December cold – unprecedented?

[Update 19th January- actual data for Armagh in December added – lower than predicted]

BBC news is reporting today that 40,000 homes are still without water in Northern Ireland after the recent spell of freezing temperatures. Many have been without water for more than 10 days, and reservoirs are being drained due to an unprecedented number of leaks since the thaw. Calls to a few friends confirmed that, yes, it is bad – friends in Lisburn have been without water since Christmas Eve due to a frozen mains supply (i.e. not in their house); others in Belfast report low water pressure.  Water is being rationed in places.

Was it really that cold? A search of the BBC site revealed “‘Baltic’ Northern Ireland” tucked away on the BBC NI news page. Castlederg in the West of the province recorded -18°C on 20th December – a new record.  The thing about Ireland is that it sits on the very western fringes of Europe, bathed by the warm Gulf Stream (which is why Doug Keenan considered the 7000 years of Irish tree ring data so important that he pursued Queen’s University through FOI requests).  Ireland, despite its latitude, just doesn’t do ‘very cold’ (or ‘very hot’ for that matter).

When I first got interested in climate I ended up corresponding with Tonyb about the temperature records of the Armagh Observatory in Northern Ireland.  These stretch back to 1796. Incidentally there are a couple of WUWT posts featuring Armagh in the last year (here, here and here). How does this current cold month compare with the historical record at Armagh?  Was the recent cold unprecedented?

The currently incomplete December record for Armagh consists of raw data – three automated readings per hour.  Rather than waiting until they calculate the December average I looked for nearby stations on Weather Underground and found Glenanne PWS, about 15km to the SW of Armagh.  The average temperatures for the two stations over the month of November is plotted in Figure 1.  This gave a good linear fit (R^2 = 0.889) with an offset – Armagh being on average colder by just over 1°C.

Figure 1. Average temperatures for Armagh and Glenanne N. Ireland through November 2010

Figure 2 shows the December data for Glenanne on the same scale. Up to the 28th December, the monthly average is -0.86°C.  Mild conditions are expected for the next three days and, if I plug the forecast max/min (29th 8/6; 30th 8/4; 31st 6/2)  into my spreadsheet to complete the month, the monthly average rises to an estimated -0.23°C for Glenanne, remembering that this is an approximation for Armagh, which is typically colder. [Update Armagh now added 19th Jan].

Figure 2. Average temperatures for Glenanne N. Ireland through December 2010 - now up updated to include Armagh data.

In the Armagh historical record, which I have for 1796-2002 from [1] the average temperature for December is 4.9°C; January average is colder (4.1°C).  There are just two individual months colder than December 2010: January 1814 (-2.2°C) and January 1881 (-0.9°C) which puts this one as the third coldest on record at Armagh (2010 might yet tie with 1881 when the actual average for the month is published).

Coldest months according to the Armagh record:

  1. January 1814 -2.2°C
  2. January 1881 -0.9C
  3. December 2010  -0.2C -0.3C (official Observatory Monthly Mean)
  4. February 1855  0.0C,  January 1963 0.0C
  5. February 1895  0.2C
  6. February 1947 0.4C
  7. January 1985 0.5C,  December 1878 0.5C

The list above also puts it in perspective with respect to other extreme years in living memory – most notably 1963 and 1947. According to the Armagh records none of the coldest months in these years saw such extreme cold as the Christmas period this year.  The Arctic cold cut though the mild Atlantic air this year resulting in a monthly average 4-5°C below normal (Figure 3).

Figure 3.

Even without all the warming we have been led to expect 😉 December’s cold probably can be described as unprecedented. I’ll await with interest the actual December figures for Armagh (and those from the Met Office).  As for this being caused by global warming – bull – it was just an extreme weather event.  They happen.  Go back >100 years and they happened then too.


[1] C.J. Butler, A. M. García-Suárez, A.D.S. Coughlin and C. Morrell. Air Temperatures at Armagh Observatory, Northern Ireland, from 1796 to 2002 Int.J.Climatol. 25: 1055-1079 (2005) [Full paper]

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3 Responses to December cold – unprecedented?

  1. John F. Hultquist says:

    I think I’ve got it. Freezing temperatures cause pipes to burst all over town in mostly private homes and businesses. As the pipes thaw water spills into buildings and then into streets. People call the water company to complain but can’t get through because Regional Development Minister Conor Murphy and Deputy First Minister Martin McGuinness are on the phone with the chief executive of the water company – keeping said person from getting on with his work. Officials want those affected to make claims but against whom and why is not explained.

    Blame global warming. Sue the coal miners. Sue power plants. Sue Ford for inventing the SUV. Blame George Bush.

    What happened in 1963, or 1985 when similar extreme cold events occurred?

    What is the rest of this story?

    • Verity Jones says:

      Well that’s just it – previous years did not have the same extreme cold. Prolonged cold and lots of snow, yes, but not the really penetrating frost as well. From what I can see it is not just leaks on private properties although undoubtedly there are many, many more than in a normal cold spell. The NI Water website reports 500 burst watermains – the public supply pipes. You have to remember this is in a relatively small area – 1.7 million inhabitants. This suggests penetrating cold that the area is unused to. It is generally milder than the rest of the UK. Also NI Water is ‘government company’ and was not privatised like the water utilities in England and Wales. I suspect this is the source of the political furore.

  2. John F. Hultquist says:

    If, as you say, the penetrating cold was more extreme than in the prior years of ’63 and ’85 then it isn’t the monthly average that is of interest but the actual nightly lows. Also, the snow cover is of interest. Snow is a good insulator, so if the cold came first it will go deeper. Once covered by snow, not so deep. The pipes in buildings are a different problem. Here, folks are advised to open doors under kitchen sinks and the like to allow warmed room air to circulate. Also, for overnight or absence from home (vacations) situations folks will let water trickle or drip. These things are not necessary in a well insulated and well heated home – as ours must be where we can expect -30° C. In unheated outbuildings heating-tape and 75 – 100 watt lights are used. Good measures for in-house also, where needed.

    All outside lines are buried deep enough that they do not freeze; 1.5 metres or more. Where the town supply meets the connection to a house or business and there is a measuring device (meter), that will have a frost plate

    that is easily replaced. Thus, one does not have to dig up a buried line. The water is shut off, the frost plate replaced, and service to the building is quickly back.

    I suspect the problems came from a combination of things – fast arriving cold; old system, housing and lines planned for more mild conditions, lack of upgrades, people being away from home, and so on. Culpability should be spread widely.

    I suspect that the water management was aware of the need to upgrade the system – just as our Corps of Engineers and the levee districts in New Orleans knew of their situation. Recently in Australia the operators of a water system were forced to “replace” water into a flooding river rather than divert that water into a low-water reservoir. Jennifer Marohasy has reported on this under the “Snowy Hydro” tag.
    The company, months ago, had asked the government to change the operating documents to prevent this – without getting a serious response.

    [My grandmother was from Ballinamore, County Leitrim; less than 100 Km southwest of the Armagh area. Relatives are still there, although we have not had any contact in about 15 years.]

    Happy New Year!

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