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MetO to call a positive / negative NAO for winter 2008-09?


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

    It is getting to the time of year where the UKMO issue their NAO forecast for the following winter based on the SST Anomaly pattern in May.

    So, what will their forecast be for winter 2008-09?

    In 2005 the UKMO went for a colder than average winter (negative NAO) based on cool SSTs in the western Atlantic / Carribbean area and warm SSTs further north. The winter actually turned out to be close to average and not especially cold although was colder than many recent years.

    In 2006 the UKMO went for a milder than average winter (positive NAO) based on warm SSTs throughout much of the north and west Atlantic. The winter then turned out to be one of the mildest on record.

    Last year the UKMO went for a milder than average winter again (weakly positive NAO) but less mild than 2006-07, and that was basically what we got.

    From what I can see the SST anomaly presently for this month shows some cold anomalies near Newfoundland and south of the Carribean but SSTs are largely above average through the north and west Atlantic. At this stage, I would say, that it does not look too promising for a negative NAO forecast from the Met Office for winter 2008-09, and already it may well be that the underlying SST anomaly pattern makes getting a colder than average winter unlikely for winter 2008-09, and average to mild looks the more likely call from the UKMO.

    What are other people's views on the current SST pattern and UKMO's likely NAO forecast for winter 2008-09?

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    Posted
  • Location: Stourbridge
  • Location: Stourbridge
    It is getting to the time of year where the UKMO issue their NAO forecast for the following winter based on the SST Anomaly pattern in May.

    So, what will their forecast be for winter 2008-09?

    In 2005 the UKMO went for a colder than average winter (negative NAO) based on cool SSTs in the western Atlantic / Carribbean area and warm SSTs further north. The winter actually turned out to be close to average and not especially cold although was colder than many recent years.

    In 2006 the UKMO went for a milder than average winter (positive NAO) based on warm SSTs throughout much of the north and west Atlantic. The winter then turned out to be one of the mildest on record.

    Last year the UKMO went for a milder than average winter again (weakly positive NAO) but less mild than 2006-07, and that was basically what we got.

    From what I can see the SST anomaly presently for this month shows some cold anomalies near Newfoundland and south of the Carribean but SSTs are largely above average through the north and west Atlantic. At this stage, I would say, that it does not look too promising for a negative NAO forecast from the Met Office for winter 2008-09, and already it may well be that the underlying SST anomaly pattern makes getting a colder than average winter unlikely for winter 2008-09, and average to mild looks the more likely call from the UKMO.

    What are other people's views on the current SST pattern and UKMO's likely NAO forecast for winter 2008-09?

    currently i think that there is a lot of cold air in the atlantic, and this could potentially make for a negative NAO winter. however, we have a long way to go yet. at present i would a say a cold and snowy winter is a 1 in 8 chance. still a possibility though. i think the UKMO will go average rather than above or below. this isn't very intelligent or scientific, but maybe the fact that the last 2 winters have been dire will account for something proper?

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    Posted
  • Location: Skirlaugh, East Yorkshire
  • Location: Skirlaugh, East Yorkshire

    Id be more interested in whether its going to be a positive or negative AO. This has been the major spoiler over the last few winters with the polar vortex anchored to Greenland and heights remaining low over the pole.

    At the end of the day we're never going to get more than the odd day of snow here and there without blocking around the Greenland area. With a +ve AO we're either stuck with zonality or have high pressure over us. These can give cold weather, but neither are really favourable for prolonged cold spells (there are exceptions though of course).

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    Posted
  • Location: W. Northants
  • Location: W. Northants

    This is the kind of Atlantic SST signal we're looking for this May;

    http://www.osdpd.noaa.gov/PSB/EPS/SST/data...t.5.17.2005.gif

    And heres the current state of play;

    http://www.osdpd.noaa.gov/PSB/EPS/SST/data...t.4.17.2008.gif

    As you can see, the Atlantic signal is not really anywhere near set up for a negative NAO signal.

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    Posted
  • Location: Liphook
  • Location: Liphook

    Yeah the state of the AO IMO is going to be every bit as interesting...as will the state of the Pacific temps and where we are with regards to the ENSO signal because this winter Dec, Feb and March all landed about where they should do with regards to the CET average in a strong la nina though interestingly the one month that came in well above was Jan and that had a very powerful +ve AO.

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    Posted
  • Location: W. Northants
  • Location: W. Northants

    What you need to look for is the warm/cold/warm banding that you see on the chart from May 2005. Thats a classic tripole pattern and thats the kind of pattern that can lead to a negative NAO set up.

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    Posted
  • Location: Ossett, West Yorkshire
  • Location: Ossett, West Yorkshire
    What you need to look for is the warm/cold/warm banding that you see on the chart from May 2005. Thats a classic tripole pattern and thats the kind of pattern that can lead to a negative NAO set up.

    It did not entirely lead to a negative NAO setup in 2005-06.

    I remember the one big time the UKMO went for a negative NAO / colder than average winter was in 1995 based on the SSTs in the May of that year. That winter actually did turn out to be the coldest of the last 20+ years and featured numerous Greenland / Scandinavian High / classic negative NAO / northerly / easterly setups.

    The UKMO did predict a negative NAO for 2005-06 but although the winter was close to average, it wasn't anything outstanding in terms of negative NAO setups and severe cold outbreaks, I mean, only March 2006 saw a classic negative NAO setup. Even one of the cold spells in the 05/06 winter (late Jan / early Feb) came from surface cold in a mid-latitude Rex block and not deep cold Arctic air, similar to the setups that brought the cold spells of mid Dec 2007 and mid Feb 2008, and also like the mid latitude Rex blocks that developed frequently during the 1991-92 and 1992-93 winters. After late Nov 2005 there were no significant northerly spells until early March, and the only easterly spells were in late December and late February, although the late Feb 2006 easterly was not particularly cold and even far less potent than the late Feb 2005 easterly, so despite the UKMO negative NAO winter forecast in 2005-06, the winter was certainly nothing special overall in terms of cold negative NAO setups, so the winter 2005-06 was still dissapointing for most given the UKMO winter forecast.

    Still, even at this early stage as Gavin P rightly points out, it is already difficult to see a negative NAO forecast from the UKMO for winter 2008-09 given the current SST anomaly pattern. Even as winter 2008-09 is still 8-10 months away, at this early stage it looks as if it may well be that the underlying SST pattern and conditions make getting a colder than average winter unlikely for winter 2008-09 and that the chances of an improvement on many recent winters in 2008-09 are already slim.

    The last time the UKMO issued an accurate cold winter forecast was in 1995, and they again issued a cold winter forecast in 2005 but it was still dissapointing for most and was certainly by no means a cold winter overall and was statistically still regarded as average overall. Up to this present day, no winter since 1995-96 could reasonably be described as cold or even having significant UK wide severe cold outbreaks with deep cold Arctic air. The longer time goes on with mild winters year after year and given the almost complete lack of UK wide cold outbreaks since 1996 and the rarity of severe cold spells since 1988, it is looking like an almost permanent change has occurred to the weather patterns that affect the UK and the rest of Europe.

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    Posted
  • Location: Stourbridge
  • Location: Stourbridge

    ok, unlikely as it is that does not mean a snowy winter, or at least an event, is unlikely, take winter 06/07, a bad winter

    til the 8th february when many people woke up to 10-15cm of snow that morning. we cannot be jumping to conclusions at this stage. it is still one outcome, despite what the SST's show at this stage. i know in the future a bias towards positive NAOs are likely, but we cannot write negative ones off the cards either, so lets not be conclusive just yet.

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    Posted
  • Location: Broadmayne, West Dorset
  • Weather Preferences: Snowfall in particular but most aspects of weather, hate hot and humid.
  • Location: Broadmayne, West Dorset

    "The longer time goes on with mild winters year after year and given the almost complete lack of UK wide cold outbreaks since 1996 and the rarity of severe cold spells since 1988, it is looking like an almost permanent change has occurred to the weather patterns that affect the UK and the rest of Europe."

    Hi Northeasterly Blast. With regard to the above bit of your excellent post. I think they were probably saying something similar in the early 20th century

    After all between 1895 and 1940 a gap of some 45 years there were only two genuinely hard winters 1917 and 1929. There were some very heavy snowfalls outside of these winters but they tended to be regionalised like the great christmas snowstorm of 1927 ( south and southeast) or the great northern snowstorm of 1933.

    In the same way in the 20 years since 1988 we have had the great midlands snowstorm of Dec 1990. the exceptional cold and snow in Scotland in Dec 1995 the western uk snowstorm of Feb 1996 ( one of the deepest widespread falls of the 20th century). All without nationwide severe cold

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    Hi all, certainly a while since we had this discussion...

    To me, most people always associate a negative NAO with cold/snow, but in reality, a negative NAO is correlated to cold/dry, so while it may not be warm, we could get a 1964 winter whereby there was very little precpitation or a winter 2006 senerio with very little warmth but very little snow due to high pressure being over us most of the winter.

    Gavin, the anomolies east of Greenland are not really important in regards to the NAO signiture, it is the anomolies south of Greenland, the anomolies east of the USA, and the anomolies around the Azores, unfortunately we currently have a positive NAO signiture because of warm anomolies right across the Sub-Tropics.

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    Having looked at the duo-monthly anologues, i have analysed the current probable patterns for the coming winter...

    MEI - Strengthening weak La Nina

    QBO - weakening westerly QBO

    Essentially, at this time, there are some conflicting signals for the winter ahead, but with a strong signal for a mid-lattiude High pressure in the western and central Atlantic.

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    Posted
  • Location: Crossgates, Leeds. 76m ASL
  • Weather Preferences: Temperatures ≤24ºC ≥5ºC.
  • Location: Crossgates, Leeds. 76m ASL

    Another strengthening La Nina for this coming winter??? :):)

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    Posted
  • Location: Crossgates, Leeds. 76m ASL
  • Weather Preferences: Temperatures ≤24ºC ≥5ºC.
  • Location: Crossgates, Leeds. 76m ASL
    Arrrggghh I thought he was stong enough already :):)

    Is it. :)

    I'm not coming out post-4333-1209160682.gif :)

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    Posted
  • Location: Stourbridge
  • Location: Stourbridge
    Is it. :)

    I'm not coming out post-4333-1209160682.gif :)

    no i think he means adjusting to moderate for winter this year. personally, i think next winter will be very unsettled and zonal just like the last one, but id love to be proved wrong on the zonal part. :) please please please give us a decent winter this year.

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    Anologues indicate that La Nina should remain weak through all three winter months, but heading towards moderate (strengthening).

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
    so your take on next winter is?

    At this moment i would say cyclonic/wetter than average, but near average temperatures.

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    Posted
  • Location: Stourbridge
  • Location: Stourbridge
    At this moment i would say cyclonic/wetter than average, but near average temperatures.

    hopefully could well be luckier than last year :) . we shall have to wait for the met offices take though.

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