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Roger J Smith

December 2013 CET forecasts -- 2013/14 Competition

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Below is the December CET, with the 10 year average in red and linear trend in black.

 

Posted Image

 

The correlation between the November and December CET is 0.25, the third lowest of all consecutive monthly pairs. With both detrended, the correlation falls to 0.22, which is still statistically significant and suggests there is a weak positive relationship between Novembers CET and the following December.

 

November looks like finishing between 6.0 and 6.6C, so the mean of all Decembers following Novembers in that range, is 4.2C.

 

A CET of 1.6C or lower is required to drop the 10 year mean below 4.0C for the first time since 1970.

Our current run with the 10 year mean above 4C (42 years) is the second longest on record, the longest being 67 years, from 1900 to 1966.

Our current run without a December CET higher than 6.5C (24 years) is the 3rd longest on the CET record, after 1869 to 1897 (29 years) and 1734 to 1794 (61 years).

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6.6C

 

Have a feeling that the MLB we currently see will eventually sink south east into continental Europe. this will open the door for a westerly or south westerly mobile regime. High minima would be the driving factor if this above average prediction were to verify.

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All Decembers since 2004 apart from 2011 have seen the atlantic blocked for quite lengthy periods when it is most likely to be at its most active during the year.

 

Dec 2012 - first 12/13 days were cold with high pressure to the NE preventing the atlantic from making any real inroads. However, thereafter we did see the classic westerly scenario dominate through to the months end.

 

Dec 2011 - whilst it was a mobile month, the first three weeks were quite cold with more of a meridional flow with alot of polar maritime air, so not the mild/sw pattern, until the 19th.

 

Dec 2010 - exceptionally blocked month, the atlantic failed to make any real progress until the 28th and it took until the second week of the new year before the westerly mobile pattern embedded itself.

 

Dec 2009 - started with a mild westerly scenario until the 10th/11th, thereafter atlantic was blocked with strong heights to the NW ruling the roost.

 

Dec 2008 - an interesting month, with a cold meridional flow until around mid month, then a mild SW pattern until christmas and a cold blocked end.

 

Dec 2007 - very blocked until just before christmas with high pressure overhead, then the atlantic came crashing in over christmas.

 

Dec 2006 - a carbon copy of 2007, it started with the atlantic ruling the roost, but high pressure anchored itself over the country from mid month through to 25th/26th, it came crashing in thereafter.

 

Dec 2005 - a very blocked pattern with strong heights over mid atlantic, yes we did see atlantic influences over the top of the high but it was very weak, the end of the month saw a weak easterly develop.

 

We have go back to Dec 2004 for a classic mild westerly atlantic dominated fest, apart from a couple of weak northerly blasts, one cooinciding with christmas day.

 

Really unsure how this December might pan out, but I wouldn't be surprised to see high pressure being a strong influence once again.

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3.6c. Something similar to 2008, perhaps. I'm also hoping for December 2011-like transient snowfall in cylonic periods, which can be quite good for northern high ground, in the absence of any significant blocking.

Edited by Harve
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I'll go for 5.3C just above normal

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i think december is going to be a mixt1. Cold mild and then cold again. So i'm going for. 4.4c. Thanks.

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Looking at 1659-1700 average was 3.4c

 

Going for that as we start to go into a LIA

 

So 3.4c for me

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I'm going for 4.5 degrees, slightly below average thanks largely to drier conditions than normal which will result in cold nights and maxima struggling under the weak sun and potential fog at times.

 

I am expecting alternating milder spells and colder spells very similiar to the current pattern we have been in for 2 weeks to dominate - so at times we will be on the cold side of the polar front increasing chances of wintry precipitation especially in the north - but nothing sustained as heights will quickly reeastablish themselves.

 

There is a possibility we could end up in the 3's if heights build to the east at times pulling in a colder continental flow.

 

I see similiarities with December 2001 and 2008 to some extent, where northerly episodes and drier cold periods - perhaps not the warm up we saw in mid December.

 

Those hoping for a white christmas - who knows one of the colder interludes could coincide exactly with christmas, conversely one of the milder ones might. 

 

So in overview following on from the theme of most Decembers since 2005, a non-atlantic dominated month with high pressure being a strong influence.

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