Updated 'normal' values

For a long time, the Monifieth station has been using 'normal' values for temperature and rainfall based on the short 3-year period from 2004-2006. I have now updated the 'normal' values by calculating them from averages of station records for the continuous 7-year interval from July 2003 to June 2010. All 'difference from normal' values reported in the archive data now use this new baseline.

As can be seen from the monthly trends shown in the recently-posted graphs (see links on the archive page), there has been a slight cooling trend in the yearly temperatures over the past few years, so the 'normal' baseline is now a bit lower for some months than it was before the recalculation. As a result, some values will show a slightly higher 'difference from normal' value than they did previously.

Although this sounds like a trick worthy of those who devised the Hockey Stick graph, I felt it was better to use a larger set of data for calculating the averages. The interesting thing to note is that even with these lower average values, 2010 still stands out as a very cold year. Only one month (June) shows an above-average temperature (so far, of course), and the yearly average is 0.8 C below normal for the corresponding period in other years. This is a very large deviation, and if the cooling trend that seems to have started early towards the end of August continues throughout the autumn, we could see some new records.