Eagle Eye

Absolutely, vertical thermal Eddy's increasing in the reliable now putting large pressure on the Strat not to mention the GFS underdoing the strength of the AAM rebound. Caution A lot of writing coming up... As we go into the New Year Trop pattern, the plausibility of an MJO driven signal also backed by the AAM is looking fairly reliable. I expect phase 6/7 to show by mid January (ish) in the NAO state as long as the AAM doesn't take a large downturn to a -VE state. Assuming horizontally and vertically stretched Eddy transfer in this 2D look at the Trop, especially the upper Trop then the transfer around the Earth of signals for blocking should be fairly good. The transfer of Poleward Eddy's relies on a holding of cn unstable inertia pattern preferably held by a fairly sustained +VE AAM signal that we might be entering now. This pattern combined with the MJO may support some form of Greenland blocking later especially if the East Asian jet retracts slightly and we can hold an amplified Rossby Wave pattern. Plenty to be cheerful about and it's Christmas time but it's still fairly far out and the strength of poleward Eddy's is yet to be determined really. Whether the GFS is overdoing the MJO signal and therefore overdriving the poleward thermal transfer or not you can argue about. Personally, it's been underdoing the AAM and MJO signal for a long time and has tried to slow down the MJO signal for a while. So I think it may be overdoing the signal beyond the end of its output slightly in terms of Eddy's and that may show in a few days time. It could also be underdoing the signal by under amplifying the forecasts and hence we may be in better luck than we even think now. Right now, I can't really tell and I won't know till after the event but looking long-term and I think a Greenland blocking signal could start showing itself in the output when we get into January. I won't go too much over the Trop pattern as of now but the AAM rebound bring stronger than initially forecast has given me hope that it can sustain itself for longer than forecast. If it can do that then we can look closer to home other than a potential SSW for colder prospects. Its a lot to ask from the AAM but I remain hopeful that it's festive cheer will keep up till my birthday on the 24th January. Looking at the arguably more impressive Strat though and there's a lot less IF's. The zonal wind is on its way down into the New Year, after the initial Vortex Intensification (VI), the Eddy's start to reach the Strat and the warmer air gets distributed away from the normal and Rossby Waves imparting easterly force and the zonal wind will weaken. Its as simple as that. Eddy's clearly strengthening into the New Year and the Wave-1 response is very clearly. This could potentially put a lot of pressure on the Strat. Seeing as it's essentially the same as earlier today I'll quote myself quickly " we should see some 'disconnect' between the two akin to thermal Eddy's slowly migrating up the Trop and into the Stratosphere because the upper Trop pattern response to the East Asian Jet Extension should be different to the Strat's reaction to the downstream energy scattering and Eddy vertical propagation simply because it is moving. Essentially what I'm saying here is that the Trop is getting moved earlier than the Strat and because the Earth is rotating the effects can look over exaggerated to what you would imagine. This is where the Earth's rotation helps us because it holds strong the unstable thermodynamics between the Trop and the Strat as energy cycles up the atmosphere and some cycles back down. This would distribute the Strat slower than the Trop and also mean that there is almost constant support for Wave-1 to at least keep it's strength slightly further beyond if/when the amount of Eddy flux starts 'drying up'. Eventually, this would lead to a radiative dampening of the Strat and the Strat and Trop connect up again so without a SSW or at least a large split, this could make the weeks worth of work and pressure on the Strat 'useless' so clearly we need to keep a large thermal gradient up as long as possible. Best things for that would be an extratropical 'wave train', an increase in AAM and/or MJO phases 6 and 7." And the latest run still supporting my view (although still fairly far away of course but it's a well supported view) on how the 'disconnect' shows increased thermal Eddy vertical profiling. Lots to be interested about going into the New Year and I'll keep updating everyone about it. Merry Christmas to this great forum and here's to a potential SSW in January (ish) if all goes well for us. Cheers.

Merry Christmas to all,nice to have talked to a lot of you this year and share my weather thoughts as well. Alqays been a lovely thread this and thanks to all the mods for allowing my deviations from weather lol. Oh and thanks to @Blessed Weather and all the others for the constant weather analysis and forecasts as well,always great to have people who are willing to give up their time to talk about the weather whereas I just don't have anything else going on in my life .

The ENSO state is minused from the RMM phases as far as I know when I did my research earlier thid month, so supposedly should have no impact on how they evolve. Although if you take it with the ENSO, the amplification looks to be similar near the Equator the amount it was before the last cold spell but without the ENSO it's clearly less amplified. Perhaps the ENSO state can help amplify VP centres?

Like I said earlier, I would expect the pressure of a Wave-1 dominance to start showing on on Strat by early January. You could say that its far out in FI but the increasing Eddy's is almost certain and the way they are evolving, a large Wave-1 is probably the most likely outcome me thinks. That was showing on the ensembles yesterday with all showing a Wave-1 dominance, so whilst it's technically where you would imagine FI to be, actually it's pretty much how things should evolve. The downwelling of the Strat-Trop should be replaced by upwelling Eddy's as thermal gradient increases and Rossby's propagate vertically. Rossby Waves look to be increasing fairly well in response potentially to the MJO or how the Pacific jet evolves and so my thinking is thermal Eddy's will be on the up which is also the thinking of most ensemble members. I'm shopping at the moment so have got time on my hands to have a proper look when the Stratobserve update comes out very soon...

As a base pattern it's more reliable and I've seen it generally verify more than the Trop. The warmth of the Strat can be quite wrong but the general direction of movement is modelled rather well. A large Wave-1 dominance looks likely as I said earlier this morning and the Trop pattern in a few days time with increasing Eddy's supports this setup so this Wave-1 and Eurasian/North Pacific Wave is probably the most likely at this stage. I think the GFS is modelling the area really well its just how well it models the warmth of the wave riding the vortex and the inner bands of the riding wave is difficult to tell. It may be overdoing it as I think its being overdoing the thermal gradient for a while now but at this range who knows. Like I said, I think it's it's the area and strength relative to the Euro warming pretty much spot on but the strength of the main warming may be slightly overdone (or it could be undercooked depending on how the upper Trop handles the Eddy's from the energy scattering due to the East Asian Jet Retraction). So right now it could go either way on this one and I think it's a case of waiting for now. Original post: https://community.netweather.tv/topic/98132-model-output-discussion-the-run-up-to-christmas/?do=findComment&comment=4777227

As a base pattern it's more reliable and I've seen it generally verify more than the Trop. The warmth of the Strat can be quite wrong but the general direction of movement is modelled rather well. A large Wave-1 dominance looks likely as I said earlier this morning and the Trop pattern in a few days time with increasing Eddy's supports this setup so this Wave-1 and Eurasian/North Pacific Wave is probably the most likely at this stage. I think the GFS is modelling the area really well its just how well it models the warmth of the wave riding the vortex and the inner bands of the riding wave is difficult to tell. It may be overdoing it as I think its being overdoing the thermal gradient for a while now but at this range who knows. Like I said, I think it's it's the area and strength relative to the Euro warming pretty much spot on but the strength of the main warming may be slightly overdone (or it could be undercooked depending on how the upper Trop handles the Eddy's from the energy scattering due to the East Asian Jet Retraction). So right now it could go either way on this one and I think it's a case of waiting for now.

Signs of pressure being put onto the Strat long-term should start cropping up fairly well but that pressure needs to be sustained of course. I'm holding out hope that the Trop pattern will support that and we keep getting rebounds of +VE AAM so that the Trop remains relatively unstable and thermal transfer can migrate both 2D vertically and 3D vertically. What all this means is that we need a sustained temperature gradient (from an oscillating jet stream, probably from either one strong mountain torque events or multiple smaller ones) because that's how Rossby waves move up as they try to link back to local thermodynamic equilibrium, their dynamic response is to typically move up. Then they impart an easterly force onto where they propagate hence we see a weakening of the zonal winds by where they reach and they can refract the Strat away from it's normal which unevenly distributes heat. As it does so, that could potentially cut of the Arctic flow and significantly warms it quickly as the warm air spills and and we see the zonal wind reverse due to this. That's a quick snapshot of how a SSW works if anyone happened to be interested. Right now, it's a long shot as the zonal mean in the Strat is quite clearly fairly strong and trying to connect up with the Trop pattern but there's a small AAM rebound and an anomalous Pacific jet which is helping to increase the local temperature gradient as the centres of systems amplify yet the jets energy is fairly differentiating around the globe. So torque increasing events have helped thermal Eddy's transfer energy and slowly we should see that leak into the Strat by the New Year with the weakening of the zonal winds. Throw in the MJO phase 6/7 lag and you've got yourself a fairly amplified Eddy flux pattern long-term and hence why we're seeing charts like this with some downwelling of the Strat still trying to occur but you can see the Eddy's vertically upwelling from the trop pattern and translating themselves into a fairly Wave-1 dominant system. It's clear that the upper Trop is shunting away from the Strat at the end of the run after a fairly brief attempt at a strong connection but how realistic is this? Well, the main way of finding that out is thinking about hoe the upper Trop evolves through zonal wind profiling to suggest how Eddy flux should evolve. The zonal development whilst it foes look fairly slow and conductive for an oscillating jet (of course we won't see the Trop effects from it that much yet, although it's clear that we can rule out the Eurasian or more specifically, African/Arabian feedback wouldn't result in a jet that could be fairly helpful in developing some sort of Euro/Scandi block perhaps initially UK based but that's just looking at the models and relies on the upwelling of the feedback to further North but I'll go more in-depth later) is probably not the best way to look at it because the thermal gradient at that area matters less in my opinion. Looking closer to home for some wave-trains and we do see something of the sort evolving. Not sure if it's classified as a wave train in itself but that's a fairly interesting look at the wind and could see a decent thermal gradient and is at least renewed flux between blocking/ridge attempts that looks similar to late November. Once again, how this evolves closer to home, I'll go over later but for the Trop-Strat pattern it's fairly good and I think shows that an anomalous energy distribution from how the East Asian jet works (whether it be extension or retraction) can affect how much the fluctuations in Eddy's can occur downstream. That's important for forming that upward wave movement which is in turn important for increasing the "riding outer wave" as Chio describes it. This isn't really an upwards split, more seems to me to be upwards wave distribution which is helpful for downward wave reflection from the Strat under SSW circumstances. Decreasing the chances that it's a minor SSW which may not affect us as much, hence why it's probably a better way of evolving a SSW than an upwards split though of course with an upwards split, the Trop pattern is split initially so without the AAM going -VE it can still be good for amplifying the downwards split, even with a 'minor' wave reflection. Yet, I still l don't think this will be enough as the unstable inertia going into the Polar pattern decreases through a relatively stable AAM compared to before, the actual fluctuation of Eddy's and thermal gradient is likely to be slightly weaker. So I think the apparent large 'disconnect' between the Trop and Strat in FI is slightly over-exaggerated. Although, that will depend on whether the AAM rebound props itself up slightly stronger and the MJO slightly more progressive and amplified. If that is true then the signal may be picking up an early 'disconnect' between the two more amplified than my current thinking. Even then though, we should see some 'disconnect' between the two akin to thermal Eddy's slowly migrating up the Trop and into the Stratosphere because the upper Trop pattern response to the East Asian Jet Extension should be different to the Strat's reaction to the downstream energy scattering and Eddy vertical propagation simply because it is moving. Essentially what I'm saying here is that the Trop is getting moved earlier than the Strat and because the Earth is rotating the effects can look over exaggerated to what you would imagine. This is where the Earth's rotation helps us because it holds strong the unstable thermodynamics between the Trop and the Strat as energy cycles up the atmosphere and some cycles back down. This would distribute the Strat slower than the Trop and also mean that there is almost constant support for Wave-1 to at least keep it's strength slightly further beyond if/when the amount of Eddy flux starts 'drying up'. Eventually, this would lead to a radiative dampening of the Strat and the Strat and Trop connect up again so without a SSW or at least a large split, this could make the weeks worth of work and pressure on the Strat 'useless' so clearly we need to keep a large thermal gradient up as long as possible. Best things for that would be an extratropical 'wave train', an increase in AAM and/or MJO phases 6 and 7. I don't know how this will evolve of course but I can see it going one way where we get close but not close enough and people are getting 'on top' of the people predicting a SSW could occur. Or the people saying a SSW won't occur will be told how wrong they were if one does occur. Please, don't do that anyone as you could dishearten the person. Right now, it's a 20-25% chance of one in my opinion as we don't know how the Trop will evolve by day 5 let alone by mid January. Hence we could see a return to the Strat downwelling into the Trop as the Eddy's 'dry up' too quickly but we have seen most forecasts keep up the Eddy's strength right up till the end of the run so good support to keep it going for a while but how it'll evolve beyond then is important as it needs to become a sustained signal for the warm air to 'leak into' the Strat PV. This whole post is just my best guess and I've left a lot open but have tried to remain positive throughout it so far. Simply put, it's too far out to fully understand for now so I'm not willing to make a call whatsoever. Looking FI into the NH Strat and you can see that high putting pressure onto the vortex but how much pressure it can put will of course determine the eventual outcome. That wrapping up looks pretty tight and considering how the Strat normally evolves and the high also probably evolving fairly normally but simply put, more runs are needed as it's way too far out to worry about positioning. The wave essentially rides the vortex but the vortex is fairly strong and wrapped up nicely, it's difficult to work out how the high would evolve from there. If I were taking it as entirely correct then the best chance would be a leaking split right through the Greenland area with the high riding pretty much all the way around the vortex as it starts in Eurasia and ends up back near Europe. On the other hand though this is out in FI for now so we're just going to have to wait and wait and wait and wait for nothing or something to occur. Interesting times Strat wise, a genuine possibility but it's also fairly far out in the distance that we can't really know what will happen here. The 1hPa is very hard to work out but that's at 384 hours so I won't worry about trying to work that out . A SSW is unlikely but cannot be ruled out to summarise all of that... Onto closer to time and closer to us... And looking for a cold pattern evolution is difficult but not impossible. Compared to the last few days the GFS is feeling the festive cheer by evolving us a UK/Scandi high going into the New Year and this sort of makes sense of the travelling of the energy scattering of the 'wave train' showed on the meridional winds earlier with weaker winds going into the Atlantic which could end up moving closer to Europe and the high rides the oscillating jet stream due to that fairly well (note that I'm looking at a slightly different level of the Atmosphere here). I'm not sure how much amplification can come from this though but one can hope. Whereas the ECM is slightly less keen but still amplifies it into an alright position just may have to hope. that it doesn't act like a Euro ridge (which now that I've said that, it probably will ) and flatten itself out. With this setup, there's not much cold bottled up to the East so it would have to be long-fetch which is unlikely but if things do evolve wel; we should at least get some decent cold and perhaps something of a good event for those further North and Scotland but only if all goes well. GEM is is the least interested and I see where it's coming from but I think the fact that we've had that air drawn up originally probably favours the ECM's stance on this. It would still be good away from the south and maybe Midlands for cold and maybe snow prospects depending on how things evolve. I think we forget the North and Scotland because apparently they 'get a lot' but I'm pretty sure I've heard about areas there which seem to come with their own mild and don't get that much snow and are perhaps on par with how much the south has typically got over the past few years. I think out of the three of them the ECM is most likely to be correct but that's simply my ECM bias that I developed after it got a Storm system pretty much spot on in the Summer even when Convective Weather was struggling to understand where it was coming from (low/slight risk and ended up being quite a large squall line I'm pretty sure) and I hold Convective Weather in very high regard. I noted the large amount of moisture still left to transfer in the North Atlantic a few days ago and the ECM seems to be picking up on a signal for another potential Atmospheric River which if shunted further North could combine with the potential cold for the North and Scotland and bring them a lot of snowfall. So let's see how this evolves as well. GFS keeps it more vertically elongated and holds it back, GEM also seems to hold it back but then brings it in with a vengeance. P.S @Allseasons-si I'm quite a slow typer (yet seeing as I use it for school as my handwriting is awful you would think I would be quick) and thanks for the kind words, much appreciated. This is Eagle Eye signing off for the night(or actually early morning)and if I can't get on later today then Merry Christmas to all of you lovely people but I'm going shopping apparently and where we're going has got WiFi so I'll need a distraction from adults talking about cheeses . Original post: https://community.netweather.tv/topic/98132-model-output-discussion-the-run-up-to-christmas/?do=findComment&comment=4777110

Signs of pressure being put onto the Strat long-term should start cropping up fairly well but that pressure needs to be sustained of course. I'm holding out hope that the Trop pattern will support that and we keep getting rebounds of +VE AAM so that the Trop remains relatively unstable and thermal transfer can migrate both 2D vertically and 3D vertically. What all this means is that we need a sustained temperature gradient (from an oscillating jet stream, probably from either one strong mountain torque events or multiple smaller ones) because that's how Rossby waves move up as they try to link back to local thermodynamic equilibrium, their dynamic response is to typically move up. Then they impart an easterly force onto where they propagate hence we see a weakening of the zonal winds by where they reach and they can refract the Strat away from it's normal which unevenly distributes heat. As it does so, that could potentially cut of the Arctic flow and significantly warms it quickly as the warm air spills and and we see the zonal wind reverse due to this. That's a quick snapshot of how a SSW works if anyone happened to be interested. Right now, it's a long shot as the zonal mean in the Strat is quite clearly fairly strong and trying to connect up with the Trop pattern but there's a small AAM rebound and an anomalous Pacific jet which is helping to increase the local temperature gradient as the centres of systems amplify yet the jets energy is fairly differentiating around the globe. So torque increasing events have helped thermal Eddy's transfer energy and slowly we should see that leak into the Strat by the New Year with the weakening of the zonal winds. Throw in the MJO phase 6/7 lag and you've got yourself a fairly amplified Eddy flux pattern long-term and hence why we're seeing charts like this with some downwelling of the Strat still trying to occur but you can see the Eddy's vertically upwelling from the trop pattern and translating themselves into a fairly Wave-1 dominant system. It's clear that the upper Trop is shunting away from the Strat at the end of the run after a fairly brief attempt at a strong connection but how realistic is this? Well, the main way of finding that out is thinking about hoe the upper Trop evolves through zonal wind profiling to suggest how Eddy flux should evolve. The zonal development whilst it foes look fairly slow and conductive for an oscillating jet (of course we won't see the Trop effects from it that much yet, although it's clear that we can rule out the Eurasian or more specifically, African/Arabian feedback wouldn't result in a jet that could be fairly helpful in developing some sort of Euro/Scandi block perhaps initially UK based but that's just looking at the models and relies on the upwelling of the feedback to further North but I'll go more in-depth later) is probably not the best way to look at it because the thermal gradient at that area matters less in my opinion. Looking closer to home for some wave-trains and we do see something of the sort evolving. Not sure if it's classified as a wave train in itself but that's a fairly interesting look at the wind and could see a decent thermal gradient and is at least renewed flux between blocking/ridge attempts that looks similar to late November. Once again, how this evolves closer to home, I'll go over later but for the Trop-Strat pattern it's fairly good and I think shows that an anomalous energy distribution from how the East Asian jet works (whether it be extension or retraction) can affect how much the fluctuations in Eddy's can occur downstream. That's important for forming that upward wave movement which is in turn important for increasing the "riding outer wave" as Chio describes it. This isn't really an upwards split, more seems to me to be upwards wave distribution which is helpful for downward wave reflection from the Strat under SSW circumstances. Decreasing the chances that it's a minor SSW which may not affect us as much, hence why it's probably a better way of evolving a SSW than an upwards split though of course with an upwards split, the Trop pattern is split initially so without the AAM going -VE it can still be good for amplifying the downwards split, even with a 'minor' wave reflection. Yet, I still l don't think this will be enough as the unstable inertia going into the Polar pattern decreases through a relatively stable AAM compared to before, the actual fluctuation of Eddy's and thermal gradient is likely to be slightly weaker. So I think the apparent large 'disconnect' between the Trop and Strat in FI is slightly over-exaggerated. Although, that will depend on whether the AAM rebound props itself up slightly stronger and the MJO slightly more progressive and amplified. If that is true then the signal may be picking up an early 'disconnect' between the two more amplified than my current thinking. Even then though, we should see some 'disconnect' between the two akin to thermal Eddy's slowly migrating up the Trop and into the Stratosphere because the upper Trop pattern response to the East Asian Jet Extension should be different to the Strat's reaction to the downstream energy scattering and Eddy vertical propagation simply because it is moving. Essentially what I'm saying here is that the Trop is getting moved earlier than the Strat and because the Earth is rotating the effects can look over exaggerated to what you would imagine. This is where the Earth's rotation helps us because it holds strong the unstable thermodynamics between the Trop and the Strat as energy cycles up the atmosphere and some cycles back down. This would distribute the Strat slower than the Trop and also mean that there is almost constant support for Wave-1 to at least keep it's strength slightly further beyond if/when the amount of Eddy flux starts 'drying up'. Eventually, this would lead to a radiative dampening of the Strat and the Strat and Trop connect up again so without a SSW or at least a large split, this could make the weeks worth of work and pressure on the Strat 'useless' so clearly we need to keep a large thermal gradient up as long as possible. Best things for that would be an extratropical 'wave train', an increase in AAM and/or MJO phases 6 and 7. I don't know how this will evolve of course but I can see it going one way where we get close but not close enough and people are getting 'on top' of the people predicting a SSW could occur. Or the people saying a SSW won't occur will be told how wrong they were if one does occur. Please, don't do that anyone as you could dishearten the person. Right now, it's a 20-25% chance of one in my opinion as we don't know how the Trop will evolve by day 5 let alone by mid January. Hence we could see a return to the Strat downwelling into the Trop as the Eddy's 'dry up' too quickly but we have seen most forecasts keep up the Eddy's strength right up till the end of the run so good support to keep it going for a while but how it'll evolve beyond then is important as it needs to become a sustained signal for the warm air to 'leak into' the Strat PV. This whole post is just my best guess and I've left a lot open but have tried to remain positive throughout it so far. Simply put, it's too far out to fully understand for now so I'm not willing to make a call whatsoever. Looking FI into the NH Strat and you can see that high putting pressure onto the vortex but how much pressure it can put will of course determine the eventual outcome. That wrapping up looks pretty tight and considering how the Strat normally evolves and the high also probably evolving fairly normally but simply put, more runs are needed as it's way too far out to worry about positioning. The wave essentially rides the vortex but the vortex is fairly strong and wrapped up nicely, it's difficult to work out how the high would evolve from there. If I were taking it as entirely correct then the best chance would be a leaking split right through the Greenland area with the high riding pretty much all the way around the vortex as it starts in Eurasia and ends up back near Europe. On the other hand though this is out in FI for now so we're just going to have to wait and wait and wait and wait for nothing or something to occur. Interesting times Strat wise, a genuine possibility but it's also fairly far out in the distance that we can't really know what will happen here. The 1hPa is very hard to work out but that's at 384 hours so I won't worry about trying to work that out . A SSW is unlikely but cannot be ruled out to summarise all of that... Onto closer to time and closer to us... And looking for a cold pattern evolution is difficult but not impossible. Compared to the last few days the GFS is feeling the festive cheer by evolving us a UK/Scandi high going into the New Year and this sort of makes sense of the travelling of the energy scattering of the 'wave train' showed on the meridional winds earlier with weaker winds going into the Atlantic which could end up moving closer to Europe and the high rides the oscillating jet stream due to that fairly well (note that I'm looking at a slightly different level of the Atmosphere here). I'm not sure how much amplification can come from this though but one can hope. Whereas the ECM is slightly less keen but still amplifies it into an alright position just may have to hope. that it doesn't act like a Euro ridge (which now that I've said that, it probably will ) and flatten itself out. With this setup, there's not much cold bottled up to the East so it would have to be long-fetch which is unlikely but if things do evolve wel; we should at least get some decent cold and perhaps something of a good event for those further North and Scotland but only if all goes well. GEM is is the least interested and I see where it's coming from but I think the fact that we've had that air drawn up originally probably favours the ECM's stance on this. It would still be good away from the south and maybe Midlands for cold and maybe snow prospects depending on how things evolve. I think we forget the North and Scotland because apparently they 'get a lot' but I'm pretty sure I've heard about areas there which seem to come with their own mild and don't get that much snow and are perhaps on par with how much the south has typically got over the past few years. I think out of the three of them the ECM is most likely to be correct but that's simply my ECM bias that I developed after it got a Storm system pretty much spot on in the Summer even when Convective Weather was struggling to understand where it was coming from (low/slight risk and ended up being quite a large squall line I'm pretty sure) and I hold Convective Weather in very high regard. I noted the large amount of moisture still left to transfer in the North Atlantic a few days ago and the ECM seems to be picking up on a signal for another potential Atmospheric River which if shunted further North could combine with the potential cold for the North and Scotland and bring them a lot of snowfall. So let's see how this evolves as well. GFS keeps it more vertically elongated and holds it back, GEM also seems to hold it back but then brings it in with a vengeance. P.S @Allseasons-si I'm quite a slow typer (yet seeing as I use it for school as my handwriting is awful you would think I would be quick) and thanks for the kind words, much appreciated. This is Eagle Eye signing off for the night(or actually early morning)and if I can't get on later today then Merry Christmas to all of you lovely people but I'm going shopping apparently and where we're going has got WiFi so I'll need a distraction from adults talking about cheeses .

Wave-1 looks to be increasing going into the New Year with it overriding the Wave-2 signal putting pressure on one slit of the Stratospheric vortex probably on the Siberia/North Ameican area of the lower Stratosphere eventually transferring into the upper Stratosphere(far into FI at the moment). This could displace it long-term although I don't think the Wave-1 amplitude is enough for a proper riding outer wave induced split just yet. Well see how we go though and I'll continue to keep an eye on it. The initial VI in the Strat should be weakened by an increased Eddy flux just beyond the coming days as the Strat-Trop don't really couple significant beyond the initial coupling instead it's the Trop Eddy's that begin vertically propagating to weaken the Strat polar vortex. That can be seen in the zonal wind weakening going into the New Year. If we can keep thermal waves propping up the Wave-1/ I guess Wave-2 and we keep away from a zonal inertial pattern then the onset of a SSW is possible. If we can keep thermal up for a while an onset of a SSW may be possible but for now its unlikely. According to European Geophysics Union,"The reversal of the polar vortex is a less important criterion for creating downward-propagating signals than the strength of the wave activy flux and the relative perturbation of the polar vortex. This interpretation is consistent with earlier findings that strong upward wave activity fluxes are a good indicator for a downward-propagating response of SSWs". Personally, a SSW would need more than this for now but it's still going down right at the end of the forecast. If FI is correct here (we'd be lucky) then the Eddy's still keep increasing for a fairly long time and a couple days to a week more at that level and we could start thinking about a SSW but tight now I find that lucky since we always seem to be unlucky with things like this. I'm trying to keep my positivity going after a bad early morning (I won't go over it here) for me. Sorry that I'm not really in the festive cheer really but hopefully the possibility of a SSW will emerge properly in the New Year and I'll feel a bit of New Year spirit .

Not necessarily it just depends on how they evolve. If you get them more East based in terms of Europe it shouldn't matter too much and would just displace the cold that we aren't even tapping in to. Case in point, this from 2010: You're right in most cases though a developing UK high isn't that bad if it can 'act' like a Scandi high then its a fairly decent shot at cold.

Fantastic post yet again, great to have you on the forum. I said earlier this Witner that a SSW would probably be our main chance of significant cold then that cold snap happened and instead of sticking to my guns I thought that a repeating pattern might happen. Let hope get the best of me but yes, I think we need to see a large increase in AAM and the MJO to hold phase 6/7 otherwise we'll have to rely on a SSW (imo). There can and should probably be snaps of cold that do make it far south but those will be short nowcasting events probably. Its not going to be the worst of early Winters but it probably won't won't the best. I wouldn't call Winter over whatsoever as we've got some help. A SSW may not be amazingly realistic right now with the VI but that looks to be dipping soon as Eddy flux looks to increase going into January with the wave-2 plot increasing pressure on the Strat vortex but still probably not significant enough yet. Its a step in the right direction but we've got a long way to go for the riding outer wave(so?)style SSW just yet but I most certainly wouldn't rule one out.

I did a really silly thing and asked someone out last night and of course got rejected so excuse me if I'm not in the festive mood but the lovely weather this morning isn't exactly cheering me up. Why can't this be falling as snow ? So, I'm going to be looking on the brighter side here rather than reverting to the assuming the models are right at 384 hours like some people seem to do (no names to be named of course). Notice the zonal packet in the 0-30E area, that's around the Eurasian area and despite no more Eurasian blocking -which was waning when the Euro ridge formed hence it didn't have quite enough oomph to form a Scandi block- but this time if the North African high is further East then maybe we can at least get some form of a Scandi block. The more likely result is a Eurasian ridge but we can't count out a Scandi blocking. Also note the jet retraction around 120E-180, that's East Asia and the Pacific . So if that strengthens further, its not all that bad because that oscillates the jet further down the line usually. There's slightly more backing for a Nino-esque pattern on the GWO which is backing the AAM rebound to last a few more days (Green line) but its clearly not as amplified as before. Its keeping the unstable inertia state propping up poleward Eddy transfer fairly well which may just fall well for us. Due to the amplification it's unlikely to but that doesn't mean that it can't. MJO looking to move towards phases 6 and 7 by the end of the year which would normally get a response 2 to 3 weeks later, so near the time of my birthday. It has a fairly good chance of a -VE NAO but to not be overriden once we get to it by let's say, a zonal signal, I would probably prefer it to be slightly more amplified than its forecast to be and phase 6/7 doesn't guarantee a -VE NAO to be fair either. It just increases the chance of us having one. My hoping is that the AAM doesn't go overly -VE and override the MJO signal as it connects up with the oceanic base state. Or that the Euro ridge signal doesn't start pushing itself too much as that's the pattern flattener so the MJO signal becomes less important for iur eventual weather here. There's still a lot of moisture in the Tropics so another Atmospheric River riding the colder air from Polar regions then the backedge drops here and that could lead to a lot of snow if it gets cold enough in let's say mid January. That's just trying to pick up a signal that doesn't exist really yet and we wouldn't know till closer to time.

Yes my thoughts as well, the actual strength of the determination of 'COD' also changes depending on the phase diagrams of the MJO and the GWO and where you get them from in my experience.

The backedge of the Atmospheric River still looks like it coilf delirver snow away from just Scotland, for areas of Northern Ireland, Ireland, Wales and the North could see some fairly decent snow due to this. It may not be a lot but any snow around Christmas time, I see as a win. It also looks like a lot in Scotland as well as the North probably ending up next best. GFS ECM GEM ICON Swiss MRF HARMONIE Swiss 4 x 4 So, still a fair amount of difference at the moment but away from the south (and I suppose the Midlands) there is a fair chance for some snow close to Christmas time (in some areas maybe on Christmas day).

I would argue that it still makes teleconnections and everything like that the best long-term forecasting system. Personally, I saw the Scandi high being quicker than other people thought and look what we saw with the Euro ridge. There just wasn't quite enough amplification and the Eurasian feedback wanes slightly too quickly. It was still showing on the models a few days before it just turned into a Euro ridge. I don't think it was the American Storm that stopped the Scandi high personally. I did see cold properly coming in late December/early New Year and I hold my hand up for that, I saw a Greenland blocking take place from the way that the zonal wind was evolving but unfortunately it just ended up phasing too quickly and now looks like it's going to end up around the European area. That was affected by the American Storm I think as when that came better modelled, that was when the zonal feedback began moving further East. Crazy to think teleconnections can get things within a hundred miles and just not handle an American Storm shunting the -VE zonal wind anomalies further East because of it, yet that results in such a large change from normal. Teleconnections are the best long-term forecasting system that we've got but they are far from perfect.

NAM is the Northern Annular Mode or otherwise known as the Arctic Oscillation (AO) What it's associated phases look like (as a general rule). VI is vortex intensification So essentially what Chio says here is that it might just be that the Arctic Oscillation is returning towards the positive phase in the Troposphere and instead of the Stratosphere (which happens to have a positive Arctic Oscillation already) 'coupling' with the Troposphere, it's just the AO in the Troposphere recovering itself. Meaning that the Troposphere going positive AO is not necessarily due to the vortex intensifying in the Stratosphere. Original post: https://community.netweather.tv/topic/98132-model-output-discussion-the-run-up-to-christmas/?do=findComment&comment=4776043

NAM is the Northern Annular Mode or otherwise known as the Arctic Oscillation (AO) What it's associated phases look like (as a general rule). VI is vortex intensification So essentially what Chio says here is that it might just be that the Arctic Oscillation is returning towards the positive phase in the Troposphere and instead of the Stratosphere (which happens to have a positive Arctic Oscillation already) 'coupling' with the Troposphere, it's just the AO in the Troposphere recovering itself. Meaning that the Troposphere going positive AO is not necessarily due to the vortex intensifying in the Stratosphere.

Not really, it's a tight corridor of concentrated water vapour transport (that can be very long in length but its not that wide usually). The pineapple express is just an example of one really, it depends more on the initial state of at Atmosphere and what air source it mixes in with. In a large zonal system it does create that pineapple express but in something like this, if it times itself with the cold(ish) air then the potential for snowfall will arise with it. Its not really a weather system in itself, its simply a large transport of water over time in a narrow corridor. Anyway, away from that and... As @Mike Poole says, it's not a 'roaring' +NAO that seems to be setting up here just yet. It does initially connect up with the Trop and we get a slight +VE zonal state going into the New Year. Yet, it doesn't look to be really strong and I think the AAM becomes fairly significant here. If we can get a significant rebound of AAM then the Trop-Strat connect up probably won't be long enough to build itself strong. Instead, thermal Rossby transfer poleward from fairly unstable inertia in a 'marginal' situation like this should probably be enough to swing us back into a slightly -VE zonal anomaly state. Original post: https://community.netweather.tv/topic/98132-model-output-discussion-the-run-up-to-christmas/?do=findComment&comment=4775779

Not really, it's a tight corridor of concentrated water vapour transport (that can be very long in length but its not that wide usually). The pineapple express is just an example of one really, it depends more on the initial state of at Atmosphere and what air source it mixes in with. In a large zonal system it does create that pineapple express but in something like this, if it times itself with the cold(ish) air then the potential for snowfall will arise with it. Its not really a weather system in itself, its simply a large transport of water over time in a narrow corridor. Anyway, away from that and... As @Mike Poole says, it's not a 'roaring' +NAO that seems to be setting up here just yet. It does initially connect up with the Trop and we get a slight +VE zonal state going into the New Year. Yet, it doesn't look to be really strong and I think the AAM becomes fairly significant here. If we can get a significant rebound of AAM then the Trop-Strat connect up probably won't be long enough to build itself strong. Instead, thermal Rossby transfer poleward from fairly unstable inertia in a 'marginal' situation like this should probably be enough to swing us back into a slightly -VE zonal anomaly state.

The track of the -VE zonal wind anomalies has shifted East over the last few runs (at around 45W to 30-15W)instead of becoming a shored up Greenland zonal setup early link, its just going to become another Eurasian signal (possible Euro ridge repeating pattern and could draw up more WAA into the Eurasian area/Scandinavian ridge or more hopefully block). I've noted the zonal packet transitioning over the North American area (this being just above the Tropics) from 120W to 30W that was probably not handled well and admittedly it probably wasn't handled that well before now but I just assumed that the way the GFS was forecasting it was how they evolve normally but I guess not. This may act to fire up the ridge/trough/ride pattern as the Atlantic jet tends to try and extend. I've also noted around 120E as the initial East Asian jet. Right now it's extending in reaction to the remnants of the 2nd wave train moving on which did scatter some fairly good energy but it was slightly too over progressive hence we didn't see a proper Greenland block being the most likely outlook right now. It's extension doesn't look too sustained and may just act to amplify the American pattern come Christmas time but beyond that how it scatters energy will be hard to tell. Like I said, it doesn't look to sustained and towards Christmas time we should see it slowly retract to around normal so outputs should become a little less complicated once we go into the New Year as we rely a little more on local dynamics. Still a lot to be interested about and note that the Greenland (area, the actual zonal is well below Greenlan) +VE zonal wanes towards the end of the run so possibly we may see another chance. The pattern doesn't look like going fully Nino-esque nor does it look to go Nina-esque plus the MJO is progressing fairly well and perhaps with more amplification of the MJO we could once again see a sustained signal for a +VE NAO. Its asking for a lot of little changes but if we get a few things in our fortune, we could be back in the game for long-term significant cold potential. Original post: https://community.netweather.tv/topic/98132-model-output-discussion-the-run-up-to-christmas/?do=findComment&comment=4775633

Atmospheric River = Plenty of moisture. Tail of an Atmospheric River = colder(for us that's the, I think Polar Maritime?). I've been saying it for a while now and the timing with this could potentially bring A LOT of snow to somewhere across Great Britain. As long as the Atmospheric River doesn't retreat back North then I think somewhere could see exactly what I've been talking about. They're very underrated these Atmospheric Rivers although I don't remember one streaming across the Atlantic since I've joined here (well, in Winter anyway) and I think they're quite rare at this strength in the Atlantic. Just wish we got them as strong as California can get them, just look at the amount of snow that fell from one of them. Ours isn't as strong as that but imagine if it was, maybe one day...

The actual back edge of the Atmospheric River (AR) loops back slightly according to the GFS and dumps a lot of precipitation (that could fall as snowfall as this part of an AR is typically colder) for our Scottish members and maybe our Northern members. A few hundred miles South and this could have been a significant snow event for a lot of the UK. It also draws up a lot of precipitation from more of a southern tail of the Atmospheric River, whether this is still the colder tail or just the main part of the Atmospheric River we'll have to work out closer to time but if it is still part of the tail, it is possible that these boxing day snow events on the models are accurate it just depends on a few miles and the exacts of the AR. Could we be saved (ish) by an Atmospheric River?

The track of the -VE zonal wind anomalies has shifted East over the last few runs (at around 45W to 30-15W)instead of becoming a shored up Greenland zonal setup early link, its just going to become another Eurasian signal (possible Euro ridge repeating pattern and could draw up more WAA into the Eurasian area/Scandinavian ridge or more hopefully block). I've noted the zonal packet transitioning over the North American area (this being just above the Tropics) from 120W to 30W that was probably not handled well and admittedly it probably wasn't handled that well before now but I just assumed that the way the GFS was forecasting it was how they evolve normally but I guess not. This may act to fire up the ridge/trough/ride pattern as the Atlantic jet tends to try and extend. I've also noted around 120E as the initial East Asian jet. Right now it's extending in reaction to the remnants of the 2nd wave train moving on which did scatter some fairly good energy but it was slightly too over progressive hence we didn't see a proper Greenland block being the most likely outlook right now. It's extension doesn't look too sustained and may just act to amplify the American pattern come Christmas time but beyond that how it scatters energy will be hard to tell. Like I said, it doesn't look to sustained and towards Christmas time we should see it slowly retract to around normal so outputs should become a little less complicated once we go into the New Year as we rely a little more on local dynamics. Still a lot to be interested about and note that the Greenland (area, the actual zonal is well below Greenlan) +VE zonal wanes towards the end of the run so possibly we may see another chance. The pattern doesn't look like going fully Nino-esque nor does it look to go Nina-esque plus the MJO is progressing fairly well and perhaps with more amplification of the MJO we could once again see a sustained signal for a +VE NAO. Its asking for a lot of little changes but if we get a few things in our fortune, we could be back in the game for long-term significant cold potential.

I think Quicksilver knows what they're talking about, no offence intended but that's not really explaining how you get cold zonality.

For what it's worth Met Ryan's tweet earlier (I don't think hes a real met forecaster though could be wrong) but he knows his stuff based off his success rate. So its clear that nothing is really nailed on going into the next few weeks as a lot of people having been saying. If you can make a forecast with 100% certainty you're going to be missing something because its just too difficult to tell how things will evolve.