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Early run up to Winter 2020/2021 discussion


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Posted
  • Location: Liphook
  • Location: Liphook

    When it comes to this winter I'm really expecting nothing sustained at all, youve got an ever strengthening upper vortex that might get close to near record levels. I can't believe there won't be synchronization at some point with the tropospheric response if that kinda vortex hangs around for meaningful amount of time. We therefore already are putting all hopes on some sort of ssw event to pop that vortex.

    Then you have a borderline strong la Nina event, and I'm personally never a fan of strong enso events (though of course 2010 December was a strong la Nina just starting to decay). However in 2010 the building blocks were basically In place already, we couldn't be much further removed it feels at the moment.

    This not to say that winter is a write off, and sometimes big events can happen in otherwise less than stellar years, but going below average is already looking unlikely imo.

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    Just a post for any newbies who have just joined. Musings and posts you WILL regularly come across in the months ahead and going into a winter: 1. October: 'This winter will be front loaded or ba

    Says it up top 02/10.   Hot off the press Met office seasonal update OCT 20 for NDJ Considerable changes in favour of a colder Front loaded winter. Gone is the negative low pressur

    Hi. Just briefly dipping into this thread, as a one off, to perhaps provide some further insight here... The spike in AAM in Oct was, of course, directly related to the eastward movement of the M

    Posted Images

    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
    6 minutes ago, kold weather said:

    When it comes to this winter I'm really expecting nothing sustained at all, youve got an ever strengthening upper vortex that might get close to near record levels. I can't believe there won't be synchronization at some point with the tropospheric response if that kinda vortex hangs around for meaningful amount of time. We therefore already are putting all hopes on some sort of ssw event to pop that vortex.

    Then you have a borderline strong la Nina event, and I'm personally never a fan of strong enso events (though of course 2010 December was a strong la Nina just starting to decay). However in 2010 the building blocks were basically In place already, we couldn't be much further removed it feels at the moment.

    This not to say that winter is a write off, and sometimes big events can happen in otherwise less than stellar years, but going below average is already looking unlikely imo.

    I'm not quite as negative because i suspect the active tropical convection is distorting things and perhaps adding to vortex pressure however i do tend to agree that we've wasted most of the Oct-Dec period now and things become much more difficult in Jan-March. I would not be surprised to see more beneficial outcomes in December though.

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    Posted
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow
  • Weather Preferences: continental climate
  • Location: Roznava (Slovakia) formerly Hollywood, Co Wicklow

    Maybe there is a hope in the post 10 day period in retaining some heights to the north - as GWO phase 5 indicates a southward momentum at 35N - diving westerly jet, unfortunately the GWO is week and AAM is not as high to show this more pronounced in the extended modeling, the first week of December anomaly on the ECMWF you can see some height being still retained up north in Scandinavia. Maybe the MJO wave will be strong enough past Indian ocean to induce more AAM and more hope for undercutting scenario. Its a pity not seing  @Glacier Point input as he is a master of reading the atmosphere conundrum. He sometimes posts some clues at the start of summer/winter season on his blog,hopefully he will do it again shortly 🙂

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    Posted
  • Location: Netherlands
  • Location: Netherlands

    https://www.weer.nl/nieuws/2020/winterverwachting-2021-het-venijn-zit-in-de-tweede-helft

    Winter forecast 2021: is the devil in the second half?
    Not the first part of the coming winter is interesting, but winter weather enthusiasts should keep an eye on the second half. There will be no early winter weather, that is now clear. But because it does not happen and also for the reasons behind it, the second half of winter has suddenly become interesting. It is time for the presentation of our final winter forecast.

    When we presented our first version of the winter forecast last September, the idea was still that today's La Niña, a cold sea current on the Pacific Ocean, along the equator between Peru and Indonesia, would determine what was to come. If the air pressure distribution in the Northern Hemisphere had neatly adhered to the image associated with such a La Niña, there were now high-pressure areas near Iceland and Greenland and a northerly wind had already at least once had a considerable amount of cold with us. brought himself. However, that did not happen.
    Image first version expectation upside down

    What we have seen is that the run-up to winter this year is very similar to that of the two previous years. In today's 30-day forecast, we explain why. The strong polar vortex at the moment, which may even become record strong for a while in the coming weeks and the warm seawater west of Canada and the United States have completely eclipsed the expected influence of La Niña. This has turned the perspective for both halves of winter upside down.

    Source: World Climate Service

    So no early winter weather for the next 4 to 6 weeks. In fact, it seems that, as in previous winters, we end up under the influence of a western circulation for a longer period of time, with changeable weather and high temperatures, often close to or even slightly above 10 degrees. The nights also seem to be warmer than normal. The influence of the expected high-pressure areas to the south and east of us will depend on the extent to which the wind will occasionally apply and how far the precipitation amounts increase.

    Until the first weeks of January, the chance of significant winter weather seems small in this way. Only if it clears up a little longer in the nights during the passage of a high-pressure ridge, the temperature can reach freezing point for a short time.
    Winters 2000 and 2012 are imperative

    As comparison years from the past (in terms of the run-up to winter), the years 1999 and 2011 are now the most important. Both years later also see between which extremes the sequel in the second half of winter can move. The winter of 2000 was ultimately mild in its entirety. Especially in December and February a western circulation reigned, in January it was a bit drier than normal and the sun came through a little easier.

    In the winter of 2012, which was dominated by a western circulation throughout the first half and again in the last two weeks of February, a sudden warming of the stratosphere (SSW) took place in January in the Arctic, which started from the end of February. January and in the first two weeks of February led to a beautiful frosty period, with a freezing cold morning on February 4. In Lelystad, the temperature dropped above freshly fallen snow to -22.9 degrees, still the lowest temperature of this century. We skated en masse and even dreamed of an Elfstedentocht.
    Sudden warming of the stratosphere

    The scenario with a colder sequel in the second half of winter is actually part of the soft start, caused by the very strong polar vortex of the coming weeks. The chances of such a colder continuation will increase if the air pressure in northeastern Europe remains high in the coming weeks and Scandinavia is not overrun by low-pressure areas.

    Source: World Climate Service

    Comparable winters in the past more often resulted in an SSW, in the middle of winter. It is not a certainty, certainly not this year. Because both the La Niña of today and the QBO-west, another jet stream in the stratosphere above the equator that has a western and an eastern phase every roughly 2 years, normally work against such an SSW.

    Yet it is not possible to make a firm statement about this now, because the link between La Niña and the pressure distribution that goes with it does not seem to be visible this year. Parts of today's pattern are even more like the response associated with an El Niño than that associated with a La Niña. The combination of a QBO-west and El Niño makes an SSW quite possible. Furthermore, the La Niña already seems to have passed its height and should it really weaken in the coming weeks, the chance of a midwinter SSW will also gradually increase.

    Or will it stay soft all winter?

    The soft and fickle option, also during the second half of next winter, will come if an SSW is dropped and the polar vortex remains intact and strong. In that case, the changeable and mild weather just continues and we get the winter as we had it last year. This happens, for example, if La Niña persists (even though it now apparently has no influence) or becomes even stronger. But the warm waters of the Pacific and the Indian Ocean point toward a soft second half.

    If you had to estimate it now, despite the uncertainties, then the chance of a mild winter (even if there is a colder, second phase) is about 80 percent. The chance of a winter continuation in the second half will increase if La Niña decreases or, as it is now, continues to have no influence on the pressure distribution in the Northern Hemisphere. The chance of such a winter continuation in the second half with an SSW now seems about 20 percent.

    Source:

    WORLDCLIMATESERVICE.COM

    Long range weather forecast tools for Meteorologists and Industry

     

    Edited by sebastiaan1973
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    Posted
  • Location: Orebro, Sweden
  • Weather Preferences: Summer time: 26-29 degrees and partly cloudy. Winter time: -4 to -7 and sun
  • Location: Orebro, Sweden
    1 hour ago, sebastiaan1973 said:


    So no early winter weather for the next 4 to 6 weeks. 

     

    That's just extremely bad news, since this winter was supposed to be front-loaded with the highest possibilities for a cold start rather than the opposite. One can hope that at least the period around Christmas is around average.

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    Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset
    5 minutes ago, Faronstream said:

    That's just extremely bad news, since this winter was supposed to be front-loaded with the highest possibilities for a cold start rather than the opposite. One can hope that at least the period around Christmas is around average.

    I think the fact that this autumn season has behaved nothing like a typical La Nina kinda suggests that winter will not follow suit either. Ergo, I'm quietly more confident that the best of the winter will actually be beyond New Year, not before. 

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    Posted
  • Location: Ludgershall, Wiltshire
  • Location: Ludgershall, Wiltshire
    Just now, MP-R said:

    I think the fact that this autumn season has behaved nothing like a typical La Nina kinda suggests that winter will not follow suit either. Ergo, I'm quietly more confident that the best of the winter will actually be beyond New Year, not before. 

    That's what Roger J Smith's winter ideas also suggest.

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    Posted
  • Location: Ludgershall, Wiltshire
  • Location: Ludgershall, Wiltshire
    19 minutes ago, Summer Sun said:

     

    Just hope this coming January and February are more like 2012 than 2000, as at least 2012 featured a cold spell from late  January through to mid February with a few snow events.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
    23 minutes ago, Summer Sun said:

     

    Looks like they've pegged risk of a SSW at 20%

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    Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield
    1 minute ago, CreweCold said:

    Looks like they've pegged risk of a SSW at 20%

    Tbh probably fair call esp the unsettled December. Average set up

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    Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset
    8 minutes ago, Don said:

    Just hope this coming January and February are more like 2012 than 2000, as at least 2012 featured a cold spell from late  January through to mid February with a few snow events.

    And at least a cold frosty spell in mid January.

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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

    I suspect already it is time to take a short break from searching for winter. The way various drivers have turned in the last 3 weeks or so I think it will be a case of letting vortex intensification occur while the MJO comes back around for another pass. Niña is borderline strong and Europe is warm and unlikely to see substantive cold in the near future.

    Intense cold is going to bottle up over the polar regions while the sub tropical ridges strengthen. We will need something to look to break this pattern, probably via momentum surges and associated tie ins with a SSW. For me that means a fallow 4 weeks coming up before we can begin to see if the grip of a +AO/+NAO combo can be loosened later on. November has turned out to be a disappointment this year.

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

    I suspect already it is time to take a short break from searching for winter. The way various drivers have turned in the last 3 weeks or so I think it will be a case of letting vortex intensification occur while the MJO comes back around for another pass. Niña is borderline strong and Europe is warm and unlikely to see substantive cold in the near future.

    Intense cold is going to bottle up over the polar regions while the sub tropical ridges strengthen. We will need something to look to break this pattern, probably via momentum surges and associated tie ins with a SSW. For me that means a fallow 4 weeks coming up before we can begin to see if the grip of a +AO/+NAO combo can be loosened later on. November has turned out to be a disappointment this year.

    Well as I say, the MetO seem to have placed a 20% chance on a SSW. I'll take that now as it's quite possible that signal will grow.

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    Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield

    Guess it's a wait and see. Ssw are a big ask if a decent winter is relient on it 

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    Posted
  • Location: The Purbeck Microclimate, Dorset.
  • Weather Preferences: Gales, T-storms, Heavy Rain, Heat, Cold - Love it all.
  • Location: The Purbeck Microclimate, Dorset.
    36 minutes ago, CreweCold said:

    Looks like they've pegged risk of a SSW at 20%

    I don't think they are bringing that in to it, if they are using those two years as examples. 2000 didn't see one. Not sure about the beginning of 2012?! I just remember recording my lowest ever temp in February 2012, under a strong high pressure.

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    Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield
    11 minutes ago, Weather-history said:

    Does a strong La Nina necessarily mean a front loaded winter for UK?

    It didn't for winter 1975-76, infact the coldest wintriest weather of that winter came in the second half and into the March

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    I think what I've seen lately la Nina isn't or won't affect our winter weather this year. Not sure going into 2021 but the confusion being created ie front loaded, back loaded, ssw ete god only knows. Chaos is the outlook imo going forward. Folk seem to be throwing comments out "Nina footprints" possible eqbo which is only a long shot. Nh snow cover the list goes on. The only current certainty is the 10pha temps are falling and zonal winds are on the up. Its weather at the end of the day and all the guess work is exactly that 🙄

    Edited by swfc
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    Posted
  • Location: Weston-S-Mare North Somerset
  • Weather Preferences: Hot sunny , cold and snowy, thunderstorms
  • Location: Weston-S-Mare North Somerset
    29 minutes ago, Catacol said:

    I suspect already it is time to take a short break from searching for winter. The way various drivers have turned in the last 3 weeks or so I think it will be a case of letting vortex intensification occur while the MJO comes back around for another pass. Niña is borderline strong and Europe is warm and unlikely to see substantive cold in the near future.

    Intense cold is going to bottle up over the polar regions while the sub tropical ridges strengthen. We will need something to look to break this pattern, probably via momentum surges and associated tie ins with a SSW. For me that means a fallow 4 weeks coming up before we can begin to see if the grip of a +AO/+NAO combo can be loosened later on. November has turned out to be a disappointment this year.

    I suspect in will be longer than 4 weeks, we'll be lucky to see anything cold this side if Christmas, most likely late Jan or early Feb.

    We just have to accept our cold spells only come when unusual events take shape away from the climatical norm.

    And living within a warming climatic just exasperates the situation even more.

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    Posted
  • Location: Ashbourne,County Meath,about 6 miles northwest of dublin airport. 74m ASL
  • Weather Preferences: Cold weather - frost or snow
  • Location: Ashbourne,County Meath,about 6 miles northwest of dublin airport. 74m ASL

    I've already started to accept another disaster of a winter for cold is likely.  

    Its going to be damage limitation for coldies. 

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    Posted
  • Location: Walsall Wood, Walsall, West Midlands 145m ASL
  • Location: Walsall Wood, Walsall, West Midlands 145m ASL

    I'm not even sure it's wise to write too much of December off at this stage, especially considering there's still another 10 days left of November still. A repeat of 2010 doesn't look likely it seems I know, but who can say where we'll be in a months time. A cold spell could arrive just in time for Christmas for all we know at this point. Far too early at this point to be writing the whole of next month off this long before it's started. 

    Edited by Walsall Wood Snow
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    Posted
  • Location: sheffield
  • Weather Preferences: cold ,snow
  • Location: sheffield
    2 minutes ago, Walsall Wood Snow said:

    I'm not even sure it's wise to write too much of December off at this stage, especially considering there's still another 10 days left of November still. A repeat of 2010 doesn't look likely it seems I know, but who can say where we'll be in a months time. A cold spell could arrive just in time for Christmas for all we know at this point. Far too early to tell at this point to be writing the whole of next month off this long before it's started. 

    The uptick in zonal winds is pretty much nailed on firing up the Atlantic and westerly flow. Transient riding may bring in a cold shot but nothing out of the normal is likely app

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    Posted
  • Location: Walsall Wood, Walsall, West Midlands 145m ASL
  • Location: Walsall Wood, Walsall, West Midlands 145m ASL
    1 minute ago, swfc said:

    The uptick in zonal winds is pretty much nailed on firing up the Atlantic and westerly flow. Transient riding may bring in a cold shot but nothing out of the normal is likely app

    Oh well. I wouldn't worry too much at this stage. January or February or Spring or next Winter or someday sometime might deliver yet 😆

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