If you live in Detroit, Chicago, or Philadelphia, and think you have had an unusually rough winter this year, there is a new quantitative "winter misery" scale to back up your hunch. According to an experimental index known as the “Accumulated Winter Season Severity Index," or AWSSI (rhymes with “bossy”), that National Weather Service meteorologists and climate experts have developed, Detroit's with a year-to-date cumulative AWSSI rank of 970 makes it “most miserable” winter on record.
That figure is likely to rise further as another round of bone-chilling cold envelops the Midwest over the next 10 days, said Barbara Mayes Bousted, a meteorologist at the Weather Service’s forecast office in Omaha, Neb., and a co-developer of the index she refers to as the "winter misery index."
The winter as a whole (which includes part of 2013) ranks as the third-worst for Detroit. The previous worst-winter-to date in the city was in 1977-78.
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In Detroit, this winter has had the highest accumulation of the AWSSI since 1950-51, Boustead said in an interview with Mashable. “For people in Detroit who think they’ve had it bad, they have.”
Chicago has had its fifth-most-severe winter to date, according to the index, and third-worst winter to date starting on Jan. 1, Boustead said. Of Detroit and Chicago, she says, “Both these sites have a lot of winter left.”
Philadelphia, Chicago, Indianapolis, and New York have had winters that rank in the top 5 most miserable, or if you’re one of the rare fans of bitterly cold and snowy winters, the top 5 best winters on record.
Other cities that have made headlines for winter weather this year but that have not ranked as high on the scale include Atlanta, which is having its 18th-worst winter on the AWSSI scale, and Washington, D.C., which came in at number 28 as of Feb. 23.
The index attempts to put the “badness” or “goodness” of winter into historical context, Bousted said. The index is based on daily temperature and precipitation data, including snowfall and snow depth. It uses thresholds of temperature and snowfall to assign a score to each day, which gets tallied up throughout a season, with a running tally and a final score at the end of the year to gauge a winter’s severity.
The scores correspond to a category, with a one-through-five system — with five being the worst — similar to those used for other severe weather phenomena. For example, the Saffir-Simpson Hurricane Wind Scale and the Enhanced Fujita Scale that ranks tornado intensity, both rank storms from category one through five, with five being the worst. According to their AWSSI rankings, Detroit and Chicago, for example, have both had Category Five winters.

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The index is not all-encompassing, however. It does not incorporate freezing rain, and therefore may rank some locations, like Atlanta, lower than it should, given the ice storm the city had earlier in February. It also does not take into account the wind chill factor, which is a measure of how cold the air feels to human skin, with extremely low wind chills indicative of a high risk for frostbite.
But even without those factors, Boustead said that Atlanta’s index score is still about 130 percent higher than their average seasonal score.
The index accumulates as the season progresses, and in doing so it allows weather forecasters to see the main drivers behind a significant winter season in a given location. For example, in Philadelphia, snowfall, rather than cold temperatures, has made the biggest contribution to the miserable winter index this year, Bousted says.
This year was the first since records began there 130 years ago that more than four snowfalls of 6 inches or more have occurred in one season. In addition, the city is already in its top 5 snowiest years, with more snow expected this week
Steven D. Hillberg, a meteorologist at the Midwest Regional Climate Center in Illinois and a co-creator of the index, said heavy snow has primarily been responsible for driving up the winter index scores in the Mid-Atlantic region. “While it has been much colder than normal in January and February, the snow is the biggest impact,” he said in an email conversation. Hillberg loves snowy weather, and views the index as a “winter awesomeness index,” according to Boustead.
“He’s really rooting for the numbers to go higher where he lives."
The index is going to be submitted to a scientific journal for publication, and is not currently in use throughout NOAA. But it fills a gap in the tool kit that meteorologists have when trying to put current conditions into historical context, since it expands the list of options from simply comparing seasonal snowfall totals or average temperatures into a more comprehensive measure.
Boustead and Hillberg said the index could even be used to help predict economic impacts, with weather-sensitive economic sectors able to monitor the cumulative index to see if it exceeds thresholds relative to their business. In addition, it may be possible for researchers to look for relationships between AWSSI scores and large-scale climate cycles, from El Nino events to manmade global warming. One global warming-related question might be whether years with high AWSSI scores have become more rare in particular areas.
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