Why the definition of 'extreme cold' is different in Duluth and Dallas
As a mass of frigid Arctic air descends on much of the United States over the next week, meteorologists and public health officials are well aware that it's unlikely a North Dakotan and a South Texan will agree on what's coming down on 'extreme cold'.
As such, the National Weather Service and the Centers for Disease Control and Prevention emphasize that there is no set definition for extreme cold, and that the point at which forecasters will warn residents that falling temperatures pose a danger to them is tailored to the prevailing conditions in the region. climate.
“Everyone's extreme is at a different level,” said Ketzel Levens, a meteorologist at the Weather Service office in Duluth, Minnesota, where the average daily temperature in January is a chilly 9.4 degrees. 'People in the north may have better protection. They may have many more clothes and layers. Our homes, our water infrastructure, they are built to a different standard.”
And so if you warned Minnesotans every time it was just freezing, you'd have a hard time getting their attention when it was dangerously cold. Mrs. Levens office only issues a wind chill warning when the temperature reaches minus 25, and a wind chill warning when it reaches 40 degrees lower.
While it won't be historically cold in Duluth this week — temperatures could reach minus 7 degrees — Ms. Levens said residents may still feel the chill as the city emerges from its second-warmest December on record.
About 1,000 miles south, the Dallas-Fort Worth area won't be as cold as Duluth this week, with a low of 15 degrees. But the freezing temperatures there could have a bigger impact, said Tom Bradshaw, a meteorologist with the service office in Fort Worthwhere the average high temperature for January is 56 degrees.
“We could see 80 to 85 hours of subzero temperatures here,” he said, “which for us is definitely on the colder side of what we normally experience.”
His office sends out an alert when the wind chill is expected to dip below zero, while an alert comes when the wind chill is likely to dip below minus 18, Mr Bradshaw said.
On the plus side, he said, this week's cold snap is not expected to be accompanied by precipitation and icing, which ravaged Texas during a storm in February 2021. More than 200 people died and millions were left without electricity and heat in the cold. . Many also lacked clean water because pipes had burst or water treatment plants had failed.
Not only is the infrastructure in the South not as comfortable in such extremes, but the population – which is less accustomed to severe winter weather – may also have a harder time, according to Dr. Gordon Giesbrecht, an expert on cold weather physiology and hypothermia at the University of Manitoba.
The body responds to feeling cold, he said, by tightening blood vessels to stop blood flow to the extremities. This protects a person's core and vital organs from cold. The body may also shiver to increase heat production, he said. But both protective tendencies cause the skin to become colder and at greater risk of frostbite.
“People who are better adapted to the cold, like if you live in Minnesota, your skin won't get as cold,” said Dr. Giesbrecht. “Your body learns through continued exposure that, 'We can afford to lose a little heat at the expense of keeping our skin warm, because it takes a lot to actually cool the core.'”
People unaccustomed to such cold are likely to experience more constriction, he said, putting them at greater risk of frostbite. Dr. Giesbrecht advised keeping the head, fingers and toes well covered.
The possibility of frostbite naturally faces anyone who feels cold, whether better adapted to extremes or not.
“People are often fooled. They don't feel anything and say, 'Okay, I'm fine now,'” said Dr. Giesbrecht about the numbness caused by frigid temperatures. “You have to do something: either add more insulation, or exercise to increase your heat production, or go indoors.”
And keep in mind that even Minnesota is relatively warm by some standards. Natalie Hasell, a warning preparedness meteorologist for the Canadian government, said that on the shores of Hudson Bay in northern Manitoba, the threshold for a wind chill advisory is minus 50 degrees Celsius, or about minus 58 degrees Fahrenheit.
It's not like the people there are “superhuman,” she explained, because someone's skin could freeze after five to 10 minutes of exposure to temperatures below minus 40, or even faster in high winds.
“But it just happens so often there that they would never hear the message about when it would be really bad,” Ms. Hasell said. She added: “If you only have two minutes before your skin can freeze, you want to hear that when you're used to 10 minutes.”
Camille Baker reporting contributed.