FIG T-12: Image courtesy of NOAA   Tornadoes kill, on average, two people a year in Canada and injure eighty. On 4 July 1996, nine tornadoes raged through Saskatoon, Maymont (the citizens of Maymont experienced the largest tornado, an F3), and Osler, Saskatchewan, dropping hail the size of softballs. While no one was killed, power lines were taken down by the tornadoes.   Tornadoes also cause a great deal of property damage. Each year, tornadoes in the US cause, on average, over $1 billion in property damage. The large outbreak of tornadoes in May 2003 - which recorded over 500 tornadoes - caused some $1.6 billion in damage.     Tornado Detection   The first step towards mitigating the effects of tornadoes is developing good methods for detecting these powerful storms. Weather services use several methods to help detect tornadoes, both when they are forming and once they are on the ground.   Storm Spotters: Storm Spotters are volunteers that call in to their local forecast office with reports of severe weather. They can be valuable life-savers with their timely reports.   Radar: Conventional radar transmits microwave pulses. When the pulses strike an object, a fraction is scattered back to an antenna. Precipitation particles are large enough to bounce back an 'echo' on a radar screen. Tornadoes often form a 'hook echo' in the southwest portion of a thunderstorm. However, not all tornadoes produce this hook shape on a radar screen.   Doppler Radar: Doppler radar can see not only the precipitation in a thunderstorm (through its ability to reflect microwave energy, or reflectivity), but motion of the precipitation along the radar beam. In other words, it can measure how fast rain or hail is moving toward or away from the radar. In the dual image below, the radar was unusually close to an F5 tornado in northern Moore, Oklahoma - close enough to make out signatures of the tornado itself. This large, violent, and extremely destructive tornado was hurling many tons of debris high into the air as it approached I-35. The debris, which reflects radar energy much more strongly than does rain, caused the brightest white blocks of reflectivity within the hook echo. To make a storm-relative velocity image, the radar system's computer programs take away thunderstorm movement to give a truer look at the motions inside the storm. Here, the mesocyclone and tornado in northern Moore are represented by progressively brighter greens (toward the radar) and reds (away from the radar). (Source: NOAA)   FIG T-13: Image courtesy of NOAA   Turtles: Turtles are small, squat, heavy, aerodynamic instrument packages which were designed to withstand tornado wind speeds while measuring temperature, pressure, and humidity at ground level. They were sometimes place on the ground at 100-250 yard intervals in the path of tornadic mesocyclones. Scientists are still analyzing data from these deployments. Turtles do not measure winds.   TOTO (TOtable TOrnado observatory): TOTO was a metal barrel weighing from 250-350 pounds. The acronym TOTO was adapted from the name of Dorothy's dog in The Wizard of Oz (the dog who was swept away with Dorothy in the tornado). TOTO was outfitted with a variety of weather instruments - anemometers, pressure sensors, and humidity sensors. However, it proved very difficult to place TOTO in the path of a tornado. It was never successful at capturing a direct hit. TOTO was retired after 1987 because of safety issues and the logistical difficulty of getting such a large, heavy, cumbersome object in front of a tornado.     Top Ten Tornadoes in Canada Rank Location Date Death and Injuiry 1 Regina, SK 30 June 1912 28 dead, hundreds injured 2 Edmonton, AB 31 July 1987 27 dead, hundreds injured 3 Windsor, ON 17 June 1946 17 dead, hundreds injured 4 Pine Lake, AB 14 July 2000 12 dead, 140 injured 5 Valleyfield, QC 16 August 1888 9 dead, 14 injured 6 Windsor, ON 3 April 1974 9 dead, 30 injured 7 Barrie, ON 31 May 1985 8 dead, 155 injured 8 Sudbury, ON 20 August 1970 6 dead, 200 injured 9 St. Rose, QC 14 June 1892 6 dead, 26 injured 10 Buctouche, NB 6 August 1879 5 dead, 10 injured     Personal Preparedness   FIG T-15: Image courtesy of NOAA   To protect yourself from tornado damage, emergency management organizations recommend the following steps:   1. Listen to the radio during tornado season. A tornado watch is issued by the Environment Canada when weather conditions make tornadoes likely. Now is the time to remind your family about the safest place in your home. Turn on a radio or television and listen for further announcements. Since tornado prediction is an inexact science, don’t expect a lot of warning.   2. A tornado warning is issued when a tornado has been sighted (visually or on radar). The danger is serious and everyone should go to a safe place, turn on a battery-operated radio, and wait for instructions   3. What to Do During a Tornado   If at home:   If you have a tornado safe room or engineered shelter, go there immediately (for more information on safe rooms click here). Go at once to a windowless interior room, storm cellar, basement, or lowest level of the building. If there is no basement, go to an inner hallway or a smaller inner room without windows, such as a bathroom or closet. Get away from the windows. Get under a piece of sturdy furniture such as a workbench or heavy table or desk and hold on to it. Use arms to protect head and neck. If in a mobile home, get out and find shelter elsewhere.   If at work or school:   Go to the area designated in your tornado plan. Avoid places with wide-span roofs such as auditoriums, cafeterias, large hallways, or shopping malls. Get under a piece of sturdy furniture such as a workbench or heavy table or desk and hold on to it. Use arms to protect head and neck.   If outdoors:   If possible, get inside a building. If shelter is not available or there is no time to get indoors, lie in a ditch or low-lying area or crouch near a strong building. Be aware of the potential for flooding. Use arms to protect head and neck.   If in a car:   Never try to out-drive a tornado in a car or truck. Get out of the car immediately and take shelter in a nearby building. If there is no time to get indoors, get out of the car and lie in a ditch or low-lying area away from the vehicle. Be aware of the potential for flooding.