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January 1969 - A mild negative NAO month


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Posted
  • Location: Ossett, West Yorkshire
  • Location: Ossett, West Yorkshire

    Many of us know that January 1969 was a very negative NAO month but was also a pretty mild month in the UK. The only spell of cold weather that month occurred during the first week. There was often a Greenland High present that month and cold air built up to the north of the UK and over Scandinavia as cold easterlies often covered that area as the Arctic High frequently appeared, but for the UK, although in a very negative NAO setup with pressure always low over the Azores, low pressure areas became slow moving to the west of Ireland leaving the UK in "no mans land", with frequent mild southerlies and south-westerlies covering the UK - although that month never featured a Bartlett and / or constant depressions running through the GIN corridor producing the classic mild winter setup.

    The point I will make is that January 1969 should have been far colder than it actually was as the synoptics / negative NAO was so close to delivering something special for the UK. When one looks at the NAO state for the 1968-69 winter, one would think that winter should have delivered something approaching the severity of 1978-79.

    One of the biggest let downs of negative NAO in January 1969 I think, and certainly a close but no cigar scenario. This week highlights this as the models predicted much colder weather from the north for the UK late this week, but the low pressure just becomes slow moving to the west of the UK and just keeps us in mild SW'lies.

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    Posted
  • Location: Shrewsbury
  • Location: Shrewsbury
    Many of us know that January 1969 was a very negative NAO month but was also a pretty mild month in the UK. The only spell of cold weather that month occurred during the first week. There was often a Greenland High present that month and cold air built up to the north of the UK and over Scandinavia as cold easterlies often covered that area as the Arctic High frequently appeared, but for the UK, although in a very negative NAO setup with pressure always low over the Azores, low pressure areas became slow moving to the west of Ireland leaving the UK in "no mans land", with frequent mild southerlies and south-westerlies covering the UK - although that month never featured a Bartlett and / or constant depressions running through the GIN corridor producing the classic mild winter setup.

    The point I will make is that January 1969 should have been far colder than it actually was as the synoptics / negative NAO was so close to delivering something special for the UK. When one looks at the NAO state for the 1968-69 winter, one would think that winter should have delivered something approaching the severity of 1978-79.

    One of the biggest let downs of negative NAO in January 1969 I think, and certainly a close but no cigar scenario. This week highlights this as the models predicted much colder weather from the north for the UK late this week, but the low pressure just becomes slow moving to the west of the UK and just keeps us in mild SW'lies.

    January 1996 was similar for the most part wasn't it? The cold air from the previous month was never far away and there was always a Scandi and/or Greenland High. On climate.uk site it's the 2nd or 3rd most easterly January on record yet had an average CET- only having that because the cold air finally won over in the last week. As well as beinmg in the top 3 most easterly Januaries it's also, remarkably, in the top 3 most southerly- the reason was as above lows that kept anchoring just west of the British Isles bringing up mild air from the south into the mix. There was hardly a day of zonal westerlies, and no Bartletts that I recall and it was a negative NAO month as was that whole winter. However whereas it could have gone down as being cold (if it had had a CET below 3C the winter would have been much more notable as all 3 months would have) it's just in the record books for being very very dull indeed- the S'lies and E'lies seemed to have a competition as to which could produce more grey murk (only the last 3 days had any real sun at all that I remember).

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    Posted
  • Location: Skirlaugh, East Yorkshire
  • Location: Skirlaugh, East Yorkshire
    has anyone got a historical synoptic chart that actually shows an arctic high ?

    Here's one, to the north of Russia.

    http://www.wetterzentrale.de/archive/ra/19...00119870108.gif

    Which we all know, led to this:

    http://www.wetterzentrale.de/archive/ra/19...00119870112.gif

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    Posted
  • Location: Llanharan, South Wales
  • Location: Llanharan, South Wales

    sorry to be an idiot but just to clarify which one of the 3 "H" I can see on that first map in the the top right corner going from left to right is the arctic high ? Or is it the combo of all them, or the H which is undercovered with the deep shade of blue ?

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    Posted
  • Location: Upper Tweeddale, Scottish Borders 240m ASL
  • Location: Upper Tweeddale, Scottish Borders 240m ASL

    Just popping this over to the historic weather section - to keep the Autumn Discussion area neat and tidy :o

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    Posted
  • Location: Shrewsbury
  • Location: Shrewsbury
    sorry to be an idiot but just to clarify which one of the 3 "H" I can see on that first map in the the top right corner going from left to right is the arctic high ? Or is it the combo of all them, or the H which is undercovered with the deep shade of blue ?

    The one beneath the "d" of "und" is the main one.

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    Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

    The key to understanding why january 1969 was so mild despite a -ve NAO (and AO for that matter):

    1) SSTA:

    Big -ve anomaly in the central Atlantic helping to influence a large Atlantic trough, perfectly placed to maintain posiitve height anomalies over Greenland;

    2) ENSO neutral conditions (there was a very weak powder-puff El Nino that Spring) allowing the SSTA in the Atlantic to prevail;

    3) A stonking -ve PDO helping to force the PNA -ve throughout January:

    http://www.cdc.noaa.gov/Correlation/pdo.data

    http://www.cdc.noaa.gov/Correlation/pna.data

    bringing about about the ingredients for a highly amplified jet pattern and troughing in the Atlantic maintaining a run of warm southerly or sw'lys interspersed by some easterly phases as the jet fractured.

    History is always relevant to today and the conclusions to be drawn are that a -ve PDO / -ve NAO is never a good combination for winter cold for the UK, especially so when the SSTA points towards mean troughing in the Atlantic.

    This year, the PDO has been negative for the last two months:

    http://jisao.washington.edu/pdo/PDO.latest

    although there are indications for some weakening of this to more neutral values. The east Pacific may however offset and impact of this factor with a tendency towards with a strong jet flow across the southern US brought about the developing El Nino and warmer sea temperatures to the NE Pacific:

    http://weather.unisys.com/surface/sst_anom.html

    GP

    Edited by Glacier Point
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    Posted
  • Location: Putney, SW London. A miserable 14m asl....but nevertheless the lucky recipient of c 20cm of snow in 12 hours 1-2 Feb 2009!
  • Location: Putney, SW London. A miserable 14m asl....but nevertheless the lucky recipient of c 20cm of snow in 12 hours 1-2 Feb 2009!
    sorry to be an idiot but just to clarify which one of the 3 "H" I can see on that first map in the the top right corner going from left to right is the arctic high ? Or is it the combo of all them, or the H which is undercovered with the deep shade of blue ?

    The arctic high is - unsurprisingly - the only "H" of those three that's in the arctic !! It's centre is in the Barents Sea, between Svalbard and Novaya Zemlya. The other two, weaker high pressure centres run from Russia south into Kazakhstan, and are not within the arctic circle.

    Pompey, I think the projection of the Wetterzentrale maps may be confusing you, and this may be a good opportunity to try and clear it up. On this type of projection (the process of trying to show a globe on a flat map), The North-South (or Longitude) line only runs vertically up-and-down in the centre of the map - basically over Britain. At the top edge of the map - left or right side - North-South runs horizontally along the top edge. The angle at places in between gradually shifts round - in fact if you look carefully at the two lesser "H" centres top right you will see a dotted line beween them: that is the North-South line there.

    You can see the set-up more clearly here: http://www.athropolis.com/map2.htm

    and here: http://athropolis.com/map3.htm

    Edited by osmposm
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    Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

    There was a big difference between 1968/69 and the present run of winters though- current winters tend to disappoint every month. January 1969 was certainly mild (and, it would seem, dull in most places), but December 1968 produced a white Christmas for some, and February 1969 had a couple of notable severe spells.

    The unforecast frontal staller on Christmas Day 1968 with cold air holding on in the north:

    http://www.wetterzentrale.de/archive/ra/19...00119681225.gif

    An unusually cold winter northerly, rivalling our coldest easterlies:

    http://www.wetterzentrale.de/archive/ra/19...00119690208.gif

    and, a while later, a good NE'ly:

    http://www.wetterzentrale.de/archive/ra/19...00119690213.gif

    In many ways, the analogy with 1995/96 is a good one, with a negative NAO but mostly mild January (albeit with snowy end) sandwiched between negative NAO months that were both cold and snowy. I'm guessing that the PDO/PNA signals may have gone more positive in those months.

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    Posted
  • Location: Ossett, West Yorkshire
  • Location: Ossett, West Yorkshire

    Yes, I know winter 1968-69 was much different and far colder than recent winters. The point I am trying to make is that January 1969 was a mild dissapointment in an otherwise cold winter. Jan 1969 was a very negative NAO month that was also well above average CETwise, and Scandy and Greeny Highs were present but they did not influence the UK with cold N'lys / E'lys. The rest of that winter was cold to severe especially the February but the mild January was the dissapointment. The point is that Jan 1969 should have been far colder than it actually was with such a negative NAO and good Greeny / Scandy Highs. Had Jan 1969 been a much colder month then winter 1968-69 would have been superb and fallen into the severe category.

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    Posted
  • Location: Powys Mid Wales borders.
  • Location: Powys Mid Wales borders.

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