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Posted
  • Location: chellaston, derby
  • Weather Preferences: The Actual Weather ..... not fantasy.
  • Location: chellaston, derby

    It appears the extreme SSW of 2018 which produced the infamous Beast From The East has tainted our expectations of an SSW?

    Now im retalively new to watching developments in the Stratosphere, i know very little, but ive seen the Met Office vid and read the comments on here and elsewhere that a SSW 2/3 of the time leads to a Big Freeze for the UK.

    But is that strictly true?

    I found a list somewhere and copied it to my files (sorry i dont know now where it came from so cannot source it, it may well have been on here) which listed major SSWs from 1958 until 2013. There were 35, (displaced vortex/split vortex half and half).
    Using the Hadley centre CET index i plotted the winter months (Dec Jan Feb) which had a very low CET which obviously indicated a long cold spell. In the time period 1958-2013 there were 17 very cold months.

    That suggests that SSWs dont really lead to a lengthy cold spell, and dont have much of a say on our wintry weather.

    Then take into consideration that most of our really notable cold spells, 62/3, 78/9, feb 86, jan 87, feb 91, jan and december 2010 didnt have a SSW at all and December 81 and January 85 had a SSW when the cold had already started, it begs the question, just how important are SSWs for cold, and more  importantly, if some of our most notable lasting cold spells werent driven by a SSW, then what DID drive them? Are we missing something here?

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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

    I'd not go as far as saying they are overrated because even in my weather time period they have produced cold spells however I do agree that they are not the be all and end all and that there are times they flop, times they produce a short cold spell then just leave a high somewhere near the UK or times they upset an already cold pattern.

    All they really do is change the pattern to one that normally generates a -AO for a time.

    I do think those expecting rampant easterlies rather than north westerlies have been spoilt though in recent years. An amplified pattern in a -AO backdrop can deliver a range of outcomes as we've seen this month.

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    Posted
  • Location: chellaston, derby
  • Weather Preferences: The Actual Weather ..... not fantasy.
  • Location: chellaston, derby
    2 minutes ago, sebastiaan1973 said:

    The question is. Overrated by whom?

    Well since TBFTE 3 years ago there seems to be a lot more interest in SSWs now then there was before. They have become the latest trend imho, so because of the extreme result of the SSW 3 years ago are held as being more important to those seeking cold?

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    Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

    I think it might have more to do with increasing background warmth than with the SSWs themselves? Either that, or we used to get about six SSWs each year, back in the 1960s!🤔

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    Posted
  • Location: chellaston, derby
  • Weather Preferences: The Actual Weather ..... not fantasy.
  • Location: chellaston, derby
    1 hour ago, pinball wizard said:

    More a case of misunderstood than overrated in my opinion...

    Good point...

    But maybe i shouldnt have used the term overrated, its rather loaded.. perhaps "are ssws that important for cold"?

     

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    Posted
  • Location: Ipswich - Suffolk
  • Location: Ipswich - Suffolk
    2 minutes ago, mushymanrob said:

    Good point...

    But maybe i shouldnt have used the term overrated, its rather loaded.. perhaps "are ssws that important for cold"?

     

    I think too many people fail to recognise SSWs are just one part of a meteorological global jigsaw, the met office did a forward look video a couple of weeks ago on this very issue. The key point they made was that this ssw was taking place during a time where goings on with the pacific ocean temperature meant that there were competing drivers influencing our weather in north west europe that could serve to cancel one another out. 

    The mod thread this year has been dominated with hyperbole surrounding charts showing snow at T240+, that combined with constant mentions of ssw has led some down the garden path.

    I personally don't bother with the ups and downs and inaccuracies of model runs beyond T144. What I'm finding more accurate and more useful is following the weatherquest weekly forecasts which go into great detail regarding week 2,3,4 ensembles. These give a view as to the broader influences and potential direction we could be heading. When these are combined with the model charts up to T144 you get a good view of what to expect over the coming days and a look to what could happen in the future without going into pointless details. Works for me. 

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    Posted
  • Location: Morecambe
  • Location: Morecambe

    I always find with a SSW it changes the weather pattern over the Arctic(polar vortex changes to high pressure) and this has happened and we can see the easterly winds on the charts but they are affecting Iceland and Newfoundland. We just not had any Atlantic ridges or Scandi highs to bring easterly winds over the UK. It's either bought a low pressure system right over us or NW'lies winds so the cold has always been quite tepid but cold enough for snowfall in places. 

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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
    1 hour ago, mushymanrob said:

    Good point...

    But maybe i shouldnt have used the term overrated, its rather loaded.. perhaps "are ssws that important for cold"?

     

    I would say yes but not definitively. All an SSW is, is a mean reversal of zonal winds at 60N. 

    I suspect that if we analyse mean monthly zonal values what we will find in your cold non SSW months is that zonal winds were weak but not reversed as a mean. Of course if only 40% of places at 60N are recording easterlies it's entirely possible for the UK to be in that 40% or Greenland ect..

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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL

    It depends whether you get snow or not I suppose.

    The SSW response so far has been very hit and miss and not exactly deep cold.

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    They sometimes seem to be related to a prior tropospheric pattern that is already interesting in its own right, in that sense they appear to me to be detrimental and unwanted. 

    In El NIno winters they're probably more welcome, helping bring an end to an active Atlantic. 

    (Anyway, in the proud tradition of the internet, that's my loudly shouted opinion on a subject that I know nothing about.)

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    Posted
  • Location: Essex Riviera aka Burnham
  • Weather Preferences: 30 Degrees of pure British Celsius
  • Location: Essex Riviera aka Burnham

    I think the 2018 event certainly has skewed what people expect or to a degree what to expect...to my little knowledge on the subject that February 2018 SSW was a 'classic' split for us in little UK to receive the goodies, which certainly doesn't happen 2 out of 3 times but usually a displacement or less favourable split and something less noteworthy. 

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    Posted
  • Location: Arendal, Norway
  • Weather Preferences: Snow, snow and more snow!
  • Location: Arendal, Norway

    What I've been told by a meteorologist it is that "Yes they are overrated".

    We have seen that heights in Urals caused the 1st SSW of this year, so the main question is "Which came first: the chicken or the egg?"

    So is SSW causing things to happen at lower levels, or the opposite? Or both? 🤔

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    Posted
  • Location: Windsor
  • Weather Preferences: Snow and cold
  • Location: Windsor

    The global warming is causing a whole new lots of anomalies such as low heights close to West Norway. Last century that wasn’t the case and it was possible for SSW’s to promote colder winters. 
     

    The Arctic profile has changed now and we can’t expect the same responses from SSWs as we used to do unfortunately.

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    Posted
  • Location: Morecambe
  • Location: Morecambe
    On 22/01/2021 at 20:27, prolongedSnowLover said:

    The global warming is causing a whole new lots of anomalies such as low heights close to West Norway. Last century that wasn’t the case and it was possible for SSW’s to promote colder winters. 
     

    The Arctic profile has changed now and we can’t expect the same responses from SSWs as we used to do unfortunately.

    I'm not sure I buy into that tbh. I think we are seeing the effects of the SSW on the weather charts but because the easterly winds have not affected us, people are thinking wrongly imo there has been little to no affect on the output.

    Pressure has been higher across the Arctic this winter and it has tried to affect our weather but not in a huge way. As I said in a previous post, all the easterly winds are happening over Iceland and newfoundland. There is small hints the UK may get easterly winds soon so if that happens, then opinions may change on the SSW.

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    Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

    No they are not overrated.  Since 2011, all bar one significant snowfalls in Oxfordshire have been linked in some way to a SSW either recently, or in Mar 2013 a couple of months ago, but still linked to it.  The exception was 10/12/17.   Snow just doesn’t tend to happen in central southern England without something really disrupting the prevailing westerlies anymore.  

    That doesn’t mean that a SSW can be expected to result in a deep freeze like 2018.  It could just provide assistance to the kind of wedge type scenario that gave a snowy week in Jan 2013, and this one looks like it is going the same way.  

    Big freezes - well they may occur infrequently and not because of a SSW - think Dec 2010.  

    So provided expectations are tempered, SSWs are significant for cold in the south of England.

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    Posted
  • Location: Port of Ness,Isle of Lewis.
  • Location: Port of Ness,Isle of Lewis.

    SSW’s may well be filed away in the same bin as the Thermohaline Conveyer shut down,with reference to their bringing Armageddon type Winter Synoptics.😜

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    Posted
  • Location: chellaston, derby
  • Weather Preferences: The Actual Weather ..... not fantasy.
  • Location: chellaston, derby
    2 hours ago, Mike Poole said:

    No they are not overrated.  Since 2011, all bar one significant snowfalls in Oxfordshire have been linked in some way to a SSW either recently, or in Mar 2013 a couple of months ago, but still linked to it.  The exception was 10/12/17.   Snow just doesn’t tend to happen in central southern England without something really disrupting the prevailing westerlies anymore.  

    That doesn’t mean that a SSW can be expected to result in a deep freeze like 2018.  It could just provide assistance to the kind of wedge type scenario that gave a snowy week in Jan 2013, and this one looks like it is going the same way.  

    Big freezes - well they may occur infrequently and not because of a SSW - think Dec 2010.  

    So provided expectations are tempered, SSWs are significant for cold in the south of England.

    But thats no timeframe, the point im trying to make is - what caused the big freezes that werent linked to an SSW? like 62/3, 78/9, 81/2, etc... It seems to me SSWs are good for late cold events, but not earlier ones?

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    Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
    2 minutes ago, mushymanrob said:

    But thats no timeframe, the point im trying to make is - what caused the big freezes that werent linked to an SSW? like 62/3, 78/9, 81/2, etc... It seems to me SSWs are good for late cold events, but not earlier ones?

    There used to be many more ways that could result in cold for the UK in the past.  That doesn’t seem to be true anymore, this thread probably not the place to discuss why that is, but in the warmer world, more disruption seems to be needed away from the status quo of westerlies, and a SSW provides that (70% of the time).  Now most of us have had some snow, this one probably qualifies as one that did deliver, but the effects are likely to be seen still for a good further month yet, so let us judge it in March!

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