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Wisconsin Tornado and Severe Weather Awareness 

Part 4 - Tornado Myths

Many myths exist about tornadoes.  If followed, these myths could be life-threatening.  Several of these myths are listed below.

  1. Seek Shelter under an Over-Pass
    • Stopping under a bridge to take shelter from a tornado is a very dangerous idea, for several reasons:
      • Deadly flying debris can still be blasted into the spaces between bridge and grade, and impaled in any people hiding there.
      • Even when strongly gripping the girders (if they exist), people may be blown loose, out from under the bridge and into the open, possibly into the tornado itself. Chances for survival are not good if that happens.
      • The bridge itself may fail, peeling apart and creating large flying objects, or even collapsing down onto people underneath. The structural integrity of many bridges in tornado winds is unknown--even for those which may look sturdy.
      • Whether or not the tornado hits, parking on traffic lanes is illegal and dangerous to yourself and others. It creates a potentially deadly hazard for others, who may plow into your vehicle at full highway speeds in the rain, hail, and/or dust. Also, it can trap people in the storm's path against their will, or block emergency vehicles from saving lives.
  2. Tornadoes Never Strike Twice
    • Cordell Kansas was struck by a tornado on May 20th, three years in a row (1916, 1917, 1918).  In Guy Arkansas, three tornadoes hit the same church on the same day.
  3. Big Cities and their Tall Buildings are Protected from Tornadoes
    • Many cities in the U.S. have been directly hit by tornadoes in recent years including Miami, Salt Lake City, Birmingham, Oklahoma City, Houston, Fort Worth, Nashville and Joplin MO. 
    • Tornadoes are typically 5 to 10 miles tall.  A tall building with a height of 500 to 1000 feet can not deflect or destroy a tornado. 
  4. Large Lakes Protect Nearby Areas from Tornadoes
    • While cold water and the cool air on top of the lake can provide a locally stable environment, chances are a thunderstorm producing a tornado moving toward a cold lake has something much larger driving it than the cold water can inhibit. 
    • Typical lake breezes found along the Lake Michigan shore are often shallow and only affect a small portion of the lower atmosphere.  Warm and unstable air above this marine layer/lake breeze could very well sustain a thunderstorm's strength.  For example on March 8, 2000 Milwaukee County experienced its earliest tornado on record at a time when Lake Michigan is climatologically coldest.  On August 8, 2011, a weak tornado developed on Lake Monona in the city of Madison.  It stayed over the lake as a waterspout and did not cause damage. This weak waterspout was associated with a rain-shower.  There were no thunderstorms in the area.
  5. Mountains, River Valleys and Large Lakes Inhibit Tornados and/or cause Splitting Storms
    • While conditions would not be optimal for tornado development on top of mountains or over Lake Michigan, tornadoes have been documented to cross the Appalachian Mountains and cross a 10 thousand foot tall mountain in Yellowstone National Park.  Strong tornadoes have also crossed the Mississippi River and other large rivers and lakes.
  6. Seeking Shelter in the Southwest Corner of your Home will Protect you from Flying Debris
    • This myth was devised slowly by the misconception that all tornadoes move to the northeast.  Therefore as the tornado hits your home, all the debris would be directed to the northeast, away from you.  Since tornadoes can move in any direction, this myth is false.
    • The SW corner is no safer than any other part of the basement, because walls, floors and furniture can collapse (or be blown) into any corner.
    • Debris such as motor vehicles can also be pushed into the basement by a tornado.  You should position yourself under the I-Beam or a heavy work bench in your lowest level to increase your chances for survival.
    • During a tornado warning, seek shelter in an interior room on the lowest level of the building, away from windows, and if possible, under a sturdy piece of furniture or staircase.
  7. Open Windows Prior to Tornado Strike to Equalize Pressure Inside the House to Prevent it from Exploding
    •  Opening the windows is absolutely useless, a waste of precious time, and can be very dangerous. Don't do it. You may be injured by flying glass trying to do it. And if the tornado hits your home, it will blast the windows open anyway.
  8. Tornadoes Only Occur in the Late Spring and Summer in Wisconsin
    • While the optimal time for tornadoes in Wisconsin is May through July, tornadoes can develop at any time of day and at any time of year.  Since 1950, tornadoes have occurred in Wisconsin during every month but February, however it's only a matter of time.
  9. The Shape and Size of the Tornado Determines it's Strength
    • Tornadoes come in all shapes and sizes and you should not correlate the size of the tornado with its strength.  The only way to determine the strength of the tornado is through damage assessments, or by taking a direct measurement of the wind.  During damage assessments, National Weather Service personnel look for clues that will tell them how strong the winds were.  The wind estimate (or measurement) is then related to the Enhanced Fujita (EF) Tornado Scale, and a tornado intensity level will be assigned to the tornado.  Tornadoes are rated on a scale from EF0 to EF5.
    • Merely by looking at the tornado's shape does not reveal it's strength.  The visible funnel of the tornado is created by condensation or dirt and debris.  Conditions that create the visible funnel will change each time a tornado develops, and therefore the funnel appearance can not be reliably used as a strength indicator.
  10. Significant Property or Crop Damage is Always a Result of a Tornado
    • Tornadoes can produce significant damage, however straight-line winds can be just as destructive.  Down-burst winds associated with severe thunderstorms are capable of reaching wind speeds of 100 to 150 mph, or the equivalent of an EF1, EF2, or EF3 tornado.  Significant damage does not always imply a tornado. 
  11. Mobile Homes attract Tornadoes
    • Of course not. It may seem that way, considering most tornado deaths occur in mobile homes, and that some of the most graphic reports of tornado damage come from mobile home communities. The reason for this is that mobile homes are, in general, much easier for a tornado to damage and destroy than well-built houses and office buildings. A brief, relatively weak tornado which may have gone undetected in the wilderness, or misclassified as severe straight-line thunderstorm winds while doing minor damage to sturdy houses, can blow a mobile home apart. Historically, mobile home parks have been reliable indicators, not attractors, of tornadoes. 
  12. The Number of Tornadoes have been Increasing due to more Favorable Weather
    • The number of tornadoes in the U.S. has increased since the pre-1950 years.  However this increase is most likely due to the general increase in the population, more trained storm spotters, better radar detection, more cameras, and better follow-up damage surveys. 

For much more information about Tornadoes refer to the Storm Prediction Center Tornado FAQ