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

[Roger J Smith]

On behalf of J10 and myself, welcome to another new competition year with the winter season of 2022-23 fast approaching. Thanks also to Summer Sun and the PIT who contribute daily updates most of the time. ... and of course thanks to you, the loyal contest entrants and supporters. ... There has been a temperature (CET) forecast contest running on Net-weather since winter of 2005-2006, and the scoring system devised by J10 was introduced just a few years into that period. The EWP contest is newer, and has been going for five years now and began in Dec 2017 for the 2017-18 contest year.

The contests include the CET forecast and the (optional) EWP forecast, with some guidance provided in two sections below ... 

 

CET averages and extremes for December

--- all CET values 1981 to 2021 are in the table --- they are in highlighted type to make them easier to find

--- --- --- bold type for warmest, italic for middle and underlined for the coldest thirds of these 40 most recent years. 

--- --- --- due to ties for 4.8 C there are 15 in total among the middle third and 12 for the coldest, 14 for the mildest. 

... all values in the CET contest have been converted to v2.0, including the averages for various intervals. 

 

13.0 ... warmest daily mean, 19th 2015

12.7 ... previous warmest daily mean, 12th 1994

 9.6 ... warmest December 2015

 8.1 ... second warmest December 1934

 7.9 ... third warmest December 1974

 7.7 ... fourth warmest December 1852

 7.6 ... fifth warmest December 1733

 7.5 ... sixth warmest December 1710

 7.4 ... tied seventh warmest Decembers 1828, 1843

 7.3 ... 1988 (tied ninth warmest with 1857, 1898)

 7.2 ... tied 12th warmest 1842, 1868, 1900

__ values and ties outside modern interval no longer noted, 7.0 and 7.1 have no instances in v2.0 __

 6.8 ... 2018

 6.4 ... 2006

 6.3 ... 2013, 2021

 6.2 ... 1994

 6.1 ... 1985, 1986

 5.9 ... 2011, 2016 (in CET legacy there never was a 5.9 recorded, now with 1977 there are three)

 5.7 ... 1997, 2019

 5.6 ... 2002

 5.4 ... 1983, 1987, 1998

 5.3 ... 1993, 2000, 2004

 5.1 ... average for 2001-21 (5.06) ... also 1984, 2014

 5.0 ...

 4.9 ... average for 1971-2000 (4.88), 1992-2021 (4.90), also 2007, 2020

 4.8 ... average for 1991-2020 (4.84), also 1999

 4.7 ... 1989, 2012, 2017

 4.6 ... average for 1901-2000 (4.58) and 2003

 4.5 ... average for 1961-90 (4.54), 1981-2010 (4.47) ... and 1991

 4.3 ... 2005

 4.1 ... 1982, 1990

 4.1 ... average for 1659-2021 (all 363 years, 4.10 C)

 4.0 ... average for 1801-1900

 3.9 ... average for 1701-1800

 3.5 ... 2008

 3.4 ... 1992, 2001

 3.4 ... average for 1659-1700

 3.0 ... 2009

 2.7 ... 1996

 2.1 ... 1995

 0.1 ... 1981 (8th coldest December)

-0.2 ... 1874 (7th coldest December)

-0.3 ... 1788, 1796, 1878 (tied 4th coldest Decembers)

-0.5 ... third coldest December 1676

-0.7 ... second coldest December 2010

-0.8 ... coldest December 1890

-10.8 ... lowest daily mean 25th 1796

_______________________________________________

Enter your forecast before midnight on Wednesday 30 November, or with the increasing late penalties for entries 1-3 Dec.

(earlier material based on CET legacy temps ...) As you might expect, the Maunder period produced cold Decembers, the mean was as low as 3.2 (1665 to 1694). It then rose as high as 4.29 by 1709-38. There was a colder period than any in the Maunder; the lowest 30-year average was 3.09 from 1783 to 1812; rounded off 1784 to 1813 was equal.

The running mean climbed as high as 4.61 for 1823-52 before falling back to 3.48 for 1867-96. Decembers in the first third of the 20th century were generally a bit milder than the mid-century period, means as high as 4.73 were reached in 1893-1922 and 1907-36. The lowest since those peaks was 4.33 for 1923-52. The last time that the running mean was 4.5 was 1957 to 1986. The table above tracks the changes since then, but worth noting that the cold December of 2010 dropped the running mean from 4.84 to 4.63 but it then went back up to 4.82 for 1982 to 2011 as that period dropped the cold December of 1981 (mean 0.3). 1981-2010 was the only 30-year mean at 4.6 after 1960-89. 

(note, v2.0 means have dropped 0.1 to 0.2 from CET legacy values, in recent decades. Dec 2000 dropped by a larger amount due to large adjustments during a cold spell near the end of the month -- this may explain why some of the values in the table appear to be "off" slightly from what you might recall from the CET legacy numbers, for example, 2015 used to average 9.7, and 1934 used to be tied with 1974 at 8.1 ... Dec 1981 has fallen from a mean of 0.3 to 0.1 in the new set).

 

_______ _ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _ ________

 

Optional EWP (Precip) Contest -- details

The EWP contest now enters its sixth year. It remains entirely optional, in the first five years more than two-thirds of the regular temperature forecasters entered this second contest. (there were no precip-only forecasters). 

The contest asks you to predict an amount in mm (not a percentage) for this statistic. Any forecasts entered as percentages are converted using 1991-2020 averages.

A tracker gives approximate values one day late, then you will have to be patient as Hadley EWP post their final numbers around the 5th of each month. Then the practice is to tweak the numbers through the following several months, but we ignore those later adjustments for contest scoring (it would be a lot of work and very little would change). 

For December, here are the averages and extremes for your guidance. Data (from the Hadley EWP tables) go back to 1766.

The last thirteen December EWP amounts appear in the table below. Both 2010 and 2012 qualified as min and max values for the period 1981-2021.

... the average of these past thirteen Decembers is 111.2 mm. It can be seen from the 30-year normals and that last figure, that a general increasing trend is underway for Dec EWP.

 

Max 1766-2021 ____193.9 mm (1876)

Max since 1981 ___ 175.2 mm (2012)

____2020 _______ 159.2 mm

____2015 _______ 145.9 mm

____2013 _______ 134.2 mm

____2019 _______ 121.4 mm

____2018 _______ 116.0 mm

____2011 _______ 113.6 mm

____2017 _______ 113.4 mm

____2009 _______ 109.1 mm

_ mean 2009-20 __ 111.2 mm

_ mean 1992-2021 _ 105.5 mm

____2021 _______ 105.0 mm

Mean 1991-2020 __103.6 mm

Mean 1981-2010 __ 97.4 mm

Mean 1766-2021 __ 89.0 mm (all 256 years of data)

____2014 ________ 77.3 mm

____2016 ________ 41.3 mm

Min since 1981 ___34.1 mm (2010)

Min 1766-2021 ____ 8.9 mm (1788)

____________________________________________________

Note, the highest 30-year mean of December EWP was 106.6 mm (1896-1925). The lowest was 67.5 for 1864-1893. 

Since the peak value the lowest was 84.8 mm (1925-54). It has been gradually increasing since then and is now within 1.1 mm of the earlier peak. 

 

Your forecast should be in mm with one decimal allowed. If you enter a percentage, that will be applied to 1991-2020 mean of 103.6 mm to derive your contest entry. Any number that appears without a % sign or mm, will be taken as that number of mm, with .0 added. It will be up to you to clarify your contest entry.

Deadlines are the same as the temperature contest. EWP late penalties are 0.3 points per day (scoring runs from zero to 10.0 points each month).

______________________________________________________

Note that in both contests, there is a scoring deduction applied to forecasts of similar rank submitted later than others. 

We encourage you to enter each month as the contest year results depend on entering at least ten of the twelve contests. There are seasonal sub-contests which is why we start the contest year in December rather than January. Once you have missed three contests, you are no longer scored in the main CET scoring table, and while the EWP does not divide into two tables, effectively by scoring no points for three contests you are probably not going to finish among the top 20-25 total points. 

Good luck !!

 

[Frigid]

Ah yes, it's that time of the year again. Predicting the first month of the Winter.

1.8C and 45mm please. Cold and dry to end a record breaking warm year

Will probably change this later on..

 

Edited November 20, 2022 by Frigid

[Don]

55 minutes ago, Frigid said:

Ah yes, it's that time of the year again. Predicting the first month of the Winter.

1.8C and 45mm please. Cold and dry to end a record breaking warm year

Will probably change this later on..

 

If you turn that around to 8.1C, you will probably be spot on!! 

[Frigid]

6 hours ago, Don said:

If you turn that around to 8.1C, you will probably be spot on!! 

I wouldn't be surprised if I have to do that

[Weather26]

5.5C and 96mm please.

[Earthshine]

4.4°C please

[Methuselah]

5.0C (so no need for any number reversal!) and 66mm please, Roger.

[chilly milly]

4.7c please and 173.1mm

[Bobd29]

5.2C and 93.5 mm please

[Polar Gael]

1.2°C and 60.2mm for me please. 

Edited November 20, 2022 by Polar Gael
To lower rainfall prediction.

[I remember Atlantic 252]

7.4C and 135mm, know the drill by now, low after low to dominate

[Dancerwithwings]

6.3c & 68mm

Cheers and a Merry Christmas  

[BlueHedgehog074]

Going for 5.9*C and 70mm of rain and snow. Thanks. 

[SteveB]

7.2c & 110mm please.

[Don]

On 20/11/2022 at 23:28, Dancerwithwings said:

6.3c & 68mm

Cheers and a Merry 'Mild' Christmas  

 

[Godber 1]

2.2c and 44mm please.

[virtualsphere]

3.8C and 66mm please

[BLAST FROM THE PAST]

Coldest Christmas to New Year since 1995/6

 

BFTP

Edited November 22, 2022 by BLAST FROM THE PAST

[Shillitocettwo]

  I too predict December 2022 will be a bit of a shock to the system with a below average month temperature wise with quite a nasty run of cold in the week before Christmas Day, damp Northerly cold that can't quite hit freezing by night but barely gets much higher in the day with 2-3.C and regular wet snow that doesn't quite stick.

  Christmas to New Year will be foggy and weirdly a little milder but 3.9.C and a surprisingly dry 26mm.

 

  PS my current thinking on the rest of the contest year...

 

  January 2023- A bit like Saudi Arabia beating Argentina this will be really unexpected, against the dominant global warmingy form and noteworthy.... biting Easterlies dominating a cold dry month with some pretty brutal nighttime lows on the minus double digits ,coldest since December 2010 at -0.3.C (11mm)

   February 2023...A real oddball month starting out with a Storm Emma into Beast from the East pattern and several days of disruptive snowfall but seguing into an extremely mild even warm second half with temperatures hitting 23.C in Kew Gardens by months end. CET 7.9.C and 73mm

  March 2023.... Back to something more normal this month after such a mild February and actually colder overall CET 7.3.C and 66mm

 

  April 2023..... An absolutely staggering build up of heat seeing records broken over 30.C and total destruction of the current CET record at 13.0.C and a bone dry 6mm

 

 May 2023..... Will be remembered as Summer for this year, tinder dry, hot, CET 16.6.C and 5mm

 

 June 2023.... An absolute collapse of the early Summer into a jammed jet stream pattern feeding Low pressure off the North Sea most of the month. Much colder than May at a dismal 13.3.C and 156mm leading to all Maine of flooding issues

 

July 2023.... Like June but with more bite, heat on the Continent will encroach into an unsettled pattern and feed thunderstorms into the mix, wettest July on record at 226mm and 16.0.C triggering a weather emergency to be declared as Nottingham and Yorkshire effectively 'underwater'

 

August 2023....Drying out by painful increments, salvaging something of a Summer as it goes on and warming up again to give CET 17.6.C and 73mm

 

September 2023..... Quite calm and Indian Summer like at 16.0.C and 28mm

 

October 2023..... Not really cooling much, very mild and a few daily records removed at 13.0.C and 46mm

 

November 2023.....Very much like this one, very mild at start and more normal by close 8.8.C and 88mm

[Kirkcaldy Weather]

 

 

[Summer18]

I’m thinking quite cold, 4.6C & 92mm

[Typhoon John]

Let's go for 5.1c

[Dancerwithwings]

On 20/11/2022 at 23:28, Dancerwithwings said:

6.3c & 68mm

Cheers and a Merry Christmas  

Can I drop my guess to 5.5c but the 68mm with stay as it is

[The PIT]

I'm going to be brave and go for 4C. High pressure dominating so 40mm of rain.

[stewfox]

3.1c 76mm cold largely dry