Derecho

CET returns from the 00z EC control, as expected it is a warm outlook. The control is definitely on the warm side from the 11th to 14th but I wouldn't call it an outlier. The result if it verified would be an impressive CET of 14.5C up to the 15th but as recent model output has shown, this output should be taken with a pinch of salt. Today for example looks likely to return a pretty average CET value.

Metwatch I think the challenge with such long series of temperature is the need for overlapping observations to homogenise the data. London is a lot more handy in this regard as there were many observers going back to the 18th century. Armagh has daily temperatures going back to 1796 (I think!) and Edinburgh has monthly means going back to 1764 I think but I'm not sure there are many other stations in the UK that have overlapping stations going back that far (Radcliffe Observatory in Oxford is another). Maybe a UK series based on Edinburgh, Armagh and London would be more handy though only London and Armagh have daily data going that far back for the duration.

B87 It's not the raw temperature used to calculate the CET mean, it's the anomaly from the average at the London station that is applied to the CET mean. It doesn't matter how much warmer London is compared to the CET mean when you are basing the CET mean off station anomalies unless you see regional variations in temperature anomalies associated with persistent weather patterns.

B87 The raw temperature was not used to calculate the CET but the anomaly from the station average. Here is a more detailed explanation from another thread I posted on: To follow my earlier post, the temperature anomaly in London will have equated to 3.9C above the 1961-90 average there, the raw value would not have been 15.1C that appears in the CET series. The CET value would have been 11.2C + 3.9C London anomaly = 15.1C. If the raw temperature for London was used you'd see a long sustained upwards spike in CET before it became 3 stations, outside of winter and especially for summer months as SE England is warmer. In order to beat the 1833 record, you'd need an average temperature anomaly of +3.9C at Rothamstad, Pershore College and Stonyhurst, rather then just a +3.9C temperature anomaly over the London area. That would be difficult even in todays climate, every once in a while you get a month of truly exceptional weather.

Sprites Indeed, it's a very unusual synoptic either way. Shame we can't see this kind of setup for storms more in the summer. It seems like anything thundery is heading further north of here though unfortunately.

reef Yup I've been saying that to others myself. I've never seen it here. Doesn't feel stormy here either. Just 11C, cloudy and calm. Bizarre.

To follow my earlier post, the temperature anomaly in London will have equated to 3.9C above the 1961-90 average there, the raw value would not have been 15.1C that appears in the CET series. The CET value would have been 11.2C + 3.9C London anomaly = 15.1C. If the raw temperature for London was used you'd see a long sustained upwards spike in CET before it became 3 stations, presumably, especially for summer months. In order to beat the 1833 record, you'd need an average temperature anomaly of +3.9C at Rothamstad, Pershore College and Stonyhurst, rather then just a +3.9C temperature anomaly over the London area. That would be difficult even in todays climate, every once in a while you get a month of truly exceptional weather.

I doubt this, they will have taken the temperature anomaly from that station to calculate the CET. The uncertainty comes in when you've got regional differences in anomalies. So for example. 1961-1990 May CET: 11.2C (I think) London station: Anomaly = 2C above 1961-1990 average. CET = 13.2C Now if you had Stonyhurst at the time and the anomaly there was only 1C above average, you'd have a CET of 12.7C (+2C anomaly in London, +1C at Stonyhurst equals an average of +1.5C assuming equal weightings). Over long time scales any discrepancies should even out generally but the uncertainty for an individual month in those earlier periods will be higher and there may be a higher standard deviation too.

raz.org.rain I guess the westerlies in 2015 were influential enough to keep the heat further SE. There is definitely evidence to support the theory that the cold blob encourages more heat to build over Europe. 2015 however was particularly unusual however in that the temperatures to the south of Greenland were record breakingly cold. This likely allowed for the cool air to influence the synoptics over a wider area. The brief period the westerlies relented was when we saw that 1 day plume at the start of July. Interestingly I recall a NAVGEM run going for 44C in Cambridgeshire in the lead up to that. GFS also had a few runs that saw temps above 40C. I remember it very well as it was the first time I saw 40C on a model run over the UK. Only other times after that were August 2018 and July 2019 before July 2022 of course came along. Some model runs indicated that plume would last several days but in the end the heat only moved across us on the 1st July before it waned.

Yeah 2015 had a reasonable June when I was in Southampton. First half of July was decent but the second half was awful, especially when I was in Norfolk. August I was back in Southampton again and that was a bit of a washout.

Latest projections according to the 12z EC control. Difficult month to call this with the control being one the coolest members of the entire suite after the 9th. CET would still be above average for the mid-month point if that came off. Some very warm ensemble members mixed in there.... so who knows where this will go. Very warm up to the 7th though, especially with overnight minima.

ANYWEATHER To be fair this bank holiday weekend always looked dubious whereas the signal on that EC mean for next week is pretty strong. Although it does seem if the weather gods can find a way of making things underwhelming this year, they will...

Another new month and it looks like the first week will be warm with the CET at an impressive 14.3C if the EC 00z Control is anything to go by. More typical temperatures for the time of year from the 9th though the control is on the cooler side of the mean here. I think another above average month of temperatures is looking like a good bet.

Looks like 9.6C will be the winning guess if my predictions are correct.

damianslaw Yesterday came in quite a bit milder then I was expecting at 6.7C. Perhaps they give more weight to Stonyhurst. My calculation was based on hourly obs so there may have been a higher max at one of the sites between the hourly obs. Stonyhurst managed an air frost last night. Pershore College wasn't far off, though Rothamstad was less cold according to the hourly obs. Expect a CET of around 6.0C today.

A pretty grim day of weather here again in the NE with a cheeky brief but heavy hail shower in Hessle.

Daniel* Yup I'd expect todays CET to come in at around 5.9C (due to minima at Stonyhurst being a bit higher from what I can see of the hourly obs).

danm Meanwhile here it is drizzly and only 6C

Don We are looking at 9.4C to finish the month So that would bring the CET for the second half of April to 7.7C. The chilly uppers are hanging on longer then expected with winds very slack later this week allowing for chillier nights. If this came off, the CET for the second half of April will be colder then the first half of February.... Also I wonder how many Aprils have recorded their coldest running mean on the 30th? Odd for a month that typically warms as it progresses. It really has felt like a backwards April and a poor one...

Addicks Fan 1981 Easterly winds are most frequent during April and May so it's hard to distinguish whether an SSW is responsible here

Dare i watch the GFS 06Z Fair enough, it wasn't a straw man argument however, it was just based on logic and what the graphs show. I agree that we can still see cooler weather in a warming climate, I don't think anyone can argue that. Though all we know at this stage is that global temperatures will increase (barring a big volcanic eruption) but atmospheric circulation determines how that extra heat is distributed. What that means locally I wouldn't want to guess. You could see 10 years of very warm April's in Sweden the next 10 years, maybe not. The long term means however will paint the best picture for changes and global temperatures will very likely carry on increasing regardless. What we are seeing is more frequent warmer extremes and shorter cooler / cold episodes. These can still be extreme as March 2018 shows but will be compensated by greater warmer extremes elsewhere. The ease of tapping into very warm airmasses is what is making colder then average months harder to come by these days but April 2021 shows it's still possible.

I'm very capable of reading graphs thank you and my comment still stands. The solid black line is only a 10 year running mean and is too short. The dashed line is a more appropriate long term average that is still increasing on almost all the graphs you posted.

Dare i watch the GFS 06Z 10 years is too short to define a climate, you need at least 30 for it to be statistically meaningful. If you took the 2001-2010 average for December in the CET series, it only came out at 4.0C, nearly a degree lower then the 1971-2000 average. Yet 2011-2020 had an average CET of 6.0C for December, 2 degrees warmer then the decade prior... The longer term means, including the ones you have posted for Sweden are heading upwards...

I don't know how you can conclude that from the graph you posted before? 2011, 2014, 2015, 2018, 2019 and 2020 all appear to be just as warm as the warm April's in the 2000s with 2011 record breaking. Looks like the 30 year running mean(?) is almost at an all time high. You aren't going to get warmer April's with every single passing year. There will be variability. Climate change means I'm pretty sure you'll see those kind of April's more regularly unless atmospheric circulation fundamentally changes.

Afternoon all, so after an unremarkable week of CET returns (even slightly above average with the last 7 days at 8.2C) it looks as though the CET may actually now be close to or even above 10C at the end of the month. According to the 00z EC control, we have a few slightly chilly days up until the 26th which should take the CET down to around 9.7C. After that the daily CET returns are above 10C again. 00z EC control is slightly on the warmer side of the ensemble mean so something between 9.8C and 10.2C is probably in the right area. Another notably above average month yet again if this run comes off. GFS handles the weekend low a bit differently so is cooler however to end the month.