Friday, January 9, 2015

Wind Chill, not Air Temperature

Updated Post (February 19, 2015)

I am thankful that Winter 2015 has been milder than Winter 2014; however, there is still potential for plenty of cold and snow in the next two months. I want to remind everyone that when I am looking at weather and forecasts, I pay much more attention to Wind Chill than I do to air temperature. Both the days in January were marked by a National Weather Service Wind Chill Warning. Today (February 19 2015) the National Weather Service issued a Wind Chill Advisory (which is not as severe).

I do take each of these decisions very seriously. This morning, I walked between Leal and Yankee Ridge to get a sense of the ambient temperature before I made my final decision to keep schools open. I do understand that every family has a different tolerance for cold, and I never want my decision to keep our schools open imply to parents that I don't value their opinion. You, as a parent, are the best judge of what is safe for your child.


Original Post (January 9, 2015)

Many people have asked why schools were closed on Thursday, January 8, but open on Friday, January 9. The main reason is the forecasted wind chill. On Thursday, the National Weather Service issued a Wind Chill Warning until Noon, with predicted wind chills between -20ºF and -27ºF. On Friday, Wind Chill Warning had been reduced to an Advisory with predicted wind chills between -10ºF and -15ºF. Yes, these wind chills are still very cold, but the difference is in the research behind the wind chill charts.

I always try to stress that the National Weather Service’s Wind Chill Charts changed dramatically in 2001. The wind chill charts used today are very different when I was a student in MN. I remember going to school in -30ºF wind chills in the early 1980s; however, by today’s formula, those same conditions would only rate as a -12ºF wind chill. There is a great article on this site:

As I stated, it is still very cold, but much less dangerous. Please dress warmly with hats, coats, and gloves.