This year’s Accumulated Winter Season Severity Index has confirmed what most residents who endured the polar vortex already have been saying: This is one of the coldest winters of our lifetime. According to an AP report on Tuesday, Indianapolis, Philadelphia, Chicago and Moline, Ill. are experiencing their third most extreme winter in 60 years.
The data is based on a report compiled by National Weather Service’s Barbara Mayes Boustead. Boustead created a winter extremity index a couple of years ago and updates it each year. The index is based on cold temperatures as well as snowfall. Two dozen cities were part of the study, but one city has had it the absolute worst.
Detroit unfortunately is ranked as having the very worst, or at least most extreme, winter so far. Detroit has experienced 100 days with a temperature below freezing and has seen over 6.5 feet of snow.
The reason that Detroit is having such a bad winter is attributed to “just bad geography.” Specifically, index co-creator Steve Hilberg says that the reason Detroit has been having such bad weather is due to a jet stream that brings down cold weather from the polar vortex, a circulating air current above the Arctic.
The index measures daily highs and lows and accumulated snowfall as well as daily amounts. The index was created to give severe winters more context. Though many believe this to be a extremely harsh winter, if you’re comparing it only to last year’s winter—which was one of the mildest in many locations—you don’t have the whole picture.