Wow! After living here for seven winters, this one just seems to stretch on and on and on! We’ve had snow on the ground constantly since mid-December, if I’m remembering right; that’s almost a month-and-a-half of snow on the ground. In past winters, the snow has always melted within two days after a storm, except for one week in January or February when we’d hit our really low temperatures. But this winter is starting to rival the memories of my wife’s childhood (you know, when they walked to school uphill both ways, barefoot in the snow?). OK, OK, not that bad, but people do say they remember a lot more snow when they were growing up, and my wife is one of them.
I’ve been thinking about different ways to look at the temperature data from my local weather station. Maybe our extreme cold temps have gotten milder, but do we actually have fewer cold days each winter? I decided to look at various thresholds of cold days. A friend plotted some graphs showing the number of days with high temps at various levels, like highs below 30, 20, 10, and such. They didn’t show a real strong trend. Then I decided to plot the number of days with lows at those temperatures. I got some other interesting graphs from it. Take a look at these:
This shows the number of days each year that had a low temperature below zero degrees.
This shows the number of days below 10 degrees each year.
Here are the number of days with low temps below 20 degrees each year.
And finally, the number of days with low temps below 30 degrees each year.
There is clearly a declining trend in each of these graphs, especially pronounced in the 1990s through 2006. 2007 shows an uptick in each of these graphs, and it sure looks like 2008 could continue that trend of more cold days. We’re not getting the extreme negative temps yet, but we’ve sure had a run of cold days, especially those with lows below 20 degrees. One caveat, though: these are by calendar year, and I need to group them by season like I did with the graphs in the earlier post (e.g., winter of 2006-07, rather than calendar year 2007, which would include parts of two separate winters).