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skatefan

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Posts posted by skatefan

  1. As far as I can see this historic SSW is in fact (slowly migrating into) the final warming. I don't see any significant restoration happening coming weeks.

    The stratospherical reverse flow has dropped but is still very neutral. I am asking myself what this dynamically quiet context will mean for the coming weeks and spring. Lingering LP's and shallow HP's don't sound good to me, and don't produce much trop-strat effects.

    Do we have comparing years? 

  2. 2 minutes ago, Bristle boy said:

    It's only 2 days ago the NW 'big guns' were confidently predicting 2 weeks of severe cold; what's gone wrong? (So to speak). A silence has descended today, on the forum, from NW's most respected posters. Stunned?

    Too fast retrogression of the HP creates a level playing field for the LP's. Impossible to say what will happen but the charts don't promiss much!

  3. 4 minutes ago, CK1981 said:

    Cast your minds back to the first SSW. The models were in chaos dealing with the outcome. Many favoured a mild solution, but they were wrong, and at a short time frame.

    Since then, we’ve had a secondary warming. The models will now be in the same position and trying to work out the solution (but with the additional chaos following the first warming)

    I firmly believe they will correct to a colder solution, as before.

    I don't believe that, how much I would like to: the SSW and secondary warming determined the positioning of the HP's: and that gives too much retrogrssion and a free game for the LP's.  

  4. 3 minutes ago, Mike Poole said:

    GEFS ensemble mean at T144 might just calm the nerves:

    gens-21-1-144.png?18

    gens-21-0-144.png?18

    Still think this will go further south, we'll see!

    Nope! The HP above Greenland retrogresses too fast and LP's coming in from the SW will create a big mess of changing conditions, merely S to SE driven..

    Although the ECM12 was at the end clearly a warm outlyer, it presents the trend in the models. After next weekend it is clearly gone with the cold.

    • Thanks 1
  5. 3 minutes ago, jethro said:

    An ode....

    The charts they have shown from long, long away

    That the SSW would hold immense sway

    Some urged caution, some said doubt

    They said 'la la la, we're not listening, our faith is devout'.

    Their ideas they have shown with chart after chart

    Their belief, their knowledge, it came from the heart

    I always reckon, credit where credit's due

    So take it from me, an enormous 'thank you'

    I can't read the charts, they're blob after blob

    I rely on you all doing a fantastic job

    So the beasterly's coming, inching closer each day

    The temperature's dropping, the rain's gone away

    What wonders await? Well no one can say

    But I do know one thing, I'm polishing my sleigh

    Pondering starts, what can it be

    Surely it means '91, maybe '63?

    With charts such as these, manna from heaven

    Sure can mean just one thing, another'47

    The cold, it's a coming, we all know that

    Wrap up warm folks and remember your hat

    Will we get an inversion or plenty of snow?

    Or that mythical beast, a channel low?

    Our dreams they've been busted many times in the past

    The cold came and it went, it just didn't last

    This time it is different, our boffins of gold

    Foresaw and predicted and then we were told

    Look up to the sky, high over the cloud

    Stratosphere it said 'yes' and it said it loud

    So when it comes, go out to play

    Sure check the charts but then step away

    Synoptics like these, well we know that they're rare

    Ski, skate, slip and slide, sledge without care

    Dear Mods I may be a tad off topic

    But charts such as these, by god, they're epic

    Please forgive me I beg, the rule, I don't mock it

    But such weather porn made this lass poetic

    Epic poetry to an epic development.........

    • Like 2
    • Thanks 2
  6. Well, the first week cold will be there, whether or not delayed by a day or so! 

    Then we go to FI-watching: will the Greenland high hold itself and tilt clockwise due to the energie on the Asian side or will there be a new pressure-rise from the south? Both scenarios open the door for a new invasion of cold.

    Obviously there are numerous other scenarios but i like to look at it from the cold side......

  7. 3 hours ago, chionomaniac said:

    I'm here - been working and have also had to pick myself off the floor after checking the 12Z.

    Best ever trop response that we have been able to track following a SSW, oh those of little faith lol.

    I did think of buying all the snow shovels and salt in B&Q yesterday and then selling it back to them next weekend....

    I have been convinced of an epic cold spell for a long time now (since before the split but my resolute belief was reinforced when I saw the residual Hudson Bay daughter vortex getting taken down).

    It may have taken the best part of 10 years but finally we are seeing the makings of an epic spell when you take the strat vortex out of the equation. Even @TEITS may finally have to concede that there is something in this teleconnections Malarkey!

    I want to pay my respects to Chionomaniac, who has tried so long to bring the effects of a SSW on the tropospheric conditions to attention!

    We are currently seeing what that means! CHIO gave the first signals on the stratosphere thread and: Yes, we are seeing an incredible SSW and we are seeing incredible tropospherical response. Let us remember how long it took for the models to take a grasp on this and, certainly with this kind of events, Keep the eyes on the large-scale movements when SSW events occur and a lot off uncertainty from models wil take a place!

     

    • Like 7
    • Thanks 1
  8. 12 hours ago, Glacier Point said:

    So far, text book.

    time_pres_HGT_ANOM_JFM_NH_2018.thumb.png.0e21c404c850136253ebb9ddd16eee03.pngbaldwin.thumb.jpg.07ac9b533e162bd52169db9dfc1402d6.jpg

    First tropospheric response will not be the last. Second and third waves, the latter with the most pronounced impact in the AO still likely, these timed around mid to final third March into early April.

    The MJO wave from January and February left a footprint in the Equatorial Pacific.

    wkd20eq2_anm.thumb.gif.809fc05ff0e0f21c4efed5d568891ecf.gif

    Don't think this was oceanic Kelvin wave given its timing and duration. 

    Yeah textbook. Currently the second wave is happening:

    jikei_uep_nh.gif

    but where will this lead us? It looks like this SSW is slowly moving into the final warming? I have never seen this before.

     

    • Like 1
  9. 3 minutes ago, Quicksilver1989 said:

    A glance through the 18z ensembles at T102 suggests that support is increasing rapidly for the development of an intense Scandi high. Phase 1 of getting things set up to our NE looks like its going to succeed. 

    Next step is to not avoid any awkward shortwaves forming in the cold air to our east like a few other members have mentioned. That stopped the core of the cold air in February 2012 hitting our shores. However with an Azores low instead of a high this time we have less to worry about.
    image.thumb.png.0622011d11cb858d65b5d4a4e498921d.png image.thumb.png.e7e4bfba3a666f266e9400601436b93e.png

    Still cautious but belief is increasing this may come off.

    Being born in the late 80's I cannot remember a truly cold easterly hitting us. That has to be the best run of the internet era.

    Fantastic runs today!

    I don't believe, as I argued earlier, that shortwaves will change the large-scale synoptics caused by the SSW:

    - Ridging N/NE of the UK and HP across the pole

    - PV energy slowly transferred to the Pacific side

    What you see today is that when the models grasp the large-scale developments without to much disturbances from small to medium scale waves, the crossmodel agreement becomes clear. 

    Obviously, shortwaves can have a big effect on local development in cold and snow but the big picture is quite clear now....

    • Like 2
  10. As I tried to point out yesterday: the developments are dominated by the largescale movements due to the SSW: as a consequence of the revearsal in the Stratosphere the tropospherical vortex-energie above Canada/Geenland is bound to move to the Pacific side. 

    It is strange to see that most models see this in the longe range but fail to incorporate it in the short-range. It is still my opinion/question that this is because hi-res models are mislead by shortwave activity!

    The positioning of the HP across Europe is an example of this: it will occur because of the large scale dynamics, the only question is: where will it land.

          

     

    • Like 2
  11. Maybe this has been discussed on this forum before, I don't know. But I was pondering about the role of shortwaves in the models in situations of large-scale stratospheric changes like the SSW we have at this moment. In my meteorology-classes I have learned that this kind of changes generally are dominated and driven by longwave activity/movement and that shortwaves are a consequence of those large-scale movements. 

    The essence of my "pondering": could it be that the high-res parts of the NWP models (specifically the OP's) in these situations inherently over-estimate the effect of short-waves and could lead to short-term fluctuations? I think that is what we are watching continiously!

    As a consequence you could say that in these situations relatively low-res (ensembles, means and low-res models) is essentially better because it keeps focus on the large-scale development?

     

     

     

    • Like 1
  12. 1 hour ago, More Snow said:

    Well been here since October looking at charts and run after run after run looking for Snow and cold. im drained ive no energy left to keep looking into the future. the only thing stopping me from saying see ya next winter is the possible SSW.. if it doesnt show up by the end of Jan then im calling an end to winter 2016/17.. so much promise at the start.. the pv looked totally battered early doors and we all was very excited because we all thought that HLB was going to kick in and send us into a winter wonder land. didnt happen then we all went into overdrive with the mega cold that the charts showed for early Jan.. didnt happen. yes some of us saw snow for about an hour or 2 at best and then here we find ourselves at the back end of Jan and still nothing to make us want to get excited...give it 2 weeks and we will all be saying plenty of time left still 4 weeks etc etc.. but i just dont see it. i dont see any cold snowy spell coming up before the end of Feb.. even if we get a SSW it does not always mean cold and snow..

    Models are what they are: models! They take into account what their creators know about the atmospherical processes and that is a lot. But there is also a lot they don't know or are unable to bring into the models. There is a lot of uncertainty, exponentially increasing after D1. When you can't stand this uncertainty don't look at models! 

    • Like 8
  13. Talking about lag-times: on the basis of what is written in this thread it is clear to me that there is a lag time between the occurrence of a SSW and the stratosferical vortex response (displacement, split etc.).

    But I am still struggling with the lag time between stratosferical vortex changes and the troposferical effects they have. I understand that there are a lot of processes involved (coupling is discussed in this thread) there but there must be a lag.

    It looks to me that the current restoration of the stratosferical vortex almost instantaneously has an effect on the enormous troposferical W-E transport of LP-energy across the Atlantic. It might be a coincidence with historical stratosferical events but I would like to understand this.

    Another question: Do (and to what extent) the weather-models take the physical interaction (including SSW's) between stratosphere and troposphere active into the modelling account or are they purely based on historical data?

    Any thoughts on these questions?

    I know Chio mentioned that the troposferical vortex above Canada is getting disconnected from the stratosferical one but the amount of energie this is moving across the atlantic currently appears to me as a strong troposferical polar Vortex. The 500 Hpa models show that HP intermittently tries to move north but is continously "ironed" away in the coming days/weeks.

    I am still very much trying to understand whether and how this troposferical condition relates to previous stratosferical events.

    My question about the models is related to that: maybe they dont model/calculate those coupling processes at all... Then I know what the value of model-predictions is.

  14. Talking about lag-times: on the basis of what is written in this thread it is clear to me that there is a lag time between the occurrence of a SSW and the stratosferical vortex response (displacement, split etc.).

    But I am still struggling with the lag time between stratosferical vortex changes and the troposferical effects they have. I understand that there are a lot of processes involved (coupling is discussed in this thread) there but there must be a lag.

    It looks to me that the current restoration of the stratosferical vortex almost instantaneously has an effect on the enormous troposferical W-E transport of LP-energy across the Atlantic. It might be a coincidence with historical stratosferical events but I would like to understand this.

    Another question: Do (and to what extent) the weather-models take the physical interaction (including SSW's) between stratosphere and troposphere active into the modelling account or are they purely based on historical data?

  15. Not a stupid question, skatefan.

    The tropospheric vortex and residual stratospheric vortex is still strong enough to create this affect. The stratospheric Canadian vortex is being further warmed at 10 hpa which is higher up than 30 hpa. It is only when the vortex is weakened at this level that the tropospheric Canadian vortex begins to wander across the Atlantic.

    So, to be sure if i understand you correctly, the warming of the stratosferical Canadian vortex at 10 hpa creates the un-coupling of the troposferical one?

    It still leaves me with the question why the movements of the stratosferical vortex and the troposferical movements seem to be happening simultaneously.

  16. 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.pn

    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.pn

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

    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.

    Dear Chio, thanks for all your interesting and exciting posts. I think that you contributed a lot to the knowledge about stratosferical processes and the the prediction and effects of SSW's! My compliments for your work here.

    I am still struggling, though, with the developments of next week. You state that the stratosferical canadian vortex (30 hpa chart) is moving to the atlantic and is trying to move to/merge with the siberian vortex. Why is that movement so strong with a heavily weakened vortex?

    Troposferically (500 hpa) i see the same movement: a lot off LP-energie comes across the atlantic and is moving to Skandinavia, the Jet is moving further North.

    Posted Image

    It suggests that those stratosferical and troposferical movements are coupled. They coincide at least in time. You wrote in your post that due to continued warming of the stratosferical vortex above Canada, the troposferical one brakes free. Am I overseeing something or is this just coincidence.

    I am eager to learn so please forgive me my possible stupid question.

  17. 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.pn

    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.pn

    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.pn

    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.gi

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

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

    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!!!!!

    I think GFS is supprting your theory. On the 500 Hpa today the (both 12Z and 18Z) western circulation will be, due to the Greenland HP, squeezed and somewhat forced a lower path. What puzzles me is the Skandinavien High: will it stay or will it go: is there any indication from the stratosferic movements?

    Posted Image

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