is reflected in the actual practices followed by individual NWS professionals in local offices throughout the country is uncertain, and represents the main research question addressed by this paper. An examination of safety guidelines promulgated by the NWS and related agencies reveals that the advice given remains in general inconsistent with the findings of the Schmidlin’s research. In fact, this has been acknowledged by Joseph Golden of the National Oceanic and Atmospheric Administration (NOAA). Golden (2002) states that the safety guidelines should not be changed because 1) although relatively few tornado fatalities occur in vehicles, many windstorm fatalities do, often due to trees falling on the vehicles, 2) there are documented cases of vehicles being lifted and smashed by tornadoes, and 3) attempts to flee tornadoes in vehicles are dangerous if traffic congestion occurs and account for many of the tornado deaths that do occur in vehicles. This points to a common concern among supporters of the current guidelines: It is difficult and confusing to issue guidelines that say to do one thing in one situation (drive away if you are in open country with no congestion) but something else in another (avoid vehicles if congestion is likely). Additionally, changing the guidelines causes confusion. Farley: Tornado Warnings 7
For example, it has been twenty years since the NWS dropped the recommendation that people open windows before a tornado strikes, but NWS meteorologists still receive questions about this recommendation (Golden, 2002). Golden does indicate support for changing guidelines to support abandonment of mobile homes for a stationary automobile, but no such recommendation yet appears in any of the safety guidelines issued by the NWS or American Red Cross. For example, the NWS Severe Weather Preparedness Guide brochure (National Weather Service, 1999)—probably the most “official” source of advice from the NWS, contains the following: MYTH If you are driving and a tornado is sighted, you should turn and drive at right angles to the storm. TRUTH The best thing to do is to seek the best available shelter. Many people are injured or killed when remaining in their vehicles. MYTH People caught in the open should seek shelter under highway overpasses. TRUTH Take shelter in a sturdy reinforced building if at all possible. Overpasses, ditches, and culverts may provide limited protection from a tornado, but your risk will be greatly reduced by moving inside a strong building. Note that the advice here is specifically against driving at right angles to the tornado. Advice on ditches and overpasses is ambiguous, as it (correctly, in the view of most researchers) states that they are less safe than a sturdy building but indicates they may “provide limited protection.” This could be, and often is, interpreted as saying that if no building is available, they may offer the “best available shelter” as referenced in the preceding statement advising abandonment of vehicles. Similar advice, but with a more positive take on getting in ditches, appears in NOAA Outlook (National Oceanic and Atmospheric Administration, no date), a Web page of the National Oceanic and Atmospheric Administration (NOAA), the parent organization of the NWS: 8 International Journal of Mass Emergencies and Disasters
Q. What actions should people take to protect themselves during a tornado? A. Move to a pre-designated shelter such as a basement in a home or building. If an underground shelter is not available, move to an interior room or hallway on the lowest floor and get under a sturdy piece of furniture. Stay away from windows; get out of cars—do not try to outrace a tornado. If you’re caught outside, lie flat in a nearby ditch or depression. Again, this statement advises against driving away from a tornado, and says to “get out of cars.” If one is caught outside (one way this could happen is by getting out of a car, if no better shelter is available nearby), the advice is to lie in a ditch. The “tornado safety tips” listed on the Web page of the NWS Storm Prediction Center (Edwards, 2004), is the most nuanced set of advice. It is written by an individual author (Roger Edwards of SPC) and does not appear to constitute an official guideline. In some regards, it offers slightly different advice than the above items: In a mobile home: Get out! Even if your home is tied down, you are probably safer outside, even if the only alternative is to seek shelter out in the open. Most tornadoes can destroy even tied-down mobile homes; and it is best not to play the low odds that yours will make it. If your community has a tornado shelter, go there fast. If there is a sturdy permanent building within easy running distance, seek shelter there. Otherwise, lie flat on low ground away from your home, protecting your head. If possible, use open ground away from trees and cars, which can be blown onto you.
In a car or truck: Vehicles are extremely dangerous in a tornado. If the tornado is visible, far away, and the traffic is light, you may be able to drive out of its path by moving at right angles to the tornado. Otherwise, park the car as quickly and safely as possible -- out of the traffic lanes. [It is safer to get the car out of mud later if necessary than to cause a crash.] Get out and seek shelter in a sturdy building. If in the open country, run to low ground away from any cars (which Farley: Tornado Warnings 9
may roll over on you). Lie flat and face-down, protecting the back of your head with your arms. Avoid seeking shelter under bridges, which can create deadly traffic hazards while offering little protection against flying debris. This advice is different from all of the other sources cited here in that it does mention the possibility of driving out of the path of the tornado under some circumstances. However, if the tornado cannot be avoided, the advice is still to get out, though the possibility of being hit by a vehicle moved by the tornado is mentioned. The advice to mobile home residents is the same as in the other statements: If there is no sturdy building or storm shelter available, get in a low place on the ground. Specifically, there is no mention of getting out of a mobile home and into a vehicle. Finally, the American Red Cross advises the following on its Web site: When a Tornado WARNING Is Issued...