Every Vermont Skier who keeps an eye on the snow-weather knows about the Mount Mansfield Stake, and its hallowed records. Thanks to Mr. Wright’s simple and effective database, any Internet user can investigate the snowfall records at Mt. Mansfield dating back to November 1, 1954. We here at FIS particularly enjoy comparing the data to some of our favorite powder skiing adventures, in search of patterns and relationships in the data previously overlooked.
One of the many graphs that can be produced by Mr. Wright’s database, and one that is commonly seen in references to snow-depths on Mansfield, is one like this, which details the snow-depths at The Stake during the 2012-2013 Vermont snow-year (which runs from September 1 to August 31).
The thin line represents the snowdepth data from the 2012-2013 ski season. The green area represents the average snow-depth on any given day throughout the year. The odd downward spike of the red line near April 19th is an error in the data.
A common mistake often made in informal discussions (and even some more formal ones) is to infer, based on graphs such as the one above, that the average maximum snowdepth on Mount Mansfield is approximately 74″, or just less than 75″. This mistake is made by basing the analysis of average maximum snow-depth on the fact that the green area appears to achieve a maximum of about 74″ on March 22nd and/or 23rd.
For example, see this discussion from the Time For Tuckerman Forums from February 2007. The chart referenced by Yuckster is reproduced below. We have added a red circle around the timeframe referenced by Yuckster.
Similar mistakes were made in a contest on ski blog Adventureskier.com. In the link, the first question asks “1. What is the average peak snowpack depth for Mount Mansfield, VT?”. Several users–making the same mistake as Yuckster–respond with answers in the mid-70 inch range, and the contest organizer even states the answer as being “75-76″.”
Likewise, ski-weather prognosticator Tim Kelly appears to make the mistake here (although based on his choice of words, it’s not clear).
Even Stowe Mountain Resort seems to have made the mistake in a press release from April 2009. (To their credit, the press release appears to have been deleted from their website, but is still available at various content-regurgitators around the Internet)
If you haven’t figured it out for yourself yet, the mistake being made in all of the above examples (and numerous other locations on the Internet that we have not referenced) is that 75-76″ is merely the average maximum snow-depth on March 22nd and March 23rd, which happen to be the days of the year when the average daily snow-depth achieves a maximum on Mansfield. This however need not be equal (nor is it equal) to the average yearly maximum snow-depth at the Mount Mansfield Stake since it’s unlikely the maximum snow-depth occurs EVERY YEAR on March 22nd and March 23rd.
Shown below is the maximum yearly snow-depth at the Mount Mansfield Stake for each snow-year.
Yr(start) Max Snow-Depth (in)
St. Dev. 21.37
The year listed is the STARTING year. So, for instance, the maximum snow-depth during the 1955-1956 snow-year was 68 inches. The maximum snow-depth during the most recent season (2012-2013) was 87″.
The above data set is available here in CSV format (right click, save as). The raw data-set that was used to calculate yearly maximum snow-depth was obtained from Mr. Wright’s Database, and is available either from him, or here in CSV format (right click, save as).
As you can see at the bottom of the data-set, the average maximum snow-depth on Mount Mansfield is 88.31″, much higher than the value of 74-75″ often cited around the Internet. In fact, the cited average is two-thirds of a standard deviation below the true average (mean); . We hope this correct calculation of the average maximum snow-depth at the Mount Mansfield Stake will help skiers and riders assess the state of future snowpacks on Mount Mansfield more accurately in the future.
Corrections are welcomed; either comment below, or feel free to email us.
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