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December CET (2012/13 Competition)


J10

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Posted
  • Location: Paris suburbs
  • Location: Paris suburbs

if you are not sub 4.5C, you are probably out of the running this month.

The first 10 days or so of December are much more likely to be milder than the last 20 days.. much more..

I agree with the suggested range of 1 to 2.5C.

I doubt that any milder interludes will sustain for long enough to prevent a sub 2.5C December, especially given the cold start to the month.

Look how things changed.

(This isn't a dig at these posters, by the way - their predictions were perfectly reasonably given the forecasts and none said anything definite)

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

Look how things changed.

(This isn't a dig at these posters, by the way - their predictions were perfectly reasonably given the forecasts and none said anything definite)

Yes the statistics show on average the first 10 days of Dec are milder than the last 20 days, and especially so the last 10 days - good examples in recent years being 1995, 2000 and 2009. However, its not always been the case, 2002 was a good example of the first 10 days being colder than the last 10 days, and also 2011. The difference this year however, has been very marked and quite unusual, the synoptics of the last 10 days are normally what we see during the first 10 days of December. What a pity we didn't see the synoptics of the first 10 days of this month occuring during the last 10 days, for cold snow lovers it would have meany a very festive feeling cold spell of weather, nothing severe but seasonal all the same with a cold frosty New Year. It has been a dire christmas period for cold snow lovers, I didn't think it would be as dire as last year but it has, and the start to the new year equally looks as dire as the start to 2012.. hopefully next christmas will be very different, probably pay back time for 2008, 2009 and 2010.

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Posted
  • Location: Rossland BC Canada
  • Location: Rossland BC Canada

As stated, it is rare for the second half of December to be considerably milder than the first half, but here's a list of all cases (in order of temperature difference) when the CET rose more than 5.0 from 1-15 to 16-31. This year looks like it might come in around a difference of 4.5, will report on that when the final data are available.

I have listed the Jan and Feb CET values of the following two months (which will be in the next year, bear in mind)

YEAR .... CET 1-15 Dec .... CET 16-31 Dec ..... diff, DEC CET ..... JAN CET ... FEB CET

_____________________________________________________________________________

1987 ............. 2.4 ...................... 8.6 .................... 6.2 ... 5.6 ............... 5.3 ........... 4.9 ........... (1988)

1803 ............. 1.2 ...................... 7.3 .................... 6.1 ... 4.4 ............... 5.8 ........... 2.9 ........... (1804)

1882 ............. 0.9 ...................... 6.8 .................... 5.9 ... 3.9 ............... 4.7 ........... 5.9 ........... (1883)

1837 ............. 2.4 ...................... 8.1 .................... 5.7 ... 5.3 ...............-1.5 ........... 0.4 ............ (1838)

1875 ............. 1.5 ...................... 6.7 .................... 5.2 ... 4.2 ............... 3.6 ........... 4.8 ............ (1876)

1991 ............. 2.1 ...................... 7.1 .................... 5.0 ... 4.7 ............... 3.7 ........... 5.4 ........... (1992)

I can guess which one of these cases appeals to most of you ... but the majority of these winters remain rather mild once the December reversal sets in.

This is now the third month in 2012 with a sharp warming trend after mid-month, February and May were the others. It also warmed considerably from late July to early August, so this has been happening about every third month on a slightly longer period. On the other hand we also had the sharp downturn in September. From the filter that I ran, would estimate 2012 to be around 10th place out of 240 cases of mid-December warmings. One of the cases not in the list was Dec 1902 which was followed by a very mild Feb with a notable windstorm near the end (in 1903).

The case closest to my own LRF scenario would be 1803-04. This is not the only time that one of these reversals has led to a mild January and cold February. 1781-82 on a scale similar to 2012 (3.2 to 7.3) went to a mild Jan and a cold Feb (D-F 5.4, 5.2, 1.9 CET). That winter saw some weak attempts to chill in January, some near record warmth 23-24 Jan, then a cold spell from about 29 Jan to 21 Feb, after which it warmed up slowly. During that cold spell the CET was close to 1.0 on average and there were six ice days in 24 days. So it wasn't even as intense as last winter's spell but certainly a lot colder than this past two weeks.

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Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

Unless there's a heatwave today we're going to finish on 4.2C in Sunny Sheffield. Close to the average of 4.5C.

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Posted
  • Location: Teston, Kent (3mls SW of Maidstone)
  • Location: Teston, Kent (3mls SW of Maidstone)

With one day to go it is worth looking at Climate UK's monthly stats based on the old Manley CET stations:-

CET: (Dec 1-30): 4.5°C (-0.2 degC)

E&W Rain: (Dec 1-30): 162.8mm (173 per cent)

E&W Sun: (Dec 1-30): 60.7hr (119 per cent)

© Philip Eden (If you wish to use or copy these figures, please acknowledge the source)

With a mild final day it looks like it will finish at around 4.7C and as I have mentioned before the adjusted Hadley figure doesn't usually stray too far from this.

Edited by Kentish Man
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Posted
  • Location: Skirlaugh, East Yorkshire
  • Location: Skirlaugh, East Yorkshire

4.8C to the 30th. Yesterday came in at 7.3C.

Today's minima is 4.7C, so with the double-digit maximum it looks like 4.9C will be the finishing point before adjustments.

The 1981-2010 average is 4.6C, so after adjustments its looking like being a very close to average month.

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Looking back to my own December forecast (which predicted a CET around the 2.5C mark, although I forgot about the CET prediction thread), the main points were as follows:

  • Forecast was generally accurate until around the 10th
  • Overestimated the strength of the link-up between the Icelandic and Siberian highs around the 10th-15th, which would have meant an easterly blast, and a slower subsequent return to milder weather from the Atlantic. In reality the Icelandic high sunk over the UK and the Atlantic came in relatively unopposed.
  • From 15th-25th, expected a milder interlude with low pressure to the west, but then a surge of Arctic northerlies towards Christmas. In reality the trough stuck around stubbornly to the west and so the Arctic blast never reached us.
  • Mild end to the month as predicted, though I did not envisage a sharp decline in the amount of northern blocking.

One major point that comes out of this is that if we get extensive northern blocking but a persistent trough to the west of Britain, the outcome often tends to be mild. There was a good example of this during January 1969, although the blocking changed position into February and gave us a cold and, for many, snowy February.

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Posted
  • Location: Edinburgh (previously Chelmsford and Birmingham)
  • Weather Preferences: Unseasonably cold weather (at all times of year), wind, and thunderstorms.
  • Location: Edinburgh (previously Chelmsford and Birmingham)

http://www.metoffice.gov.uk/hadobs/hadcet/cetml1659on.dat

CET confirmed at 4.8C for December.

The annual CET is 9.70C.

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No one got 4.8c spot on

However 3 players were 0.1c out.

The PIT, Alex and Carl46Wrexham

Well done to each of these.

Full Results to follow later

Edited by Jackone
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Posted
  • Location: Essex Riviera aka Burnham
  • Weather Preferences: 30 Degrees of pure British Celsius
  • Location: Essex Riviera aka Burnham

I'll settle for 0.5c out my brief forecast for the month wasn't far out and on top of my record last winter pretty happy overall but well done to the above lads only .1c out!

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Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

Hey 0.1C not bad. Can I get big headed now???

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As promised full scores now out.

Being the first month of the year, no point in splitting the overall and monthly comps,

The leader is The PIT, Alex is 2nd with Roger J Smith 3rd.

Excel Format Dec 2012 CET.xls

PDF Format Dec 2012 CET.pdf

For this year, I have started a new thread which will have the scores only, so it should be easier to keep track of the competition.

Edited by Jackone
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Posted
  • Location: Wrexham, North East Wales 80m asl
  • Weather Preferences: Snow and thunderstorms
  • Location: Wrexham, North East Wales 80m asl

0.1c out.

Hoping my January prediction is miles out.

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