There is now growing consensus between most weather computer models that cold air from the east is likely to spread across Britain next week.

If so, it will be the first time since March that high pressure has properly dominated our weather, and will end a long sequence of at times record breaking wet weather.

And it looks to be a classic winter-time set up, with a powerful anticyclone developing across Scandinavia and into western Russia, pulling in cold easterly winds across a large part of the country, hence the old saying 'the beast from the east'.

The diagram below is what's known as an 'ensemble mean' from the ECMWF model for the middle of next week.



The computer program is run 51 times, each time with slightly different starting conditions.

The solutions are then compared, and give forecasters an indication as to how likely a particular outcome is.

From the midnight run of the computer, 41 out of 51 of the solutions suggest an easterly weather pattern developing next week, with varying degrees of cold.

10 solutions do not agree with this cold easterly outcome, hence there is still some uncertainty. But, there's clearly a large majority in favour of this scenario at the moment.

What is much less certain is how much snow is likely to be associated with this change in the weather.

Quite often in these situations, there's a distinct lack of precipitation apart from wintry flurries which can develop as the air picks up moisture as it heads westwards across the North Sea.

But some solutions are suggesting 'disturbances' in the easterly flow, which would bring the risk of more general snowfall.

And of course there's always the risk of milder air trying to re-assert itself from from the west, which would also bring the risk of snow.

At the moment though, the cold but relatively dry scenario is the most likely outcome.

One way or the other, our weather is likely to become more seasonal in the lead up to Christmas.

Follow me on twitter @Hudsonweather

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  • Comment number 148. Posted by QuaesoVeritas

    on 12 Dec 2012 23:56

    #146 - newdwr54 wrote:
    "Do we really need to ask Werner how to round decimal places? Surely the problem is with Spencer's 3 d.p updates?"

    I agree there is an issue with the differences between the quoted figures to 3 decimal places and the published figures to 2 decimals.

    I have never understood why Spencer's blog shows 3 and yet the data files show only 2 and sometimes the rounding isn't correct.

    I think the question has been asked on the blog every now and again, but I don't ever recall seeing an explanation. Perhaps a direct e-mail might be in order.

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  • Comment number 147. Posted by greensand

    on 12 Dec 2012 22:07

    146. newdwr54 wrote:

    "Do we really need to ask Werner how to round decimal places? Surely the problem is with Spencer's 3 d.p updates?"

    In that case I expect you will take it up with Spencer?

    You referenced my comment to QV about Werner's post. It was posted because I know QV follows multiply datasets, It made no comment about Spencer or his rounding. That appears to be your interest, it has nothing to do with my comment, is of no interest to me, so I leave you with it. You know where Spencer blog is.

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  • Comment number 146. Posted by newdwr54

    on 12 Dec 2012 21:54

    145. greensand:

    Do we really need to ask Werner how to round decimal places? Surely the problem is with Spencer's 3 d.p updates?

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  • Comment number 145. Posted by greensand

    on 12 Dec 2012 21:47

    144. newdwr54 wrote:

    "What I found of most interest in that comment is the rounding."

    Good, pleased you found it of interest, expect you will take it up with Werner Brozek?

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  • Comment number 144. Posted by newdwr54

    on 12 Dec 2012 21:40

    141. greensand wrote:

    "... you may find the following comment by Werner Brozek at Spencer's blog of interest"

    What I found of most interest in that comment is the rounding.

    August 2012 is given to 3 d.p.s as 0.208; yet it's published by UAH to two d.p.s as 0.20. As far as I'm aware 0.208 rounds to 0.21, not 2.0?

    and October is given as 0.333; yet it is published in the official UAH data as 0.34. Surely 0.333 rounds to 0.33, which in fact is what Spencer says in his own blog?

    Most odd. Something is amiss.

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  • Comment number 143. Posted by newdwr54

    on 12 Dec 2012 21:25

    138. greensand:

    Thanks GS. That makes 2012 the third warmest November in the UAH record.

    I see that, for the second month running, Dr Spencer has dropped the bizarre polynomial trend line from his UAH chart.

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  • Comment number 142. Posted by QuaesoVeritas

    on 12 Dec 2012 21:02

    #141. - greensand wrote:
    "QV, you may find the following comment by Werner Brozek at Spencer's blog of interest:-"

    Yes, I had a quick glance at that. Unfortunately the WFT link didn't seem to work.

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  • Comment number 141. Posted by greensand

    on 12 Dec 2012 20:59

    QV, you may find the following comment by Werner Brozek at Spencer's blog of interest:-

    "2012 in Perspective so far on Six Data Sets"

    http://www.drroyspencer.com/2012/12/uah-v5-5-global-temperature-update-for-november-2012-0-28-deg-c/#comment-66943

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  • Comment number 140. Posted by greensand

    on 12 Dec 2012 20:37

    139. QuaesoVeritas wrote:

    "which suggests that AQUA CH5 is still an unreliable guide to UAH."

    Agreed, have left alone since the last hiccup.

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  • Comment number 139. Posted by QuaesoVeritas

    on 12 Dec 2012 20:21

    #138. - greensand wrote:
    "Our Version 5.5 global average lower tropospheric temperature (LT) anomaly for November, 2012 is +0.28 deg. C"

    A fall of 0.05c since last month in the Global anomaly.
    Also, the N.H. figure is almost unchanged at 0.30c, while the S.H. is down about 0.1c at 0.26c.

    So the global reduction is not as large as for RSS but larger than GISS, while the fall in the S.H. anomaly is almost the same as for RSS.

    My calculations based on AQUA CH5 V UAH (v5.5), for 2002-11 suggested that the UAH figure should have been around 0.36c, which suggests that AQUA CH5 is still an unreliable guide to UAH. After having previously had to add 0.08c to AQUA to get a reliable UAH figure, I now find I have to deduct about the same.

    Once again, I suspect this all points to very little change in the monthly HadCRUT3/4 figures for November.

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