Fact or Fiction

Fact or Fiction

Meteorologist and contributing editor Beth Carpenter crunches the data to determine if the industry’s belief in the three-year winter cycle has merit.

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December 3, 2019

 

 
Recently, I was introduced to the idea of a “Three-Year Snow Cycle,” which has been widely discussed among contractors and suppliers in the professional snow and ice management industry some time. The idea is that every three-year period includes one winter of average snowfall, one with above average snowfall, and one with below average snowfall.

 

As a consulting meteorologist, I decided to take a closer look to determine whether this was an industry myth that needed to be busted.

I chose six major cities from across the Snow Belt as sample cities and I looked back at seasonal (September through May) snowfall accumulations for the last nine years, the equivalent to three of these supposed three-year snow cycles.

My initial hunch before digging into the data was that three-year periods would be too short to be representative of a cycle, but that maybe a nine-year stretch would show, on average, three average snowfall years, and three above and below.

My hunch proved to be mostly true.

Click the image for an expanded version of this chart.

For this analysis, data were given an “average” indicator if the annual total was within 5 inches of the average climatological snowfall for the location.

For example, Indianapolis has seen average to below-average snowfall for the past five winters, but of the four prior to those featured three years of above-average snowfall. This totaled out to two years with average snowfall, four years with below-normal snowfall, and three years with above-average snowfall in the past nine years. Generally, this suggests that maybe the three-year cycle should be given more merit, but over a longer period of time.

Pittsburgh supports this idea relatively well, too. In the past nine years, the city has seen three years of average snowfall, four years of above average snowfall, and two years of below average snowfall. Data for Green Bay, Detroit, Cleveland, and New York City can also be seen in the chart.

Beth Carpenter is a co-founder and meteorologist at Thermodynamic Solutions, based in Indianapolis. You can reach Beth at info@tdsweather.com.