Kinlochewe DCNN0445 – “Foehn City Central” and the magnification effects of site surroundings change over time.

FOEHN EFFECT

To its credit the Met Office does offer a readily understandable web page explaining Foehn Effect which encompasses the known 4 main contributing factors. The wikipedia page also adds a few more graphics to demonstrate the main causes. In the UK context, large parts of Scotland and Wales (though rarely England) are often subject to Foehn Effect with Kinlochewe being a notably frequent location. This effect is well known and studied in detail specifically at Kinlochewe as the above image from this research paper indicates. In this review of the weather station, the issue is whether the frequency, intensity and/or containment of these events is changing over time as the nature of the surroundings changes.

56.61287 -5.30644 Met Office CIMO Assessed Class 4 Installed 1/1/1953

Kinlochewe is a village in Wester Ross in the Northwest Highlands area of Scotland. It lies in the River Kinlochewe valley at 25m amsl though the surrounding topography rapidly rises to in excess of 460 metres/1500 feet. The Dutch Meteorological Agency (KNMI) holds an international stations register that describes the site as:

Land use

Garden in partly wooded rural valley

For my part I feel “field” is a more appropriate term, however the wooded nature of the site is the important aspect to consider. Historical imagery indicates a much more open site in the past. This 2005 image looks far more like a tended garden with vastly less and much lower tree growth indicated by shorter shadowing. The pathway clearly visible below is now completely obscured with growth ever encroaching nearer the screen. This area enclosure is very similar to the “McDonalds” effect demonstrated at Liscombe

Looking at the site from ground level on google street view, is only possible in winter/early spring prior to the leaf growth of the roadside deciduous trees. Firstly a close up shot to identify the screen from March 2022. The screen is just visible centre image.

The principal issue becomes evident when the image is pulled back and the mass of the highlands becomes visible. It is the warm downslope wind in the lee of this mountain range that is responsible for the frequent Foehn Effect with the occasional and sudden dramatic elevations of temperature.  

The World Meteorological Organisation accepts that readings caused by stochastic weather events such as Foehn Winds should be recorded in the historic climate record. Many other meteorologists argue that Foehns are so random and variable that they should not be included as it is highly improbable that homogenisation of data (adding all areas together and coming up with a spurious average) can smooth out such significant distortions.

Kinlochewe is a location specific long term averages site (formerly termed “Climate Averages”) consequently its frequent Foehn effects are embedded in the historic record. What is becoming of even greater concern is the apparent willingness of the Met Office to regularly add more Foehn affected sites into their homogenisation process which can only induce ever upward temperature trends. The nearby manually recording Achfary site was only added for temperature recording in 2006 and yet already holds 2 month’s national highs. Indeed all meteorological winter highest temperature records are known Foehn Effects – is this deliberate “record chasing” that also conveniently and artificially elevates the modern temperature trend?

Whether or not the recent degradation of the Kinlochewe site with its ever enclosing trees would directly affect the recorded intensity of Foehn Effects is debatable. The increased “surface roughness” is known to diminish wind speed so may actually reduce the effect. Alternatively the enclosed area will already often be recording, on average, warmer due to low ventilation wind speed within the Stevenson screen due to known Aitken Effect. Regular Foehn uplifts will raise the base mean yet further.

In addition, the principle of substituting mean readings from other “Well Correlated” sites to cover periods when station data is missing for any reason, becomes incredibly untenable. How can data from a Foehn event be “well correlated” to a nearby site that may never experience one?

In summary I very much doubt Kinlochewe was chosen as a site back in those post WW2 years to deliberately record these Foehn Winds and there is even anecdotal evidence that such readings were routinely discounted in former times and “quality controlled” out. However, it is again quite apparent that the site is progressively becoming less suitable for climate reporting (now CIMO Class 4) and also that the Met Office is quite probably actively record chasing with the inclusion of additional modern Foehn affected sites.

Source: https://tallbloke.wordpress.com/2026/04/03/kinlochewe-dcnn0445-foehn-city-central-and-the-magnification-effects-of-site-surroundings-change-over-time/