High Mowthorpe DCNN2337 – Close up studies of a Class 1 site.

54.10505 -0.64314 Met Office Assessed CIMO Class 1 Installed 1948, digital temperature records archived from 1/1/1959

Again I have to thank Dave Ward for his assistance in diverting his travels to Malton in North Yorkshire to take in High Mowthorpe weather station which is about 10km/6.2 miles east-southeast of the town. Close up photography as featured below is always very revealing and often highlights previously unknown aspects of the site. It is important to start by saying High Mowthorpe is a good site and is curiously typical of several northern English locations which tend to be of a higher standard than elsewhere. Class 1 Cawood is not very far away (Dave has also supplied images for later publication) and Cumbria is spoilt for multiple Class 1 locations.

The history of High Mowthorpe is important to give context to sites of such good quality – it is not an accidental trait of such sites, as a lot of careful thought went into it. The weather station is located at what was an “EHF”- Experimental Husbandry Farm site. These EHF sites were established just after WW2 to improve and modernise agriculture in the UK with a goal of food self-sufficiency.

Over the ensuing years the EHF morphed into the government’s “Agricultural Development Advisory Service” (ADAS) which was ultimately privatised in 1997. This site continues as High Mowthorpe ADAS and is a working research centre still.

Agricultural research centres tend to host the very best of Met Office sites. Rothamsted Research, with its 4 sites at Brooms Barn, North Wyke, Woburn and Rothamsted itself is a prime “Benchmark” of quality. The University of Warwick site at Wellesbourne, Newcastle University’s Morpeth Cockle Park, Sciantec’s Cawood site, Aberystwyth’s Trawsgoed and SRUC’s Craibstone are all good examples. Such sites will always have plenty of open space available and knowing both the weather and climate of the area are essential for their function. These small “c” conservative institutions are also highly unlikely to be driven by any latest fad or agenda and will only be motivated by science – politics and/or ideology are cold comfort if a crops fail or animals suffer.

Dave’s first take on the site was:

“This site looks to be pretty good, although an anemometer only a few feet above the ground is going to be affected by tall crops like the Oil Seed Rape I observed today. There are trees in the surrounding area, but nothing particularly close, apart from one you can see in the shots I took. “

This photo below demonstrates why close up imagery is so important. From this perspective, the trees Dave mentions look alarmingly close.

However, taking the google aerial image into context shows the trees to be very distant, though as Dave noted, there is a newer and closer one possibly needing attention sooner rather than later to avoid any potential problems. The angle below gives a much more realistic perspective. This is one of the reasons such on site viewing is so useful. It can be very easy for me to misjudge measurements just from online sources and I continually have to cross reference images and measurements to avoid giving the wrong impression. Dave approaches his photography extremely methodically and sends me several “locator” views and angles which are so helpful.

The roadway itself does not contravene the percentages of artificial area with the 100 metre radius “exclusion” zone of the CIMO guide and is apparently very lightly used. This site would not though meet the ultra strict conditions of the US Climate Reference Network due to the roadway but I do feel it is reasonable to not allow “perfection to be the enemy of the good” – this is definitely a good site.

The opposite angle view becomes very interesting indeed as Dave offered close up views. There is not one but TWO weather stations. The Stevenson Screen sits at the northern end with its own solar panel power source whilst there is another completely independent system to the south.

High Mowthorpe is not an official wind monitoring site as it would require a 10 metre high mast to achieve that. However it does have an anemometer mounted with a second set of temperature and pressure sensors. The almost magic of AI identified this set up as a “R.M. Young Company Model 41002 (12-plate Gill Multi-Plate Radiation Shield)”.

There are probably very good reasons for their being two independent weather reporting systems within the same enclosure, the “Gill Type” model is almost certainly part of the ADAS units own reporting system. I have contacted them to ascertain whether or not it definitely is theirs (I am confident it will be) and, if it is, whether its historic data would be available. These types of temperature sensors are shown to be as reliable and accurate (possibly more so) as those mounted in Stevenson Screens and they are also much easier to artificially aspirate to overcome low wind speed problems. In fairness, however, High Mowthorpe is unlikely to frequently suffer from low wind speed Aitken Effect or rather as Dave put it:

“Oh, and by the way, you said “High Mowthorpe might be a bit on the windy side though” – you certainly got that right!”

It could prove to be an interesting exercise if the independent set of data is available to compare the different sets of equipment – there should not be any discrepancies between them in the same enclosure but you cannot know until you have checked.

Regarding observational quality, the site reported manually up to 2007 – its record was pretty much perfection as would be expected from the nature of the site. There is a gap in the archived data with readings re-started in 2009 on conversion to an automatically reporting site. This gap is quite possible while standard checks were being made to verify reliability. In a similar manner to Rothamsted I suspect the onsite staff here would have had input to the changeover and wanted to ensure accuracy and consistency.

Given this site’s good location and long term nature with data back to the late 1940’s I do feel it would be worthy of inclusion in a new UK historic temperature reconstruction. Along with near neighbour Cawood an accurate area representation over time should be perfectly reasonable.

Again many thanks to Dave Ward for all his efforts that really do simplify matters.

Source: https://tallbloke.wordpress.com/2026/05/04/high-mowthorpe-dcnn2337-close-up-studies-of-a-class-1-site/