Friday, November 16, 2012

November Snowfall: 1970s vs Present

Cleveland Plain Dealer - Shoreway Near East 55th
Those late 70s winter were brutal. I remember driving to Fairview Park Hospital for the birth of my sister in 1978 in my dad's 1977 Buick on the Ohio Turnpike. The snow was unlike anything I had EVER seen. The winds were unbearable. It was the poster child of a typical winter back in the late 1970s in northern Ohio.

After last winter, our perceptions have become twisted. We hadn't had a winter with little snow (38.5"; 62" is the average) and mild temperatures like 2011-2012 in a while. Using the National Climate Data Center temperature data for all of northeastern Ohio, the December-February period in the winters of 2001-02, 1997-98 (El Nino), 1982-83 (El Nino), 1948-49 & 1931-32 were the only winters milder than last.

So when I show an 8day forecast that features temperatures trending slooowly back to normal or slightly above into Thanksgiving week, we immediately think of last winter. We remember how lackluster the snow was. We try to paint a similar picture now since we've had little to no snow this month. I bet if I surveyed 1000 people on the street, most would say that this winter will be similar to last winter. The RECENCY EFFECT (our instinctive ability of placing too much significance on more recent experiences or events) is a very powerful cognitive bias.

How about those 1970s snowfalls specifically in November. Were they extraordinary? Here are the November snowtotals from 1975 to 1983. Surprisingly, nothing out of the ordinary.

What about the DECEMBER and JANUARY snowtotals that followed compared to our last 9 winters? It seems that DECEMBER-JANUARY snow totals since 2004 have outpaced the same months in the late 1970s and early 1980s.

What should we take from the numbers? NEVER fall victim to thinking that a snowless November will always lead to a winter will less than normal snowfall. It happens of course. It happened last year. It didn't happen during the 2004-05 season which ended up as the SNOWIEST WINTER EVER!

It didn't happen in the 1970s and it probably won't happen this year. Next post, I'll take a look at the temperatures for the same period.

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