Tornadoes, among the planet's most destructive weather events, occur when violently rotating columns of air are in simultaneous contact with the ground and the base of a cumuliform cloud. Although tornadoes are capable of suddenly changing direction, most follow a southwest to northeast path. Two officers at Oklahoma's Tinker Air Force Base made the first documented successful forecast of a tornado in March 1948. Before then, use of the word "tornado" in forecasts was discouraged, to avoid panic, states the National Oceanic and Atmospheric Administration.
All U.S. tornado warnings come from the National Weather Service, which has offices throughout the country. Only a few other nations sponsor tornado warning services, most notably the Meteorological Service of Canada. In order to spawn a tornado, a thunderstorm must generate enough moisture, lift, instability and wind shear. Without all four of these ingredients, tornadic activity is impossible. While the likelihood of severe storms may be accurately predicted a day or two ahead, whether they include tornadoes allows a warning time of only a few minutes, according to NOAA.
Basic Tracking Tools
At the NWS Storm Prediction Center, forecasters draw analyses of surface and upper-air patterns by hand every day to intimately acquaint themselves with the current weather situation. A large variety of computer software displays satellite image loops, wind patterns, data coming from surface weather stations, upper-atmosphere data from balloons and airplanes, historic weather tables and lightning strike plots. Meteorologists must sort through all this information and interpret the probability that a tornado-bearing thunderstorm will threaten a certain locale in the foreseeable future.
Role of Doppler Radar
Doppler radar is an important tool for tracking tornadoes, but it has limitations. While the radar beam can enlighten forecasters about a thunderstorm's structure, it cannot show the actual formation of a tornado. The Doppler may detect strong wind circulation, but that may or may not indicate a tornado. On-the-ground spotters are necessary to confirm the possibilities picked up by radar, NOAA explains.
Following the success of the VORTEX (Verification of the Origins of Rotation in Tornadoes) experiment, which gathered critical data on dangerous supercells in stormsin 1994 and 1995, 100 scientists launched VORTEX2, the largest study of tornadoes to date, in 2010. Employing 50 chase vehicles, researchers plan to follow tornadoes and surround them with a fleet of mobile radars to learn all they can about how tornadoes form and their patterns of damage, the Christian Science Monitor reports. Stretching from Texas to Minnesota, the study area encompasses more than 900 miles. Project participants hope to increase tornado warning time to 30 minutes to allow more people to reach shelter. Another of their goals is to reduce the current 70 percent error rate on tornado warnings. When the majority of warnings prove wrong, research indicates that people are likely to ignore all warnings, according to PBS Newshour.
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