WEATHER

It's tornado season in Wisconsin. Here's what you need to know to help keep you and your family safe.

Joe Taschler
Milwaukee Journal Sentinel

It's tornado season in Wisconsin.

June is typically the month when the Badger State sees its largest number of tornadoes and severe thunderstorms, according to the National Weather Service. July typically has the second-most tornadoes in Wisconsin. 

The Upper Midwest is not immune from potentially lethal severe weather. A deadly tornado that ravage a small city on May 20 in Michigan — only about 130 miles due east of Door County, Wisconsin, — is a brutal reminder of that.

This image provided by Steven Bischer, shows an upended vehicle at a Culver's restaurant after a tornado touched down in Gaylord, Michigan, on May 20, 2022. The tornado, which killed 2 people, demonstrated that the Upper Midwest is not immune from deadly storms, forecasters said.

That twister, in Gaylord, Michigan, produced 140 mph winds and killed two people. Another 44 people were injured.

"That (type of storm) can happen anywhere here in the Great Lakes," said Tim Halbach, warning coordination meteorologist with the weather service in Sullivan. "Everything came together. It just happened to run right through the city of Gaylord. 

"Storms like that are not very common around here," Halbach added. "It was a supercell thunderstorm which is typically our worst kind of thunderstorm where you have the potential for large  tornadoes, large hail, damaging winds and heavy rainfall.

While rare, all it takes is one such storm moving through a populated area to have a devastating impact.

When severe weather is possible, forecasters will issue a thunderstorm risk outlook. Southern Wisconsin was under a moderate -- 4 out of 5 -- risk when severe thunderstorms and tornadoes moved across the region on July 28-29, 2021.

"It's something that has happened here in Wisconsin," Halbach said. "Fortunately, it's been a while since we've had a tornado like that go through the southern part of the state. If things come together just right we can get it here. 

"There are a lot of days when the ingredients just don't quite come together. But the times that they do, it can be disastrous," Halbach said.

This time of year is when the warm, moist air needed to generate severe thunderstorms arrive in Wisconsin.

"We're heading into our typical peak for severe weather," Halbach said. "June tends to be when we have the most tornadoes, but we have them throughout the summer in June, July and August."

A thunderstorm is considered severe when it produces any of the following:

  • Hail an inch or larger in diameter.
  • Wind at or above 58 mph.
  • A tornado.

"Having multiple ways to receive warnings is important," Halbach added. "Be prepared and be ready to act."

"Our goal is to keep people safe." Halbach said. 

Tornado database:History of tornadoes in Wisconsin

What's the difference between a tornado watch and a tornado warning?

Tornado watch.  A tornado watch defines an area where tornadoes and other kinds of severe weather are possible, according to the weather service Storm Prediction Center. A tornado watch does not mean tornadoes are imminent, just that everyone should be alert and prepared to go to safe shelter if tornadoes occur. 

A tornado warning means a tornado is occurring. A tornado watch means tornadoes are possible in the watch area.

Tornado warning.  A tornado warning means that a tornado has been spotted, or that Doppler radar has detected a thunderstorm capable of producing a tornado. When a tornado warning is issued for your town or county, take immediate safety precautions.

What are the signs of a tornado? 

"Weather forecasting science is not perfect and some tornadoes do occur without a tornado warning," according to the storm center. "There is no substitute for staying alert to the sky."

Besides an obviously visible tornado, here are some things to look and listen for that would indicate the possible presence of a tornado:

  • Strong, persistent rotation in the cloud base.
  • Whirling dust or debris on the ground under a cloud base -- tornadoes sometimes have no visible funnel.
  • Hail or heavy rain followed by either total calm or a fast, intense wind shift.
  • Many tornadoes are wrapped in heavy precipitation and can't be seen.
  • A loud, continuous roar or rumble, which doesn't fade in a few seconds.
  • At night, watch for small, bright, blue-green and/or white flashes at ground level near a thunderstorm. The flashes will occur along the ground. The flashes are power lines are being snapped by very strong wind, maybe a tornado.

What about severe thunderstorm warnings and watches? 

Severe thunderstorm warning. This is issued when a severe thunderstorm is indicated by radar or a storm spotter reports it to the weather service. People in the affected area should seek safe shelter immediately. Severe thunderstorms can produce tornadoes with little or no advance warning.

Severe thunderstorm watch. This is issued by the National Weather Service when conditions are favorable for the development of severe thunderstorms. The watches are normally issued well in advance of actual severe weather. Be prepared to move a place of safety if threatening weather approaches.

What to do if a tornado warning is issued

Responding to and taking action to keep yourself and others safe in a tornado or severe storm depends where you are when the storm hits. Here are some examples:

A house with a basement. Avoid windows. Get in the basement and under some kind of sturdy protection such as a heavy table or work bench. Know where very heavy objects are on the floor above, i.e., pianos, refrigerators, waterbeds, etc., and do not go under them. They may fall down through a weakened floor.

A house with no basement, a dorm, or an apartment. Avoid windows. Go to the lowest floor, a small center room like a bathroom or closet, under a stairwell, or in an interior hallway. Crouch as low as possible to the floor, facing down; and cover your head with your hands.  "Even in an interior room, you should cover yourself with some sort of thick padding (mattress, blankets, etc.), to protect against falling debris in case the roof and ceiling fail," the storm center says on its website.

Tornadoes occurred across all but far northern Wisconsin last year, according to the National Weather Service.

Office building, hospital, nursing home or skyscraper. Go directly to an enclosed, windowless area in the center of the building, away from glass and on the lowest floor possible. Crouch down and cover your head. "Interior stairwells are usually good places to take shelter," according to the storm center. 

Mobile or manufactured home. "Get out! Even if your home is tied down, it is not as safe as an underground shelter or permanent, sturdy building," according to the Storm Prediction Center. "Go to one of those shelters, or to a nearby permanent structure, using your tornado evacuation plan." 

School. Follow the procedures from tornado drills. Go to the interior hall or windowless room in an orderly way. Crouch low, head down, and protect the back of your head with your arms. Stay away from windows and large open rooms like gyms and auditoriums.

This graphic shows where tornadoes have occurred the most in Wisconsin and also shows how many people have been killed or injured in the storms.

Car or truck. Vehicles are extremely risky in a tornado. "There is no safe option when caught in a tornado in a car, just slightly less-dangerous ones," according to the Storm Prediction Center. "If the tornado is visible, far away, and the traffic is light, you may be able to drive out of its path by moving at right angles to the tornado." Park the vehicle out of traffic lanes and seek shelter in a sturdy building or underground if possible. "If you can safely get noticeably lower than the level of the roadway, leave your car and lie in that area, covering your head with your hands," according to the SPC. "Avoid seeking shelter under bridges, which can create deadly traffic hazards while offering little protection against flying debris."

In the open outdoors. If possible, seek shelter in a sturdy building. If not, lie flat and face-down on low ground, protecting the back of your head with your arms. Get as far away from trees and cars as you can; they may be blown onto you in a tornado.

Shopping mall or large store. Move as quickly as possible to an interior bathroom, storage room or other small enclosed area, away from windows.

Church or theater. Move quickly but orderly to an interior bathroom or hallway, away from windows. Crouch face-down and protect your head with your arms. If there is no time to do that, get under the seats or pews, protecting your head with your arms or hands.

Contact Joe Taschler at (414) 224-2554 or jtaschler@gannett.com. Follow him on Twitter at @JoeTaschler or Facebook at facebook.com/joe.taschler.1.