Steve's WunderBlog

The new winters

Posted by: SteveDa1, 15:10 GMT le 12 mai 2012

F = 1.8C + 32

Winter's cold shots are less extreme today
It doesn't just seem like winters are not as cold as they used to - it's a fact. The coldest three months of the year - December, January and February - are not only getting warmer overall, they are also experiencing weaker (not necessarily shorter) cold snaps. I'm aware that I'm only looking at one particular area but I'm certain that if I broadened my field of view I'd obtain similar results. If it's happening in my own backyard chances are it's unfolding elsewhere in this country and continent and that it's probably happening in most places. Also, to graph data for each city would be very time-consuming and would make this hobby a grind. Finally, although I cannot conclude anything, assumptions are always verified with every graph I make.

The following graph shows the numbers of days (or nights, if you prefer) where the low drops below -10C, -20C and -30C with trend lines showing the obvious decline.

I like to keep it short and let the graphs tell the story... because they really do tell a thousand (...or more) words!

Trend of days with lows less than or equal to -10C: -1.3/decade

Trend of days with lows less than or equal to -20C: -1.1/decade

Lows below -30C are becoming extremely rare with the last occurrence in the winter of 1993-1994. An event that used to happen once in while, is now almost non-existent.

Click on the following images for a larger resolution.

The number of days with a high above the freezing mark is also on an obvious trend - on the rise.

Trend of days with highs above 0C: +0.7/decade

Also, older folks who were born in the 40's may actually be right about the lack of snow (compared to the past) today. This, however, is very regional and does not indicate anything in any other area across North America

Trend: -6.6cm/decade

I have formulated the above graphs using data courtesy of Environment Canada's National Climate Data and Information Archive.

Full Resolution American Radar Loop
Sea Surface Temperatures
Sea Ice Cover
250mb Winds

Latest Surface Analysis
00z, 06z, 12z, 18z

Updated: 14:15 GMT le 14 mai 2012

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April 2012 Summary

Posted by: SteveDa1, 15:13 GMT le 06 mai 2012

F = 1.8C + 32

Above normal is the new normal?
Yet another above normal month has gone by - unbelievably the 30th such month in a row, dating back to October 2009. Since the turn of the century, the enormous amount of months above the 1971-2000 averages seems to indicate that new normals are a given when the new 1981-2010 base period is published. In fact, I am 100% confident that the new 1981-2010 averages will be higher for every month. Indeed, the next project I will be undertaking will involve data from every month since records began in September 1941. From this data, I will get a clear picture of the rising linear trend in temperatures based on the 1961-1990 and 1971-2000 base periods. Hopefully, Environment Canada's National Climate Data and Information Archive will publish the 1981-2010 averages soon so that I can use this base period as well. It is already known that the anomalies will trend in an ascending nature as the decades go by, however, until the graphs are formulated, we can only imagine the degree of this rise.

A picture always tells a thousand words... which is one reason why I love to make graphs.

April 2012 in comparison to the 1961-1990 base period. (anomaly in parentheses)
Average high temperature for April 2012: 11.8C (+1.1)
Average low temperature: 1.8C (+1.2)
Average mean temperature: 6.8C (+1.1)

...1971-2000 base period. (anomaly in parentheses)
Average high temperature: 11.8C (+1.1)
Average low temperature: 1.8C (+1.2)
Average mean temperature: 6.8C (+1.1)

Notice how they are completely similar. Interestingly, april is the only month where the averages have stayed the same between both base periods. Every other month has been trending slightly warmer by a few tenths of a degree which is significant given the short time span.

April average high temperatures since 1942 for Montreal, Quebec

Linear trend: +0.26C/decade

April average low temperatures since 1942

Linear trend: +0.08C/decade

April total precipitation since 1942

Linear trend: +3.14mm/decade

I have formulated the above graphs using data courtesy of Environment Canada's National Climate Data and Information Archive.

Full Resolution American Radar Loop
Sea Surface Temperatures
Sea Ice Cover
250mb Winds

Latest Surface Analysis
00z, 06z, 12z, 18z

Updated: 03:51 GMT le 16 mai 2012

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