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Stratosphere and Polar Vortex Watch


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Posted
  • Location: Netherlands
  • Location: Netherlands

    SUMMARY

    We now know what the polar vortex is and what the QBO is. But how is it all related? The QBO is in the stratosphere above the equator and is connected to the global larger-scale circulation. The west or east phase of the QBO can have a different effect on the polar vortex and the development of a Stratospheric Warming event. In most cases, the east phase of the QBO is more favorable for a better winter pattern. This year we are in the west phase of the QBO. But this is where La Nina comes into play.

    We have discussed the La Nina phase of the ENSO and its influence in our Fall forecast 2020, so check it out for more details on what exactly is the La Nina and the ENSO cycle. Historically, a La Nina winter has around 60-75% chance of producing a stratospheric warming event. It has produced them in the past, and a fair share of those has been in the west QBO phase. Below we have the ENSO forecast from BoM Australia, which shows the La Nina phase for late Fall and through the Winter 2020/2021

    Without a stratospheric warming event, a La Nina winter can generally be milder in Europe and the United States. The same goes for the west QBO, individually. But combined, they have already produced quite cold winters in the past. This is why the state of the stratospheric polar vortex is important, as well as the phase of the QBO. Current signals show the potential for a stratospheric warming event in mid-winter, based on current parameters. A lot depends on the positioning of the massive high and low-pressure systems in the North Pacific.

    This is where other short-term factors also come into play, like weekly weather variability, tropical convection, ocean temperature anomalies, etc…

    https://www.severe-weather.eu/long-range-2/polar-vortex-formation-winter-2020-2021-fa/

    So, perhaps a SSW in midwinter and bigger chances for cold weather then. Seems to me, in contradiction with the idea of a front loaded winter (?)

     

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    Some useful tropospheric developments upcoming which are likely to have stratospheric impacts towards the end of November and more particularly into December. A strong convectively coupled tropic

    so after many days the GFS & FNMOC & canadian finally now follow the Euro with 44 out 64 Members with a split at day 9- The ECM is day 8. We will call it - SSW & Split for 1st Ja

    For all that watch the zonal winds. Let me urge you to look at the geopotential heights more. At least as far as weakening/strengthening trends go. Because as the polar vortex cries for help, you migh

    Posted Images

    Posted
  • Location: BIRMINGHAM B6 ASTON WM. About 112MASL 367.36FT
  • Weather Preferences: SNOWY WINTERS AVRAGE SPRING HOT SUMMERS WITH THUNDERSTORMS.
  • Location: BIRMINGHAM B6 ASTON WM. About 112MASL 367.36FT
    3 hours ago, sebastiaan1973 said:

    SUMMARY

    We now know what the polar vortex is and what the QBO is. But how is it all related? The QBO is in the stratosphere above the equator and is connected to the global larger-scale circulation. The west or east phase of the QBO can have a different effect on the polar vortex and the development of a Stratospheric Warming event. In most cases, the east phase of the QBO is more favorable for a better winter pattern. This year we are in the west phase of the QBO. But this is where La Nina comes into play.

    We have discussed the La Nina phase of the ENSO and its influence in our Fall forecast 2020, so check it out for more details on what exactly is the La Nina and the ENSO cycle. Historically, a La Nina winter has around 60-75% chance of producing a stratospheric warming event. It has produced them in the past, and a fair share of those has been in the west QBO phase. Below we have the ENSO forecast from BoM Australia, which shows the La Nina phase for late Fall and through the Winter 2020/2021

    Without a stratospheric warming event, a La Nina winter can generally be milder in Europe and the United States. The same goes for the west QBO, individually. But combined, they have already produced quite cold winters in the past. This is why the state of the stratospheric polar vortex is important, as well as the phase of the QBO. Current signals show the potential for a stratospheric warming event in mid-winter, based on current parameters. A lot depends on the positioning of the massive high and low-pressure systems in the North Pacific.

    This is where other short-term factors also come into play, like weekly weather variability, tropical convection, ocean temperature anomalies, etc…

    https://www.severe-weather.eu/long-range-2/polar-vortex-formation-winter-2020-2021-fa/

    So, perhaps a SSW in midwinter and bigger chances for cold weather then. Seems to me, in contradiction with the idea of a front loaded winter (?)

     

     and if I am right then the winter of 2017 2018 was a Lanina winter and had that major SSW which bought us the beast from the east end of February

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    Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK

    Seasonal forecasts as a whole from ECM and UKMO paint a pretty grim picture for cold here in the UK. Still cold chances of course, but the overriding message is mild, wet and windy again. Let’s see how accurate this is in 2020/21, last year it was spot on. A Pacific high that strong is never a good look.

    Edited by mb018538
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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL
    1 minute ago, mb018538 said:

    Seasonal forecasts as a whole from ECM and UKMO paint a pretty grim picture for cold here in the UK. Still cold chances of course, but the overriding message is mild, wet and windy again. Let’s see how accurate this is in 2020/21, last year it was spot on. A Pacific high that strong is never a good look.

    Goes against some background signals, so will be interesting to see how it pans out.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    6 minutes ago, mountain shadow said:

    Goes against some background signals, so will be interesting to see how it pans out.

    Interestingly, I don't seem to be the only one thinking that the Nina signature maybe being overplayed in the long range modelling...

    I believe blocking will be more N Atlantic based.. but we'll see!

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    Posted
  • Location: Cambridge, UK
  • Weather Preferences: Summer > Spring > Winter > Autumn :-)
  • Location: Cambridge, UK
    14 minutes ago, CreweCold said:

    Interestingly, I don't seem to be the only one thinking that the Nina signature maybe being overplayed in the long range modelling...

    I believe blocking will be more N Atlantic based.. but we'll see!

    Fingers crossed 🤞🏻 

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

    Also, the ECM output does not preclude some slider type events against a Scandi block. This scenario is supported by ECM (given orientation of the HP anomalies) but not by the UKMO output.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    3 minutes ago, Gael_Force said:

    All 3 trimesters have slp as very strong in the Atlantic. Most separation of the cell for D/J/F so it has possibilities.

    2cat_20200901_mslp_months46_global_deter

    December seems to be coming up as the month with the most potential for Atlantic HP to be N enough to allow a cold NW'ly flow (with weak mean Scandi troughing)

    Also showing on CFS-

    image.thumb.png.af339fd8d1042af81c3ef8c8a4a519bf.png

    Edited by CreweCold
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    Posted
  • Location: Ludgershall, Wiltshire
  • Location: Ludgershall, Wiltshire
    3 hours ago, CreweCold said:

    December seems to be coming up as the month with the most potential for Atlantic HP to be N enough to allow a cold NW'ly flow (with weak mean Scandi troughing)

    Don’t you think things are looking a tad ropey, albeit very early days?

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    28 minutes ago, Don said:

    Don’t you think things are looking a tad ropey, albeit very early days?

    No. I'm actually very optimistic for this winter.

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    Posted
  • Location: Bedfordshire
  • Weather Preferences: Warm summers with thunderstorms, stormy or fog/frost autumns, cold winters
  • Location: Bedfordshire

    With the obvious background planetary warming, why is it that the polar vortex seems to be cold and intense winter after winter? I know this is probably a stupid question but it seems counter-intuitive/paradoxical that a warming planet leads to a colder atmopshere at all levels at the pole. Especially that sea ice and Glaciers are melting too.

    I'm probably missing something here but what?

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    Posted
  • Location: Netherlands
  • Location: Netherlands

    For me this is an important presentation: https://www.youtube.com/watch?v=xhBEBVEnrV8

    The Exceptional Winter of 2019-2020 explored through Global Teleconnections

    & this article

    Skilful climate predictions of the winter North Atlantic Oscillation and Arctic Oscillation out to a few months ahead have recently been demonstrated, but the source of this predictability remains largely unknown. Here we investigate the role of the Tropics in this predictability. We show high levels of skill in tropical rainfall predictions, particularly over the Pacific but also the Indian and Atlantic Ocean basins. Rainfall fluctuations in these regions are associated with clear signatures in tropical and extratropical atmospheric circulation that are approximately symmetric about the Equator in boreal winter. We show how these patterns can be explained as steady poleward propagating linear Rossby waves emanating from just a few key source regions. These wave source ‘hotspots’ become more or less active as tropical rainfall varies from winter to winter but they do not change position. Finally, we show that predicted tropical rainfall explains a highly significant fraction of the predicted year‐to‐year variation of the winter North Atlantic Oscillation.

    https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/qj.2910

    We have to be careful obserce the rainfull in december in the outlined areas. 

    plaatje 3.JPG

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    Posted
  • Location: Netherlands
  • Location: Netherlands
    16 hours ago, CreweCold said:

    No. I'm actually very optimistic for this winter.

    Well with the potent high pressure area around the Gulf of Alaska (La Nina and SSTs in that area driven) we probably have a strong polar vortex.  And we all know what this will do to our weather. Especially in the second half. 

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    Posted
  • Location: Broadmayne a few miles north of Weymouth in Dorset
  • Weather Preferences: Snowfall
  • Location: Broadmayne a few miles north of Weymouth in Dorset

    I don’t have the information to hand but I,d be interested to know what Glosea was suggesting at this time of year in 2008, 2009 and 2010.

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    Posted
  • Location: Netherlands
  • Location: Netherlands
    1 hour ago, Broadmayne blizzard said:

    I don’t have the information to hand but I,d be interested to know what Glosea was suggesting at this time of year in 2008, 2009 and 2010.

    HI you can see them in the archive https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean

    go with your mouse to issued, go to the right side of the box which states september 2020 and select the years you want. 2008 is not available. 

    E.g. september 2009 en 2010

    2cat_20090901_z500_months46_global_deter_public.png

    2cat_20100901_z500_months46_global_deter_public.png

    Edited by sebastiaan1973
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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    GLOSEA did very well for 2009 and 2010...but made a complete balls up of 2013 as close as the December 2012. The CFS had 2013 nailed from very early on.

    image.thumb.png.123dc91d9b0880462c031e4b29b092b1.png

    Didn't do too well at the back end of winter 2018 either

    image.thumb.png.e930a0db45857579ef337e62c1e2a98e.png

    Current CFS charts for DEC and JAN-

    image.thumb.png.c39162bd108ae1355d40d1f6ac047b85.png

    image.thumb.png.2ecdfa3b20dfac47dcb1aa03195b5d68.png

    Feb a total write off with that intense Pacific ridging- but tbf with a Nina in command the winter was always going to be 'front loaded' for winter potential.

    image.thumb.png.f807ed8bfa19ef161b53484fa81e6761.png

    Edited by CreweCold
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    Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
    7 hours ago, LRD said:

    With the obvious background planetary warming, why is it that the polar vortex seems to be cold and intense winter after winter? I know this is probably a stupid question but it seems counter-intuitive/paradoxical that a warming planet leads to a colder atmopshere at all levels at the pole. Especially that sea ice and Glaciers are melting too.

    I'm probably missing something here but what?

    Think it may be that in the heart of winter the pole is still very cold, but the tropics and subtropics are warmer, so more of a temperature gradient fuelling an even stronger polar night jet?  On average of course, because there are still times when the vortex breaks down most notably recently Spring 2018. 

    Edited by Mike Poole
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    Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
    1 hour ago, CreweCold said:

    GLOSEA did very well for 2009 and 2010...but made a complete balls up of 2013 as close as the December 2012. The CFS had 2013 nailed from very early on.

    image.thumb.png.123dc91d9b0880462c031e4b29b092b1.png

    Didn't do too well at the back end of winter 2018 either

    image.thumb.png.e930a0db45857579ef337e62c1e2a98e.png

    Current CFS charts for DEC and JAN-

    image.thumb.png.c39162bd108ae1355d40d1f6ac047b85.png

    image.thumb.png.2ecdfa3b20dfac47dcb1aa03195b5d68.png

    Feb a total write off with that intense Pacific ridging- but tbf with a Nina in command the winter was always going to be 'front loaded' for winter potential.

    image.thumb.png.f807ed8bfa19ef161b53484fa81e6761.png

    Would be good to see how winters fared under different La Nina states, weak, moderate and strong. That Pacific high seems a permanent feature in recent winters since 2013, but it is just one feature in a list of many others.

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    Posted
  • Location: Broadmayne a few miles north of Weymouth in Dorset
  • Weather Preferences: Snowfall
  • Location: Broadmayne a few miles north of Weymouth in Dorset
    18 hours ago, sebastiaan1973 said:

    HI you can see them in the archive https://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/ens-mean

    go with your mouse to issued, go to the right side of the box which states september 2020 and select the years you want. 2008 is not available. 

    E.g. september 2009 en 2010

    2cat_20090901_z500_months46_global_deter_public.png

    2cat_20100901_z500_months46_global_deter_public.png

    Thanks Sebastian.🌕👍

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    Posted
  • Location: Rotherham
  • Weather Preferences: Snow, severe frost, freezing fog and summer sunshine
  • Location: Rotherham
    14 hours ago, damianslaw said:

    Would be good to see how winters fared under different La Nina states, weak, moderate and strong. That Pacific high seems a permanent feature in recent winters since 2013, but it is just one feature in a list of many others.

    Am I right in thinking there is a correlation between the Pacific high and the very warm SST's in that region over the past few years? And given the developing La Nina, would that not cool the seas in the northern Pacific over the next few months reducing the chances of such a stubborn area of high pressure developing?

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

    ^ just for some more info on the Pacific blob / heatwave it’s a bit complex but does link with the persistent high pressure in that area but the researchers haven’t linked it to the El Niño events so the key thing would be to try understand why the high pressure there has been so persistent, also devastating effects for the marine life 🙁 https://earthdata.nasa.gov/learn/sensing-our-planet/blob

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    Posted
  • Location: Bedfordshire
  • Weather Preferences: Warm summers with thunderstorms, stormy or fog/frost autumns, cold winters
  • Location: Bedfordshire
    16 hours ago, Mike Poole said:

    Think it may be that in the heart of winter the pole is still very cold, but the tropics and subtropics are warmer, so more of a temperature gradient fuelling an even stronger polar night jet?  On average of course, because there are still times when the vortex breaks down most notably recently Spring 2018. 

    I can certainly see the logic in that explanation. I s'pose what I would say is that the relative temp gradient should still be weaker if the atmopshere is warming up at the pole as it is in the tropics. 

    But you could well be right with that theory

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    Posted
  • Location: Ludgershall, Wiltshire
  • Location: Ludgershall, Wiltshire
    1 hour ago, Premier Neige said:

    Am I right in thinking there is a correlation between the Pacific high and the very warm SST's in that region over the past few years? And given the developing La Nina, would that not cool the seas in the northern Pacific over the next few months reducing the chances of such a stubborn area of high pressure developing?

    This is something Gavin Partridge has been talking about recently.  Whilst a La Nina could lead to a cooling of the northern Pacific, it may not been in time for winter, as there is currently little sign of this occurring.

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