Wind chill calculated for safety reasons

McClatchy-Tribune Information Services

DULUTH — A lot of Northlanders like to brag about the arctic wind chills every winter as if they are a right of passage.

But what’s the point of keeping track of those ultra-low "feels-like" wind chill temperatures? Is it just to make it seem colder? Make us seem tougher? Make the misery worse?

The National Weather Service and its counterpart, Environmental Canada, revised wind chill tables in recent years to more accurately reflect how cold winds make us feel. Lost in the effort was why the change was made.

"We’re trying to emphasize the human impact from the conditions, not just the conditions," said Amanda Graning, a forecaster at the National Weather Service office in Duluth.


The Weather Service wants people to know that when wind chill advisories and warnings are issued, it means the weather is dangerous. So this year, the service’s Duluth office is placing new emphasis on a "minutes to frostbite" chart that shows exactly how soon skin can freeze if we venture outside.

"We issue wind chill advisories and tell people we’re going to have wind chills of 60 below zero, but that doesn’t seem to hit home with some people," Graning said. "But if we tell mothers that their children’s flesh can freeze in 10 minutes if they don’t keep it covered up, that might get people to pay attention."

At 20 below zero with a 20 mph wind, for example, exposed flesh can freeze to frostbite in just eight minutes.

The new wind chill table was developed a few years ago to more accurately reflect the reality of wind chill. The revised tables actually lowered wind chills to make them, on the surface, seem less severe. The earlier tables were found to be over-stating the impact.

At the same time, the effort aimed to put more emphasis on frostbite, so more scientific evidence was needed.

Clinical trials were conducted at the Defense and Civil Institute of Environmental Medicine in Toronto. Sensors were placed on the participants’ skin as they walked on a treadmill in increasingly lower temperatures and increasingly higher winds. The sensors determined the point at which the skin began to freeze.

Duluthian John Stetson doesn’t need a wind tunnel to know what frostbite feels like. An avid musher, he’s felt it in his cheeks while on dogsled races and training.

"I haven’t had it bad. Nothing on my toes or fingers, thankfully," Stetson said. "When it gets to the level of cold, it happens almost instantly on your face. You feel the sting and say, ‘Oh, darn,’ and then you get covered up and go on. Hopefully, it doesn’t turn black on you."


Graning said the "minutes to frostbite" notice will be used more often as meteorologists see frigid temperatures ahead, even when wind isn’t a factor.

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