Has The UK Had Exceptional Winter Rainfall Or Is It Just Weather As Normal?

oldgifford
As a manufacturing engineer I was introduced to the wonderful world of control charts so I have constructed these to see if our current winter UK rainfall was exceptional.
The ASQ (American Society for Quality) suggests these criteria for an out of control process:

• A single point outside the control limits.
• Two out of three successive points are on the same side of the centreline and farther than 2s
• Four out of five successive points are on the same side of the centreline and farther than 1s
• A run of eight in a row are on the same side of the centreline.
• Obvious consistent or persistent patterns that suggest something unusual about your data and your process.

When we look at the graphs below we see that in 2014 we have one point outside the Upper Control Limit, but looking at the previous years we see that the system was very much in control, the rainfall figures bouncing around the average, so is the Met Office basing its comments on a single data point? The figures also suggest that the period 1909 to 1930 was one of the most consistently wettest periods."