Wet end to September raises autumn flooding concerns

Friday 14 September 2012, 16:13

Paul Hudson Paul Hudson

The second half of September look set to be dominated by low pressure, with little chance of a prolonged dry settled spell of weather.

All computer weather models are indicating that temperatures are likely to be below normal, with rain expected at times across the UK - although there will be some dry, bright days especially in the south and east at first.

Heavy rain on wednesday led the River Aire to burst its banks into the flood plain near Skipton, shown in the picture below.



This highlights the fact that the water table remains high, following the wettest April on record, and the wettest summer in 100 years.

Since March, there hasn't been a prolonged spell of dry weather which would naturally allow the land to dry out and the water table to fall, and should the traditionally wet months of October and November materialise, then a renewed risk of flooding is a distinct possibility.

The floods of autumn 2000 were unprecedented in their scale and severity, and such was the volume of rainfall that fell, that it became the wettest autumn in the Central England data set which goes back to 1766.

But the flooding was made far worse because there were no spells of settled, dry weather in any of the previous months.

April 2000 was the wettest on record and June 2000 was also very wet, with the River Ouse rising to its highest ever June level, as parts of the region experienced flooding.

But crucially July and August 2000 - the warmest two months of the year, when evaporation rates are at their highest - whilst not classed as a washout, saw no period of prolonged dry weather over a period of weeks which would have allowed the land to dry out.

So in 2000, far less rainfall in October of that year would have caused some flooding, because the land was already so wet.

We can only hope that whilst the rest of September is likely to see more rainfall, the rest of autumn shows some improvement, or further flooding may become a reality.

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Comments

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  • rate this
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    Comment number 41.

    #34. - john_cogger wrote:
    "But it's 5% higher than 2000 and 2001? :-)"
    Trend in 1925 = -0.011c/decade
    Trend in 1946 = +0.141c/decade
    Trend in 1967 = -0.037c/decade
    Trend in 2003 = +0.179c/decade (gain over 1946 = 0.038c)
    Trend in 2012 = +0.166c/decade
    Trend in 2032 = ???
    The important thing is how much higher the peaks and troughs are at the same part of the cycle.
    The cycle appears to be increasing but it is misleading to look at the current trend, since it may be at it's peak.

  • rate this
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    Comment number 42.

    Has RSS stopped functioning?

  • rate this
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    Comment number 43.

    Re 31
    Future warming will contribute to the trend, but I can't obviously tell for sure what that will be. On the otherhand the 82/83 El Nino is certain to drop off the last 30 year period by 2014 which will increase the 30 year warming trend.

    A PDO switch and deep solar minimum have all failed to significantly reduce the warming trend. ENSO has contributed to wobbles. Wobbles in this graph are hardly significant:
    http://www.woodfortrees.org/plot/gistemp/mean:360:/from:1970

    In the longterm I expect the 30 year trend to continue upwards at about the same rate as shown in that graph, with wobbles. Maybe the rate will appreciatively change, but I see no evidence of that at the moment and it could change in either direction.

    "so ask yourself just where will the +2C by 2050 come from?"

    None of the IPCC projections show that. I expect about 2C by 2100 which is in line with the current rate of increase.

  • rate this
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    Comment number 44.

    actually delete this part: "A PDO switch and deep solar minimum have all failed to significantly reduce the warming trend."

    I forget we are dealing with the 30 year mean here (not a 30 year record) and any changes would not affect that much.

  • rate this
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    Comment number 45.

    For those frantic about Arctic ice the Antarctic has now exceeded past sea ice cover records. It now has 1M sq.Km more ice than normal (If there is such a thing). It has been found that planetary sea ice seesaws between north and south cyclically and low Arctic ice does not foretell doom just a natural cycle as is rainfall.
    The problem in this country is that the Environment Agency cannot afford to dredge rivers, a vital maintenance measure. Rivers transport sediment which gets deposited downstream raising the river bed levels. This causes even a normal rain storm to cause flooding of flood plain. A good reason not to build on flood plain.

  • rate this
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    Comment number 46.

    #45. - John Marshall wrote:
    "It has been found that planetary sea ice seesaws between north and south cyclically and low Arctic ice does not foretell doom just a natural cycle as is rainfall."
    Do you have a source for that ? I know that is how it appears at the moment but I wondered if it had been the subject of a scientific paper.

    "This causes even a normal rain storm to cause flooding of flood plain. A good reason not to build on flood plain."
    I think there is a problem with drainage in general. There was a flood near me caused by the blockage of a culvert, which caused water to build up on a railway line, which overflowed into an adjacent street.
    Local councils are not cleaning drains until after there has been a flood, and not being proactive.
    A National Trust site near where I live, has cut down trees and is busy covering fields with tarmac next to a river, to build a car park, (to encourage more visitors), which will of course cause water to run into the river faster and possibly make flooding worse downstream. This sort of thing is happening on a wide scale but the idiots don't seem to realise the effect it is having on drainage.

  • rate this
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    Comment number 47.

    Sorry to disagree with an ex colleague so to speak but for me High pressure looks quite dominant now http://www.mountaindays.net/synoptic/chart.php?period=120.
    Nadine is interesting though looks set to meander around the 40 north mark. I wonder if its associated heat will assist in the high pressure to the north to build?

  • rate this
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    Comment number 48.

    Some of you may find this interesting. The increase in the Antarctic is not necessarily what one first might think. http://www.aoml.noaa.gov/phod/docs/Shu_etal_2012.pdf

  • rate this
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    Comment number 49.

    @48, Adrian Buckland

    It is extremely disappointing to see a paper published in 2012 reference the deeply flawed Steig 09 paper. If the authors are unaware or unable to understand the problems with Steig 09 then we can have no confidence that they can understand anything else.

    Even some members of the SkS private members club understand the issues although they wont say so in public.

  • rate this
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    Comment number 50.

    38. QuaesoVeritas wrote:

    "Are you really aiming that question at me, or at quake?"

    Sorry QV! I was trying to juggle too many discussions last night, the best I can say is I got the right blog! One comment left on another blog was not so lucky!

    Many thanks for "If you look at how the 30 year trend has changed on a rolling basis since 1909...."

    I will go away and have a look. Up to now I have restricted myself to the satellite period. Partly due to the numerous discussions/arguments re the retrospective changes to the terrestrial based databases. Your comments about 50/60 year cycles sure are interesting.

    Also I certainly agree about calculating the rolling 30 year trend, once plotted, trends and most importantly changes in trends are very easy to observe

  • rate this
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    Comment number 51.

    #50. - greensand wrote:
    "Sorry QV! I was trying to juggle too many discussions last night, the best I can say is I got the right blog! One comment left on another blog was not so lucky!"
    No problem, it is easy to get confused.
    BTW, you can see the apparent cycle in the 50 year HadCRUT3 trend on the "Climate4You" website, put there by Ole Humlum at my suggestion.
    http://www.climate4you.com/
    Click on "Global Temperature", then "Cyclic Air Temperature Changes".
    Of course, it is entirely possible that we don't have sufficient data to confirm that the cycle is real, but if it is, the trend should start to fall.
    I have heard references to 60 year cycles elsewhere on the internet, but I don't know their origins.

  • rate this
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    Comment number 52.

    Having said the above, if the cycle is real, it still suggests that temperatures are rising overall, but not as fast as currently is the case.

  • rate this
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    Comment number 53.

    There seems to be a lot of discussion about rolling 30-year temperature trends (which gives the rolling rate of temperature rise) and 30-year average temperatures (which give real world measured temperatures).

    You can have a decreasing 'rate of rise' alongside rising 'real world temperatures'.

    In fact that's where are at present.

    A decreasing rate of temperature rise is *not* a decrease in rising temperatures.

  • rate this
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    Comment number 54.

    #53. - newdwr54 wrote:
    "A decreasing rate of temperature rise is *not* a decrease in rising temperatures."
    I think what you meant was that "it is not a decrease in temperatures". Putting the word "rising" in front of the word "temperatures" is slightly misleading.
    But it is, as you say, a decrease in the rate of rise of temperatures, which MAY eventually be reflected in a decline in temperatures.

  • rate this
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    Comment number 55.

    johncogger - indifference?

    Ask yourself what lies behind the Lewandowsky study.

    A. Do you think the survey is a genuine attempt to reveal a psychological flaw, common to climate sceptics?

    B. Do you think the survey is a tactical ploy, designed to discredit or undermine the sceptic community.

    C. I can't think of one.

    My view is that anyone who answers (A) needs to step back for a moment and take a good look in the mirror. How have they allowed themselves to become a person of such intolerance that they consider a contradictory opinion a sign of mental illness or frailty.

    Anyone who answers (B) accepts that there is a game being played out which has little to do with science, and everything to do with policy. This answer undermines AGW science in that it implies that anything and everything which we hear from the consensus might also be part of the game. Genuine scientific studies and tactical 'policy driven' studies would be indistinguishable to the layman. Result - credibility down the plughole.

  • rate this
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    Comment number 56.

    Woops! Looks like the Met Office have got it wrong. Their outlook at the end of August forecast "September will be slightly warmer than average" and "For UK averaged rainfall the predicted probabilities weakly favour below normal values during September."

    http://www.metoffice.gov.uk/media/pdf/k/s/A3-plots-temp-SON.pdf

    http://www.metoffice.gov.uk/media/pdf/i/e/A3-plots-precip-SON.pdf

  • rate this
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    Comment number 57.

    56.PaulHomewood:

    CET to 17th is currently +0.7C above normal, i.e. slightly above average: http://www.metoffice.gov.uk/hadobs/hadcet/cet_info_mean.html

    Too early to say if MO is wrong again.

  • rate this
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    Comment number 58.

    #46 QV The relationship between Arctic/Antarctic sea ice cover is covered on the wattsupwiththat web site.

    Culverts are a problem both from blocking and being installed at a smaller size than is really required, presumably to save money. In Spain, where rains in spring can be torrential thunderstorms, the use of culverts is avoided by the use of the French style open drains. Blockages are easily seen and cleared and excess rain overflows without backing up, as happens here. They also move water quicker than a covered system which is the best way to avoid flooding.

  • rate this
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    Comment number 59.

    #58. -, John Marshall wrote:
    "The relationship between Arctic/Antarctic sea ice cover is covered on the wattsupwiththat web site."
    Thanks, I don't regularly visit there, but I will have a look.

    "Culverts are a problem both from blocking and being installed at a smaller size than is really required, presumably to save money. In Spain, where rains in spring can be torrential thunderstorms, the use of culverts is avoided by the use of the French style open drains. "

    Of course, the argument will be that in the past we have never needed such large Culverts and/or open drains, so the need for them will be seen as evidence of "climate change".
    However that doesn't take into account the other widespread changes to land use, which I think is having a major impact on drainage patterns.
    "Climate change" is a useful scapegoat.

  • rate this
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    Comment number 60.

    I see my request for discussion on the paper by Ole Humlum et al 1012, regarding the phase relation of C02 and temperature was followed by a closure of further comments, so at the risk of closing this thread down, I repeat the request.

 

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I worked as a forecaster with the Met Office for nearly 15 years locally and at the international unit, after graduating with first class honours in Geophysics and Planetary physics at the University of Newcastle upon Tyne in 1992. I then joined the BBC in October 2007, where I divide my time between forecasting and reporting on stories about climate change and its implications for people's everyday lives.

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