Weather

Only two thirds of average rainfall needs to fall across the UK in December for 2012 to end up in the top ten wettest years on record, according to Met Office data which was first collated over a hundred years ago in 1910.

Should this be the case, it would also mean that nearly half of the years since 1998 would be in the UK's top ten wettest years on record.

2000 (wettest), 2008, 2002, 1999, 1998, and if rainfall is sufficient, 2012, would all make it into the top 10.

1923, 1927 and 1928 are also in the top 10, illustrating that wet years do come in clusters, but the 1920's sequence is nothing like what we have experienced in recent years.

Such a rainfall sequence suggests that over and above any cyclical change to weather patterns that are naturally occurring, other factors are likely to be at work, fuelling suspicions that climate change is playing its part.

November was another wet month.

Across England and Wales, rainfall was 128 per cent of the 1981-2010 average, making it the 8th successive month with above average rainfall.

And in the last 100 years only 20 Novembers had more rainfall, despite the fact it was only the wettest since 2009.

The continued positioning of the jet stream further south than normal is responsible for the very wet weather.

Current computer projections suggest that December is unlikely to be another washout month dominated by the Atlantic.

Although more rain (or snow) is expected at times, high pressure is likely to exert much more of an influence than in recent months, leading overall to colder but somewhat drier conditions to develop.

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  • Comment number 31. Posted by Leedschris

    on 10 Dec 2012 15:45

    re 25 QuaesoVeritas

    Yes, it's a few years back I did some work on this. The data for the East Midlands (Leicestershire) were taken from the British Rainfall series, updated by the then Monthly Weather Reports from the Met Office. For London the information could be found in the work by Brazell on a 'Century of London Weather'.

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  • Comment number 30. Posted by ukpahonta

    on 8 Dec 2012 09:18

    #28 Stephen Wilde

    That would explain it.

    #29 lateintheday

    Some good stuff at Tallblokes recently, impressed.

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  • Comment number 29. Posted by lateintheday

    on 7 Dec 2012 13:40

    Ukpahonta - possibly related/also worth a look.

    http://tallbloke.wordpress.com/2012/11/22/tim-cullen-the-problem-with-tsi-total-solar-irradiance

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  • Comment number 28. Posted by Stephen Wilde

    on 7 Dec 2012 11:35

    ukpahonta

    Ah, I've come across that before.

    They are just talking about the density at the height of the satellites.

    They orbit at a high enough level such that when the thermosphere shrinks then density reduces at the level of the satellite.

    However the density of the contracted thermosphere below the satellite is actually increasing.

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  • Comment number 27. Posted by ukpahonta

    on 7 Dec 2012 07:30

    #26

    Stephen Wilde

    From the same link:
    'Their work built on several recent studies. Earlier this year, a team of scientists from the Naval Research Laboratory and George Mason University, measuring changes in satellite drag, estimated that the density of the thermosphere declined from 2007 to 2009 to about 30 percent less than during the previous solar minimum in 1996.'
    http://lasp.colorado.edu/home/blog/2010/08/26/press-release-shrinking-atmospheric-layer-linked-to-low-levels-of-solar-radiation/

    A conundrum indeed, how could this be explained?

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  • Comment number 26. Posted by Stephen Wilde

    on 6 Dec 2012 19:17

    ukpahonta,

    You gave us this quote as regards the therosphere:

    "It typically cools and becomes less dense during low solar activity"

    That puzzles me because cooling and contraction usually increase density.

    Could it be a typo ?

    Thanks for your favourable comments.

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  • Comment number 25. Posted by QuaesoVeritas

    on 6 Dec 2012 17:35

    #24. - Leedschris wrote:
    "I have previously studied rainfall records in the East Midlands that show a strong peak around 1879/80 and in London 1878/79"

    Thanks. Are the rainfall records you have studied from the Met. Office, or some other source?

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  • Comment number 24. Posted by Leedschris

    on 6 Dec 2012 16:29

    As QuaesoVeritas points out there have been significant runs of wet years in previous centuries. The Met Office artificially restricts itself to post-1910 whereas there are reasonable rainfall estimates for England that go back to the 18th Century. If we are going through a run of wet years now, there certainly was another run in the 1920s and, like QuaesoVeritas says, there was another series of very wet years that centred around the early 1880s. I have previously studied rainfall records in the East Midlands that show a strong peak around 1879/80 and in London 1878/79 - these were followed by runs of particularly dry years in the 1890s that would be comparable to the sorts of cycles we have seen in the last couple of decades. Indeed what I have seen appears to show that there is quite a variation in 'average' rainfall across various areas of England over periods of years. I don't see anything particularly different about our recent rainfall patterns.

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  • Comment number 23. Posted by QuaesoVeritas

    on 6 Dec 2012 11:52

    Personally I find it more informative to use the HadUKP data series, for which England & Wales figures start in 1766, than the more recent 1910 series.
    Assuming average rainfall figures in December, the annual Engalnd & Wales figure will be 1166 mm, which would make it the 6th wettest year on record, after:
    1872 = 1284.9mm
    1768 = 1247.3mm
    2000 = 1232.4mm
    1852 = 1213.0mm
    1960 = 1195.0mm
    If rainfall is 6 mm below average in December, this year will also be lower than 1903, with 1160.3 mm.
    Six of the top 10 years in this series were in the 18th or 19th centuries, i.e. before "climate change" allegedly began.
    Again, assuming average rainfall for December, the 30 year average in 2012 will be 946.7mm, while the 30 year average in 1886 was 943.2 mm.
    The 10 year ma will be 933 mm in 2012, but the 10 year ma exceeded 1000mm between 1880 and 1884.
    As far as variability is concerned, the 30 year standard deviation will be 120.6mm but the 30 year sd in 1877 was 151.4 mm.
    The 10 year sd will be 135.7mm in 2012, but it reached 167 in 1789 and was picture is different when you take a longer-term perspective.
    This may be because the "natural cycles" have longer periods than are visible in the relatively short-term.

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  • Comment number 22. Posted by QuaesoVeritas

    on 6 Dec 2012 11:07

    #12. - Ian H wrote:
    "How come the year 2007 did not make it into the top ten, with the solid two months of very heavy rain night and day, every single day. This caused devastating floods, particularly in the North and also in the South such as Tewkesbury."

    As far as I can see, 2007 was the 16th wettest year, based on the 1910 series.
    This is presumably due to the fact that while May-July were all relatively wet, the other months must have been relatively dry, although I haven't been through all of the months.

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