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