What exactly is wind chill, and how is it calculated? Boston braces for arctic blast.
Massachusetts is set to experience extreme cold this week, and powerful wind gusts could make it even more dangerous.
Later this week, an icy blast of arctic air is expected to sweep over Massachusetts, plunging the state into sub-zero temperatures.
To make matters worse, wind gusts could reach 33 mph Friday and Saturday, making it seem even colder. In Boston, wind chills could plummet to around -30 degrees. It will likely be worse in other parts of the state.
The ability to calculate wind chill is massively important for meteorologists and for the safety of the general public. But what exactly is wind chill and how does it work?
Simply put, wind chill is how cold people and animals feel when they are outside. When exposed to higher winds and cold temperatures, the rate of heat loss from exposed skin increases. Heat is drawn from the body, first cooling skin temperatures and eventually internal body temperatures.
To calculate wind chill, scientists developed a relatively simple formula: Wind chill (ºF) = 35.74 + 0.6215T – 35.75(V^0.16) + 0.4275T(V^0.16). In this equation, “T” equals air temperature in Fahrenheit and “V” equals wind speed in miles per hour. The National Weather Service also offers a handy wind chill calculator online.
Wind chill only applies to people and animals, according to NWS. It can affect inanimate objects, but only by increasing the rate at which they cool to the current air temperature. These objects cannot cool below the actual air temperature.
The lower the wind chill temperature is, the quicker people and animals can get frostbite. This occurs when body tissue actually freezes. If wind chills drop as low as meteorologists expect them to on Friday night and Saturday, frostbite could occur in just 10 minutes. Body extremities, such as fingers, toes, and earlobes are the most susceptible to frostbite.
Wind chill can also increase the risk of hypothermia, which occurs when body temperature drops below 95 degrees. Uncontrollable shivering, memory loss, disorientation, and drowsiness are all warning signs.
In order for frostbite to develop on exposed skin, the air temperature must be below freezing. Wind chill itself cannot pull temperatures below freezing when thermometers register above-freezing readings, according to NWS. Essentially, frostbite will only occur if the actual air temperature, not the wind chill temperature, is below freezing near skin. However, hypothermia can still occur.
Meteorologists, like Bill Leatham of the NWS Boston office, recommend “hunkering down” and staying inside whenever possible on Friday and Saturday. If venturing out into the cold, people should be sure to stay dry, avoid exposing any skin, and wear many layers. People should also limit the amount of time that their pets are outside in these dangerous conditions.
As of Tuesday night, forecasters are expecting temperatures to slowly drop throughout Friday afternoon and overnight, with the coldest temperatures expected early Saturday morning. The Boston area could see a temperature of -6 during this stretch, a potentially historic figure, Leatham said. The coldest temperature observed in the Boston area on Feb. 4 came in 1886, when thermometers read -2, he added.
The coldest wind chills in Boston will also come Friday night into Saturday morning. The wind chill could make it seem like it is -10 or -20 outside Friday afternoon and evening, with -30 wind chills expected later on, according to Leatham.
The last time Boston experienced temperatures and wind chill like this was in February 2016. On Valentine’s Day, Feb. 14 of that year, the wind chill hit -36, Leatham said.
Wind chills will remain around or below zero throughout Saturday, but the extreme conditions are not expected to last long.
“The one good thing about this cold is that it’s really short-lived,” Leatham said. “We’re still going to be cold Saturday night into Sunday with low temperatures in the teens above zero, but then we’ll rebound really nicely on Sunday with highs getting into the lower 40s.”
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