Harris:Quidnish DCNN 0411 – Incorrect Classification.

57.78007 -6.89739 Met Office CIMO Assessed Class 3 Installed 1/9/1997

Obviously being a northern and westerly location in the Outer Hebrides (Na h-Eileanan an Iar) stations like this are critically important for weather prediction. By the same token the local climate is significantly different here even to places on the same latitude over on the east coast of Scotland such as Banff. The issue with this site is that its readings are added to the national climate record from a very improperly sited station with an even stranger quality assessment.

Harris:Quidnish is a regular regional star performer in the “Climate Extremes” league tables both regionally and even occasionally nationally. This national rating in winter months when easterly continental winds prevail is not surprising, these Isles are often very mild when the rest of the UK is very cold. The most recent appearance was yesterday when notably east coast Scotland temperatures were not much above freezing and the UK highest was equally westerly at only 9.9°C on the Isles of Scilly.

So what is the problem with Quidnish? The below image is orientated with the house to the north.

Basically this screen has been installed under a metre from a south facing wall (albeit a natural formation) on a significantly sloping site. Another perspective indicates it must be quite a squeeze to get around the front to open the northwards facing door that screens must have. This is an automatic site but still requires regular inspection.

And why must screen doors be on the north face? So as not to have undue warming effects when opened to take readings or make inspections from thermometers facing that direction. In this case the instruments are continually picking up on the south facing wall’s inevitable effects and hence clearly inaccurate at times. However, that has not stopped the Met Office from assessing this site as CIMO class 3 and by their own standards (Excellent, Good, Satisfactory & Unsatisfactory) this is classed as the second best (a minority high grade) of “Good”.

A reminder of what the Met Office say about weather station siting:

Very clearly this falls into the “Undesirable site” qualification. What do the WMO standards require for Class 3?

How can this site possibly meet “At more than 10 m from artificial heat sources and reflective surfaces (buildings, concrete surfaces, car parks, etc.); Or is it a case that rock formations do not count as they are neither “concrete” surfaces nor artificial? Surely the “etc” covers rock outcrops under 1 metre away.

The Class 3 and “Good” classifications for this site are clearly not appropriate. Again this may seem I am being pernickety but clearly there was no shortage of space in the immediate vicinity to have installed the screen both further away from rock formations and on more level ground. My personal view is that it is not appropriate to include this site’s readings in the historic temperature record. I welcome any views on this.

Source: https://tallbloke.wordpress.com/2024/11/23/harrisquidnish-dcnn-0411-incorrect-classification/