The cold September of 1952

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The coldest September in the UK on record, well in the abridged 1910 temperature series from the Met Office that is, was that of 1952, with a mean anomaly of -2.79°C (fig 1), in fact the headline in the Monthly Weather Report for the month read – Unusually cold.

Figure 2

It was also the fourth coldest September in the CET series that started in 1659, and still holds three extreme minimum daily CET records from 1878, and also four extreme low maximum records as well (fig 2).

Figure 3 – September 1952

September 1952 was generally anticyclonic from the 7th to the 16th, which did allow some night frosts to occur, before turning very cyclonic from the 25th (fig 3). You may have noticed that September 1986 was the joint third coldest in the UK since 1910 (fig 1), but unlike 1952 this was mainly due to the anticyclonic nature of the weather (fig 4), in fact 1986 is the joint 10th most anticyclonic on record since 1871 in the Objective LWT series. So September 1952 was cold both by night and day, whilst 1986 was colder at night than day. In contrast to either of those two years, 2017 has so far turned out so far to be generally colder by day than by night.

Figure 4 – September 1986

Early taste of autumn in northeast

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Colder air has been pushing down across the northeast of Canada and the United States overnight, bringing that part of the world an early taste of Autumn, and starting to turn the leaves a lovely golden brown colour I should imagine. The highlighted station is Mount Washington, where it was already -2.8°C at 06 UTC this morning (fig 1). Further west, warmer air is being pushed up into the middle states from the south by tropical depression Harvey.

Exeter – top of the shop

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Exeter was narrowly the warmest place in the British Isles today with a maximum of 19.3°C, contrast that with the maximum of just 12.9°C at Kenley airfield in Surrey.

 

Summer 2017 failed on the 20th of July

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Temperatures in the summer of 2017 in the UK crashed on the 20th of July and have never recovered in the almost three weeks since it’s been since then. You can see clearly how the temperature has almost flat lined in the NCEP reanalysis data for the grid point 52.5° north and 2.5° west (just to the west of Birmingham), with almost all the 6 hour anomalies negative since then, negative (fig 1). I remarked in a blog only yesterday about how unusually flat the daily CET values had been since the 20th of July. Its probably all tied up with that ‘ribbon of high wind speed high in the atmosphere‘ that we like to call the jet stream.

Meanwhile in stark contrast to the UK, just to the northeast of Rome in Italy, at the 42.5° north 12.5° east grid point, things have been slightly different. A part from three short cold spells, the temperature anomalies there have all been well above average since early June (and before), with the recent heatwave this month clearly evident.

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Coldest start to an August in 30 years

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I notice that the latest provisional mean maximum daily temperature for the first eight days of August in Central England of 18.89°C (-1.38°C) are the lowest for that period since 1987 (fig 2). The 10 year average mean temperature for this period, has been on a downturn since 2000, and even the linear trend shows only limited warming since 1772 (fig 1).

Figure 2

A cool start to August

Figure 1

A cool start to August in most places, but particularly so across southern areas, with daytime maximum temperature anomalies typically 2°C or more below the long-term average for the first eight days of the month. The chart is from the mean maximum temperatures [06-18] for the 1st to the 8th of August 2017 compared with the 1981-2010 daily averages than I’ve calculated from the SYNOP records that I have (fig 1). I think the low value for St Catherine’s point is probably due to missing data.

Cool out last night

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Quite a cool night in places across the country last night under clearing skies and cool air for August (fig 2). Marked contrast between the coastal stations and the more rural inland stations as you would expect with SST around the coast of 16 or 17°C. Exeter with a min of 5.1°C and Portland 14.1°C is just one example (fig 1).

Figure 2

A cool night was well anticipated by the BBC, but it was a little colder than they thought in the south of Scotland, the west Midlands and Devon. They never can quite anticipate just how cold it can get at Exeter airport, with a grass minimum of just 2°C (fig 3), and the Met Office supercomputer just a couple of miles up the road.

Figure 3 – Courtesy of the BBC on the 5 August at 1pm

The crafty Met Office

Of course the Met Office and the BBC are very crafty, and since the demise of the magnetic weather charts, they now always quote a spot value for a particular time as the minimum temperature, rather than the true ‘minimum’ temperature for the whole night, which in my opinion is much more useful, and less misleading. It’s my belief that they don’t display a minimum or maximum temperature chart to hinder any verification of their forecasts, and prevent smart Alec’s like me from saying just how far their forecasts were out by.

A miserable cold July day…

A miserable cold July day here in our part of Devon, and also by the looks of it in a lot other places across the country. Cloudy with occasional outbreaks of light rain to go with it, and anomalies at 12 UTC around 3°C below the average for the 28th of July (fig 1). Tomorrow looks no better in this neck of the woods, although Sunday’s forecast does promise some brighter spells between occasional heavy and thundery showers.

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Colder than Christmas!

I know it sounds incredible, but at 12 UTC today many places in Eastern England and Scotland, it was colder than it was at the same time last Christmas day (fig 1).

Figure 1

The temperatures at some places were more than 6°C below the long-term average for 12 UTC on this day (fig 2).

Figure 2


Late frost and egg on face

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I knew that I was tempting fate by publishing a story the other day about the total number of frosts in the last year and saying that we wouldn’t be seeing anymore. Well last night there was a widespread ground frost (fig 3) and touch of air frost across the country (fig 2), and I’m still busy trying to get what’s left of the egg of my face as I type. I’m in good company though, because David Braine always seems to forget just how cold it can get at Exeter airport (-0.5°C). The 10th of May is not particularly late for an air frost in the UK, but I bet gardeners on chalky soils in Oxfordshire aren’t too pleased this morning, if the -2.8°C at Benson is anything to go by.

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Figure 3