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Stratosphere temperature watch - 2016/17


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Posted
  • Location: Manchester
  • Location: Manchester
    29 minutes ago, bluearmy said:

    Instantweathermaps.com

    doubt will be too impressive - just checked and vortex displaced to nw scandi as per Steve m's initial ens vista 

     

    Due to the shape and orientation of Scandinavia I am struggling to visualise what would count as northewest. Do you mean northern Norway?

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    The current projected Wave 1 displacement of the stratospheric vortex looks to be following the script nicely. During the last few days and for the next 2-3 we will see a series of unusually deep

    Well this is getting interesting and a possible game changer. Why chop down a tree when you can squash a seedling ? Following the lead of the models of late last week, we have begun to tick down

    The importance here I think is the consistency over the GEFS in terms of pretty much all the ENS members falling below zero and obviously indicating a wind reversal, to an extent the GFS DET can do wh

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
    44 minutes ago, bluearmy said:

    Instantweathermaps.com

    doubt will be too impressive - just checked and vortex displaced to nw scandi as per Steve m's initial ens vista 

     

    Thanks for that, useful site albeit a bit clunky to navigate :good:

    10hPaGPH-168to384-GFS06z18thJan'17.gif

    Your intuition proves accurate as usual. 168, 240, 300, 348 and 384 hours in sequence. Would have done more frames but very short on time.

    300 hours looks closest to a split as the second area of increasing GPH comes into play. 

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    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    That's not a split, S, at T+300 just a reinforcement of the warming wave 1 displacement. The vortex is displaced and weakened but not destroyed. Looks like almost a SSW, but not quite

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    Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

    The warming now looks like it will die out at 1mb now at the end so doesn't look like it will completely obliterate the vortex, the displacement (should it propgate), will manifest itself IMO as a southerly tracking jet with some cold air dragged south, early signs already in the ensembles although no one knows what timescale yet, if I hadn't looked at the Met Office 30 dayer, based on the strat forecasts, I would be thinking coldish conditions from around 10th feb onwards, whether we can get Greenland blocking I'm very dubious to, I'm not sure any scandi blocking and proper Easterly is on the menu for at least the next month, surely the logical progression to cold here (if one does materialise) is NW winds mid feb, the met office don't seem too interested though.

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    Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
    3 hours ago, feb1991blizzard said:

    The warming now looks like it will die out at 1mb now at the end so doesn't look like it will completely obliterate the vortex, the displacement (should it propgate), will manifest itself IMO as a southerly tracking jet with some cold air dragged south, early signs already in the ensembles although no one knows what timescale yet, if I hadn't looked at the Met Office 30 dayer, based on the strat forecasts, I would be thinking coldish conditions from around 10th feb onwards, whether we can get Greenland blocking I'm very dubious to, I'm not sure any scandi blocking and proper Easterly is on the menu for at least the next month, surely the logical progression to cold here (if one does materialise) is NW winds mid feb, the met office don't seem too interested though.

    Although there has been a lot of anticipation that we will soon see a SSW, there is decent probability that the current wave 1 induced warming may not be enough to produce an official SSW, i.e. a reversal of zonal winds, with the potential that the displaced PV will bounce back toward the pole with an uptick in zonal winds. However, strat charts show stratospheric high over Alaska which may re-in force wave 1 forcing which may keep the PV off the pole and a second warming in Feb could I guess be better placed to seal the fate of the PV. Often it takes a few attempts before we see an official SSW. That's not to say the current warming won't have an effect on the troposphere pattern, but it remains to be seen, that this displacement in conjunction with the lagged tropospheric forcing from amplified MJO phase 1/2, will favour a pattern change for the UK that will bring deep cold and snow. Certainly no positive direction from NWP high res runs yet, other that the odd hint of a Scandinavia high in FI

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    Back in December (15th), in response to a charge that after the Canadian warming, the strengthening vortex was not forecast, Fergieweather posted a Glosea chart of 10mb wind to show that on the contrary it was predicted from the end of October, see here - https://www.netweather.tv/forum/topic/86783-model-output-discussion-5th-december-2016-into-winter-we-go/?page=121#comment-3494556

    I mooted that this was not an uncommon situation and quickly put together a composite from two analogue years based on the guessed Glosea forecast start of 28th October, giving the dates 17/10/09 and 24/10/04 - https://www.netweather.tv/forum/topic/86783-model-output-discussion-5th-december-2016-into-winter-we-go/?page=125#comment-3494710

    OK, verification time!

    After extracting the values from the Glosea graph (how the long winter nights fly by) it could be seen that it covered approximately the period 27th October to 7th January. Here are the Glosea forecast, the analogue (starting a day earlier from guessed start), and the actual wind speeds -

    glosea.png

    Broken down into 27th Oct - 14th Dec and 15th Dec - 7th Jan to counter possible cherry picked analogue -

    Glosea RMSE (root mean square error) wind speed, lower is better -

    27/10 - 14/12 = 6.47 m/s

    15/12 - 7/1 = 12.81 m/s

    Overall = 9.06 m/s

     

    Analogue RMSE -

    27/10 - 14/12 = 5.57 m/s

    15/12 - 7/1 = 9.33 m/s

    Overall = 7.03 m/s

     

    On this occasion, the analogues win, not only on a hindcasted period but forecast also, as well as overall.

     

    Edited by Interitus
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    4 hours ago, chionomaniac said:

    That's not a split, S, at T+300 just a reinforcement of the warming wave 1 displacement. The vortex is displaced and weakened but not destroyed. Looks like almost a SSW, but not quite

    It is a feature that has been noted in the literature, that transient anticyclonic areas such as that do reinforce from the European side - it could make the difference. 4 m/s on the GFS 06z -

    Z_temp_10hpa_360_17020206.png

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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

    In my years of watching i would note that its not uncommon to see a reversal diluted closer to the time however it's probably not vital so long as the vortex stays relatively weak afterward.

    Also worth saying to people that the effect on the AO will not happen overnight (we can see a lag) so i would be looking for any pronounced effect to be after the 10th Feb.

    Finally worth saying that with a +QBO this could be one of the strongest events. 

    ..

    Interitus, i remember a while ago that you were looking at analogies and concluded no SSW for at least 51 days. I was just curious whether this beats that.

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
    9 hours ago, chionomaniac said:

    That's not a split, S, at T+300 just a reinforcement of the warming wave 1 displacement. The vortex is displaced and weakened but not destroyed. Looks like almost a SSW, but not quite

    Sorry I wasn't clear enough in my post - I meant the closest we get, although come to think of it, that's not how it works so I should have said to a SSW... I've a lot on my plate at the mo so that's my excuse :laugh: Thanks for pointing out my error though so I could recover... well, sort of;

    What I see is the second, very expansive warming displacing the vortex and then lingering in-situ in association with  a stratospheric ridge. New warming emerges from the same area as before but all this can do is prolong and perhaps further increase the extent of the displacement. Had there instead been warming on the Canadian side making its first arrival at +300 or so, with the vortex still near or over the pole, there would have been a pincer move I.e a wave-2 attack. If only eh? Assuming I'm making sense now...!

    Some interesting looking posts this afternoon, I hope to read them tomorrow and will edit this post to add comments if relevant :good:

    Edited by Singularity
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    Posted
  • Location: Wakefield, West Yorkshire
  • Weather Preferences: Anything except blazing hot summers!
  • Location: Wakefield, West Yorkshire
    34 minutes ago, Interitus said:

    Z_temp_10hpa_312_17011900.png

    Bit of a surprise.

    Is that a good chart?

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    Posted
  • Location: County end Oldham 202 m Above sea level
  • Location: County end Oldham 202 m Above sea level
    3 minutes ago, Paul_1978 said:

    Is that a good chart?

    I believe its showing a reversal so yes its a good chart ..

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    Posted
  • Location: Shanklin, Isle of Wight
  • Location: Shanklin, Isle of Wight
    44 minutes ago, Paul_1978 said:

    Is that a good chart?

    Im using a really naff tablet to view this but on here that looks like a displaced Strat PV towards scandinavia, although I expect its rather weak. I cant see much on here though!

    Edited by Jamie R
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    Just now, Jamie R said:

    Im using a really naff tablet to view this but on here that looks like a displaced PV towards scandinavia, although I expect its rather weak. I cant see much on here though!

    The GFS 0z from last night goes for SSW by Feb 1st 0z - chart shows wind reversal of -2 m/s at that time. Makes the tweets above quite amusing.

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    Posted
  • Location: Shanklin, Isle of Wight
  • Location: Shanklin, Isle of Wight
    1 minute ago, Interitus said:

    The GFS 0z from last night goes for SSW by Feb 1st 0z - chart shows wind reversal of -2 m/s at that time. Makes the tweets above quite amusing.

    I wont pretend to know how it interprets the data but wouldn't it show a reversal if the PV temporarily shifted well off the pole before shifting back closer to it again? I always thought a full reversal is literally a reversal other than the odd mini core here and there? Wouldn't it therefor get confused if the PV was away from the pole interpreting the data as a reversal even though its just a shift?

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    Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire

    Im assuming this is the wave 1 attack that is going to cause this potential SSW? 

    Looks potent at day 10 on ECM

    IMG_1787.GIF

    Still learning with regard to the strat so if that's not correct I'm sure someone will let me know :) 

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    Several more entries on here already this morning so it's time for a new post from me after all rather than updating my last;

    Something that has struck me from looking at displacements to Eurasia is that where the stratospheric winds decelerate at 30 hPa as they move south on the west flank of the vortex there is an apparent tendency (I've not done a detailed analysis so this is currently by eye, and only working with Siberian displacements at the 30 hPa level) for a troposphere-stratosphere coupled blocking high develop in the lower levels near or over Scandinavia. The strength of the Atlantic jet then determines how that block orientates and hence what surface conditions we experience. When the jet is strong due to other forcing factors, we end up locked into a SW flow and generally balmy. When it's weak... need I say more? :cold:

    What I'm not very sure about is how reliable this decelerating and descending tendency right down to the troposphere actually is, but a look at 500 hPa GPH charts for the 2-3 weeks following historical such displacements in late winter seems to support the broad idea.

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    Posted
  • Location: st albans
  • Location: st albans
    1 hour ago, Singularity said:

    Several more entries on here already this morning so it's time for a new post from me after all rather than updating my last;

    Something that has struck me from looking at displacements to Eurasia is that where the stratospheric winds decelerate at 30 hPa as they move south on the west flank of the vortex there is an apparent tendency (I've not done a detailed analysis so this is currently by eye, and only working with Siberian displacements at the 30 hPa level) for a troposphere-stratosphere coupled blocking high develop in the lower levels near or over Scandinavia. The strength of the Atlantic jet then determines how that block orientates and hence what surface conditions we experience. When the jet is strong due to other forcing factors, we end up locked into a SW flow and generally balmy. When it's weak... need I say more? :cold:

    What I'm not very sure about is how reliable this decelerating and descending tendency right down to the troposphere actually is, but a look at 500 hPa GPH charts for the 2-3 weeks following historical such displacements in late winter seems to support the broad idea.

    The ec 50hpa charts at day 8/10 develop a high anomoly to our north which migrates ne.  Presumably this is earlier than you are looking at 

     

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    Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire
    26 minutes ago, bluearmy said:

    The ec 50hpa charts at day 8/10 develop a high anomoly to our north which migrates ne.  Presumably this is earlier than you are looking at 

     

    Is the kink to our north east the ridge? Or am I looking at the wrong charts/wrong interpretation?

    IMG_1788.GIF

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