Cold calculation: Wind chill as important as temperature, meteorologist says
GRAND FORKS — Many of us living in the Upper Midwest consider ourselves weather warriors, proudly bearing the coldest of the cold.
Meteorologist Greg Gust, of the National Weather Service office in Grand Forks, said people should pay attention to both wind chill and actual temperature, because both are important in judging whether it’s safe to go outside.
Contrary to what some may think, extreme cold by either measurement isn’t better or worse than the other, he said.
Science of wind chill
Wind chill may not be measured by a thermometer, but the formula that it’s measured by takes into account temperature, wind speed and humidity, Gust said.
And unlike the measure of temperature alone, wind chill is measured with its effect on the human body taken into consideration, Gust said.
Early measurements of wind chill started in Antarctica, he said. “It was human beings going outside to work in Antarctica under different temperatures and wind conditions, and they could only be outside working for so long before frostbite started.”
The measurement has developed over the years, and the formula for wind chill used now was adopted by the U.S. and Canadian weather services in 2001.
Compared to the previous wind chill formula, the current one doesn’t show as cold of wind chill in extreme temperatures, Gust said, calling it “a better representation.”
The current wind chill formula was developed after research at a university in Canada, which put more emphasis on humidity and the effect of wind chill on the human body.
“It has more experimentation behind it,” Gust said.
Wind chill and temperature
And although the wind chill reported by meteorologists is in relation to humans, wind chill affects everything, Gust said. He often hears people saying wind chill won’t affect things like their dog or their car.
“Whether it’s animate or inanimate, living or dead, rock, dog or human being, they’re all responding to wind chill,” Gust said.
People need to look at both wind chill and temperature when deciding how to prepare for going outside, Gust said.
A wind chill of minus 40 should have the same effect on the body as a temperature of minus-40, Gust said.
“The sensation of how quickly your skin tells you ‘Uh-oh, I’m in trouble’ is going to vary,” he said. A 40-below wind chill may feel colder if high winds are blowing directly on your skin, he said, but cold without wind is still dangerous.
“The sensation of cold is different than the reality of cold, and that’s how people get in trouble,” he said.
Capt. Douglas Stern, of the Grand Forks Fire Department, reiterated the need for people to put on extra layers and be careful in the cold.
Because they often work outside, the firefighters know from their jobs how important it is for people to not let their skin be exposed to wind chill.
“It’s the same with anything, a tow truck driver or if you’re out cross-country skiing,” Stern said. “You can’t leave skin exposed in these cold wind chills.”
Wind chill elsewhere
The Red River Valley has been under almost constant wind chill advisories this winter because along with extremely cold temperatures, this season has brought “a fairly high frequency of storms,” with a lot of wind, Gust said.
But despite what Midwesterners may brag about, they aren’t the only ones with wind chill advisories.
A colleague of Gust’s in Tampa, Fla., told him that the weather service there issues wind chill advisories at 40 degrees, and tells people to bring their parakeets and flowers inside.
By contrast, a wind chill advisory in Grand Forks is between minus 25 degrees and minus 39 degrees.
“They have different concepts of what cold is,” Gust said. “When we talk about extreme cold, we’re talking about 20, 30, 40 below. Extreme cold to someone in Miami is freezing or below.”
Wind chill advisories vs. warnings
The National Weather Service issues both wind chill advisories and warnings. But why are some alerts just an “advisory” instead of a full-out warning? The wind chill has to be below minus-40 to be a wind chill warning, said meteorologist Dan Riddle of the National Weather Service office in Grand Forks.
Wind chill warning conditions will result in frostbite and can lead to hypothermia, or even death, if precautions aren’t taken, according to the weather service website.
Only an advisory is issued between wind chills of minus-25 and minus-39, Riddle said. According to the website, wind chill advisory conditions will result in frostbite and can lead to hypothermia if people aren’t careful.
Those are guidelines for North Dakota, Riddle said. The weather service also considers the forecast before declaring a wind chill advisory or warning, he said.