October 2023 C.E.T. and EWP contests

[The PIT]

Sunny Sheffield at 13.6C +0.1C above normal. Rainfall 12.3mm 14.9% of the monthly average.

[Roger J Smith]

5 hours ago, BlueSkies_do_I_see said:

Can anyone make an estimate based on current GFS output what our projected CET running total would be into mid month?  I would do it myself, but I don't know how to!

Today, Saturday to Tuesday 10th all look very warm (averages 16-17) so CET will likely be around 15.5 by 10th, possibly 16 C.

From there, would estimate running means at 15.3 to 11th when it begins to turn cooler, 14.8 to 12th, 14.3 to 13th, 13.8 to 14th, 13.6 to 15th, and 13.4 to 16th. According to list I created yesterday, those would be in 11-20 range rather than top ten, if the cooling trend is that sharp, so close to record pace by 10th to around 15th place or so by 15th-16th October.

For the interval 17th to 22nd, GFS suggests average around 10 C which would drag CET down gradually to about 12.6 by 22nd. If all this proved accurate, it would take a fairly prolonged warm spell in last third to keep 2023 in running for warmest October, and further cooling trends could drag it below 12 C eventually. Probably all forecasts are still "alive" at this point.

EWP by the way was around 15 mm to 5th and looks like adding 40-50 by 22nd to reach 55-65, a bit lower than an average October pace (1991-2020 average 102.9 mm, by 22nd average would be around 70 mm). 

[WYorksWeather]

Interestingly the GFS mean is still running quite a bit higher than the OP though - not sure what to read into that. It's been very consistent - almost every GFS run I've looked at the last four or five days shows this big cool down that lasts quite a while on the OP - we'll see if it is onto something. So far though the mean is much less dramatic.

I think this cold spell is probably the big chance to get the CET down  - if the GFS OP ends up overdoing it, probably very difficult to get the CET below 12. Likewise if it does happen, anyone with a 13+ prediction (including myself) is likely going to end up with egg on their face!

[BlueSkies_do_I_see]

51 minutes ago, Roger J Smith said:

Today, Saturday to Tuesday 10th all look very warm (averages 16-17) so CET will likely be around 15.5 by 10th, possibly 16 C.

From there, would estimate running means at 15.3 to 11th when it begins to turn cooler, 14.8 to 12th, 14.3 to 13th, 13.8 to 14th, 13.6 to 15th, and 13.4 to 16th. According to list I created yesterday, those would be in 11-20 range rather than top ten, if the cooling trend is that sharp, so close to record pace by 10th to around 15th place or so by 15th-16th October.

For the interval 17th to 22nd, GFS suggests average around 10 C which would drag CET down gradually to about 12.6 by 22nd. If all this proved accurate, it would take a fairly prolonged warm spell in last third to keep 2023 in running for warmest October, and further cooling trends could drag it below 12 C eventually. Probably all forecasts are still "alive" at this point.

EWP by the way was around 15 mm to 5th and looks like adding 40-50 by 22nd to reach 55-65, a bit lower than an average October pace (1991-2020 average 102.9 mm, by 22nd average would be around 70 mm). 

Thank you for that Roger. It feels like a less extreme repeat of September. A strong spike in temperatures and then the rest of the month petering out.

We shall see. It was never likely to see two record breaking CET months in a row.

Have there ever been 2 or more month records broken in a calendar year?

[Roger J Smith]

Yes in 2006 until 2023 took away September (2006 still has July).

Also Nov 1994 and Aug 1995 are within a twelve-month interval and remain warmest.

Years or at least twelve-month intervals with current multiple entries in top five (using one decimal) would be:

2023 _ two (June 5th, Sep 1st) _ three if we count Oct 2022 (see below) also Nov 2022 7th

2022 _ two (Aug 3rd, Oct t5th) _ also Nov 2022 7th

2015 _ two (Nov t4th, Dec 1st)

2011 _ two (Apr 1st, Nov t2nd) _ also mar 2012 t4th for three in 12 months

2006 _ three (July 1st, Sep 2nd, Oct 4th) _ also Jan 2007 5th, so four top five out of seven, and Apr 2007 2nd, makes a total of five in ten consecutive months.

1997 _ two (mar t4, Aug 2nd)

1994-95 _ two (Nov 1st, Aug 1st) _ also July 1995 t7th and Oct 1995 7th

(1990 Feb 3rd, mar t6th, Aug 10th)

(1976 June t6th, July 6th)

1974-75 _ two _ Dec 3rd, (Jan 7th), Aug t4th

(1947 had t8th may and t4th Aug) 

1938 _ two (mar 2nd, Nov t4th)

1921 _ two (Jan 2nd, Oct t5th) _ also t7th July 

1865 _ two (Apr 3rd, Sep t4th)

1852 _ two (July 5th, Dec 4th)

1833-34 _ two (may 1833 1st, jan 1834 4th)

list may not be complete, will be checking for others

 

Edited October 7, 2023 by Roger J Smith

[Addicks Fan 1981]

2 hours ago, Roger J Smith said:

Today, Saturday to Tuesday 10th all look very warm (averages 16-17) so CET will likely be around 15.5 by 10th, possibly 16 C.

From there, would estimate running means at 15.3 to 11th when it begins to turn cooler, 14.8 to 12th, 14.3 to 13th, 13.8 to 14th, 13.6 to 15th, and 13.4 to 16th. According to list I created yesterday, those would be in 11-20 range rather than top ten, if the cooling trend is that sharp, so close to record pace by 10th to around 15th place or so by 15th-16th October.

For the interval 17th to 22nd, GFS suggests average around 10 C which would drag CET down gradually to about 12.6 by 22nd. If all this proved accurate, it would take a fairly prolonged warm spell in last third to keep 2023 in running for warmest October, and further cooling trends could drag it below 12 C eventually. Probably all forecasts are still "alive" at this point.

EWP by the way was around 15 mm to 5th and looks like adding 40-50 by 22nd to reach 55-65, a bit lower than an average October pace (1991-2020 average 102.9 mm, by 22nd average would be around 70 mm). 

There's suggestions that a west based negative NAO could herald a record breaking warm October in the model thread.   

[reef]

13 hours ago, Addicks Fan 1981 said:

There's suggestions that a west based negative NAO could herald a record breaking warm October in the model thread.   

The other day the models were hinting at this but it's +NAO all the way as any signs of heights building over Greenland have vanished. Still mild though so it's possible we could end up warmest. It all depends how much of a headstart we get from the warm start, similar to September.

[Summer Sun]

14.8c to the 6th

4.3c above the 61 to 90 average
2.5c above the 81 to 10 average

[MattStoke]

1 minute ago, Summer Sun said:

14.8c to the 6th

4.3c above the 61 to 90 average
2.5c above the 81 to 10 average

Year to date mean CET anomaly: +1.67°C

Record (2022) year mean CET anomaly: +1.68°C.

Closing the gap and should overtake last year over the next few days. Still reckon we’ll end up falling short of last year, though. 

[Addicks Fan 1981]

25 minutes ago, MattStoke said:

Year to date mean CET anomaly: +1.67°C

Record (2022) year mean CET anomaly: +1.68°C.

Closing the gap and should overtake last year over the next few days. Still reckon we’ll end up falling short of last year, though. 

According to the CFS there is a very good chance that the record will be smashed.    

[Addicks Fan 1981]

This is no joke of where we are heading for this month.    

 

[The PIT]

Sunny Sheffield up to 14.3C +0.9C above normal. Rainfall unchanged at 12.3mm 14.9% of normal.

[LetItSnow!]

1 hour ago, Addicks Fan 1981 said:

This is no joke of where we are heading for this month.    

 

Seems as though especially for southern/central Europe that 2023 is the year warming went on steroids. They've dealt with extremely above normal anomalies throughout each eason and October is keeping the trend.

[Maz]

2 hours ago, Addicks Fan 1981 said:

According to the CFS there is a very good chance that the record will be smashed.    

If come end of October, annual mean is very close to last year, I would have thought it’s 50/50 whether the record is broken.  Last year had mild November and coldish December, so quite likely we would at least match those months.

Given the massive difference between July and August last year and this, I would not have thought a record breaking year would even be possible.  Just goes to show how persistent the warm anomalies have been.  Even the “cool” Synoptics in July/August ended up around about average.

Edited October 7, 2023 by Maz

[Roger J Smith]

Latest GFS guidance is a bit warmer, would probably leave CET around 14.0 by 16th and 13.0 by 23rd. Increasing but not "nailed on" chances of a top five or even record warm October. A few days ago GFS showed nearly wintry cold for a week, now it barely drops below long-term average at any point. Peak CET will likely occur on 11 (for the report on 12 Oct), could be close to 16 C and record for running CET average 1-11 is 16.5 in 1921. 

[WYorksWeather]

2 hours ago, Maz said:

If come end of October, annual mean is very close to last year, I would have thought it’s 50/50 whether the record is broken.  Last year had mild November and coldish December, so quite likely we would at least match those months.

Given the massive difference between July and August last year and this, I would not have thought a record breaking year would even be possible.  Just goes to show how persistent the warm anomalies have been.  Even the “cool” Synoptics in July/August ended up around about average.

The anomaly to September was 1.61. Here's a few scenarios:

October CET / October anomaly / Year-to-date anomaly / Nov + Dec average anomaly needed to exceed record (assuming record is exactly 1.68)

10.5 / 0.0 / 1.45 / 2.9

11.0 / 0.5 / 1.50 / 2.6

11.5 / 1.0 / 1.55 / 2.4

12.0 / 1.5 / 1.60 / 2.1

12.5 / 2.0 / 1.65 / 1.9

13.0 / 2.5 / 1.70 / 1.6

13.5 / 3.0 / 1.75 / 1.4

Overall, I'd say based on that it's odds-on favourite to be the warmest CET year if we get a 13.X October, less than 50% but still fairly likely with a 12.X, unlikely with an 11.X or lower.

[Don]

5 hours ago, Addicks Fan 1981 said:

According to the CFS there is a very good chance that the record will be smashed.    

With the current outlook for the rest of the year, there is a strong chance that 2023 will fail to have a monthly CET below the 1961-90 average, something that I don't think has happened before?

[LetItSnow!]

11 minutes ago, Don said:

With the current outlook for the rest of the year, there is a strong chance that 2023 will fail to have a monthly CET below the 1961-90 average, something that I don't think has happened before?

All hopes for a more tame 2024! Goes to show how much things have changed that a 10.3C year is seen as rather cool nowadays. 9.5C would be positively Artic! 

[Don]

48 minutes ago, LetItSnow! said:

All hopes for a more tame 2024! Goes to show how much things have changed that a 10.3C year is seen as rather cool nowadays. 9.5C would be positively Artic! 

It's almost certainly not going to be a more tame 2024 globally, what with El Nino kicking into action!!  I agree that a 10C year would be seen as cool now, when 30 years ago it would have been classed as rather warm.  9.5C these days would indeed seem decidedly chilly and would give some on here nightmares lol!!  Just think, 30 years ago, 9.5C was the average for the year! 

[reef]

23 minutes ago, Don said:

It's almost certainly not going to be a more tame 2024 globally, what with El Nino kicking into action!!  I agree that a 10C year would be seen as cool now, when 30 years ago it would have been classed as rather warm.  9.5C these days would indeed seem decidedly chilly and would give some on here nightmares lol!!  Just think, 30 years ago, 9.5C was the average for the year! 

2010 was 8.9C and we've warmed 0.1-0.2C since then so I imagine about 9.0C is the lowest we could go now. It's about equal to a 7.7C pre-1900.

[WYorksWeather]

I think one of the reasons this has snuck up on us is that it has been subtle this year rather than dramatic. Even the poor spells of weather in the summer are not as bad as they could have been. Obviously it's not much comfort if like you like warm summer weather, but a poor spell of weather being 18C and rainy instead of 16C and rainy makes quite a big contribution. Same thing in September - even the wetter and cooler interludes later in the month had as much to do with the record-breaking CET as the initial heatwave, simply because they were cooler, but not enough to really collapse the CET.

[alexisj9]

2 minutes ago, WYorksWeather said:

I think one of the reasons this has snuck up on us is that it has been subtle this year rather than dramatic. Even the poor spells of weather in the summer are not as bad as they could have been. Obviously it's not much comfort if like you like warm summer weather, but a poor spell of weather being 18C and rainy instead of 16C and rainy makes quite a big contribution. Same thing in September - even the wetter and cooler interludes later in the month had as much to do with the record-breaking CET as the initial heatwave, simply because they were cooler, but not enough to really collapse the CET.

Agreed. 

[WYorksWeather]

31 minutes ago, reef said:

2010 was 8.9C and we've warmed 0.1-0.2C since then so I imagine about 9.0C is the lowest we could go now. It's about equal to a 7.7C pre-1900.

I think the more recent warming trend is something like 0.2C per decade, so it's actually closer to 0.2-0.3C. Factor in an adjustment for land warming faster than ocean, and you probably arrive at a figure closer to 0.4C.

Anyway, we have the rest of October to look at before we consider the annual! All in all I think we can probably say that outcomes above 14C and below 11C are unlikely, but that frankly doesn't tell us much!

I think we need more clarity from the models about whether this cold spell will come off - in the last few days we've seen GFS getting the -5C isotherm in next week, and ECM has some bonkers ensemble members in the other direction, including one earlier today that got the +18C isotherm in on the 22nd!

Hopefully we'll have a better idea of the road ahead by early next week.

 

 

[Don]

48 minutes ago, reef said:

2010 was 8.9C and we've warmed 0.1-0.2C since then so I imagine about 9.0C is the lowest we could go now. It's about equal to a 7.7C pre-1900.

Yes, I agree that 9.0C is probably the lowest we could go now.  It's a challenge to get a year below 10C these days!

[The PIT]

Sunny Sheffield at 14.9C +1.6C above normal.  Rainfall 12.3mm 14.9% of the monthly average.