Tornadoes are nature’s most violent storms. Spawned from powerful thunderstorms, tornadoes can cause fatalities and devastate a neighborhood in seconds. A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can reach 300 miles per hour. Every state is at some risk from this hazard.
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.
Know the terms
Tornadoes are possible. Remain alert for approaching storms. Watch the sky and stay tuned to NOAA Weather Radio , commercial radio, or television for information. Watch for alerts on your cell phone and check social media for additional information from trusted sources.
A tornado has been sighted or indicated by weather radar. Take shelter immediately.
- Wisconsin averages 23 tornadoes a year.
- The peak tornado season in Wisconsin is April to August, but tornadoes can occur any time of year.
- Tornadoes can occur any time during the day or night, but are most frequent between 4 p.m. and 9 p.m.
- About 80% of tornadoes that hit Wisconsin are relatively weak, with winds under 100 mph. Only 1% are violent with winds over 200 mph.
- 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.
- Waterspouts are tornadoes that form over water.
What to do Before a Tornado
Be alert to changing weather conditions.
- Listen to NOAA Weather Radio or to commercial radio or television newscasts for the latest information.
- Look for approaching storms
- Look for the following danger signs:
- Dark, often greenish sky
- Large hail
- A large, dark, low-lying cloud (particularly if rotating)
- Loud roar, similar to a freight train.
What to Do During a Tornado
|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.|
|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.