4/29/2024 0 Comments National weather wind chill chartOne day has 5 mph winds while the other has 35 mph winds, giving them a wind chill index of minus 20 and minus 40, respectively. Both days have dipped down to 10 below zero. Without protective clothing, hypothermia or frostbite could set in within minutes.Ĭonsider two days with the same air temperature. “You basically look at the temperature, compare it to the winds, and if that number is, say, negative 25 degrees, that’s when frostbite can occur in about 30 minutes.” A wind chill index that dips into the negative 60s, as the Midwest is expected to do this week, can strip heat away from the body at an incredible rate. “The wind chill value is important because it gives the user an idea of how quickly the body is susceptible to frostbite or hypothermia,” Brusky says. If the body enters a hypothermic state-temperatures below 95 degrees Fahrenheit-it can be deadly. The measurement is nonetheless important, as wind can increase the risk of bodily damage from the cold. The resulting values are assigned rough temperature estimates to represent what the conditions “feel like,” but there is no way to actually measure the subjective wind chill temperature. The National Weather Service's wind chill chart, expressed in degrees Fahrenheit and miles per hour. (Using the metric system, the wind chill value is expressed in watts per meter squared, which is a measure of irradiance, or the flux of radiant energy over a given surface area-the amount of heat change applied to the surface area of a body.) In the United States, wind chill is calculated with a formula using degrees Fahrenheit and wind speeds in miles per hour, but wind chill values can also be calculated using degrees Celsius and meters per second. Higher winds strip heat away from the body more quickly. A wind chill index accounts for a combination of air temperature and how fast the wind is blowing. The actual air temperature, which is unchanged by the wind, is not the only way to determine if your body is at risk in the cold. The wind chill index was adopted by NWS in the 1970s and then updated in 2001 to reflect modern understandings of human body temperature. Those venturing near the South Pole wanted to figure out how much heat the human body loses when exposed to wind. In Chicago, for example, wind gusts of up to 24 miles per hours will generate a temperature with wind chill of minus 50 or 60 degrees Fahrenheit.īut what exactly is wind chill, and how does it work?Īccording to Gene Brusky, the Science and Operations Officer at the National Weather Service office in Green Bay, Wisconsin, wind chill models were derived from research by Antarctic explorers during World War II. The cold may be difficult to endure, but the relentless wind is making conditions even more miserable, driving perceived temperatures down to ungodly levels. A polar vortex has descended upon the United States, plunging temperatures across much of the Midwest into the negatives-as low as minus 33 degrees Fahrenheit in Fargo, North Dakota (colder than Antarctica).
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