This thread is for all comments, discussion and analysis of temperatures in the UK during December, with particular emphasis on the Central England Temperature (CET), for the simple reason that it is the longest running temperature series in the world with over 360 years of data. But you can comment on any interesting temperature statistics or data from across the UK, including your own back yard. 

For those taking part in the competition all CET predictions for December should be sent directly to me via the forum private message system. Do not post them directly into the thread. 

Historic CET summary for December

1971-2000 5.1C (30 years) 

1981-2010 4.6C (30 years) 

2000-2019 5.1C (last 20 years) 

The warmest December in recent times was 9.7C in 2015, a record. In 2018 there was another warm December with 6.9C. We have not had a significantly colder than average December since the famous 2010 which was the second coldest on record at -0.7C. 

Here is a chart of the December CET for all years since 1961

Direct link to larger version of the chart

Current model output   

GFS 850s generally below average although not hugely so at this point. But definitely looks a very different position to November. 

GFS 850s https://www.wetterzentrale.de/de/show_diagrams.php?model=gfs&var=2&geoid=49069&lid=ENS&bw=

GFS T2m https://www.wetterzentrale.de/de/show_diagrams.php?geoid=49069&model=gfs&var=5&run=12&lid=ENS&bw=

ECM looks to be similar to GFS - i.e. on the cool side.

ECM ENS http://cdn.knmi.nl/knmi/map/page/weer/waarschuwingen_verwachtingen/ensemble/detail/ensemble-verwachtingen-detail10.png

Met Office contingency planners outlook

Not yet available. Will likely be issued on Monday

Given the outlook from the models, it would be tempting to go for quite a cold month, but as we've seen time and time again, especially this year, the initial outlook at the start of the month has no bearing on what the rest of it will do. The first half of December could indeed be cold, but it only takes a milder second half or even final 10 days to completely stuff up the CET. That's not to say it won't be a cold month, but from past experience, I've gone for quite a conservative, near-average guess for this month.

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GW you have a full inbox.

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Inbox still full, 

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Inbox still full, 

Still full. 

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Sorry now sorted

Anyone tempted to go for a 'sh*t or bust' guess?

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Exactly what I was thinking
Is 2nd place really so different to 7th
But so unsure I dont even know which way to go on it ...

Anyone tempted to go for a 'sh*t or bust' guess?

Tempted to play it safe. 

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Metcheck Is running the figure of 3.82c   Anomaly    1.18c.   

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I went for 2.9c so expect record breaking warmth.

 

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The first half of the day is 3.5c. Difference -3.2c

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Tempted to play it safe. 

 

If I were in first place, I'd do exactly the same. If you were winning going into the final month and there wasn't the PM'ing of entries, you could wait for your rivals to post their estimates, then calculate what you had to do to win either way. But only a scoundrel would do that 

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I went for 2.9c so expect record breaking warmth.

 

 

Yeah, I went for a very cold month too. Was temped to go mild, so I was onto a win-win.

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I thought I was veering cold with my guess but going to be unexceptional if the barometer of this chat is anything to go by

I so wanted to estimate a 'properly cold' December but in the end there just wasn't a clear enough signal for that to happen, so I've only gone slightly below average .

A large part of that is this big ball of dusty straw... the models have no idea what the tropical cycle will do next!

What it does is crucial - will it fight the La Nina base state (move away from the central circle while progressing through the triangles numbered 5-7, ideally 8 too) or will it shrink away from the battle?

The former scenario would promote continued sluggish weather patterns with a chance that blocking highs align in the right way to bring us a more noteworthy cold spell than the chilly dross that most of us will face in the coming days.

The latter opens the door to a more zonal pattern developing: frequent Atlantic westerlies with a mild tendency overall. High pressure can become influential from western Europe during a moderate La Nina setup, keeping southern parts on the dry side, but that's about the most positive take I can offer in that scenario!

I have a feeling the tropical cycle will rise to the fight again but not with great strength, which could mean that the current blocking pattern generally persists but struggles to ascend fully to the high latitudes.

 

On top of this, further complicating matters is the problem of cold air availability over northwest Asia and northeast Europe - it's unusually poor at the mo. Tough times!

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Metcheck               4.77c      Anomaly      -0.23c

Netweather            4.39c      Anomaly      -0.72c

Peasedown St John 4.5c        Anomaly      -2.2c.     

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Metcheck               4.77c      Anomaly      -0.23c

Netweather            4.39c      Anomaly      -0.72c

Peasedown St John 4.5c        Anomaly      -2.2c.     

https://www.metoffice.gov.uk/hadobs/hadcet/cet_mean_est_2020 

Met Office Hadley      4.7c        Anomaly     -0.5c   Provisional to 1st.

November 8.5c  Anomaly 2.0c

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Met Office Hadley     5.1c     Anomaly    -0.0c Provisional to 2nd

Metheck                    4.74c    Anomaly    -0.25c

Netweather                4.74c    Anomaly    -0.37c

Peasedown St John    4.81c    Anomaly     -1.89c.  

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