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SUDDEN STRATOSPHERIC WARMING (Watch 2012-2013)

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  • odyboody wrote: »
    Cheers Red,
    Suppose my question is , was the 09 SSW identified as an event which could bring cold and lived up to its billing, or is this the first identified event prior to cold and we are waiting for it to verify

    The 09 event was well flagged. I started a thread on it 4 years ago. Haven't time to look for it but we were all Green then. I presume it's useless now anyway as graphics were all live and will have changed.

    Here is a link from my book marks.
    http://m.earthobservatory.nasa.gov/IOTD/view.php?id=36972




  • @ Mr Bumble

    All other additional warmings help to keep the PV reforming into its favourite state. It's always trying to reform so it can bottle up the cold. The polar night jet is not happy.

    It's a waiting game in seeing where we come out in this. Perhaps Canada/parts of USA come out best but cold is leaking from the pole and is just looking for the gaps to pour through.
    Hang fire for a while.




  • Excellent Video here on SSW folks , fill your boots

    http://www.bbc.co.uk/weather/feeds/20992173




  • Excellent video! I'll be using that one in the classroom next week. Thanks!




  • Trotter wrote: »
    Excellent video! I'll be using that one in the classroom next week. Thanks!

    have it as a youtube vid now



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  • anyone know if the SSW is causing the cold on the west coast of the US? Baltic in AZ, never seen it before.




  • Nice graphic of the ssw from matt hugos twitter
    http://i50.tinypic.com/1zwgkmd.gif




  • Remarkable thing.
    After watching the chaos in models on the other threads here over the last few weeks why is something so big so predictable....ie once identified, the more learned among us seem to have been able to name dates for the SSW, predict three separate warmings with total confidence and everything has come to pass on schedule. This thread was kicked off again on November 10 and with a reasonably confident prediction that December would brings signs of an impending SSW. Long way of asking a question but if every other facet of weather is so unpredictable, why is an SSW less so....or am i surrounded by savants??:o




  • Mr Bumble wrote: »
    Remarkable thing.
    After watching the chaos in models on the other threads here over the last few weeks why is something so big so predictable....ie once identified, the more learned among us seem to have been able to name dates for the SSW, predict three separate warmings with total confidence and everything has come to pass on schedule. This thread was kicked off again on November 10 and with a reasonably confident prediction that December would brings signs of an impending SSW. Long way of asking a question but if every other facet of weather is so unpredictable, why is an SSW less so....or am i surrounded by savants??:o

    Tropospheric modeling is so unpredictable because the atmosphere interacts with oceans, landmasses and mountains among other things. Far more variables. Many of which are not possible to model. Due to the butterfly effect, small unpredictable changes on the surface can have big consequences.

    The stratosphere doesn't have so may influences and is far more stable. As a result it is much less complex to model. It is also much easier to use your intuition to forecast if you know how the few variable there are interact. This in turn makes forecasts for changes in the stratosphere much more reliable and accurate.




  • QED!...thanks for that....two more!....is an SSW a wild card event or are there specifics to look for months in advance. Do we know what triggers one? I note that they were first recognised in the 50s and wondered why everyone is so hot on them now?? SImple hype or are they potentially more profound in terms of future modelling??


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  • Mr Bumble wrote: »
    QED!...thanks for that....two more!....is an SSW a wild card event or are there specifics to look for months in advance. Do we know what triggers one? I note that they were first recognised in the 50s and wondered why everyone is so hot on them now?? SImple hype or are they potentially more profound in terms of future modelling??

    I'll leave those two to somebody a lot more knowledgable. Redsunset!? You're needed!




  • Since the SSW has peaked out, its time to look at model performance of GFS and ECMWF in the last 31 days (ending on 14.1, so its fresh). Might be interesting for some, and boring for others. smile.png The area of the verification is 20N-80N, basically where all the main action was. smile.png

    First we have the 10mb temperature bias. We can see that GFS had a warm bias which increased with the forecast time, while ECMWF had a cold bias, also increasing with the forecast time. This means that GFS has slightly too warm forecasts with time, and ECM slightly too cold.

    biasdieofftp10g2nhx.png

    The 10mb GPH bias. Both GFS and ECM had a negative bias for heights, increasing with forecast time. Basically meaning, they were promoting a stronger vortex with the increased forecast hour, especially the ECM.
    biasdieoffhgtp10g2nhx.png

    The "die off" for 10mb GPH. Skill score reducing with time (GFS still very good at 240h). Basically GFS outperformed the ECM in the stratosphere, especially on the actual SSW event, as I will show below.

    msessdieoffhgtp10g2nhx.png

    10mb 20N-80N, 10-day zonal wind forecast. At the time of the SSW event, GFS outperformed ECMWF (higher the score, better the forecast). This is the accuracy of the forecast issued 10 days before the forecasted date.

    msessday10up10g2nhx.png

    50mb Temperature forecast. GFS outperformed the ECM in 10day forecasts, in the SSW period.

    msessday10tp50g2nhx.png

    10mb Temperature. GFS outperformed the ECM in the 10 day forecasts, except for the last 2 days.

    msessday10tp10g2nhx.png

    10mb GPH, 10day forecast skill. GFS nicely outperformed the ECM in 10 day forecasts of the SSW.

    msessday10hgtp10g2nhx.png

    GFS basically had better performance with the 8-10 day forecasts of the SSW. But notice the very high skill score of the 10 day forecasts, prior to the SSW, where there is much less complex dynamics. And that is what I was telling about the power of the model stratosphere forecasts in the 240h-300h period, compared to tropospheric reliability.




  • More interesting stratospheric charts today.

    So, so far this winter we have seen early tropospheric wave breaking into the lower strat whilst simultaneously the mid strat has cooled dramatically. A massive increase in wave 1 activity then has led to a displacement SSW and this has immediately been followed by an increase in wave two activity leading to a split vortex and another warming. And that is pretty much where we are today.

    Looking at the 10 hPa charts we see a strong Canadian vortex with a weker Siberian vortex in situ with a ridge keeping them apart.

    post-4523-0-41249600-1358240600_thumb.png

    BY day three the Canadian vortex comes under further attack and weakens further increasing the strength of the ridge:

    post-4523-0-11783900-1358240711_thumb.png

    The net result at 100 hPa is that the ridge displaces somewhat towards the Atlantic sector but not fully, and critically there is a developing Greenland ridge in place at this level by day 5.

    post-4523-0-61409500-1358240933_thumb.png

    The net result is that any tropospheric trough trying to cross the Atlantic is likely to weaken and be displaced on a more southerly track - perhaps even more so then we have seen on the tropospheric model output so far.

    And behind this is there a possiility that tropospheric Greenland heights are being under estimated? (Remember Cohen?)

    So does a strong Atlantic trough fit in with the MJO phases?

    http://www.cpc.ncep....clivar_wh.shtml

    Errr, no not at all - the MJO is showing signs that it will move into phase 7 which the anomaly suggests the outlook is this:

    post-4523-0-72726600-1358241339_thumb.gif

    A stonking Atlantic ridge - compare this to the GFS ensemble mean anomaly chart:

    post-4523-0-44059800-1358241472_thumb.gif

    Unable to get ECM ones but the earlier output suggested better ridging.

    So my thoughts - well I think that the GFS is overplaying the strength of the mid Atlantc ridge some what. Yes we are likely to see some energy cross the Atlantic however this is likely to be followed by pressure rises behind linking up with the retrogressing high and a strong greenland block to develop after.

    So any breakthrough is likely to be either temporary, non existant, or limited to the very south followed by a blocked Atlantic.

    This is then going to allow one mighty cold blast from the NE get jolly close to the UK!!!!!

    http://forum.netweather.tv/topic/74587-stratosphere-temperature-watch-20122013/page__st__2060#entry2502849




  • Thanks Ed, appreciated, was going to try and run through a few charts myself as its been rather quite here, but as ever that answers my questions! As an additional note the EC32 maintains a signal for higher than average pressure over Greenland and the North Pole in general really throughout the forecast period but it also signals a particularly -ve pressure anom across and to the W of the UK signalling a particularly cyclonic and 'active' mid and eastern Atlantic and into the UK. Clearly whether this occurs or not I don't know, but it is attempting to model lows on a more southerly track, but overall the EC32 day doesn't paint a particularly cold outlook towards the end of January with temps forecast to rise to near average. Clearly it'll be interesting to see whether it is way off or not.

    I can't but help think that if we do get the scenario you describe then we are really looking at a prolonged period of cold weather for the UK and potentially very cold if that N or NE'ly flow can be achieved. It's interesting to note that some of the recent GFS ENS are particularly cold later in the month. All to play for throughout the second half of the winter and I certainly believe there is little chance of the vortex restrengthening or returning to a more organised state, enough to affect the troposphere.

    One question I have for you, which reply when you get chance is as follows;

    What variables evident did you acknowledge or know to look for weeks in advance to give you a solid grounding to suggest that a SSW would occur in January?. I remember this being mentioned way back in early to mid-December at a time when the ECMWF charts were clearly not even touching late December, let alone early January and the GFS model may have only been reaching late December as well?.

    What is fascinating here is that whilst we all acknowledge the conditions in the stratosphere are more 'stable' than that in the troposphere I would be interested to hear your thoughts, detailed if possible, as to what was being acknowledged at the start of the winter to gauge the event we have just experienced. I am certainly playing 'catch up' here in terms of what signs and signals to look for on a longer term basis.




  • Hi Matt,

    The likelihood of a January SSW was increased in November when the snow gain charts for October came through. When this was choreographed to the descending easterly QBO, weakening El NIno and previous similar years composites then the chance of one occurring was higher than one not. We had also witnessed extremely strong wave 1 activity in the southern hemisphere during our autumn leading to a dramatic warming there. It seemed likely that that could be reproduced in the NH once the tropical strat had recovered.

    If we go back to this post below

    http://forum.netweat...00#entry2440103

    and the chart posted at 10 hpa, then those signs were coming to fruition with the build up of warming in the far East mid latitudes, suggesting an increase in wave 1 activity was imminent. Once this had occurred (deep in FI) in more than 1 run then I suspected that the GFS was onto something. From there, with a little bit of experience, I could work out the chain of events and timeframe leading to the possible SSW - I couldn't have predicted that a split would follow, but did think that the wave activity would be strong enough from the snow cover gain feed back loop, to produce vortex disintergration. And that has proved the case.




  • Now plenty there for the lot of you to get your teeth into !




  • So in layman terms its not looking good for snow lovers in Ireland.

    That info is way over my head!




  • Bejubby wrote: »
    So in layman terms its not looking good for snow lovers in Ireland.

    That info is way over my head!
    The opposite it looks great ...the full effects haven't even started yet...




  • The opposite it looks great ...the full effects haven't even started yet...



    Excellent.




  • Now plenty there for the lot of you to get your teeth into !

    Is it me or has the ECM 32 day been a total joke this winter?
    EC32 maintains a signal for higher than average pressure over Greenland and the North Pole in general really throughout the forecast period but it also signals a particularly -ve pressure anom across and to the W of the UK signalling a particularly cyclonic and 'active' mid and eastern Atlantic and into the UK.


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  • Hi does anyone know if the strat is due to reboot the warming over the coming weeks?




  • The BBC is saying that SSW is largely responsible for the coming snow in the UK. (link)
    Not every SSW event leads to a bitter spell for us in the UK, and not every cold spell is caused by SSW - the atmosphere is far more complicated than that.

    But SSW is a powerful tool for forecasters, and at the end of last week it became clear that this particular SSW would have a big impact on our weather. Indeed further snowfall is anticipated across the UK in the next few days.

    The history of military conflict in Afghanistan [has] been one of initial success, followed by long years of floundering and ultimate failure. We’re not going to repeat that mistake.

    -- President George W. Bush, in a speech at the Virginia Military Institute.





  • Looking like this SSW is above the trend and is going strong.

    http://ds.data.jma.go.jp/tcc/tcc/products/clisys/STRAT/html_e/pole30_n.html

    http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_TEMP_MEAN_ALL_NH_2013.gif

    http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/30mb9065.gif

    Second warming event is in play and the longer these events go on , the better the chances are for Feb. Well that is my thinking anyway.

    Thanks to Chiono over on Netweather.tv forum for the AO chat below
    and all the info.

    http://forum.netweather.tv/topic/74587-stratosphere-temperature-watch-20122013/page__st__2120

    index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=156033




  • Stratospherically we are still seeing a NH pattern dominated by the recent SSW. Contrary to some opinions, this has downwelled from the mid stratosphere and affected the troposphere. It is always hit and miss how and where the SSW can have knock on effects in the troposphere and it appears that we have been lucky to see the split vortex favourably positioned to prevent the jet stream powering through during the two week mid January period.

    However, that is about to change as further warming of the stratospheric Canadian vortex which allows it's tropospheric counterpart to break free. West to east momentum initially is set to carry this across the Atlantic to its Siberian counterpart as can be seen in this 30 hPa chart.

    post-4523-0-08087600-1358854751_thumb.png


    As this occurs there will be a corresponding increase in Atlantic mobility allowing the westerlies to reach the UK rather than be held at bay. The stratospheric vortex even though weak will be positioned on the Atlantic sector meaning a far less meridional jet stream whereas the Pacific sector will have a far more disturbed flow due to the upper ridge holding strong. This pattern will be as of a direct consequence to recent stratospheric events - but the wheel of fortune will be dropping off the meridional cold flow elsewhere in the NH.

    So the main question that everyone is asking is will we likely to see a pattern re- emerge that can bring back the cold and blocking to our shores. And the answer is not immediately but definitely not no!

    With the weakened vortex conditions likely to persist for a period of time then it is only a matter of time before realignment occurs in line with the MJO and GWO.

    The stratospheric forecasts during the next 10 days right up to 10 hPa are showing and will show signs of increased fluctuations in the exact position of the vortex.

    There are signs of another split occurring around day 10 and this will need to be watched carefully.

    post-4523-0-30403700-1358855796_thumb.png

    post-4523-0-98373000-1358855810_thumb.gif

    If this does occur then we could quite easily see the door to returning cold opened back up again. I think we will need to keep an eye on the strat forecasts very closely in this period.




  • Dont mean to offend anyone, but this SSW blown up to be something fantastic has turned out to be the greatest load of rubbish. A total and complete damp squib. M.Ts predictions seem to be at odds with the Met O. Hopefully the Met O are wrong:(:mad:




  • Dont mean to offend anyone, but this SSW blown up to be something fantastic has turned out to be the greatest load of rubbish. A total and complete damp squib. M.Ts predictions seem to be at odds with the Met O. Hopefully the Met O are wrong:(:mad:

    It's clear you haven't a clue what your talking about.




  • Graupel wrote: »
    It's clear you haven't a clue what your talking about.
    Really :confused:A SSW can be a hit or miss affair. We have missed it or are you clutching to straws. There are a lots "maybes" and "what ifs" complete bull. It has occurred and is still occurring. If you could point out where the models in the next ten days show us the effects of this present SSW. After all it takes anything up to three weeks to manifest itself, this warming event has being going on for over two and a half weeks now (6th of January) The present cold snap has nothing to do with a SSW event. If it did we would the have the full effect of it




  • Really :confused:A SSW can be a hit or miss affair. We have missed it .

    Utter nonsense. Further warmings taking place in the Canadian section look like displacing the vortex from the across the Atlantic. This will again shift the pattern. Potentially in our favour as it could allow for height rises over Greenland. Return to normal a normal PV situation doesn't seem likely or some time.




  • Trying to follow this and thread on netweather and am I wrong in saying that the full impact of the SSW still has to be felt??? And that successive warmings are both projected and happening??
    I asked about the big low off the NW for the weekend on the model thread and whether the storm has it's roots in the SSW event. My understanding of the above is the the low is a part of the split vortex which went to Canada and is now migrating east to link up with it's siberian mate. A big storm like that would certainly rate as a 'hit' I would have thought even if there's no snow with it......and until the Feb projected cold spell has been and gone or not, is it too early to suggest that we've missed?


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  • BEASTERLY wrote: »
    Utter nonsense. Further warmings taking place in the Canadian section look like displacing the vortex from the across the Atlantic. This will again shift the pattern. Potentially in our favour as it could allow for height rises over Greenland. Return to normal a normal PV situation doesn't seem likely or some time.

    That warming is fizzling out at the moment (at the 10hPa level at least) with the forecast showing the strat cooling down again.

    What do you mean by displacing the vortex across the Atlantic? At lower tropospheric level there's a strong signal for the PV to stay in-situ over Canada right out to 384h. My limited knowledge of SSW's is that they can weaken or even disintegrate the PV but there's no clear signs of anything like that happening. I'm not trying to argue your point, just a bit confused by it all with nothing really happening with the vortex other than that Arctic High and the painfully slow flow pattern of late

    gensnh-21-1-384_zfg5.png


This discussion has been closed.
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