Enhanced Fujita Scale; how National Weather Service ranks tornadoes
MILWAUKEE - Tornadoes are categorized on what is called the Enhanced Fujita Scale or EF Scale.
What is the EF scale?
What we know:
The Enhanced Fujita Scale became operational on February 1, 2007. It was designed to rate tornadoes based on estimated wind speeds and related damage. The strength of a tornado has nothing to do with the size of it.
When a tornado is surveyed, it is compared to a list of Damage Indicators and Degrees of Damage which help estimate the range of wind speeds the tornado produced to damage specific structures and/or materials.
FREE DOWNLOAD: Get breaking news alerts in the FOX LOCAL Mobile app for iOS or Android
It is important to note that the EF Scale is a set of wind estimates, not measurements based on damage. It uses a three-second gust estimate at the point of damage. Estimates vary with height and exposure.
What is EF-U rating?
Dig deeper:
Wisconsin has had tornadoes that are rated EF-U, standing for EF-Unknown. The National Weather Service rates a tornado an EF-U when the tornado's intensity can not be determined due to the lack of visible damage to buildings, trees, or other structures in order to assess the wind speed needed to classify a tornado.
Typically, Wisconsin experiences an average of 23 tornadoes per year with the peak months being May through June.
SIGN UP TODAY: Get daily headlines, breaking news emails from FOX6 News
It has been an active season across portions of the Ohio and Mississippi River valleys and the south. Wisconsin has a preliminary count of 20 tornadoes so far in 2025.
FOX6 Weather Extras
Meanwhile, FOX6Now.com offers a variety of extremely useful weather tools to help you navigate the stormy season. They include the following:
FOX6 Storm Center app
FOX LOCAL Mobile app
FOX Weather app
What is the FOX Model?
What is the FOX Model?
FOX Weather Expert Tom Wachs explains the value of the FOX Model for our team -- and our viewers.
FOX Weather
Maps and radar
We have a host of maps and radars on the FOX6 Weather page that are updating regularly — to provide you the most accurate assessment of the weather. From a county-by-county view to the Midwest regional radar and a national view — it’s all there.
School and business closings
When the weather gets a little dicey, schools and businesses may shut down. Monitor the latest list of closings, cancellations, and delays reported in southeast Wisconsin.
FOX6 Weather Experts in social media
- CLICK HERE to "Like" the FOX6 Weather Team on Facebook
- CLICK HERE to "Like" Rob Haswell on Facebook
- CLICK HERE to "Like" Tom Wachs on Facebook
- CLICK HERE to "Like" Stephanie Barichello on Facebook
- CLICK HERE to "Like" Lisa Michaels on Facebook
- CLICK HERE to "Like" Holly Baker on Facebook
- CLICK HERE to "Follow" the FOX6 Weather Team on X
- CLICK HERE to "Follow" Rob Haswell on X
- CLICK HERE to "Follow" Tom Wachs on X
- CLICK HERE to "Follow" Stephanie Barichello on X
- CLICK HERE to "Follow" Lisa Michaels on X
- CLICK HERE to "Follow" Holly Baker on X
The Source: Information in this report is from the FOX6 Weather Experts and National Weather Service.
The Source: Information in this report is from the FOX6 Weather Experts and National Weather Service.Information in this report is from the FOX6 Weather Experts and National Weather Service.