Trassey Slievenaman DCNN 9245 – Now you see it, now you don’t. Met Office “Excellent”

52.20557 -6.00618 Met Office CIMO Assessed 4 Installed 1/1/1985

Trassey Slievenaman was installed in 1985 but not at its above location. Met Office public records do NOT show any relocation nor give any re-identification to indicate any move. The reality is that its location has been has been significantly changed from a poor low grade one to a completely unacceptable one. However, the Met office also classify this site as one of their thirty top quality ones in the entire UK – ” La crème de la crème,” or is it really no better than turned milk? Hera are the facts.

The World Meteorological Organisation (WMO) in association with the International Standards Organisation (ISO) formed the Commission for Instrumentation and Meteorological Observation (CIMO) to establish international comparative standards for the acceptable location for “Climate Reporting” weather stations. I link to these regulations under every review I do.

Despite the Met Office being a major contributor to the establishment of these international standards, they continued to use their own unique assessment procedure of sites being rated – Excellent, Good, Satisfactory and Unsatisfactory. Unlike CIMO, the exact details of these “standards” are not clearly defined to the public. Instead the Met Office seems to expect everyone to just accept them marking their own homework. This is their web page providing nothing more than excuses for their own failings to meet adequate standards https://weather.metoffice.gov.uk/learn-about/how-forecasts-are-made/observations/observation-site-classification. An interesting point to note regarding these standards is that the Met Office recording database system automatically assumes all sites are CIMO Class 1 and Met Office “Excellent” as they revealed to me in my review of Hastings

“Dear Mr Sanders

Thank you very much for your enquiry. This has highlighted an issue in our database. My original recorded inspection data was ‘CIMO Class 4’ (and I’ve reviewed the exposure diagram, which confirms), with the Stevenson screen exposure recorded as ‘Acceptable’ (and Satisfactory overall, taking into account the CIMO 4 rating).

The default CIMO rating is 1 on our site visit application (and Met O ‘Excellent’), so it looks like the class hasn’t been entered correctly, human error.

I trust this answers your question.

Sincerely

Angus Bruce BSc MIET

Regional Network Manager (South East England)”

This database default system was further shown to be inaccurate when I contested the rating of Edenbridge as Class 1 with it being “downgraded” to a more correct Class 4 though I would personally claim it should be Class 5. Having such errors publicly exposed I genuinely feel the Met office should have taken steps to correct the accuracy of their database as having to make further corrections would be more embarrassing. In September last year under Freedom of Information request I obtained the full listing of all Met office CIMO assessed weather stations by their unique Met Office assessed grade. Below is the entry for Trassey Slievenaman.

Trassey Slievenaman is clearly rated as “Excellent” – or is that yet another database error? Firstly the just 3 metre radius circled area is clearly in deep shade

Below is the 2021 Streetview image.

Revealed above is yet another dismally bad amateur garden screen compromised by proximity to the house, there is actually a car in the frame, overgrown hedging, heavy shading and it can only ever be classified as an unregulated Class 5. But then things get even worse. Below is the previous Streetview image from 2011.

So where is the Stevenson Screen? It clearly is not there nor anywhere visible within the grounds of the house. As stated above there are no public records of a re-location – thus started a long search! Eventually this revealed the answer 125 metres to the rear, in a field behind barns.

As luck had it it was also just captured on Street view in the distance in this shot.

This original site would also not have made Class 4 either, the hedging running hard alongside from the south-south east to north-north west would immediately cause unacceptable wind sheltering and sun shading and the area was then a continuously change cropped “market garden” area failing natural ground cover.

In summary, the current site is unacceptable, or put in Met Office parlance “Unsatisfactory”. It has been moved from an almost equally bad site that would have been unquestionably climatologically quite different to present but neither re-identification nor notification of the move was made. The Met Office, however, claims a wrong Class 4 grading but that does assume (quite possibly wrongly) that the Met Office even actually knows of the move at all. It could well be they do not know and the observer may simply have done that themselves to reduce their morning walk. The “Excellent” rating is obviously wrong and if not would be a damning indictment of Met Office standards. If, as I suspect, it is yet another “default error” it shows just how “sloppy” the Met Office data recording of even site basics so regularly is.

Source: https://tallbloke.wordpress.com/2025/05/23/trassey-slievenaman-dcnn-9245-now-you-see-it-now-you-dont-met-office-excellent/