September 2021 C.E.T. and EWP forecast contests

[Don]

13 minutes ago, North-Easterly Blast said:

The final September CET comes in at 15.92*C, which was the seventh warmest September since records began in 1659, and just behind 2016.  A notably warm September we have just had, which actually makes it that four of the ten warmest Septembers in the 363 year CET record have occurred in the last 22 years, which is a remarkable statistic.

Will 2021/22 be the first cold winter to follow a notably warm September I wonder?!

[Methuselah]

6 minutes ago, Don said:

Will 2021/22 be the first cold winter to follow a notably warm September I wonder?!

I wonder what happens when you reduce your definition of 'notably' by 0.1C?

[Scorcher]

51 minutes ago, mulzy said:

Looks like final CET for September came in at 15.9C.

Disappointing that it dropped below 16C in the end, I'm surprised at how big the adjustments are at the moment.

[Scorcher]

It does mean September was warmer than August though (just). Joining the likes of 2006 and 2014 in the list. Seems to be happening more often than it used to.

[North-Easterly Blast]

33 minutes ago, Don said:

Will 2021/22 be the first cold winter to follow a notably warm September I wonder?!

Statistics show that it is very rare to get a cold winter after a warm September - it is a well known fact of the UK's weather patterns.  In recent times at least after 1999, 2005, 2006, 2011, 2014 and 2016 the winter that followed was largely mild with not much in the way of cold weather, or at best on a couple of those occasions the following winter was fairly average.  Also Septembers 1998 and 2004 were in the high 14s and neither of those following winters were cold either.  That said, I can think of a couple of occasions where September was slightly above average rather than insanely warm (14.2 in 1978 and 2009) where it led to a good cold winter.   Prior to a significantly colder than average winter the warmest the September before it has been, that I can think of, was 14.6 in 1985.

Whilst I do not believe that it is clear that a cool or average September has any bearing on the following winter's weather, the theory appears to work for increasing the chance of the following winter being mild after significantly warm Septembers, with just a slight chance of a near average winter to follow and virtually no chance of a colder than average winter to follow, thus certainly implying that anomalous warmth in September does at least reduce the chance of cold weather in the following winter.  

[Roger J Smith]

The downward adjustment was 0.33 C and looks like 0.4 because of rounding (16.25 to 15.92). As such, this became the seventh warmest September on record and filled a gap not utilized before by September CET values. (15.5 remains the most notable gap however and 15.8 is yet to be taken down). There was one daily record, 21.4 on 8th narrowly edged out 21.3 from 1898 which holds on to a lower record the next day. 

This large adjustment has rather unpleasantly dropped shillitocettwo quite a way down the scoring table, had there been no adjustment that entry would have finished first, but instead look where it ended up due to the large number of guesses just around the reflection point at 15.0 ... 

as always this is not official CET scoring, J10 will confirm that ... and the EWP looks like somewhere between 62 and 65 mm to me, but that will be confirmed (at least as the first estimate) tomorrow. 

TOP CET SCORING for SEP 2021

Rank _ CET _ EWP _ FORECASTER (order of entry)

 

 

01 _ 15.5 _ 65.0 _ syed2878 ( 23 ) 

02 _ 15.3 _ 60.0 _ bobd29 ( 3 ) 

03 _ 15.2 _ 42.7 _ Roger J Smith ( 29 ) 

04 _ 15.1 _ 63.0 _ Ed Stone ( 62 ) 

05 _ 15.0 _ 60.0 _ The PIT ( 16 )  

06 _ 15.0 _103.0_ Emmett Garland ( 22 ) 

07 _ 15.0 _ 61.0 _ rwtwm ( 39 ) 

08 _ 15.0 _ 67.0 _ noname_weather ( 41 ) 

09 _ 15.0 _ 63.0 _ daniel* ( 48 ) 

10 _ 15.0 _ 60.0 _ seaside60 ( 50 ) 

13 _ 15.0 _ ------ _ Duncan McAlister ( L2-1 ) (shown 13th due to late penalty)

11 _ 14.9 _ 78.0 _ I Remember Atl 252 ( 27 ) 

12 _ 14.9 _ 65.0 _ davehsug ( 46 ) 

14 _ 14.8 _ 65.0 _ Feb91Blizzard ( 4 ) 

15 _ 14.8 _ 72.0 _ Weather26 ( 17 ) 

16 _ 17.0 _ 29.0 _ Shillitocettwo ( 14 )

17 _ 14.8 _ 62.0 _ Captain Shortwave ( 31 ) 

18 _ 14.8 _ 81.0 _ J10 ( 47 )  

19 _ 14.7 _ 48.0 _ Reef ( 30 ) 

20 _ 14.7 _ ------ _ Quicksilver 1989 ( 37 )  

21 _ 14.6 _ ------ _ dancerwithwings ( 28 ) 

22 _ 14.6 _ 75.0 _ Mulzy ( 40 ) 

23 _ 14.6 _ 85.0 _ February1978 ( 54 ) 

27 _ 14.6 _ 65.0 _ Frigid (late edit L3-1) (shown 27th due to late penalty)

24 _ 14.5 _ 80.0 _ JeffC ( 9 ) 

25 _ 14.5 _ 92.0 _ summer18 ( 18 ) 

26 _ 14.5 _ 55.0 _ sundog ( 43 )   

28 _ 14.5 _ 80.0 _ Don ( 52 )  

Edited October 1, 2021 by Roger J Smith

[Methuselah]

22 minutes ago, North-Easterly Blast said:

Statistics show that it is very rare to get a cold winter after a warm September - it is a well known fact of the UK's weather patterns.  In recent times at least after 1999, 2005, 2006, 2011, 2014 and 2016 the winter that followed was largely mild with not much in the way of cold weather, or at best on a couple of those occasions the following winter was fairly average.  Also Septembers 1998 and 2004 were in the high 14s and neither of those following winters were cold either.  That said, I can think of a couple of occasions where September was slightly above average rather than insanely warm (14.2 in 1978 and 2009) where it led to a good cold winter.   Prior to a significantly colder than average winter the warmest the September before it has been, that I can think of, was 14.6 in 1985.

Whilst I do not believe that it is clear that a cool or average September has any bearing on the following winter's weather, the theory appears to work for increasing the chance of the following winter being mild after significantly warm Septembers, with just a slight chance of a near average winter to follow and virtually no chance of a colder than average winter to follow, thus certainly implying that anomalous warmth in September does at least reduce the chance of cold weather in the following winter.  

1978 must stand out as something of an outlier then? October was warm, and so were the first three weeks of November!

Edited October 1, 2021 by Ed Stone

[Earthshine]

September 2021 had a mean maximum CET of 20.3°C which is the 6th warmest on record and the warmest since 2006 (20.9°C).  The mean minimum CET was 11.6°C which is the 4th warmest on record and the warmest since 2016 (12.1°C).

Edited October 1, 2021 by Earthshine

[Don]

37 minutes ago, Ed Stone said:

1978 must stand out as something of an outlier then? October was warm, and so were the first three weeks of November!

September 1978 wasn't particularly warm though at 14.2C.  

Edited October 1, 2021 by Don

[Don]

1 hour ago, Ed Stone said:

I wonder what happens when you reduce your definition of 'notably' by 0.1C?

A 1962/63 redux?! 

[Summer8906]

Looks like September was quite a lot warmer than expectations (I didn't experience most of it, only the cool cloudy first three days and largely dull and damp final week) - there seemed to be something of a consensus for dry but frequent cool spells (my forecast was along those lines).

Guessing the link between warm Septembers and non-cold winters is just coincidence though. There are certainly examples of warm-by-day Septembers and cold winters, such as 1985 or 2009, as mentioned above - and other examples of October/November being warm and the winter being cold (1995, and 2009 again, spring to mind here).

Might be interesting to compare the synoptics of this September just gone, as several of the quoted warm Septembers were more cyclonic from what I can make out, while this September has been anticyclonic westerly I think with frequent Tm airmasses. Was out of the country so haven't checked the charts yet to see if that was indeed the case, but that's the impression I've been getting so far and it would fit the warm conditions by day and night. But I wonder if the same signal for non-cold winters would be still obtained if we put this September in a group with other anticyclonic and warm Septembers (so years like 1985, 1989, 1991, 1997, 2003, 2009 - a pretty mixed bag of winters there), and rejected the more cyclonic ones (1999, 2016, 2011, perhaps even 2006 as it was fairly changeable from about the 12th onwards)?

Edited October 1, 2021 by Summer8906

[North-Easterly Blast]

1 hour ago, Don said:

September 1978 wasn't particularly warm though at 14.2C.  

Yes, it was only slightly above average and not extraordinarily so, like September 2009 also was.  I was meaning to say that these years are two examples of really cold winters following Septembers that were only slightly above average and not significantly so.  

[The PIT]

Sunny Sheffield finished on 16.2C +2.2C above normal. Rainfall 45.5mm 69.1% of normal.

Nights were the warmest on record here while days were the third warmest. Overall second warmest on record.

[Stationary Front]

Finished 16.5 Bablake weather station Coventry 

[J10]

Excel -> September 21 CET.xlsx

PDF -> Sept 2021 Summary.pdf

Monthly

No correct entries this month, with syed2878 the closest 0.4c out.
Only 1 within 0.5c.

Seasonal

The top 3 matches the monthly postion.

So the 1-2-3  syed2878, Bobd29 and Roger J Smith

Overall

A few changes from last month, nonameweather now in 1st (from 3rd)

Stargazer in 2nd (from 1st), feb1991blizzard in 3rd (from 2nd).

It still remains close with at least the Top 5 in contention for the overall win.

[J10]

Looking back into this month's compeition, Frigid made a late change from 13.1c to 14.6c. ( in the CET competition)

If this change was not made, they would have been in 35th position not 27th, despite the 15pt penalty.

Edited October 1, 2021 by J10

[Roger J Smith]

37 minutes ago, J10 said:

Looking back into this month's compeition, Frigid made a late change from 13.1c to 14.6c.

If this change was not made, they would have been in 35th position not 27th, despite the 15pt penalty.

In the EWP portion Frigid probably didn't lose any position by changing from 45 mm to 65 mm, the late penalty combined with the fact that it became the fourth entry at 65 mm means that the highest rank the entry can attain is 7th, but for every mm below 65 mm the outcome, it would probably sink down one or two ranks, however the 45 mm unpenalized will likely finish in the 15th to 20th range. At an outcome around 59 mm it won't make any significant difference (for one thing there are fewer forecasts between 45 and 59 than between 59 and 65). However, it was overall a good late edit (others in the past have been either good or unfortunate). 

There are two months left now so I would think anyone in the top ten has some chance of a high finish, depends on how far you are willing to stray from the herd if you're in the chase pack (like me). If I get lucky in October that forecast would go up more positions than somebody who blends into the middle of the group photo. And of course if I am way off then bye bye to the top ten altogether. 

[Shillitocettwo]

That downward correction is horrific! Oh well! 

[SummerShower]

If not for the last week we would definitely have finished well into the 16s

[Don]

57 minutes ago, SummerShower said:

If not for the last week we would definitely have finished well into the 16s

Indeed and would have likely challenged the 2006 record!

[Roger J Smith]

Report on Consensus and the two Normals in CET contest

For the CET contest, we do not officially score consensus or the two recent normals. (In the EWP contest they are tracked). So here's an update which shows how our consensus (median rather than mean) and the two normals have been doing. 1991-2020 played December as 1990-2019. All I can report here is their rank in each contest, as the other scoring parameters are a bit too complex for me to recreate after the fact. The rank shown is equivalent to the highest scoring forecaster at that temperature level, some others would have ranked lower (higher rank numbers). 

The number in brackets beside the rank is the number of forecasts submitted. 

 

Robotic forecaster ____ DEC rank __ JAN rank __ FEB rank __ MAR rank __ APR rank __ MAY rank__ JUN rank__ JUL rank__AUG rank _ SEP rank ___  average rank

Consensus ____________ 27th (97) __ 16th (78) __38th (80) __ 22nd (62) ___ 30th (62) __ 31st (64) __ 14th (66) __ 25th (58) __ 26th (56) __ 25th (55) __ 25th (68)

1981-2010 normal ____ 27th (97) ___51st (78) __ 5th (80) ___ 36th (62) ___ 37th (62) __ 48th (64) __ 28th (66) __ 30th (58) __ 24th (56) __ 42nd (55) __ 32nd (68) 

1991-2020 normal* ___ 4th (97) ____56th (78) __ 3rd (80)___ 33rd (62) ___ 48th (62) __ 51st (64) __ 31st (66) __ 28th (58) __ 26th (56) __ 36th (55) __ 31st (68)

Consensus error _______ --0.4 _______ --0.3 ______ --2.1 _____ --0.3 ________ +1.9 ______ +1.0 ______ --0.2 ______ --0.8 ________ +0.7 ______ --1.4 avg abs 0.91

1981-2010 error _______ --0.4 ________ +1.3 ______ --0.7 _____ --0.6 ________ +2.1 ______ +1.6 ______ --1.0 ______ --1.0 ________ +0.6 ______ --1.9  avg abs 1.12

1991-2020 error _______ --0.1 ________ +1.6 ______ --0.2 _____ --0.5 ________ +2.6 ______ +1.8 ______ --0.8 ______ --0.9 _________+0.7 ______ --1.7 avg abs 1.09

mean bias of consensus is --0.19, mean bias of 1981-2010 is +0.00, mean bias of 1991-2020 is +0.25

ANALYSIS: Our consensus made further gains on the two normals, as the field generally opted for warmer than normal outcomes so that after ten months, the difference is finally showing some signs of group forecaster skill overall. This was not the case as recently as the Dec to July averages. 

[Roger J Smith]

(5 Oct edits) _ The EWP has been adjusted from the tracker estimate on 2nd (68 mm) to a finish of 67.8 mm. This means the table posted on the 2nd will require very little modification, but I will now add some further scoring details for positions 21 to 45 (this month's number of entries). The post will be edited in stages, whatever you see at any point later today will have been edited to that point in the table ...

SEPTEMBER scoring _____________________________________ ANNUAL scoring

Rank __ Forecaster _________ Fcst ____ Score _____________ Rank __ Forecaster __________ Points ___ Avg err (mm)

_01 ____ Godber 1 __________ 68.0 ____ 10.00 ______________ 01 ___ Feb91Blizzard ______ 73.20 ___ 27.69 (2)

_02 ____ Kirkcaldy Weather _68.6 _____ 9.77 ______________ 02 ___ snowray ____________ 70.54 ___ 26.06 (1)

_03 ____ noname_weather __67.0 _____ 9.54 ______________ 03 ___ noname_weather __ 63.67 ___ 31.49 (10)

_04 ____ jonboy _____________66.0 _____ 9.30 _______________ 04 ___ bobd29 _____________ 62.04 ___ 32.63 (13)

_05 ____ Feb91Blizzard _____ 65.0 _____ 9.06 _______________ 05 ___ Midlands Ice Age __ 61.60 ___ 29.42 (5)

_06 ____ syed2878 _____ (2) _ 65.0 _____ 8.94 _______________ 06 ___ davehsug __________ 61.13 ___ 29.45 (6)

_07 ____ davehsug _____ (3) _ 65.0 _____ 8.82 _______________ 07 ___ Don ________________ 60.84 ___ 29.29 (4)

_08 ____ EdStone ___________ 63.0 _____ 8.12 _______________ 08 ___ Godber 1 ___________ 60.74 ___ 31.65 (11)

_09 ____ daniel* ________ (2)_ 63.0 _____ 8.00 ________________09 ___ Reef _______________ 59.15 ___ 28.52 (3) *

_10 ____ Frigid ^ ________(4) _ 65.0 _____ 7.80 _______________ 10 ___ virtualsphere ______ 58.02 ___ 32.01 (12)

_11 ____ Weather26 ________ 72.0 _____ 7.68 ________________11 ___ The PIT _____________ 55.28 ___ 35.57 (20)

_12 ____ Capt Shortwave ___ 68.0 _____ 7.44 _______________ 12 ___ Mr Maunder _______ 54.92 ___ 34.13 (16)

_ 13 ____ SteveB _____________ 74.0 _____ 7.20 _______________ 13 ___ seaside60 __________54.70 ___ 33.07 (14)

_14 ____ MrMaunder ____(2)_74.0 _____ 7.08 _______________ 14 ___ February1978 ______53.62 ___ 33.99 (15)

_15 ____ Polar Gael __________61.2 _____ 6.74 _______________ 15 ___ Ed Stone ___________ 51.73 ___ 34.39 (17)

_16 ____ rwtwm _____________ 61.0 _____ 6.52________________16 ___ Relativistic __________51.05 ___ 31.19 (7) **

_ 17 ____ Dr(S)No ____________ 75.0 _____ 6.28 _______________ 17 ___ Kirkcaldy Weather _ 50.84 ___ 37.83 (26)

_18 ____ Mulzy ___________(2)_ 75.0 _____ 6.16 _______________18 ___ Dr(S)No _____________ 48.58 ___ 35.95 (21)

_19 ____ Midlands Ice Age____75.5 _____ 5.80 _______________19 ___ SteveB _______________47.81 ___ 38.21 (36)

_20 ____ bobd29 _____________ 60.0 _____ 5.57 _______________20 ___ Frigid ________________47.63 ___ 31.17 (8) *

_21 ____ The PIT _________ (2) _ 60.0 _____ 5.45 _______________21 ___ Jonboy ______________47.46 ___ 35.03 (19) *

_22 ____ seaside60 ______ (3) _ 60.0 _____ 5.57 ______________ 22 ___ JeffC ________________ 47.44 ___ 34.93 (18)

_23 ____ NeilN ________________ 76.0 _____ 4.89 _______________23 ___ Federico ____________47.41 ___ 34.67 (---) ***

_24 ____ I Remember Atl252 _ 78.0 _____ 4.66 ______________ 24 ___Roger J Smith _______ 46.85 ___ 36.69 (24)

_25 ___ Weather Enthusiast91 _80.0 ____4.42 ______________ 25 ___ Mulzy _______________46.70 ___ 36.11 (22)

_26 ___ Jeff C ______________ (2) _80.0 _____ 4.30 ______________ 26 ___ daniel* _____________ 46.01 ___ 38.47 (29)

_27 ___ Don _______________ (3) _80.0 _____ 4.18 ______________ 27 ___ Leo97t ______________ 45.76 ___ 42.12 (37) *

_28 ___Walsall Wood Snow ____55.0 _____ 3.74 ______________28 ___ syed2878 ___________ 45.31 ___ 39.84 (32)

_29 ___ sundog ____________ (2) _55.0 _____3.62 ______________ 29 ___ Polar Gael __________ 45.27 ___ 31.63 (10) 

 

_30 ___ snowray _______________ 81.0 _____ 3.28 ______________ 30 ___ J10 __________________ 44.46 ___ 36.48 (23)

_31 ___ J10 _________________(2) _ 81.0 _____ 3.16 ______________ 31 ___ Weather26 _________ 43.11 ___ 36.80 (25) *

_32 ___ February1978 __________85.0 _____ 2.84 ______________ 32 ___ Stationary Front ___ 41.89 ___ 38.13 (27)

_33 ___ snowsummer __________ 50.0 _____ 2.64 ______________ 33 ___ sundog _____________ 41.20 ___ 40.30 (35) **

_34 ___ stargazer _______________ 49.0 _____ 2.40 ______________ 34 ___ Walsall Wood Snow_41.12 ___ 38.66 (30)

_35 ___ Reef _____________________ 48.0 _____ 2.16 _____________ 35 ___ Diagonal Red Line __ 39.63 ___ 44.17 (40) *

_36 ___ Stationary Front ________ 89.0 _____ 1.88 _____________ 36 ___ Summer Blizzard ___ 38.67 ___ 39.89 (34)

_37 ___ summer8906 ___________ 46.0 _____ 1.70______________ 37 ___ Blast from the Past _ 38.62 ___ 43.11 (39) **

_38 ___ Summer Blizzard _______ 90.0 _____ 1.40 _____________ 38 ___ weather-history _____ 38.38 ___ 39.49 (33)

_39 ___ Summer18 _____________ 92.0 _____ 1.20 ______________ 39 ___ BornFromTheVoid ___37.82 ___ 39.10 (31) *

_40 ___ Roger J Smith ___________ 42.7 _____ 1.00 ______________40 ___ Emmett Garland ____ 35.96 ___ 41.01 (36)

_41 ___ weather-history ________ 93.0 _____ 0.80 ______________41 ___ Neil N ________________ 33.94 ___ 42.39 (38)

_42 ___ Diagonal Red Line ______40.0 _____ 0.60 ______________ 42 ___ shillitocettwo ________ 33.15 ___ 44.45 (41)

_43 ___ virtualsphere ___________ 97.0 _____ 0.40 ______________43 ___ I Rem Atl 252 ________ 33.00 ___ 49.99 (46)

_44 ___ Emmett Garland _______103.0 _____ 0.20 _____________ 44 ___ stargazer _____________30.70 ___ 44.91 (42)

_45 ___ shillitocettwo ____________29.0 _____ 0.00 _____________ 49 ___ summer 18 ___________ 27.35 ___ 47.93 (45)

_t02 _____ consensus ____________ 67.0 _____ 9.77 _____________ 50 ___ WeatherEnthusiast91_27.10 ___ 28.54 (---) 5 ent

_t23 _____ 1981-2010 avg ________76.0 _____ 4.89 _____________ 53 ___ rwtwm (5) ____________ 23.65 ___ 23.70 (---) 5 ent

_23.6 ____ 1991-2020 avg ________77.2 _____ 4.76 _____________ 79 ___ Captain Shortwave (3)_ 8.18 ___ 53.10 (---) 3 ent

_________________________________________________________________ 98 ___ snowsummer (1) _______2.64 ___ 17.80 (---) 1 ent

_________________________________________________________________103 ___ summer8906 (1) ______ 1.70 ___ 21.80 (---) 1 ent

(after 44th in annual ranks, only those who played Sep are listed.)

Consensus has 65.03 points in the annual contest and ranks "2.8" (meaning close to but above our 3rd place score).

(The two normals have 56.35 and 56.07, ranking 10.5 and 10.6. All three have avg error ranks slightly better than our 7th lowest). 

 

___________________________________

Forecasters must have entered 8/10 or more contests to be ranked for average error.

^ 3d late penalty (forecast revised on 3 Sep) ... drops score from 8.70 as fourth entry by 0.90. 

* entered 9/10 contests ... ** entered 8/10.  *** entered 7/10.

(note daniel* is a username, the asterisk for missed contests is after the scoring data)

... entries 6 or fewer are shown by a number in brackets beside the forecaster's name. 

 

_____ The full list of forecasts in review ____

103.0_EG ... 97.0_virt ... 93.0_wh-his ... 92.0_sum18 ... 90.0_SB ... 89.0_SF ... 85.0_Feb78 ... 81.0_snow, J10 ...

 80_we91, Jeff, Don ... 78.0_IRem ... 77.2_81-10 ... 76.0_91-20 ... 76.0_NN ... 75.5_MIA ... 75.0_DR(S), mul ...

 74.0_Ste, MrM ... 72.0_Wx26 ... 68.6_KW ... 68.0_godb ... 67.0_non con ... 66.0_jon ... 65.0_Feb91, syed, dave, frig^

 63.0_EdS, dan ... 62_Capt ... 61.2_PG ... 61.0_rwtwm ... 60.0_bobd, PIT, sea ...  55.0_WWS, sun

 50.0_snowsum ... 49.0_star ... 48.0_Reef ... 46.0_sum8906 ...  42.7_RJS ... 40.0_DRL ... 29.0_shil

_________________________________

45 forecasts

=================================================================

Note this was a tough month to score well, with a much narrower range of forecasts than we sometimes get. In fact, every forecast here

verified at some point between 26 Sep and 5 Oct in terms of the amount of rain that fell from 1 Sep to some point in time within that span.

 

 

Edited October 5, 2021 by Roger J Smith

[Roger J Smith]

The EWP has been announced now as 67.8 mm. This is close enough to 68 mm that there won't be much change in the above previously posted scoring summary. I have gone into that post and edited it where needed, adding in more scores below 20th position. 

The best combined forecast belongs to CET winner syed2878 (1st CET, 6th EWP) with noname_weather second (8th CET, 2nd EWP) and EdStone (General Cluster to some) third (4th CET, 8th EWP). 

Edited October 5, 2021 by Roger J Smith