Achfary DCNN0337 – More Foehn Effects

58.31084 -4.91636 Met Office Assessed CIMO Class 5 & “Satisfactory” Installed (elsewhere) 1/1/1914 Originally a rain gauge site, archived temperature records only date from 1/10/2006 hence probable Screen installation date.

A station in a remote Sutherland village showing a long term history but only as a rain gauge site and one that has had several relocations and numbering changes. What appears to be a front garden site it records data manually and is a lowly rated CIMO Class 5 with inaccuracy due to siting recognised as up to 5 °C. Despite the relatively unassuming nature of the site it is a double UK all time record holder.

In just 16 years of 21st Century operation, Achfary holds both the January and December highest temperature records with the December record late in the month. Clearly the typical climate of northern Scotland is not warmer than for example southern England (far from it) so these must be exceptional events. As has been highlighted here before, mountainous areas (for the UK typically Scotland and North Wales) frequently experience Foehn Effects.

Locating the site from google aerial view clearly indicates mountainous terrain.

The general panorama is of spectacular Scottish scenic beauty.

An issue is, should recording what are relatively rare, usually very short lived and localised phenomena be included in the long term historic record? And even should they be really noted at all in the way the Met Office highlights them? Including such slightly “freak” events seriously risks distorting comparison over time. The issue of breaching thresholds (as highlighted regarding Wiggonholt ) currently seems to be an imperative at the Met Office with regular historic comparisons of “apples with oranges”. In the case of Achfary, its two recent monthly records (set over the last 16 years of operation) cannot possibly be compared with the same period of the early 20th century as it simply was not there to record any of the transient events that would most certainly have occurred.

There is obviously nothing wrong with recording exceptional localised weather events. Despite the likely siting inaccuracy of “normal” temperature recording this Class 5 site has, it almost certainly has accurately recorded the Foehn winds temperature. What actual relevance these effects should be given in the historic temperature record is very much a debatable point.