2023 CET - all 12 months above 1961-1990 average?

[Don]

21 minutes ago, LetItSnow! said:

That’s all well and good but people complaining on a forum like that isn't relevant to me for a climate analysis. As stated, I think both should be used. Our climate is changing so fast. A 3.0C January is about 1.5C below average nowadays, but that doesn’t make it a cold January in the wider scheme of things. Exactly the same as a 16.0C July being about 1C below average - it may feel “cool” but it isn’t in a recent historical context. It can be used by rampers with an agenda to paint a picture that a month has been abnormally below normal when it hasn’t.

A 1991-2020 average is a great tool for recent perspective but old values should remain in place to drive home the changing climate. 

100% agree with this.

[WYorksWeather]

With today's update taking the CET to 4.7C, perhaps the guess of 4.9C by the 14th won't be so bad after all. Still waiting for a little more certainty on the run up to Christmas. Early thoughts probably a mild weekend into early next week, then turning colder, but how cold and for how long will make a big difference to CET predictions.

I think the odds are now favouring an above average month. We would need quite a cold spell of weather - probably some sub-zero CET means for three or four days, if the rest of the month is otherwise average. In any case, here's the update. On the next update, I will make a decision on where I think we'll be as Christmas approaches.

Update based on data up to 12th December

Today's average: 4.7C (12 days)

10-year average for rest of December: (4.7 * 12 + 5.9 * 19) / 31 = 5.4C

30-year average:  (4.7 * 12 + 4.9 * 19) / 31 = 4.8C

As you may have noticed by now, the gap between the two methods of calculating the average is falling, and of course towards the end of the month there won't be much difference. In any case, a continuation of the rise in the CET, which will most likely continue with more upside than downside overall until at least early next week.

[reef]

22 hours ago, LetItSnow! said:

That’s all well and good but people complaining on a forum like that isn't relevant to me for a climate analysis. As stated, I think both should be used. Our climate is changing so fast. A 3.0C January is about 1.5C below average nowadays, but that doesn’t make it a cold January in the wider scheme of things. Exactly the same as a 16.0C July being about 1C below average - it may feel “cool” but it isn’t in a recent historical context. It can be used by rampers with an agenda to paint a picture that a month has been abnormally below normal when it hasn’t.

A 1991-2020 average is a great tool for recent perspective but old values should remain in place to drive home the changing climate. 

Spring 2023 is a good example of this. It was a season bemoaned as cold but it was actually the 33rd warmest in the 365 years of the CET series. It was actually just 0.9C below the record.

For reference, a Spring 33rd coldest in the CET series would have a mean of 6.9C - exactly the same as Spring 2013.

The 1991-2020 average for Spring is 9.2C, a number in itself that would put the season in the top 50. Things have changed a lot. 

[WYorksWeather]

2 hours ago, reef said:

Spring 2023 is a good example of this. It was a season bemoaned as cold but it was actually the 33rd warmest in the 365 years of the CET series. It was actually just 0.9C below the record.

For reference, a Spring 33rd coldest in the CET series would have a mean of 6.9C - exactly the same as Spring 2013.

The 1991-2020 average for Spring is 9.2C, a number in itself that would put the season in the top 50. Things have changed a lot. 

Same applies to annual CET. If we look at very warm years reaching at least 10.50C on the CET, there were 18 up to 2019, to which we can add 2020 and 2022, and almost certainly 2023 for a total of 21. Of those, 11, or more than half, are in this century. The others are made up of eight in the whole of the 20th century (mostly in the latter half), and then one each in the 19th and 18th centuries. That's simply extraordinary if you think about it. What would have been considered an extraordinary mild year in the Victorian period was then a very warm but not once-in-a-lifetime warm year in the 20th century, and is now an entirely unremarkable occurrence.

The opposite pattern is seen with extreme cold. The coldest year this century, 2010, still had an annual CET of 8.86C, which ranks 94th coldest, so on the cool side of the historic record but entirely unremarkable. And that is the only year this century that is ranked on the colder side of the record.

 

[WYorksWeather]

Another upward revision today, but less than 0.1C on both averages. I'll also take another go at a forward projection.

Update based on data up to 13th December

Today's average: 4.8C (13 days)

10-year average for rest of December: (4.8 * 13 + 5.9 * 18) / 31 = 5.4C

30-year average:  (4.8 * 13 + 4.9 * 18) / 31 = 4.9C

Projection up to 20th December

I think there's now enough confidence in the upcoming period to have a go. If we assume our starting point is 4.9C when data for the 14th comes in tomorrow in line with my last prediction, I'm going to go for the following:

Projected maxima, 15th-20th

7, 11, 9, 12, 7, 8

Projected minima, 15th-20th

9, 8, 9, 4, 6, 6

If we take (min + max) / 2, we get daily means of 8, 9.5, 9, 8, 6.5, and 7. So the mean from the 15th-20th I am projecting at 8.0.

So, our new average would be (14 * 4.9 + 6 * 8.0) / 20 = 5.8C by the 20th.

Projection based on 5.8C by the 20th

10-year average for rest of December: (5.8 * 20 + 5.9 * 11) / 31 = 5.8C

30-year average:  (5.8 * 20 + 4.9 * 11) / 31 = 5.5C

Looks very likely that if this prediction comes off, we'd have an above average December.

Alternatively, we can solve for the value required for an average of 4.5C (to miss out on the 1961-1990 average).

(5.8 * 20 + 11x) / 31 = 4.5

116 + 11x = 139.5

11x = 23.5

x = 2.1C

We therefore need a very cold last third of December, if my projection to the 20th is broadly right.

[WYorksWeather]

No change today. 

Update based on data up to 14th December

Today's average: 4.8C (14 days)

10-year average for rest of December: (4.8 * 14 + 5.9 * 17) / 31 = 5.4C

30-year average:  (4.8 * 14 + 4.9 * 17) / 31 = 4.9C

[WYorksWeather]

A slightly uptick to 4.9C today, but not enough to change either estimate. These estimates will move more slowly as we head towards the end of the month. There is still the uncertainty around a late cold spell, but I feel confident enough to revise up my chance of this record going to 80%. 

Update based on data up to 15th December

Today's average: 4.9C (15 days)

10-year average for rest of December: (4.9 * 15 + 5.9 * 16) / 31 = 5.4C

30-year average:  (4.9 * 15 + 4.9 * 16) / 31 = 4.9C

[TillyS]

On 12/12/2023 at 22:04, Don said:

100% agree with this.

Seconded

[LetItSnow!]

It's funny how 2023 of the two years will be (most likely) the one to do it. Of course the weather doesn't work on "should have beens" but it would have been fitting for December 2022 and December 2023 to switch place because 2022 is far more deserving a year to have every year above average as it very much is one of those years that'll be referenced alongside 1995 and 2003 in the future, whereas 2023 has been majorly drab for a lot of it with generally above but unexceptional average temperatures doing the heavy lifting for a couple notably well above average spells like September. Imagine September 2023 heatwave occuring in September 2022... would have been insane and probably smashed past 35C with the dry ground. That would have been the ultimate hot summer really.

[WYorksWeather]

3 hours ago, LetItSnow! said:

It's funny how 2023 of the two years will be (most likely) the one to do it. Of course the weather doesn't work on "should have beens" but it would have been fitting for December 2022 and December 2023 to switch place because 2022 is far more deserving a year to have every year above average as it very much is one of those years that'll be referenced alongside 1995 and 2003 in the future, whereas 2023 has been majorly drab for a lot of it with generally above but unexceptional average temperatures doing the heavy lifting for a couple notably well above average spells like September. Imagine September 2023 heatwave occuring in September 2022... would have been insane and probably smashed past 35C with the dry ground. That would have been the ultimate hot summer really.

Or, as I imagine will happen before too long, imagine creating a combined 'warm season' (May to September) out of the two years. You take the first half of May 2022, then the second half of May 2023, June 2023, July 2022, August 2022, and September 2023.

That would give you quite a warm May, then the other months as they turned out, but probably with an increment of 1-2C on the maxima given how dry the ground would have been. July 2022 could have reached 41 or 42C instead of 40C, August maybe 35C or 36C instead of 34C, and September after all that might have gone far enough to challenge the all-time record, given it would have come after one of the driest summers ever, so possibly a bigger increment for that one from the 33-34C recorded to nudge it up to 36C.

In terms of CET, maybe half a point on each month, so you could have had a year with a 13C May, 17.5C June, close to 19C July, 19.5C August, and 17.5C September.

This is probably still quite unlikely to happen in any particular year, but what we've seen elsewhere in Europe does shown that if we'd been right in the midst of this year's European heat dome rather than more on the fringes, it is certainly possible. I wouldn't be at all surprised if it happened by 2030. I'd probably put it at a 50-50 chance of having a year with all five warm season months at least 2C above the 1961-1990 average, which is what we'd be talking about. I'm not sure if that has ever happened before?

[SqueakheartLW]

It would be a remarkable feat to see all 12 months above the 1961-90 average but what I think 2023 doesn't deserve is for us to see yet another 11C CET mean year. I have been creating the rolling CET for 2023 for some time now and it is looking like a very close run thing as to whether we not only get all 12 months above 1961-90 but we also get another 11C year.

Now looking at the table above you can see how we are doing against the previous top 10 years. Currently we are tracking a little behind 2022 but we are very close to 2014. So what now looks very certain is that we are going to see a top 3 finish for 2023. We are provisionally at 11.190C up to 16th December and if the 17th December GFS 00z mean predictions come true then 2023 will finish in 2nd position on the mean CET record. We will also set a December 2023 mean CET of 5.855C.

We will have achieved based on this prediction

• Another 11C CET year out of what seemed no where considering much of the year has been unremarkable except for June 2023 and the September heatwave. 2022 deserved it's 11C CET mean but to me 2023 doesn't and it would be such a shame for an unremarkable year overall to take another 11C CET mean.
• All 12 months above 1961-90. A December 2023 CET of 5.855C would easily see this record fall. We should have done this last year as 2022 deserved it but 2023 is going to steal this remarkable feat from an unremarkable year for big extremes in the UK at least.
• A top 2 year immediately following the warmest year on the CET record last year. Again undeserved really considering how 2023 has been but it is only June 2023 and 10 days of September 2023 that have really put us in this position.

[SollyOlly]

Really interesting post @SqueakheartLW, thank you. I completely see your point about 2023 being 'undeserving' (as it were) for the full set of above average CET months, and that also speaks to a point that has been made elsewhere too - that it is this creeping uptick in temperatures, both by night and by day, that is raising the overall average/ level. It's also acclimatising people to feel that what used to be excessive heat is considered less remarkable (take the 30c threshold, for instance) and to gradually redefine what 'cold' is. It's looking likely now that we'll have 23 out of 24 months above the average...and the overall temperatures this century are remarkable.

[WYorksWeather]

Yes, I think we are starting to lose perspective on what cold is. If we pick a year which had a cooler than average but not crazily cold summer from the first half of the 20th century, you could use something like 1930 as an example. It had a 15.3 CET June, which would now be considered fairly average, despite being ranked 87th in the CET. It then had a 15.2 CET July, which ranks 97th coldest, which would now be considered not merely below average but absolutely horrendous. It then had a 15.7 CET August, which is ranked roughly in the middle of the CET record at 169th warmest, and would be considered well below average.

So, a more middle of the road summer CET-wise it'd be hard to find - an above average June, a below average July, and a middle of the road August. The closest modern equivalent would be something like 2012, which is now considered up there as a truly horrible summer, when in a historical perspective it's really not all that bad, at least temperature wise.

[WYorksWeather]

Gah, forgot my update for today. The rise to 5.1C today is enough to send both predicted averages up by 0.1C. Any chance of a colder than average month now rests on a late cold spell.

Update based on data up to 16th December

Today's average: 5.1C (16 days)

10-year average for rest of December: (5.1 * 16 + 5.9 * 15) / 31 = 5.5C

30-year average:  (5.1 * 16 + 4.9 * 15) / 31 = 5.0C

[TillyS]

On 03/12/2023 at 10:08, Summer8906 said:

On a knife-edge I guess depending on whether this month is Atlantic-dominated or whether we get another easterly in; models suggest either could occur.

As I said above it would certainly be ironic if such a dismal, wet year takes this record. Given that much of the summer was cool by day and dull, and July/Aug were almost completely devoid of 30C+ temps with even 25C+ rare, it shows the power of mild nights in influencing the CET. Or perhaps it just shows how anomalously cold the 60s were (which are of course part of the 1961-90 period).

It was the warmest June recorded in the UK and the joint warmest September. Where I live in Teignmouth June was glorious: day after day of deep blue skies. This followed a very sunny spring. I can understand what you are saying with regards to July and, less so, August. But then September (17C) was hot and people were sunbathing on Dawlish beach in early October.

But generally I know what you mean. I think what you’re getting at is that, and this is subjective on my part, we seem to have had a more typically tropical type of experience, or perhaps sub-tropical would be more accurate. As you will doubtless know, the tropics are often characterised by warmth and cloud and moisture.

If this is true, and it might be, then the generally warming climate might be impacting in an unusual way here: almost turning Britain sub-tropical?

 https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/weather/learn-about/uk-past-events/summaries/mwr_2023_06_for_print.pdf

 https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2023/joint-warmest-september-on-record-for-uk

 

Edited December 18, 2023 by TillyS

[LetItSnow!]

An excerpt of an earlier message I sent but which fits here:

I wonder if 2024 will tone down our weather and we'll have something a bit more standard or will it follow in the footsteps of 2022 and 2023 and bring more extremes. I never thought that we'd challenge the hottest year ever recorded two years in a row. It's absolutely shocking that 2023 is set to be the second warmest year on record behind 2022. If we challenge or beat the record in 2024, we know the scale has tipped!

[WYorksWeather]

5 hours ago, LetItSnow! said:

An excerpt of an earlier message I sent but which fits here:

I wonder if 2024 will tone down our weather and we'll have something a bit more standard or will it follow in the footsteps of 2022 and 2023 and bring more extremes. I never thought that we'd challenge the hottest year ever recorded two years in a row. It's absolutely shocking that 2023 is set to be the second warmest year on record behind 2022. If we challenge or beat the record in 2024, we know the scale has tipped!

I really doubt 2024 will be more standard. Next year is likely to be the warmest on record globally, breaking this year's record, as the effect of El Nino is lagged. At some point, that record warmth will likely affect the UK I feel.

My prediction is that at least one monthly mean CET record, or absolute max record, will be broken next year.

[WYorksWeather]

Rising quite rapidly now - up to 5.4C. A below average month getting less and less likely with every passing day. Probably now reliant on the outcome being close to one of the coldest GFS ensemble runs, e.g. P15 from today's GFS 12z.

Update based on data up to 17th December

Today's average: 5.4C (17 days)

10-year average for rest of December: (5.4 * 17 + 5.9 * 14) / 31 = 5.6C

30-year average:  (5.4 * 17 + 4.9 * 14) / 31 = 5.2C

[LetItSnow!]

Kissing goodbye another winter month. Funny how it still stings despite being the norm!

[WYorksWeather]

36 minutes ago, LetItSnow! said:

Kissing goodbye another winter month. Funny how it still stings despite being the norm!

Seems ridiculous, but it's now not out of the question that we finish above 6.4. That would make this December milder than a 1961-1990 average November.

[kold weather]

Looks almost certain now we will be above the 61-90 average and thus make it 12/12, and 23/24. Impressive sustained warmth but to be expected in a warming world

[WYorksWeather]

A further rise today. I'm now raising the probability of an above-average month to a subjective 90%. Another couple of days for the end of the month to start to come into the reliable, and if there's no strong cold signal by then we can call it done.

Update based on data up to 18th December

Today's average: 5.6C (17 days)

10-year average for rest of December: (5.6 * 18 + 5.9 * 13) / 31 = 5.7C

30-year average:  (5.6 * 18 + 4.9 * 13) / 31 = 5.3C

[WYorksWeather]

And we reach 5.8C ahead of schedule. Pretty much all of the cold signal has been erased from the latest GFS runs to the end of the year, so a finish in the upper 5s or even the 6s is now quite likely.

Quite extraordinary really considering how cold the first week was. The average for the first week was only 2.2C, so the average since then has been just under 8C.

Update based on data up to 19th December

Today's average: 5.8C (19 days)

10-year average for rest of December: (5.8 * 19 + 5.9 * 12) / 31 = 5.8C

30-year average:  (5.8 * 19 + 4.9 * 12) / 31 = 5.5C

[LetItSnow!]

3 hours ago, WYorksWeather said:

And we reach 5.8C ahead of schedule. Pretty much all of the cold signal has been erased from the latest GFS runs to the end of the year, so a finish in the upper 5s or even the 6s is now quite likely.

Quite extraordinary really considering how cold the first week was. The average for the first week was only 2.2C, so the average since then has been just under 8C.

Update based on data up to 19th December

Today's average: 5.8C (19 days)

10-year average for rest of December: (5.8 * 19 + 5.9 * 12) / 31 = 5.8C

30-year average:  (5.8 * 19 + 4.9 * 12) / 31 = 5.5C

I actually would have preffered the cold to come a week earlier as then we would have at least had the novelty of a warm December. My comments of a potential double whammy of cold Decembers have aged horrendously! December 2022 a fly in the ointment of a run of ridiculously mild Decembers since 2011 bar a couple slightly mild ones. Surely December must be the month that is warming the fastest now. It feels like an extension of autumn now and being someone who isn't into Christmas too much it must be my least favourite month of the year. It's like the darkness taunts you. I'm feeling the "winter" blues admittedly and it's scary when that happens because I stop caring if the rest of the winter is mild! 

[WYorksWeather]

19 hours ago, LetItSnow! said:

I actually would have preffered the cold to come a week earlier as then we would have at least had the novelty of a warm December. My comments of a potential double whammy of cold Decembers have aged horrendously! December 2022 a fly in the ointment of a run of ridiculously mild Decembers since 2011 bar a couple slightly mild ones. Surely December must be the month that is warming the fastest now. It feels like an extension of autumn now and being someone who isn't into Christmas too much it must be my least favourite month of the year. It's like the darkness taunts you. I'm feeling the "winter" blues admittedly and it's scary when that happens because I stop caring if the rest of the winter is mild! 

I might do some checking on the CET on fastest warming months over the next few days - not sure if it will be December or not. I did do some checking a couple of months ago, and September is the only month that has warmed so much that it has moved into another season in all but name! In other words, Septembers are now warmer on average than a typical mid-20th century June, whereas that's not true for e.g. February into March, May into June, or December into November.

I imagine the fastest warming month might depend very much on what starting point you pick, so I think the only way to do it fairly might be to look at the 30-year warming trend from all possible start dates, divide by three for a warming trend per decade, and then compare those lines between months.

In terms of a warm December, the remainder of this month actually looks so mild we may get a warm December anyway.