A look back at the wettest June day on record

The Met Office seem to think that the 212.8 mm (8.38″) reported by the EA gauge on the Honister Pass in Cumbia between 09 UTC on Sunday the 28th of June and 09 UTC on Monday the 29th of June set a new June day record. It’s not clear from their June weather summary if it’s the record for the Honister Pass, Cumbria, England or the whole of the UK because they don’t say. I’m also not clear as to why they had to specify that it was based on digitised data – surely isn’t all climate data ‘digitised’? The reason that I’m looking back at this story is that Paul Homewood has written an article in his blog Not a lot of people know that and has taken objection to the UKMO announcing it as a June record when it’s well documented in the British Rainfall Organisations report for 1956 that in Bruton, Somerset on the 28th of June 1917 9.56″ (242.8 mm) of rain fell (09-09 UTC), not only that two other nearby stations recorded totals higher than the one half way up a mountain in Cumbria. I don’t have a problem with that, he’s absolutely right about that and I agree with that the Met Office are too quick to claim that any extreme, beit drought or flood, is more than likely caused by AGW.
I think it’s very difficult for the Met Office to say what the wettest June day was, because recently their archive of rainfall records has been flooded with a deluge of newly digitised data collected by the British Rainfall Organisation. This organisation was formed in 1860 by G.J.Symons, and the data they collected has been treated with disregard for many years, even though the organisation itself was absorbed and became the responsibility of the Met office in 1919. The Met Office have been content to sit on these records until recently when along came a group of enthusiastic members of the public in the Rainfall Rescue Project who digitised the records for them. They did in a few months, what the Met Office couldn’t be bothered to do for over a hundred years. I suspect the Met Office aren’t really too bothered with the individual daily records for places like Bruton, all they really want is as much rainfall data as they can plot on a map so that they can interpolate it on to a UK grid. And that’s why recently the gridded monthly rainfall series now all of a sudden extends back to 1862 not just 1910.

Another issue

The EA Honister Pass AWS

My issue with the 212.8 mm that was recorded by that rain gauge, is not whether or not it set a new record, but if the reading was way too high in the first place. I must say this is not helped by how the EA gauge appears to have just been plonked on the hillside above the pass, with little regard to its siting or its exposure. I have been estimating rainfall by means of 5 minute weather radar images for eight years or more, and the results I get aren’t generally too far from the totals reported by the stations in the SYNOP network across the country. There’s no doubt that Sunday was very wet across the mountains of the Lake District, but my estimates suggest 100 to 125 mm of rain in the 24 hours ending at 09 UTC on Monday the 29th, rather than the 212.8 mm. I will admit that I don’t have access to the highest resolution data, which I now believe is down to 500 metres, nevertheless I am still very skeptical about the readings from that AWS.

Estimated rainfall accumulation from weather radar
June 28 0900 – June 29 0900 2020

I’ve included the 24 hour accumulations for the whole of Sunday, which as you can see do suggest higher totals up to 150 mm.

Estimated rainfall accumulation from weather radar
28th June 2020

The Met Office AWS sites are much better that those of the EA, that’s understandable because the EA gauges are used to monitor rainfall in the catchment areas of rivers in the event of flooding rather than for climatological purposes. Here is an example of one of the Met Office stations in the Highlands close to us above Loch Glascarnoch. That grass is shorter and in better condition that our lawn.

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