Do you understand how wind chill and cold warnings work? Meteorologist Tawana Andrew and LPM’s Bill Burton explain in the latest Science Behind the Forecast.
This transcript was edited for clarity and length
Bill Burton: It's time for us to take a look at the Science Behind the Forecast, as I'm joined by WAVE 3 meteorologist Tawana Andrew. Good morning, Tawana.
Tawana Andrew: Good morning. You could say that this topic has no chill.
BB: That's a great way to phrase it, because chill is what we're discussing. Wind chill. What do we need to know about wind chill?
TA: The wind chill is a vital part of any winter weather forecast. According to the National Weather Service, the wind chill is based on the rate of heat loss from exposed skin caused by wind or cold.
Basically, it's a quantitative measurement of how cold people and animals feel when you're outside in wintry weather. As that wind blows, it's pulling heat. It's literally pulling a layer of heat from our bodies, and that lowers skin temperature. If you're outside in that kind of weather for an extended amount of time, you can actually lower your internal body temperature as well, and that is why the wind makes us feel like we are colder. There's a very complicated formula, but I will spare you from that.
BB: I appreciate that.
TA: The calculation is based on wind speed measurements at an average height of five feet, which I love, because I'm short.
BB: They had you in mind when they created it.
TA: I love that they did that. It also takes into account the body heat being lost to the surrounding environment on those cold and windy days. But it does not take into account the sun, which is important because on a lot of these days it is cloudy and we're dealing with some sort of precipitation. So that is why the sun is not taken into account. But it is important to note that if you have that bright, beautiful sunshine, then that can increase the wind chill temperature by 10 to 18 degrees Fahrenheit. So it does have a significant impact.
BB: That's a big impact!
TA: We love those sunny days, they do help. Not by a whole lot sometimes, but they do help.
BB: When it's that cold, we'll take anything we can get.
TA: By the way, the wind chill only applies to people and animals. The wind can shorten the amount of time for your car to cool down, it does not have a significant impact overall. And if your car can feel how cold it is, I have a bunch of other questions.
BB: That makes sense, though. I've never seen a rock shiver.
TA: The National Weather Service classifies the wind chill as dangerous when it’s 20 degrees below zero or lower. The National Weather Service used to issue wind chill warnings and watch advisories, but they no longer do that. Now, they have switched gears, and they provide cold weather advisories and extreme cold warnings. Each National Weather Service office in our area has their own criteria for these alerts. In Louisville, they actually split their coverage area. In South Central Kentucky, they will issue a Cold Weather Advisory for you, if your air or wind chill temperatures are believed between zero and negative 10 degrees Fahrenheit. Then for the rest of us, they'll issue that cold weather advisory if the air temperature or wind chill is between negative five or negative 15.
