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Stratosphere watch 2020-21

245

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  • #32
    bazlers
    Registered Users Posts: 692 ✭✭✭bazlers


    Great post Sryanbruem. Starting to get giddy myself.
    Anothe question yoy dont gave to go into great detail with reply but was 1947 and 62/63 consideed as ssw events?


  • #33
    nacho libre
    Registered Users Posts: 16,621 ✭✭✭✭nacho libre


    Billcarson wrote: »
    It would be ironic and just our luck if we got into a decent cold pattern which is possible from what the models are showing...........

    .... and then for an ssw to change the pattern to something less cold. I think I'd cry......

    Yeah, that would be a real kick in the teeth if it happened. As Sryan mentioned if there is a SSW it will ask questions of long range models like Glosea5. Personally i'll be glad if they get it wrong, aside from the obvious reason, i don't like the idea of models being able to predict 3 months ahead. I know a lot of people will say this will never happen, but if it did a lot of the fun of model watching would be gone.


  • #34
    Strangegravy
    Registered Users Posts: 356 ✭✭Strangegravy


    gfsnh-10-384_pdm0.png

    Well this is interesting :cool:


  • #35
    Captain Snow
    Registered Users Posts: 600 ✭✭✭Captain Snow


    Strangegravy wrote: »
    gfsnh-10-384_pdm0.png

    Well this is interesting :cool:

    Its been pulled apart...good news.:)


  • #36
    sryanbruen
    Registered Users Posts: 13,492 ✭✭✭✭sryanbruen


    bazlers wrote: »
    Great post Sryanbruem. Starting to get giddy myself.
    Anothe question yoy dont gave to go into great detail with reply but was 1947 and 62/63 consideed as ssw events?

    1947 predates stratospheric records in the 1950s unfortunately but has been part of many discussions before of how it became so severe and so suddenly from the second half of January as pressure rose initially from the south.

    1962-63 had a Canadian Warming event in November which is another type of SSW event that occur mostly in Nov/Dec. These are similar to minor SSW events in that they are generally not associated with a reversal in zonal mean zonal winds at 60N 10hPa (with some exceptions like Nov 2000). This likely had some impact in displacing the Greenland lobe of the vortex allowing high pressure to build, helped by the fact there was the developments of a North Atlantic tripole which favours negative NAO. January 1963 did have a major SSW event which likely helped prolong the cold winter pattern into February.

    Photography site - https://www.sryanbruenphoto.com/

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  • #37
    sryanbruen
    Registered Users Posts: 13,492 ✭✭✭✭sryanbruen


    Strangegravy wrote: »

    Well this is interesting :cool:

    Yesterday, we saw the first GFS run with a reversal at 60N 10hPa although just barely at -1.0 m/s. This still constitutes as a major SSW event. The consistency from the GFS on this SSW event has been notable. It is still showing now with the prospects of the split in early January.

    This is being driven by the forecast of possibly near or record breaking heat flux, and may occur at a similar time to the major SSW events of January 1985, January 2013 and January 2019.

    Continues to look interesting in the stratosphere indeed. If (there's always ifs involved!) the strat were to follow with a quick tropospheric response for Europe, the upcoming seasonable period with a series of polar maritime NW'lies and N'lies will be more of a teaser if anything.

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  • #38
    igCorcaigh
    Moderators, Recreation & Hobbies Moderators Posts: 11,042 Mod ✭✭✭✭igCorcaigh


    Thoughts?

    https://twitter.com/SimonLeeWx/status/1340345382056972289?s=19


  • #39
    Gonzo
    Moderators, Science, Health & Environment Moderators Posts: 16,697 Mod ✭✭✭✭Gonzo


    the 12z has updated and is looking most interesting.

    A fairly major warming by New Years Eve.

    gfsnh-10-252.png?12

    Another warming takes place between Newfoundland and Cork/Cornwall/Essex

    gfsnh-10-318.png?12

    January 3rd, Goodbye PV, looks like a fairly decent displacement and split.

    gfsnh-10-384.png?12


  • #40
    sryanbruen
    Registered Users Posts: 13,492 ✭✭✭✭sryanbruen


    igCorcaigh wrote: »
    Thoughts?

    https://twitter.com/SimonLeeWx/status/1340345382056972289?s=19

    Mentioned it in above post :)
    sryanbruen wrote: »
    Yesterday, we saw the first GFS run with a reversal at 60N 10hPa although just barely at -1.0 m/s. This still constitutes as a major SSW event. The consistency from the GFS on this SSW event has been notable. It is still showing now with the prospects of the split in early January.

    This is being driven by the forecast of possibly near or record breaking heat flux, and may occur at a similar time to the major SSW events of January 1985, January 2013 and January 2019.

    We have now had the second GFS run that sees a major SSW event happening and the central date (day the reversal happens) being January 2nd. This run shows a bigger reversal than the previous one. In fact, as far as the run goes to t384, the 10hPa zonal mean zonal wind drops to -24.6 m/s at 60N on 5 January. That is a solid major SSW event if I ever saw one.

    dIqhGpG.jpg

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  • #41
    nacho libre
    Registered Users Posts: 16,621 ✭✭✭✭nacho libre


    What are your thought on these comments, Sryan:

    "That was the big lesson taught by 2019's failed downward propagation. That SSW was huge, featuring some record-breaking vertical wave activity flux, but predominantly wave-1 driven.

    In such a situation, it seems to be much less likely that the vertical structure of the stratosphere aligns in a way that permits rapid downward propagation.

    Instead we're left looking for 'drip-down' of anomalously warm stratospheric temps to produce a negative NAM (i.e. negative AO in the troposphere), which tends to produce smaller-scale impacts that more easily miss the UK. It can also be stalled by an unreceptive troposphere, much as we saw in Jan-Feb 2019.

    In a wave-2 dominated SSW, there's still no guarantee of the rapid downward propagation, but at least some slower propagation seems to be very likely and the resulting cold weather outbreaks tend to cover wider areas and persist for longer. Of course, the UK can still miss out, being such a narrow slither of the hemisphere."

    Do you think this will be a wave 2 dominated SSW? Also, are you concerned
    that the Glosea model isn't on board with this yet?


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  • #42
    sryanbruen
    Registered Users Posts: 13,492 ✭✭✭✭sryanbruen


    nacho libre wrote: »
    What are your thought on these comments, Sryan:

    "That was the big lesson taught by 2019's failed downward propagation. That SSW was huge, featuring some record-breaking vertical wave activity flux, but predominantly wave-1 driven.

    In such a situation, it seems to be much less likely that the vertical structure of the stratosphere aligns in a way that permits rapid downward propagation.

    Instead we're left looking for 'drip-down' of anomalously warm stratospheric temps to produce a negative NAM (i.e. negative AO in the troposphere), which tends to produce smaller-scale impacts that more easily miss the UK. It can also be stalled by an unreceptive troposphere, much as we saw in Jan-Feb 2019.

    In a wave-2 dominated SSW, there's still no guarantee of the rapid downward propagation, but at least some slower propagation seems to be very likely and the resulting cold weather outbreaks tend to cover wider areas and persist for longer. Of course, the UK can still miss out, being such a narrow slither of the
    hemisphere."

    Do you think this will be a wave 2 dominated SSW? Also, are you concerned
    that the Glosea model isn't on board with this yet?

    All good and fair points brought forward by that Netweather poster. Difficult to say personally until we get into the event itself but GFS seems to suggest a wave-2 split of some kind from my amateur observation though this needs to become a trend (only the second GFS run to show a reversal for instance).

    No, I am not overly concerned that the Glosea5 isn't on board with the idea of a major SSW event. Models playing catch up can come at short notice, just look at the ECM this evening for the weekend of the 26th/27th - not saying it will though the GFS consistency as of late has been noteworthy.

    Just a reminder of what made 2019 different in comparison to Jan 2009, Jan 2013 and Feb 2018.

    https://twitter.com/SimonLeeWx/status/1081255703053041664?s=20

    Photography site - https://www.sryanbruenphoto.com/

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  • #43
    sryanbruen
    Registered Users Posts: 13,492 ✭✭✭✭sryanbruen


    18z is another reversal and wave-2 split. In fact, a very notable split. One of the most beautiful charts I have seen - still not quite February 2018 beautiful in my opinion though but up there most definitely.

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  • #44
    sryanbruen
    Registered Users Posts: 13,492 ✭✭✭✭sryanbruen


    0z showed a major SSW event (reversal) again but 06z shows zilch though a significant warming regardless. Shows it's still up in the air rather than totally certain, we're still talking about quite deep FI here.

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  • #45
    Storm 10
    Registered Users Posts: 5,870 ✭✭✭Storm 10


    sryanbruen wrote: »
    0z showed a major SSW event (reversal) again but 06z shows zilch though a significant warming regardless. Shows it's still up in the air rather than totally certain, we're still talking about quite deep FI here.

    What are we talking about here is it a storm or what


  • #46
    Artane2002
    Registered Users Posts: 1,983 ✭✭✭Artane2002


    Storm 10 wrote: »
    What are we talking about here is it a storm or what

    a warming of the stratosphere, check out the excellent first post of the thread by Sryan which explains what a sudden stratospheric warming is.


  • #47
    bazlers
    Registered Users Posts: 692 ✭✭✭bazlers


    If an ssw occurs will it enhance the cold spell forecast or hinder or is it just a wait see?
    Im also aware that neither this forecast cold spell may occur or the SSW event but just wondering how it would interact with a given forecast?


  • #48
    nacho libre
    Registered Users Posts: 16,621 ✭✭✭✭nacho libre


    bazlers wrote: »
    If an ssw occurs will it enhance the cold spell forecast or hinder or is it just a wait see?
    Im also aware that neither this forecast cold spell may occur or the SSW event but just wondering how it would interact with a given forecast?

    It's really impossible to tell, a split, as oppose to a displacement, increases our chances of a cold spell, but it could go awry and flip the pattern to a milder set up for us.

    I think Sryan could be right about the GFS leading the way.


  • #49
    bazlers
    Registered Users Posts: 692 ✭✭✭bazlers


    Thanks Nacho.

    Matt Hugo
    @MattHugo81. i see this guy is bigging the cold potential up big style. I know nothing about him if this is credable or not. He posted a chart aswell that i dont understand but seemingly ECM had a big change. Good or bad for those who like cold? I have no idea..


  • #50
    Artane2002
    Registered Users Posts: 1,983 ✭✭✭Artane2002


    bazlers wrote: »
    Thanks Nacho.

    Matt Hugo
    @MattHugo81. i see this guy is bigging the cold potential up big style. I know nothing about him if this is credable or not. He posted a chart aswell that i dont understand but seemingly ECM had a big change. Good or bad for those who like cold? I have no idea..
    the ECM brought a good change, the mean zonal wind speed in the stratosphere is predicted to dip down to 5 m/s by the ECM mean, so getting close to a reversal, ie. a major SSW.


  • #51
    bazlers
    Registered Users Posts: 692 ✭✭✭bazlers


    Artane2002 wrote: »
    the ECM brought a good change, the mean zonal wind speed in the stratosphere is predicted to dip down to 5 m/s by the ECM mean, so getting close to a reversal, ie. a major SSW.

    Cheers Artane, the charts looked more or less the same to me. Il have to do a good bit of research on this topic.


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  • #52
    Artane2002
    Registered Users Posts: 1,983 ✭✭✭Artane2002


    bazlers wrote: »
    Cheers Artane, the charts looked more or less the same to me. Il have to do a good bit of research on this topic.

    the mean (the thick blue line) has reduced by 15m/s compared to Thursday's update.

    https://twitter.com/MattHugo81/status/1341112679130419209


  • #53
    bazlers
    Registered Users Posts: 692 ✭✭✭bazlers


    Yes just roughly at the 5th and 6th. Metres per second. Missing the woods from trees. Thanks.


  • #54
    Kermit.de.frog
    Registered Users Posts: 23,433 ✭✭✭✭Kermit.de.frog


    It certainly seems things will be getting more interesting if we see some zonal wind reversal however this does not automatically equate to cold here. It depends on where the cold air is ejected out of the northern latitudes and the downstream synoptic situation from there but it certainly increases our chances.


  • #55
    sryanbruen
    Registered Users Posts: 13,492 ✭✭✭✭sryanbruen


    ECM and Glosea5 both showing a significant weakening of the SPV with Glosea5 now predicting a reversal at 65N - only a matter of time before it shows it for 60N (where the reversal needs to happen for it to be an official major SSW event) in my opinion.

    Recent GFS OP runs, before the most recent 12z, had backed off somewhat on the split and reversal signal but still very much showed an unhealthy vortex that's pretty much inevitable to severe disruption.

    I'm almost at the point of saying "it's game on" with regards to the stratosphere on a major SSW event occurring (not necessarily a split) but I'll give it more time. :cool:

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  • #56
    nacho libre
    Registered Users Posts: 16,621 ✭✭✭✭nacho libre


    Well Sryan, do you agree with those who are saying a major displacement is now more likely than a split?


  • #57
    sryanbruen
    Registered Users Posts: 13,492 ✭✭✭✭sryanbruen


    nacho libre wrote: »
    Well Sryan, do you agree with those who are saying a major displacement is now more likely than a split?

    I find that more of a safe bet than what is "likely" to be honest albeit can see where they are coming from (nature is always willing to surprise). All major SSW events begin with displacements to greater or lesser degrees. Need to keep an eye on developments of a secondary warming in the North Atlantic which would be a highly unusual location to see a warming to say the least. This warming event might be more conducive to a Greenland block rather than the development of a Scandi High which is a bit unusual. Just seen that ECM is showing a modest wave-2 warming around New Year, wouldn't be enough to suggest a big split I don't think but it's the first time ECM has shown something like this. It doesn't go out as far as GFS does anyway when that was showing a split to occur.

    Everything else remains the same and in fact, the latest ECM ensemble mean goes for a major SSW event (reversal) in early January. I'd say that's game on now, let's see how it evolves. Be a pretty big flop if it wasn't a major SSW event from the model output.

    I don't use "this is the most excited I have been" pretty lightly ;)

    Merry Christmas to you all! Hope you have a good one.

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    Weather photo portfolio - https://sryanbruen.myportfolio.com/weather-1



  • #58
    Kermit.de.frog
    Registered Users Posts: 23,433 ✭✭✭✭Kermit.de.frog


    How fast will the down-welling through the layers occur? - that's the question. It can take many weeks for the results to be seen at 500hpa.


  • #59
    bazlers
    Registered Users Posts: 692 ✭✭✭bazlers


    sryanbruen wrote: »
    I find that more of a safe bet than what is "likely" to be honest albeit can see where they are coming from (nature is always willing to surprise). All major SSW events begin with displacements to greater or lesser degrees. Need to keep an eye on developments of a secondary warming in the North Atlantic which would be a highly unusual location to see a warming to say the least. This warming event might be more conducive to a Greenland block rather than the development of a Scandi High which is a bit unusual. Just seen that ECM is showing a modest wave-2 warming around New Year, wouldn't be enough to suggest a big split I don't think but it's the first time ECM has shown something like this. It doesn't go out as far as GFS does anyway when that was showing a split to occur.

    Everything else remains the same and in fact, the latest ECM ensemble mean goes for a major SSW event (reversal) in early January. I'd say that's game on now, let's see how it evolves. Be a pretty big flop if it wasn't a major SSW event from the model output.

    I don't use "this is the most excited I have been" pretty lightly ;)

    Merry Christmas to you all! Hope you have a good one.

    It could be a winter of biblical proportions. I winter that could contest the best.
    It could also be the biggest let down we have seen in forever. Flip of a coin where the PV ends up if a split does occur.
    Although as i have said a while back my thinking is 20ft drifts!


  • #60
    nacho libre
    Registered Users Posts: 16,621 ✭✭✭✭nacho libre


    Hopefully if we do get a split, it would be similar to what took place 2018. As, if i'm not mistaken, the response in the troposphere was fairly quick to that.


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  • #61
    Gonzo
    Moderators, Science, Health & Environment Moderators Posts: 16,697 Mod ✭✭✭✭Gonzo


    nacho libre wrote: »
    Hopefully if we do get a split, it would be similar to what took place 2018. As, if i'm not mistaken, the response in the troposphere was fairly quick to that.

    The split seems to be gone for now, the GFS backtracked on a big split few days ago. It still looks a decent warming, a displacement and stretch rather than a split. Perhaps in January we will see further warming and perhaps a split.

    gfsnh-10-384.png?6


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