Tornado Information

A tornado is a violent windstorm characterized by a twisting, funnel-shaped cloud. It is spawned by a thunderstorm (or sometimes as a result of a hurricane) and produced when cool air overrides a layer of warm air, forcing the warm air to rise rapidly.

Some tornadoes are clearly visible, while rain or nearby low-hanging clouds obscure others. Occasionally, tornadoes develop so rapidly that little, if any, advance warning is possible.

Before a tornado hits, the wind may die down and the air may become very still. A cloud of debris can mark the location of a tornado even if a funnel is not visible. Tornadoes generally occur near the trailing edge of a thunderstorm. It is not uncommon to see clear, sunlit skies behind a tornado.

The following are facts about tornadoes:

• They may strike quickly, with little or no warning.
• They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.
• The average tornado moves Southwest to Northeast, but tornadoes have been known to move in any direction.
• The average forward speed of a tornado is 30 MPH, but may vary from stationary to 70 MPH.
• Tornadoes can accompany tropical storms and hurricanes as they move onto land.
• Waterspouts are tornadoes that form over water.
• Tornadoes are most frequently reported east of the Rocky Mountains during spring and summer months.
• Peak tornado season in the southern states is March through May; in the northern states, it is late spring through early summer.
• Tornadoes are most likely to occur between 3 p.m. and 9 p.m., but can occur at any time.

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A tornado watch is issued by the National Weather Service when tornadoes are possible in the area. This is the time to remind family members where the safest places within your home are located, and listen to the radio or television for further developments.

A tornado warning is issued when a tornado has been sighted or indicated by weather radar. If a tornado warning is issued for your area and the sky becomes threatening, move to your pre-designated place of safety.

Fujita-Pearson Tornado Scale
F-0	40-72 mph	Chimney Damage, Tree Branches Broken
F-1	73-112 mph	Mobile homes pushed off foundation or overturned
F-2	113-157 mph	Considerable damage, mobile homes demolished, trees uprooted
F-3	158-205 mph	Roofs and walls torn down, trains overturned, cars thrown
F-4	207-260 mph	Well-constructed walls leveled
F-5	261-318 mph	Homes lifted off foundation and carried considerable distances, Autos thrown as far as 100 meters
Interactive Twister

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Precautions

Before a tornado strikes

• Know the terms used to describe tornado threats; tornado watch and tornado warning.
  
  
• If you see any revolving, funnel shaped clouds, report them immediately by telephone to 911.
  
  
• Know the locations of designated shelter areas in public facilities, such as schools and public buildings.
  
  
• Have emergency supplies on hand during tornado season.
  
  
• Be sure everyone in your household knows in advance where to go and what to do in case of a tornado warning.
  
  
• Make an inventory of your household furnishings and other possessions. Supplement the written inventory with photographs. Keep inventories and photos in a safe deposit box or some other safe place away from the premises.
  

During a tornado

• Whenever severe thunderstorms threaten your area, listen to radio and television newscasts for the latest information and instructions.
  
  
• When a tornado has been sighted, stay away from windows, doors and outside walls. Protect your head from falling objects or flying debris. Take cover immediately, wherever you are.
  

If you are in:	Then:
A structure (e.g. residence, small building, school, nursing home, hospital, factory, shopping center, high-rise building)	Go to a pre-designated shelter area such as a safe room, basement, storm cellar, or the lowest building level. If there is no basement, go to the center of an interior room on the lowest level (closet, interior hallway) away from corners, windows, doors, and outside walls. Put as many walls as possible between you and the outside. Get under a sturdy table and use your arms to protect your head and neck. Do not open windows.
A vehicle, trailer, or mobile home	Get out immediately and go to the lowest floor of a sturdy, nearby building or a storm shelter. Mobile homes, even if tied down, offer little protection from tornadoes.
The outside with no shelter	Lie flat in a nearby ditch or depression and cover your head with your hands. Be aware of the potential for flooding. Do not get under an overpass or bridge. You are safer in a low, flat location. Never try to outrun a tornado in urban or congested areas in a car or truck. Instead, leave the vehicle immediately for safe shelter. Watch out for flying debris. Flying debris from tornadoes causes most fatalities and injuries.

After a tornado

• Use great caution when entering a building damaged from high winds. When entering or cleaning a tornado-damaged building, be sure that walls, ceiling and roof are in place and that the structure rests firmly on the foundation.
  
  
• Look out for broken glass and downed power lines.
  
  
• Check for injuries. Do not attempt to move seriously injured persons unless they are in immediate danger of further injury. Call for help immediately.
  

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Can it Happen to You? It did for us...

June 7, 2007 Tornado

Fast moving supercell thunderstorms with damaging winds, hail larger than 5 inches in diameter, and tornadoes ripped across central and northeast Wisconsin on June 7, 2007.  Five tornadoes touched down in central and northeast Wisconsin.

A long-track tornado touched down at 4:31 pm east of Mattoon in Shawano County and continued northeast to the Oconto-Marinette County line.  The tornado was on the ground for at least 40 miles, and was over 1/2 mile wide at times.  Over 14000 acres of trees were snapped or flattened and many dozens of buildings were damaged or destroyed.  The twister was rated an EF3 on the Enhanced Fujita scale, with estimated winds of 140 to 160 mph.   Damage by this tornado alone exceeded $15 million (property and timber).

As the tornado moved northeast into the Nicolet National Forest in Oconto County, it flattened tens of thousands of trees as it headed toward Highway 64.  The damage path near Highway 64 was three-quarters of a mile wide!  The twister caused EF2 damage four miles north of the city of Mountain on Highway 32, in the town of Riverview, with estimated winds of around 130 mph.  The width of the tornado in this area was almost 1/2 mile.

Tens of thousands of trees, many pines, were snapped or uprooted along the damage path.  Few, if any trees exhibited debarking.

To learn more about the June 7th Tornado, visit the NOAA Website

This is what remained of a double-wide mobile home in the town of Riverview.  The owner heard the Tornado Warning and went into the bathtub (circled in large view), and escaped without a scratch!

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Other Information & Resources

Thunderstorms, Tornadoes, Lightning...Nature's Most Violent Storms