A-1 Farley Call to Action Statements in Tornado Warnings
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1 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.