Grain Journal - January/February 2009 - (Page 40) Tornado Safety SURVIVING ONE OF NATURE’S MOST DEVASTATING STORMS For better or worse, much of North America’s grain production takes place in areas where tornadoes are fairly frequent occurrences. And sometimes they strike grain handling facilities. With the spring tornado season coming soon to the Midwest and Great Plains regions, the National Weather Service (NWS) offers these tips on surviving a tornado. Some Definitions The Glossary of Meteorology defines a tornado as “a violently rotating column of air, pendant from a cumuliform cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud.” The most destructive and deadly tornadoes occur from “supercells,” which are rotating thunderstorms with a well-defined radar circulation. Supercells also can produce damaging hail, severe straight-line winds, unusually frequent lightning, and flash floods. The NWS issues two types of weather alerts related to tornadoes. A tornado watch is an area where tornadoes and other kinds of severe weather are possible in the next several hours. It does not mean tornadoes are imminent, just that you need to be alert and prepared to go to safe shelter, if tornadoes do happen or a warning is issued. Now is the time to turn on local TV or radio, turn on and set the alarm switch on your weather radio, and make sure you and your coworkers and family have ready access to safe shelter. A tornado warning means a tornado has been spotted or that the NWS Doppler radar indicates a thunderstorm circulation that can spawn a tornado. When a tornado warning is issued for your town or county, take immediate safety precautions. Signs of a Tornado However, weather forecasting is not 40 GJ J/F This tornado struck Dimmitt, TX in 1995, but tornadoes often are not as dramatic appearing as this and may not even be visible. Photo by Harald Richter, National Oceanic & Atmospheric Administration Central Library. a perfect science, and some tornadoes do occur without a warning. Besides an obviously visible tornado, here are some things to look or listen for: • Strong, persistent rotation in the cloud base. • Whirling dust or debris on the ground under a cloud base. • Hail or heavy rain followed by either dead calm or a fast, intense wind shift. • Day or night, a loud, continuous roar or rumble that doesn’t fade in a few seconds like thunder. • At night, small, bright, blue-green to white flashes at ground level near a thunderstorm, which indicate power lines are being snapped by a very strong wind. • At night, persistent lowering from the cloud base illuminated or silhouetted by lightning, especially if it’s on the ground or you see those bluegreen-white power line flashes. Taking Shelter • In a house or building with a basement, avoid windows. Get in the basement and under some kind of sturdy protection like a heavy table or workbench or cover yourself with a mattress or sleeping bag. Know where very heavy objects (like a refrigerator) are located on the floor above, and do not go under them. • In a house or building with no basement, avoid windows. Go to the lowest floor, small center room (like a bathroom or closet), under a stairwell, or in an interior hallway with no windows. Crouch as low as possible to the floor facing down, and cover your head with your hands. A bathtub may offer a shell of partial protection. Even in an interior room, you should cover yourself with some sort of thick padding like a mattress or blankets, to protect against falling debris in case the roof and ceiling fall. • At a grain elevator, the same rules apply as in a house or office building. Go directly to an enclosed, windowless area in the center of the building, away from glass. Then, crouch down and cover your head. Depending on its construction, the very safest location around grain storage may be an enclosed, below-ground tunnel beneath upright concrete storage tanks. Concrete tanks usually will stand up to a tornado a lot better than steel tanks; full tanks do better than empty ones. Avoid being caught outside. Legs, conveyors, and other equipment often are torn off and blown around in a tornado, even when attached to the sturdiest concrete structure. Consult your facility Emergency Action Plan for instructions on where to go in the event of a tornado or other emergency. • In a car or truck, your best bet is to get away from the vehicle. If the tornado is visible and far away, and traffic is light, you may be able to drive out of its path by moving at right angles to the tornado. Otherwise, park out of the traffic lanes. Get out, and seek shelter in a sturdy building. In open country, run to low ground away from any vehicles. Lie flat and face down, protecting the back of your head with your arms. Avoid seeking shelter under bridges or overpasses.
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