December 2022 C.E.T. and EWP contests _ start of a new contest year

[Earthshine]

8 hours ago, Summer Sun said:

4.0c to the 4th

0.5c below the 61 to 90 average
1.8c below the 81 to 10 average

Watch this plummet by the weekend.  A few model runs have this dropping below 1°C by mid-month .

[damianslaw]

6 hours ago, summer blizzard said:

Will be interesting to observe a CET collapse not seen in a while. I'm a tad north of the CET zone but GFS estimates the 8th-12th to average -1.5C here.

Would be good to know last time CET mean for 7 days running was below 0 degrees, benchmark of a cold spell I say. Possibly at some stage in winter 20-21, late Dec- early Jan perhaps or first week of Feb.

Dec 2010 was exceptional with two very lengthy sub feeezing CET mean periods, about 2 weeks late Nov to early-mid Dec, and again from the 16-27th Dec I think.

 

2 hours ago, Earthshine said:

Watch this plummet by the weekend.  A few model runs have this dropping below 1°C by mid-month .

We could well see our coldest December since 2010, but there is a long way to go...

[Frigid]

29 minutes ago, damianslaw said:

Dec 2010 was exceptional with two very lengthy sub feeezing CET mean periods, about 2 weeks late Nov to early-mid Dec, and again from the 16-27th Dec I think.

If the cold started on the 1st instead of late Nov, it would've easily been the coldest on record. I don't think we'll be close to the 2010 figure this month, as Feb 2021 reminded me anything can happen to scupper the cold. Either way if the 18z is correct we could be near sub zero by mid December. Fascinating stuff given the warmth we've faced this year. 

[Greyhound81]

1 hour ago, damianslaw said:

Would be good to know last time CET mean for 7 days running was below 0 degrees, benchmark of a cold spell I say. Possibly at some stage in winter 20-21, late Dec- early Jan perhaps or first week of Feb.

Dec 2010 was exceptional with two very lengthy sub feeezing CET mean periods, about 2 weeks late Nov to early-mid Dec, and again from the 16-27th Dec I think.

 

We could well see our coldest December since 2010, but there is a long way to go...

Do you think that there is a good chance that 2022 will not become the warmest year in the CET record?  It was mentioned on a another thread that we would need a CET of over 1.4 to overtake 2014.

[Roger J Smith]

Within the usual range of model uncertainty, and the unknowns beyond about the 15th, this month could probably finish anywhere from -1 to +5 C. 

This coming cold spell could slightly underperform, seas are warm and 850s don't drop very low on some guidance. Then there's that storm way out in the Atlantic of subtropical origins moving towards Azores. ECM keeps changing outlook about the track of that, it remains within realm of model variability for that to cut further north and replace the cold spell with much milder temperatures, for how long ??? and then this could go Feb 21 on us too. 

[Summer Sun]

4.3c to the 5th

0.2c below the 61 to 90 average
1.6c below the 81 to 10 average

[kold weather]

13 hours ago, Greyhound81 said:

Do you think that there is a good chance that 2022 will not become the warmest year in the CET record?  It was mentioned on a another thread that we would need a CET of over 1.4 to overtake 2014.

A CET of 1.4c would put us into the top 30 coldest Decembers ever. For context, only 3 Decembers since 1900 are in that list, 1950, 1981 and obviously 2010.

A below average month is looking more likely than not already, though with the caveat that in a amplified pattern it could well swing very mild as well if things fall a certain way once this cold blast goes through.

With all that being said, we probably do have a legitimate risk of a pretty cold December CET, if things line up.

[The PIT]

Sunny Sheffield at 3.7C -3C below normal. Rainfall 12.4mm 14.2% of the monthly average.

[Summer Sun]

4.2c to the 6th

0.4c below the 61 to 90 average
1.5c below the 81 to 10 average

[ItNeverSnowsInWindsor]

Watch the drops accelerate in coming days with sub zero minimas  

Looking at over 3c below the 1981-2010 averages by early next week.

Edited December 7, 2022 by prolongedSnowLover

[Shillitocettwo]

Despite the coldish weather here the Arctic anomaly is horrific at present at nearly 7 degrees ABOVE average.

    (Climate Reanalyzer website courtesy of the University of Maine)

[The PIT]

Sunny Sheffield unchanged at 3.7C -2.9C below average. Rainfall 12.4mm 14.2% of the monthly average.

[Roger J Smith]

7 hours ago, prolongedSnowLover said:

Watch the drops accelerate in coming days with sub zero minimas  

Looking at over 3c below the 1981-2010 averages by early next week.

No disagreement but did you take in the exchange back on the OCT thread that established that these reports are comparing current running mean to (a) 1961-90 Met Office end of month averages and (b) in-house running means 1981-2010. Therefore at this time of year with gradually falling running means, the actual comparable 1961-90 value is higher and we are already further below that. If you knew that, perhaps other thread readers didn't. This differential will fade out after 21st which is about when the running mean begins to oscillate instead of steadily keep falling. I think in some 30-year averages a date around 19-21 Dec has been either annual low or similar to a Jan or Feb daily minimum point (on a daily basis). 

[Roger J Smith]

7 hours ago, Summer Sun said:

4.2c to the 6th

0.4c below the 61 to 90 average
1.5c below the 81 to 10 average

Just for the benefit of casual thread readers who might not be aware, as discussed in my previous post, the "61 to 90 average" refers to end of month 4.6 C 1961-90 December mean, and the 1.5 below refers to our in-house running mean for 1-6 Dec which is 5.7 C. The two things are therefore not directly comparable, the 1-6 Dec 1961-90 running mean was very likely in the range of 5.3 to 5.6, they usually ran .1 to .3 below when the Met Office was using them in their tables. They stopped using them when we switched from CET legacy to CET v2.0 in May 2022. (this was confirmed by looking at values from March and April 2022 in our threads, the 61 to 90 values were not always the same when back-calculated). Also if you really want a deep dive, the Met Office differential is internally calculated from two decimal places you can't see on their site, and thus the back-calculated 4.6 may some days be 4.5 or 4.7. It's going to be 4.6 most days because it would take an unusual convergence of those two-decimal values to move outside the rounding boundaries. 

The main point is, the 61 to 90 averages were not as low as this makes it appear in these falling-temperature months. When we get into rising temperature months it will be raising eyebrows because we'll be getting reports that make it appear that the 61-90 averages are higher than 81-10 values. I can almost guarantee that somebody will post on this and say it is either a mistake or a sign of a globalist conspiracy to hide what is actually a temperature decrease. Maybe we should just give up and report these relative to 81-10 monthly averages instead, then it's apples and apples instead of apples and oranges. Then somebody at the Met Office will notice and change their reporting protocol back to what existed before CET v2.0 arrived. 

[Optimus Prime]

3 hours ago, Shillitocettwo said:

Despite the coldish weather here the Arctic anomaly is horrific at present at nearly 7 degrees ABOVE average.

    (Climate Reanalyzer website courtesy of the University of Maine)

It's about 3.5 degrees above the 1971-2000 avg although that anomaly is likely to drop closer to average over the next week.

Compared to December 1962 as a whole:

[Roger J Smith]

EWP currently about 6 mm, GFS shows 30-40 mm grid average for 8th-23rd, so the month may not be overly wet at that point, however if a southerly flow develops as shown and it turns stormy, the end result could still be fairly high. Many forecasts are still in play, we haven't passed the lowest of them (22 mm) and may not do so for at least a week. 

CET will probably drop to around 0.5 to 1.0 C or even lower by about Monday, then stay near there (1.0 to 1.5 possibly) for a few days in a chilly southeasterly, before steadily recovering if current GFS run can be believed (I want to believe, YMMV). I would estimate the mean from 16th to 23rd to be close to 7 C which brings the running mean back to around 3.5 C with eight days left which could see it heading anywhere from 2 to 5 as a final result, so not very many forecasts are really scuppered yet. Should be noted however that ECM is considerably colder and delays the warming trend. The ECM is your friend if you went 2.0 or below, I would say. 

I'll throw in a wild card saying that there could be some very stormy weather from 21st on, a lot of energy to be released if this block repositions. This would be stormy weather within the regime established by then, if it does turn mild it could be powerful Atlantic storms and if it stays cold it could be snow and sleet storms targeting the south. All depends on how things break 15th-17th. 

Edited December 8, 2022 by Roger J Smith

[Roger J Smith]

Let's see if we can break any of these ... it may not stay cold this long but just in case. 

 

Record low maxima for CET (1878 to 2021) ______ Record low minima (1878 to 2021)

Date ___ CET legacy _ CET v2.0 ____________________ CET legacy _ CET v2.0

08 Dec __-0.7 1967 __-0.7 1967 ____________________ -7.5 _ 1879 __ -6.9 _ 2010 __ 1879 was incr to -5.1 (v2.0)

09 Dec __ 0.8 1981 __ 0.6 1981 _____________________-5.6 _ 1967 __ -5.6 _ 1967

10 Dec __-1.2 1981 __-1.5 1981 _____________________-6.8 _ 1981 __ -7.0 _ 1981

11 Dec __-0.8 1882 __-1.5 1882 _____________________-6.7 _ 1879 __ -6.8 _ 1882 __ 1879 was incr to -6.1 (v2.0)

12 Dec __-3.8 1981 __-4.0 1981 ____________________-13.2_1981 __ -13.5_ 1981

13 Dec __-1.9 1920 __-1.3 1878,1920 _______________-15.9_1981 __-16.1_ 1981

14 Dec __-2.2 1878 __-2.4 1878 ______________________-8.4 _1890 __ -8.6 _ 1878 __ 1890 was incr to -7.7 (v2.0)

15 Dec __-0.3 1890 __ 0.4 1890,1950 _________________-8.4 _1878 __ -8.3 _ 1878

16 Dec __-0.3 1890 __-0.2 1981 _______________________-5.5 _1899 __ -5.6 _ 1899 __ around -10 in 1859 (see below)

17 Dec __-0.5 1981 __-0.7 1981 _______________________-7.3 _ 1878 __ -7.8 _ 1878 __ around -12 in 1859

18 Dec __-1.3 1927 __-1.2 1927 _______________________-7.2 _ 1981 __ -7.5 _ 1981 __ around -12 in 1859

19 Dec __-3.2 2010 __-3.2 2010 ______________________-10.3 _ 2010 __-10.4_ 2010

20 Dec __-2.2 1938 __-2.1 1938 ______________________ -12.4 _ 2010 __-12.5_ 2010

_________________________________________________

A majority of the daily mean records are from pre-1878 which may indicate that some of the above had lower values then: 

Date ____ CET legacy ____ CET v2.0

08 Dec ... -5.4 (1807) ... ... -5.4 (1807)
09 Dec ... -4.0 (1803) ... ... -4.0 (1803)
10 Dec ... -4.5 (1784) ... ... -4.5 (1784)

11 Dec ... -6.7 (1784) ... ... -6.7 (1784)
12 Dec ... -8.5 (1981) ... ... -8.7 (1981)
13 Dec ... -6.5 (1981) ... ... -6.7 (1981)
14 Dec ... -5.3 (1878) ... ... -5.5 (1878)

15 Dec ... -5.4 (1788) ... ... -5.4 (1788)

16 Dec ... -6.6 (1859) ... ... -6.4 (1859)
17 Dec ... -7.7 (1859) ... ... -7.5 (1859)
18 Dec ... -7.1 (1859) ... ... -7.0 (1859)
19 Dec ... -6.8 (2010) ... ... -6.8 (2010)
20 Dec ... -7.0 (2010) ... ... -7.0 (2010)

[Summer Sun]

3.8c to the 7th

0.8c below the 61 to 90 average
1.8c below the 81 to 10 average

[The PIT]

Sunny Sheffield down to 3.5C -3C below normal. Rainfall unchanged.

[Frigid]

CET zone looking very cold once again. Curious to know where the figure will be in 10 days time

[JeffC]

7 hours ago, Summer Sun said:

3.8c to the 7th

0.8c below the 61 to 90 average
1.8c below the 81 to 10 average

Thinking I overshot with 4.1C

[Cymro]

So far so good with my 1.4 I think we may just do it

[Relativistic]

CET min of -5.1°C, imagine that's a top 5 for the date and possibly a top 3 behind 1879 and 2010.

The min and max today would have the mean below zero. Should be the start of a decent run.

[ItNeverSnowsInWindsor]

Love a sub-zero mean day.

Would love an ice day even more with some Snow thrown in!

[Summer Sun]

3.8c to the 8th

1.4c below the 61 to 90 average
2.2c below the 81 to 10 average

Edited December 9, 2022 by Summer Sun