Storm brewing about tornado safety
Posted May 15, 2009
Consider this scenario.
It's around rush hour on an early May afternoon. Like a normal rush hour, traffic is slow and congested. Unlike normal, though, the skies are dark and foreboding, and the wind is kicking up. Suddenly, the radio station sounds an alarm and a strange voice announces a "tornado warning"!
What would you do? Would you drive home? Find an overpass to take shelter in? Bail out of your car and lie in a ditch?
My scenario could be a description of the scene around here on Tuesday, May 5th, but it's not. It's actually a description of a small slice of what happened on May 3, 1999, in Oklahoma City. Dozens of people were killed as violent F5 tornadoes raked across the Oklahoma landscape -- including a dozen people who were killed either in a mobile home or who had abandoned their cars in favor of taking shelter under an overpass.
Where to take shelter?
Until recently, the guidelines for how to take shelter during a tornado were pretty widely accepted, if a little odd in the details. Your best bets have always been to be underground, or at least in an interior room on the lowest level of a sturdy building or other structure with a foundation. A mobile home, even one that is "tied down", has never been considered a safe place to be. All of the options in between, however, are varying shades of "not good", and it's in that gray area where there has been some controversy in the last few weeks.
That's because the American Red Cross (ARC) has changed their guidance on what to do if you're in a car or mobile home. Before, if you were stuck in either a car or mobile home, the advice was to abandon both in favor of sturdier structures or, absent that, lie down flat in a ditch and cover your head. However, the new guidelines -- released late last month -- suggest taking refuge in a car may be a better option than lying in a ditch.
The new guidelines
Specifically, the relevant new guidelines from the ARC read as follows:
- If you are caught outdoors, seek shelter in a basement, shelter, or sturdy building. If you cannot get to shelter, a recent study* suggests doing the following:
- Get into a vehicle, buckle your seat belt, and try to drive at right angles to the storm movement and out of the path.
- If strong winds and flying debris occur while you are driving, pull over and park, keeping seat belts on and the engine running. Put your head down below the windows, covering with your hands and a blanket if possible.
- If you are unable to get to a building or vehicle, as a last resort, lie in a ditch or depression and cover your head with your hands.
Astute readers will notice the asterisk in the first bullet point above. The "recent study" to which that asterisk applies was published in 2002 in the Bulletin of the American Meteorological Society. A group of researchers, led by Dr. Thomas Schmidlin of Kent State University, collected anecdotal information from storm chasers, performed field studies of tornado-torn areas, and studied the effects of winds on scale models of cars in a wind tunnel. They wanted to know at what wind speed would various types of vehicles be moved or flip over.
Their research suggests that, by and large, the wind speeds required to lift or flip typical passenger vehicles were only found in the strongest of strong tornadoes, and that for the majority of storms, a car would afford sufficient protection from the tornado winds -- more so than being in a mobile or manufactured home or lying in a ditch. Based on these results, they recommended modifying the tornado safety guidelines to reflect their belief that cars are safer than mobile homes or the ditch.
The American Red Cross made the changes in their guidelines after their Preparedness Sub-council spent more than a year reviewing this study, along with other scientific literature on the issue. Their finding, according to Rick Bissell, associate professor of emergency health services at the University of Maryland-Baltimore County, was that there was "no evidence to support the NWS suggestion that people should lie in a ditch during a tornado if they cannot find solid shelter."
What's curious is that, the American Red Cross appears to have made this change without coordinating with their partners at the National Weather Service (NWS) or Federal Emergency Management Agency (FEMA). When this came up a couple weeks ago, I spoke with Jeff Orrock, the Warning Coordination Meteorologist at the Raleigh NWS office. At the time, he was unware that the change had even happened. Since then, he has followed up with an official response from the NWS, saying that these changes were made "against the recommendations of [the] NWS" and that the official position of the NWS "hasn't changed".
As we've seen recent political campaigns, it's important to stay "on message" and to be consistent in what you're saying. This is even more important in helping people prepare for emergency situations. Conflicting information, or failing to "speak with one voice", can cause people not to plan or to hesitate in taking shelter at the critical moment. In other words, it you've got a tornado bearing down on you, that's simply not the time to figure out whose recommendations you should follow. Of course, the hope of everyone involved is that people will have evaluated the situation and taken steps long before the tornado even forms; however, we know that isn't always the case.
It's unclear right now about the degree to which ARC consulted the NWS or FEMA regarding the change; although, I'm told that officials from the Red Cross and NWS met in Washington shortly after the changes were announced. I would have enjoyed being a fly on the wall during that get-together.
As you might imagine, this new research has reignited a discussion amongst the meteorological community about the safety of cars in tornadoes. On the one hand, the research suggests that for weaker tornadoes, a car may afford superior protection than a mobile home or being out in the open. However, this still leaves a lot of unanswered questions:
- What about debris? Research has shown time and again that even "weak" tornado winds are sufficient to drive debris through even the body of a car.
- Why stay stationary? If you're in a car, attempting to outrun the tornado may be an option. (That is controversial in its own right!)
- How can you tell how strong the tornado is? The research really only holds for weaker tornadoes. Stronger ones -- EF3 and stronger, for example -- were shown to cause all of the nasty things we tend to associate with cars in tornadoes. In a critical moment, could you accurately determine the strength of the tornado, just by looking?
- What about the air bag? The guidelines suggest crouching down in the car while you ride out the tornado. What happens if your air bags deploy?
- Other factors?
When I go to talk to kids about weather, I always try to address the difference between a watch and a warning and the different steps you should take when one or the other is issued. Specifically, I'll say, "a tornado watch has been issued for this evening. Would tonight be a good night to go camping?" Of course, the answer is "no!" -- especially if the camping trip will take you away from sturdy shelter or a reliable way to hear about weather warnings. This same idea applies to any situation where severe weather might be an issue. The goal is always to ensure that if a storm comes up, you are able to decide between "good" options for taking shelter.
For now, we at WRAL will continue to rely on the NWS and FEMA guidelines that prioritize finding sturdy shelter instead of relying on a mobile home or car to keep you safe. More than that, however, we continue to preach being "weather aware" and taking action while your choices are amongst "good" options. Naturally, this means you can't wait until the last minute to evaluate your options! By then, your choice may be down to options that are "bad' or "worse" -- exactly the decision we hope you'll never have to make. Much like arguing with your spouse, once you're down to having to choose between "bad" and "worse", you've already lost!