There are many points in talking about the weather daily where we compare things to "normal" or "average" conditions. You've probably noticed that snowfall the last two years (and so far this year) has been well above normal.
But how are the normals computed? Well, the official "NORMAL" (although I prefer the term "average," since Michigan weather is rarely normal!) snowfall is the average of the totals for a 30-year period, currently 1971-2000. Every decade, those numbers are recalculated, so we'll be due to adjust the averages at the end of 2010.
Where does that put us? I checked the numbers from 1981 to present and found, as you might expect, that recent higher snowfall numbers push our overall average up a few inches, from 72.2" for the season to around 75.5". December, January, and February averages go up, while the fringes of the snow season see numbers drop a bit.
If you take out some of the early-80s seasons with low snow totals, the effect is even greater. From 1989-2009, the average has been about 80.9", with increases in every month except March and April.
It's obvious based on that information that snow totals have trended upward through the last couple of decades. But how much of that is cyclical (there is evidence of ups & downs in such numbers back to the 1950s), and can any of it be attributed to climate change or other factors? That's for us to try to gather data to analyze, and for future meteorologists to decide!
But how are the normals computed? Well, the official "NORMAL" (although I prefer the term "average," since Michigan weather is rarely normal!) snowfall is the average of the totals for a 30-year period, currently 1971-2000. Every decade, those numbers are recalculated, so we'll be due to adjust the averages at the end of 2010.
Where does that put us? I checked the numbers from 1981 to present and found, as you might expect, that recent higher snowfall numbers push our overall average up a few inches, from 72.2" for the season to around 75.5". December, January, and February averages go up, while the fringes of the snow season see numbers drop a bit.
If you take out some of the early-80s seasons with low snow totals, the effect is even greater. From 1989-2009, the average has been about 80.9", with increases in every month except March and April.
It's obvious based on that information that snow totals have trended upward through the last couple of decades. But how much of that is cyclical (there is evidence of ups & downs in such numbers back to the 1950s), and can any of it be attributed to climate change or other factors? That's for us to try to gather data to analyze, and for future meteorologists to decide!
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