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Stratosphere and Polar Vortex Watch 2020


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

    https://atmos.uw.edu/~dennis/GarfinkelHartmannSassi_09.pdf

    Reading this paper, I gather that when there's a high over East Asia, there has historically tended to be an Aleutian low as well, resulting in wave-2 activity flux via simultaneous interaction with the mountains of East Asia and the Rocky Mountains of the western USA (see examples below, from just prior to vortex splits in 2009 & 2018).

    image.thumb.png.f735c793c9029a88c438e04ac7e60752.pngimage.thumb.png.dc167b46067edd43f4785528e20519a6.png

    In recent years, though, we've also seen quite a few very strong warmings from the Asian side without the Aleutian low providing any warming to propagate over the Atlantic and produce the pincer movement on the polar vortex.

    That's what GFS is now predicting around the turn of the year. Remains to be seen if the Aleutian low will really be so absent - much depends on whether we see continued opposition of the sub-seasonal tropical cycle to the La Nina base state.

    From other reading over the years, I'm of the impression that the strongest wave-2 flux tends to occur during such times of tropical cycle conflict with La Nina. It seems that you get a more vigorous setup out of that compared to when you have an El Nino encouraging a persistent Aleutian low. Perhaps this is a big part of why analysis of mid-late winter in La Nina years tends to find a distinct division of outcomes, with a predominance of +NAO dominated cases but a distinct cluster of considerably -NAO cases.

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    Posted
  • Location: Trowbridge, Wilts
  • Weather Preferences: hot summers; frigid winters; golden fall; bright spring
  • Location: Trowbridge, Wilts

    Where’s recretos?

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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.
    11 hours ago, ghoneym said:

    Sorry to be a pain in butt...but it looks to me that the mean wind speed for this time of year is 40 m/s and to be up at 60m/s we would be looking at breaking records? I'm not trying to be pedantic or anything but just want to try and understand what I'm looking at from the various different charts available.

    539410832_ScreenShot2020-12-13at23_14_04.thumb.png.605aef30b681e3ebca39ebb6222c83c4.png

    Wave 1 is on top for now that is for sure.

    1220401425_ScreenShot2020-12-13at23_14_24.thumb.png.36519c8294fef654b71ee0e40d0775fa.png 1323704466_ScreenShot2020-12-13at23_20_28.thumb.png.2f00e6bb22839b0e6cbae3f53a44a973.png

     

    When there are no warming events and trop disruption then the mean u wind is higher and 60m/s is at the higher end but I have seen it and when that occrs blocking has pretty much zero chance of succeeding

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    Posted
  • Location: Neath Valleys, South Wales 109m asl
  • Location: Neath Valleys, South Wales 109m asl

     

    image.thumb.png.e16cdee939b0d3e3366048a89e997a63.png

     

    Some serious warming getting going right through from +300. 

    All getting interesting as they say? 

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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL
    22 minutes ago, ALL ABOARD said:

     

    image.thumb.png.e16cdee939b0d3e3366048a89e997a63.png

     

    Some serious warming getting going right through from +300. 

    All getting interesting as they say? 

    If it get to +144 I might show some interest.

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    Posted
  • Location: Neath Valleys, South Wales 109m asl
  • Location: Neath Valleys, South Wales 109m asl
    4 minutes ago, mountain shadow said:

    If it get to +144 I might show some interest.

    You know as well as I do the strat dosent tend to flip flop like operational runs. 

    The slight warming that will get underway from 144 has been counted down all the way from 384 on the new GFS

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    Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
    1 hour ago, ALL ABOARD said:

    You know as well as I do the strat dosent tend to flip flop like operational runs. 

    The slight warming that will get underway from 144 has been counted down all the way from 384 on the new GFS

    What can still vary is the intensity. The current warming happening right now was slightly undermodelled up until this weekend. This is why SSWs can be so hard to predict - the pattern is clear from distance but not the intensity nor the precise angle of attack which is very difficult to work out. Wave 1 warming on the ECM yesterday hardly fades at all right out to day 10 and is more intense over the next 5 days than previously forecast. It will be interesting once we get to day 8 when wave 2 pinching begins to fade away to see just how much this attack has taken out of the vortex. This is all good news.....but we really really want a split. A wave 1 driven ssw could deliver cold...BUT all too often the direction of attack forces the displaced vortex over to the Atlantic sector and that just pumps up our jet.

    Actually I’m interested now to know if any past wave 1 SSWs have originated from this side of the globe and shoved the vortex over to Alaska. @chionomaniac - is there an archive of vortex shapes for past SSWs freely available anywhere?

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    Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

    The zonal winds just can't get going at higher latitudes.A lot of the energy going into the sub-tropical jet.

    Wave 1 action picking up as current wave 2 activity dies away.


    ecmwfzm_u_f240.thumb.png.d91d334d2a95d8f86f45d94ced358c66.pngwaves.thumb.png.823a1092d3c907cea8ee454e4ff3aadb.png

    This all helps to keep the spv on the back foot for now.

     

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    Posted
  • Location: Hoyland,barnsley,south yorkshire(100m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(100m asl)

    An uptick at 10 hpa,but how much of an uptick is yet to come?,we will know more in the next few days.

    pole10_nh.thumb.gif.f10015b40bdde0a366405d02bfec7a75.gif

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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.

    I love following these warming’s from Lala land down to T+0.  Many don’t make it, lots get watered down, but a few do and this is a very strong warming signature at 1hPa

     

    481C4E01-F5FA-4CEC-BD69-8961F76D3041.thumb.jpeg.1adc3ba0265355c4734c5a23e11b9db7.jpeg

     

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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.

    @Catacol the sites that used to show the SSWs are no longer working. Don’t know if there are any others.

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    Posted
  • Location: South Oxfordshire
  • Location: South Oxfordshire
    On 10/12/2020 at 20:45, Griff said:

    Always surprised no one has posted this sooner, in any case I'm staying away from the model thread, far too emotional... 

    20201210204243-d39829585002f5157a7eeea9bb569f27bd21a148.thumb.png.a57374b328967176f6e92762c88d017d.png

    Seems to continue the theme with a lot of scatter but signs of a weaker than normal means... 

    I'd love to see how this compares to the equivalent chart from a year ago... 

    20201214200055-8e8df73c20149f06764d438bc31e912c741df07b.png

    And yes, I made a note to myself to check when it was available this evening 😉 

     

    Looks like the mean may have dropped... Happy to be told otherwise. 

    Edited by Griff
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    Posted
  • Location: Netherlands
  • Location: Netherlands
    6 hours ago, Catacol said:

    What can still vary is the intensity. The current warming happening right now was slightly undermodelled up until this weekend. This is why SSWs can be so hard to predict - the pattern is clear from distance but not the intensity nor the precise angle of attack which is very difficult to work out. Wave 1 warming on the ECM yesterday hardly fades at all right out to day 10 and is more intense over the next 5 days than previously forecast. It will be interesting once we get to day 8 when wave 2 pinching begins to fade away to see just how much this attack has taken out of the vortex. This is all good news.....but we really really want a split. A wave 1 driven ssw could deliver cold...BUT all too often the direction of attack forces the displaced vortex over to the Atlantic sector and that just pumps up our jet.

    Actually I’m interested now to know if any past wave 1 SSWs have originated from this side of the globe and shoved the vortex over to Alaska. @chionomaniac - is there an archive of vortex shapes for past SSWs freely available anywhere?

    Ask Simon Lee. He should know it.

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    Posted
  • Location: Exile from Argyll
  • Location: Exile from Argyll
    11 hours ago, Catacol said:

    What can still vary is the intensity. The current warming happening right now was slightly undermodelled up until this weekend. This is why SSWs can be so hard to predict - the pattern is clear from distance but not the intensity nor the precise angle of attack which is very difficult to work out. Wave 1 warming on the ECM yesterday hardly fades at all right out to day 10 and is more intense over the next 5 days than previously forecast. It will be interesting once we get to day 8 when wave 2 pinching begins to fade away to see just how much this attack has taken out of the vortex. This is all good news.....but we really really want a split. A wave 1 driven ssw could deliver cold...BUT all too often the direction of attack forces the displaced vortex over to the Atlantic sector and that just pumps up our jet.

    Actually I’m interested now to know if any past wave 1 SSWs have originated from this side of the globe and shoved the vortex over to Alaska. @chionomaniac - is there an archive of vortex shapes for past SSWs freely available anywhere?

    If you know the years and dates, the Japanese site has 5 day means for 30, 100 and 500 heights.

    DS.DATA.JMA.GO.JP

    Climate System Monitoring / TCC

     

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    Posted
  • Location: Kirkcaldy, Fife, Scotland 20m ASL
  • Weather Preferences: Snow, Thunderstorms
  • Location: Kirkcaldy, Fife, Scotland 20m ASL

    Im pretty sure that I posted the links to the papers a few winters ago but just posting this as a kind of experiment 54520137-DC34-4940-A2FC-DD669BC81203.thumb.jpeg.60fe11b5966f0aae2127f4e7ab53720b.jpeg4BD3A2B0-8032-45CA-BDDE-4662B5D91C9B.thumb.jpeg.42267ba42a7c0739b306a0e92897068a.jpegusing the data from the bom site the MJO phases were

    phase 2 15th - 20th November 

    phase 3 21st - 23rd November 

    phase 4 24th November- 7th December 

    using the amount of days those papers mention gets a bit complicated in the figuring out but something along the lines of 10th/16th December - 26th / 29th December and 7th / 18th December - 20th / 31st December for possible stratospheric warming which doesn’t look too far off in the current modelling. *not sure if the amplitude of MJO is a factor as the recent phases have mostly been low amplitude/ COD but were still associated with those phases mentioned in those papers*

    https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053144

    https://journals.ametsoc.org/view/journals/clim/30/21/jcli-d-17-0044.1.xml

    http://www.bom.gov.au/climate/mjo/graphics/rmm.74toRealtime.txt

     

     

     

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

    Something looks slightly different in the warming end of GFS 12z, T324:

    63A9A30F-8C6A-4286-B759-91E7F39D41F8.thumb.png.804ae31b0c184480605af6380104c5ca.png

    As we might expect to see, and then it wanes, but T384, the warmest part in a different location, this might have more going for it:

    EB99F4A2-EAB5-4097-A2D6-E7D00C7FE9C3.thumb.png.b9fefb84559a0e64880e0ebb73278f69.png

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    Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

    An interesting 10 day ECM chart at 100hpa - not only a split once again, but a shift of one daughter over to Scandy while the bigger half heads to Siberia. This must surely open the door....and note the amplified pattern over the Western Hemisphere. 
    image.thumb.png.1edfe0cd311db032e1b00c2a6255ea41.png

    Zonal wind profile continues, as it has for several days, to emphasise an easterly average down as far as 60N

    image.thumb.png.c23071a771cf140d013a13ced8f64a6d.png
    Still watching the various signs of warming develop - wave 1 continues to be sustained out to 10 days....but regardless of warming for a SSW in January we have a chance of a cold blast through Scandy around New Year I think. Tropospheric drivers are lining up....

     

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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL
    26 minutes ago, Catacol said:

    An interesting 10 day ECM chart at 100hpa - not only a split once again, but a shift of one daughter over to Scandy while the bigger half heads to Siberia. This must surely open the door....and note the amplified pattern over the Western Hemisphere. 
    image.thumb.png.1edfe0cd311db032e1b00c2a6255ea41.png

    Zonal wind profile continues, as it has for several days, to emphasise an easterly average down as far as 60N

    image.thumb.png.c23071a771cf140d013a13ced8f64a6d.png
    Still watching the various signs of warming develop - wave 1 continues to be sustained out to 10 days....but regardless of warming for a SSW in January we have a chance of a cold blast through Scandy around New Year I think. Tropospheric drivers are lining up....

     

    Are you thinking Greenland High or Scandinavian High possibilities Catacol?

    I guess if this 10hpa was mirrored down to trop level it would be a Scandi trough and Atlantic ridge?

     

     

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    Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
    4 hours ago, mountain shadow said:

    Are you thinking Greenland High or Scandinavian High possibilities Catacol?

    I guess if this 10hpa was mirrored down to trop level it would be a Scandi trough and Atlantic ridge?

     

     

    I think given that profile probably Greenland. Slightly mixed feelings about this because my vortex-smashing personality really wants to see a ridge develop over Scandy and across towards the Urals...but that might follow later. A Scandy trough dropping over us with heights to the NW would be a good way to finish a 2020 most of us will want to forget....

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    Posted
  • Location: 50/50 Greece/Germany
  • Weather Preferences: Cold winters, hot summers
  • Location: 50/50 Greece/Germany

    I would like to show you the synoptic outlook from DWD (German Weather Service), which is today looking on the PV (=SPW / Stratospheric Polar Wirbel[Vortex]) WLA = WAA KLA = CAA

    I used Google to translate it, hope it didn't crippeld it to much 🙂

    Enjoy reading

    Source:

    WWW.DWD.DE

    Die Synoptische Übersichte Mittelfrist führt die Kurzfrist-Einschätzungen weiter (3. bis 7. Folgetag) unter besonderem Hinblick auf die verschiedenen Modellrechnungen.

    With regard to the polar vortex in the stratosphere (SPW) there is a lot currently required and everything cannot be done in this medium-term due to time and overview be treated. After a short period of weakness, the SPW will recover over the medium term and this is shown in the IFS-EPS (zonally averaged zonal winds in 10 hPa in 60 degrees North) due to a marked increase well above the mean value of Model climatology - also supported by GEFS with similar values. All that also coincides with a now occurring phase of reduced zonally averaged Heat flows together. In 10 hPa, i.e. in the upper range of the SPW, weakens temporarily off a powerful anticyclone over the Pacific sector, while the polar vortex is in the elevation under reinforcement of Greenland relocated to Spitzbergen / Nordkapp. This print configuration is therefore of Interest, because it is the so-called "wave number 1", which is in the Reality of an anticyclone over the Aleutian area and a center deep Geopotential, i.e. the polar vortex as a counterpart (other Wavenumbers are currently not dealt with here). This increases Anticyclones, it ensures peripheral degradation of the polar vortex like that important vorticity, so that the SPW weakens and shrinks. Over this medium term, however, the opposite happens. The anticyclone weakens a bit and the SPW comes back in thanks to the lack of heat flows Drive (but contracts significantly, which is also due to a second, weak Anticyclones off Africa). In summary, the SPW is shifted from the pole, robust, but increasingly deformed.

    Let's take a look at the period between Christmas and New Year (extended medium term), it is constantly indicated, that repeated striking heat flows and corresponding positive ones Temperature anomalies from the Siberian and Asian sectors in the area of the Move the stratosphere to the east and the anticyclones - now over the Aleutian Islands placed - amplify again (also visible through a second peak the anomaly values for the wave number 1). The SPW therefore begins to Turn of the year to weaken again. This can be seen in the form of the geopotential a slight increase. With zonal averaging of the wind this is indicated by a marked drop in values recognizable thanks to the displacement of the polar vortex from Pole and thus away from the 60th parallel. If you give the ensemble forecasts Believe, then the year 2021 could begin with an SPW that is related to the mean wind is below the mean value of the model climatology - and that clearly (but still far from a possible wind reversal). Has for us This development has no direct effects for the time being, but all the more so in Asian sector and thus indirectly also for us. The medium-term flows there over repeated arctic air masses (850 hPa temperature values partly clear below -35 degrees) to the south (10 day mean with a negative EFI of 2m Temperature from -0.6 to -0.8 or with snow masses for the Japanese mountains), east of the Ural Mountains, these push the ground pressure upwards. Driven The polar front jet in the North Pacific is released from this massive body of cold air partly reinforced over 200 kn. The jet then becomes repeatedly unstable and breaks off Alaska and Canada in constant wave patterns. Thus change in the North American / North Atlantic sector during the (extended) medium term the wave amplitude increasing from "short" to "long" and the wave displacement from "progressive" to "quasi-stationary". That will be us in Europe then in the employ extended medium term.

    But we come back to our medium term and there in the border area between SPW and the polar vortex in the troposphere (TPW). Also here is doing the medium term via geopotential reduction over the Scandinavian area noticeable as a result of the intensifying and towards Spitsbergen shifting vortex. Looking at the wind at the level of the tropopause is therefore a reduction in the persistently diffluent and comparatively low-gradient flow towards a temporarily zonally aligned high-altitude current over west and To recognize Central Europe. Especially during this medium term, the Relocation of a trough from Greenland to Scandinavia on what is in phase with a progressive wedge moving to south-western Europe happened, so that western and Central Europe temporarily found itself in a strong geopotential crowd. This is within the so-called "time series" of IFS-HRES nice to see where over Benelux / West Germany at the beginning of the next week the wind in 200 hPa up to Midweek blowing steadily from W / SW with 70-85 knots. Certainly off From a kinematic point of view, not amazing, but with regard to the model climate slightly abnormal (or statistically with around 1 sigma deviation) and above all overlapping with an influx of humid, labile subtropical air that forms the wedge accompanied (positive EFI of the moisture flow directed towards Central Europe). Everything basically beneficial ingredients for the development of powerful cyclones in the North East Atlantic. However, there are so far within the IFS-EPS Members only little evidence. One reason could be that the wedge in 150 hPa rapidly migrates eastwards or flattens out and then a trough in Western Europe reached who interacts with the trough via Scandinavia and to the end of the Medium term / start of the extended medium term after Christmas to one pronounced positively inclined trough configuration mutated from Scandinavia extends as far as Morocco (with a strong wedge upstream in Towards Iceland). As a result, the geopotential gradient spreads out Central Europe back up and any subsurface development quickly becomes the Deprived of beneficial altitude vergence. With a then beginning increasingly Axis-vertical floor depth / height trough configuration begins eastward moving trough over Central Europe gradually to nestle what later in a quasi-stationary wave pattern opens.

    However, in terms of ground pressure, it is quite a complex one Interplay of a central low off Norway and one in Newfoundland Storm depression migrating eastwards (responsible for a snowstorm in the northeast the USA). KLA of one and WLA of the other ensure a pronounced Air mass limit, which extends over the medium term from the Azores to after Western Europe is supposed to build up and is prone to ripple what repeats is / was indicated. It is precisely this that has the greatest potential for stronger ones Peripheral deep developments over England / Northern France / Benelux. Shouldn't be so his would in turn be the potential for one across Western and Central Europe dragging air mass limit increased. Let's take a quick look at the AO, thanks to vehement blockages in the area of Greenland and Urals or potential bridges that are partially spanned near the pole remains negative. The NAO remains neutral / slightly negative. The tropics are still comparatively calm. The Madden-Julian Oscillation (MJO) is in the transition area from phase 4 to 5 (i.e. from the western maritime Shifting continent to the western Pacific) continues to weaken, which i.a. also due to the destructive interaction with which La Nina should be (supported in the guidance through a homogeneous acceptance of the members in the unit circle of so-called "Realtime Multivariate MJO Index", short: RMM). GEFS and IFS-EPS match well. This standing wave promotes between the Philippines, Australia and the Southwest and West Pacific, the development of tropical cyclones, apart from that, however, no direct impact on the extra-tropics is expected.

    As a result, the extended medium-term between Christmas and New Year, In the European sector, as already mentioned, we are getting back to a rather stationary wave pattern with a long wave trough whose axis is above us or should come to rest just east of us. This crystallizes in Trend out that the pivoting is delayed more and more, from today's Even after the holidays. That would take Germany longer in the warm sector leave. But depending on the ground pressure geometry, a further wave formation, a scenario with wet snowfalls down to deep elevations set - the potential for regionally a white surprise to the Holidays remain in any case, but with the emphasis on: muddy, locally and with little confidence. As a zustom of continental cold air from Siberia is effectively suppressed we must continue with modified polar sea air and with a then indicated cooling over Greenland / Eastern Canada should not be long before the Atlantic gets going again.

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    Posted
  • Location: Northallerton, N Yorks
  • Location: Northallerton, N Yorks

    What is interesting to me is how organized the polar vortex is over on the Pacific side of the northern hemisphere so far this winter (and late autumn). Recent winters have seen the bulk of the vortex over on this side of the hemisphere (and an angry one too). Why is this? Can anyone enlighten me? If this keeps up, then surely the Atlantic sector would be much more prone to amplification?

    David

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    Repeated suggestions by the GFS now that the SPV will be on its last legs come the new year

    image.thumb.png.b7465e8ac3e046d38245055d5e50e78c.png

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    Posted
  • Location: Orpington Kent.
  • Location: Orpington Kent.
    1 hour ago, CreweCold said:

    Repeated suggestions by the GFS now that the SPV will be on its last legs come the new year

    image.thumb.png.b7465e8ac3e046d38245055d5e50e78c.png

    Looks promising. I’ve read that usually there is a lag off several weeks between any SSW event and the impact being at ground level.. with the strat already being in a fair degree of stress is it logical and correct to think that any impacts of ssw would become apparent far sooner...

    Edited by TSNWK
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    Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

    Zac's site is really cool in terms of it's moved our visibility beyond the Berlin plots.

    Have admittedly been obsessed with EP flux vectors for a wee while, and this looks again massively promising for TPV if not SPV disruption. Factor in EAMT in the post, MJO cycle in the post.. it's a great winter where our winter foe attempting as hard as it can to revert to climo - just isn't getting it's own way.

    Am a big fan of this winter in terms of the variation happening.. it's pretty much the opposite of last seasons uniform - none shall pass.. into - proper chaos.

    Yes, Jan you may say is another 'climo' pick statistically for a SSW to happen, however beyond the 'bookies shout' there is plenty of evidence that backs up that call, just a matter of when not if IMO.

    EpduHl1WwAAMuVh.png

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    Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl
    2 hours ago, lorenzo said:

    Zac's site is really cool in terms of it's moved our visibility beyond the Berlin plots.

    Have admittedly been obsessed with EP flux vectors for a wee while, and this looks again massively promising for TPV if not SPV disruption. Factor in EAMT in the post, MJO cycle in the post.. it's a great winter where our winter foe attempting as hard as it can to revert to climo - just isn't getting it's own way.

    Am a big fan of this winter in terms of the variation happening.. it's pretty much the opposite of last seasons uniform - none shall pass.. into - proper chaos.

    Yes, Jan you may say is another 'climo' pick statistically for a SSW to happen, however beyond the 'bookies shout' there is plenty of evidence that backs up that call, just a matter of when not if IMO.

    EpduHl1WwAAMuVh.png

    I agree Lorenzo - his charts are better - I just need to be able to gauge them properly! Poleward flux is what we want - and we have some here above 100hpa. Just how much more than normal are these magnitude and direction signals? Benchmarking what we are seeing here is my problem....

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