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Tamara

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Tamara last won the day on January 13

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    The most likely outcome. The MJO is only half the story!

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  1. Nick F This is my last response on this subject as your latest resply tells me you didn't read the (albeit very brief) explanation about wind-flow, torque, angular momentum (and what it means in parlance of weather patterns) . It should be clear from that, that the jetstream is influenced by the basis science of what causes acceleration of momentum, or conversely, deceleration of momentum in the atmosphere and a background to the waxing and waning & movement of cyclones and anticyclones across the globe. It might be technical in its GSDM data sets with a lot of acronym speak, but it is actually in truth a basic starting point for getting a structure of the global patterns. If it is not understood what influences basic jet stream patterns,and also the cyclical nature of teleconnection phenomena (which is another part of the equation) then how can any of the other drivers be placed in the jigsaw?. I am more and more convinced that if this winter had produced more widespread and sustained snowfall this thread would never have been triggered. I resent being implied as some kind of cherry picking soothsayer and equally that there is some arrogance about being right and not admitting errors. Why is it my responsibility to be held account for the lack of desired winter weather? I have produced continuity analysis throughout my more recent years on this site, for the very purpose of being transparent. In an effort to stand up for myself, I am going to say that these continuity analyses have left little room for conspicuous error and so the latest charge of yours of not admitting any error is deeply untrue, unfair & unreasonable and I am not going to stand for it. And yes this is defensive, and yet you winder why!... I have not been paid to contribute anything on this site, and while we all (including you actually!) make mistakes, none of us, including me (though sometimes I wonder!) have any particular obligation to be apologist to anyone. It just so happens that I have been pro-wintry weather patterns for this particular season. The truth, which I am not going to be pressured into conceding on, is that very fine lines have driven the outcomes of this winter. It *should* have been, or it should be, a spectacle of interest and discussion as to outcomes and not a scapegoat seeking exercise for those, like you, who want to vent their frustrations onto other people. As far as I am concerned the present evolution of the pattern between troposphere and stratosphere are playing out accordingly to expectations. Feel free to go pick out the recent summaries and dismantle them to pieces if you wish. Tropospheric +EAMT pathway in tandem with eastward propagating tropical convection triggering rossby wave perturbing of the stratosphere ( upcoming) and amplified state mid latitudes. Now, what that means in respect of cold air advection to mid latitudes, and where, remains uncertain and there are complex and somewhat countervailing aspects of fluxing between the stratosphere & troposphere- but it does NOT debunk the GSDM mechanisms which have played a part, already, in creating the evolution of the pattern underway.
  2. Nick F The availability of the data has been already answered in most part with the references to Ed Berry etc & his rights to his work. He retired and took those rights with him. Hence NOAA no longer published them at his request. NOAA did not stop publishing the data due to some lack of credibility as you appear to want to imply. Many have been on this site, or referenced it long enough, to know that the GSDM has been sourced for analysis since at least 2007/08. Glacier Point pioneered it for Net Wx with much success in its use. So much so that it led to his further employment opportunities with Centurea weather, where he was appointed a head forecaster using the GSDM as the forefront of forecasting. The names (implied) under criticism in this thread are just some who have aspired to try and get their heads around the complexities of the science. Difficulty in understanding does not equate to lack of credibility or simply tossing under File 101 as gobbledy-gook.. Quite modest, very ordinary amateur enthusiasts have taken the challenge, very much including me. so not really any excuse for anyone thinking somehow they are treated as also rans by being left out from the GSDM data sets. If the will and enthusiasm is there, then it is open to be studied. The fact there is now a mix of both pro-Mets and amateurs across UK, mainland Europe and US who engage the GSDM methodology is testament to its credibility. I can see, therefore, why a pro-Met like Matt H might feel a little peeved as he made the effort to engage the GSDM diagnostic and include it in his professional analysis. As for the METO, they have actually made enquiries about the GSDM on a private basis to some Net Wx and also US based forum members and there has been a background inspection of the diagnostic which includes recognition of angular momentum processes in the role of inducing jet stream pattern changes. I know this for a fact - but cannot be expected to answer to their actual decisions on whether or not they would be inclined to engage the methodology formally & officially but then again, it is the copyright of a late NOAA official and have no idea of the protocols etc involved in this. Whichever way, its a bit disappointing to say the least to be trying all these rather confected avenues as means to discredit GSDM analysis as some kind of over hyped mystic meg thesis. Especially bearing in mind what seems to have triggered this particular pique and GSDM bashing is some unbridled dissatisfaction with a UK winter! You yourself have employed some of the related teleconnection aspects in your (well laid out) forum seasonal forecasts. So with respect, it seems to be rather a contradictory position to take to your own efforts. As for papers on GSDM there is a wealth of them. Including references to them on this site. There has been at least one dedicated thread in recent years to compiling a library of information on this very site. It took me a few years from about 2014 when I decided to take a big interest in this diagnostic to get my head around quite a bit of it. But just reading the in depth discussions between 2008/9 and about the time I started to try to get involved with learning about it, it was surprising how rewarding it was when some understanding started to click into place. Like chionomaniac and the strat threads also in the late 2000's, other have got inspired in this way.
  3. I echo the words of @MattH And no, there is nothing unreasonable in he what said at all. I have lost count of the number of times that I have tried to implore that the MJO is only one part of the total components that make up the "global wind-flow budget". This sounds a fancy term no doubt to the naysayers piling into threads like this in a queue to use it as a scapegoat for their snow being stolen, but if the atmospheric circulation is considered as the vacuum that it is, then it is not difficult to envisage that to maintain its parity, wind-flow that decelerates in one part, has to be compensated in another. And vice versa when acceleration occurs in one part, there has to be equal compensation in another to maintain parity. Angular momentum refers to the turning force (torque) exhibited where convergence, or divergence meet as inflection points to create that turning force on the jet stream. When decelerating wind-flow exceeds +ve momentum, then there is a greater requirement for more and more flow to be sucked back into the void that is left. This is represented by a -ve torque mechanism. The converse again holds true to produce a +ve torque mechanism The MJO represents wind-flow & momentum changes in the tropics. As part of Mother Nature's natural vacuum, it is necessary to consider the rest of the atmospheric circulation system in the extra tropics and top layers when catalysts for change of wind-flow begins in the tropics c/o MJO related forcing. In winter this means greater focus on not just interactions between the tropics and extra tropics in respect of +ve and -ve wind-flow interactions, but how both the troposphere itself as a whole further interacts with those "top layers". Namely the stratosphere. This is undoubtably the hardest task of all. And anyone who tries to relay context of the GSDM in respect of ultimate stratospheric evolutions and the subsequent tropospheric impacts is going to struggle and make errors. But that doesn't make the diagnostic wrong. It is simply the immense difficulty in making judgements set against complex and sometimes countervailing aspects. There is so, so much more to this subject of the "global wind-flow budget". But it is the scientific essence of the Global Synoptic Diagnostic Model (or GSDM). I guess the title name itself makes it sound like it is the home for an elite echo chamber - but it is simply a title given by the late NOAA official Ed Berry in conjunction with others like David Gold. Who now has taken over fully its operation with others. As @Met4Castsays, these are not untouchable gurus - and those of us who have been given access to the GSDM data plots are not a privileged elite, but people who have a genuine fascination & equally recognition of the insight into the atmospheric system that dictates wind-flow changes (aka the jet stream paths and strengths) and how convergence & divergence of wind-flows (torque mechanisms) change angular momentum tendency and in turn carve out the global synoptic patterns. Not just for UK postcodes. Anyone else can choose to do this is they genuinely wish, by asking permission to the plots. The cautious issuing of permission rights over the years has been the late Ed Berry's wish for his pioneering work to be protected, as it developed more and more. In the same way as study of the stratosphere has come on leaps and bounds over the past couple of decades, this tropospheric diagnostic has slowly (more slowly) come forward as well. But somehow has contrived to be misrepresented as some kind of cultist elite movement. That is a big pity. Meteorology as a study as a whole loses out. Other than incomplete over focus on the MJO in isolation of the rest of the wind-flow budget, the biggest factor for failure of messaging & understanding the value of these diagnostics is the emotional attachment to one desired synoptic outcome. Its one thing using an MJO composite in isolation (which increases likely error rate of probabilistic outcome anyway) but when these are also attempted to be fitted to bias outcomes as part of a bias confirmation process, then this further ups the error rate and ultimate disappointment when the bias outcome proves AWOL in reality. The consequence? "The workman blames his tools" To be blunt if these "workmen" are going to do this, then it is quite reasonable that anyone who tries to genuinely understand the purpose of the diagnostic as an objective, neutral process to ascertain ALL probabilities (as one does with ensemble & ensemble cluster groupings as per @Mike Pooleetc) to express resentment at the discrediting of the methodology. The frank answer is to either express a desire to hook up to the data and try to study the diagnostic objectively, or not bother at all . It is possible of course to continue to rely on NWP to look for outcomes. But as with the GSDM, continue to be disillusioned when persistent attempts to skew model data information or expectations to a bias outcome founders more often than verifies. Neither using NWP and/or GSDM are wrong, and both of course are wholly valid. But the GSDM is meant to compliment NWP as a diagnostic insight into how synoptic patterns might evolve over time . Not some magic silver bullet to give faux insight into how it might increase the chance of snow in a given post code. The GSDM is a diagnostic process not just for analysing winter patterns, but for all year round. The atmospheric circulation doesn't stand still from around March to October/November. So viewing tropical convection patterns is not a toy to play with snow-making for a few months and putting away in a cupboard till the next time - it is one component, just one component, of aggregate global wind-flow which is in constant flux 24/7, 365 days a year. We would all not be here if it wasn't... It is always quite possible to give an overview of the GSDM as an update to the present synoptic outcomes. However, as emphasised, this is only possible within a neutral framework as discussed in this post. That neutral framework would not justify its effort & existence as no-one would show interest because it would not be geared towards a favoured outcome. That is, if it was being used for the trur purpose it is geared towards & intended. Sensible to leave it to one side based on the time it takes to put together analysis of the data. I can only say reasons have been given for why the disillusion itself is to blame and the "workmen" have to look at their own responsibility in inviting their own disillusion. Melhores cumprimentos.
  4. Met4Cast Based on a likely spontaneous tropospheric response to what looks like a very robust SSW reversal of -ve zonal winds upcoming, the timing of tropospheric switch to a falling angular momentum regime implies that returning polar jet energy faces a roadblock across higher latitudes and result in actually perpetuating blocking effects across the NH. I say this from a purely diagnostic viewpoint of a macro scale synoptic response & objectively as to how such a blocked regime may play out - without regard to surface weather responses at any given geographical location. So protracted +AAM transport c/o +EAMT and tropical convection rossby wave driving has been incipient in initiating stratospheric diminution, and it could be that falling momentum heading into late winter & early Spring wavelengths augments -ve AO/NAO synoptic responses. The same was said in January of course & the nature of the briefest of reversals underwent a reflective u-turn which allowed the polar jet to return unencumbered as angular momentum fell back The circumstances this time are quite different & the sheer scale of the stratospheric diminution heading towards the start of Spring puts at least a preliminary question mark over the return of the vortex as a final warming event. In turn it suggests a relatively lengthy period of fractured jet flow betwixt & between blocking structures Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5034002
  5. Met4Cast Based on a likely spontaneous tropospheric response to what looks like a very robust SSW reversal of -ve zonal winds upcoming, the timing of tropospheric switch to a falling angular momentum regime implies that returning polar jet energy faces a roadblock across higher latitudes and result in actually perpetuating blocking effects across the NH. I say this from a purely diagnostic viewpoint of a macro scale synoptic response & objectively as to how such a blocked regime may play out - without regard to surface weather responses at any given geographical location. So protracted +AAM transport c/o +EAMT and tropical convection rossby wave driving has been incipient in initiating stratospheric diminution, and it could be that falling momentum heading into late winter & early Spring wavelengths augments -ve AO/NAO synoptic responses. The same was said in January of course & the nature of the briefest of reversals underwent a reflective u-turn which allowed the polar jet to return unencumbered as angular momentum fell back The circumstances this time are quite different & the sheer scale of the stratospheric diminution heading towards the start of Spring puts at least a preliminary question mark over the return of the vortex as a final warming event. In turn it suggests a relatively lengthy period of fractured jet flow betwixt & between blocking structures
  6. I posted the VP200 anomalies earlier These will have resolution to identify tropical convection convergence much better than the RMM plots which lose reliability more than 4 to 5 days ahead. This winter has already proved this fallibility based on the previous undercooked RMM forecasts of wave orbit (set against a Nino standing wave to engage convergence in the Pacific at and beyond the dateline) Based on the GSDM analysis - gravity wave amplitude> significant +EAMT> engagement of a robust upstream jet - all are hand in hand with a Phase.6,7,8 progression. Those of you looking for the outcome you desire in UK/NW Europe would appreciate a slow but complete progression of the tropical wave through the whole of the Pacific - not withstanding the longevity of the poleward extra tropical momentum transport in respect of how it impacts the polar field. I think a comparison analysis to follow with that of the events of Feb 2018 are valid. Not saying at all that the outcome and more especially the surface conditions will be precisely the same - but because there are a lot of tropospheric forcing similarities with that time. Following the ongoing marvellous weather down here in PT, the return of the STJ would be very much welcomed by folk here who are eager for rain ahead of the heat and dryness of summer to come. @Dennis Comments do not apply to your proactive posts in any way
  7. Grateful to be immune to mood swings over the (emotionless) depictions of computer models. Enjoyment and great interest is derived from seeing how the diagnostic processes related to the atmospheric circulation play out in real time. Admittedly lucky for sure, related to where I live, to be fully indulged by a remarkable (record breaking) spell of weather down here in Portugal, but that doesn't detract from being immersed in February outcomes, whatever they may be, and are two quite separate and different things. What is unfolding at the moment is a huge drive of planetary rossby waves. Amplitude intra-seasonal tropical convection (propagating across the tropics and to head right through the Pacific), which the velocity potential anomalies identify much better than the RMM plots..... .....which has already triggered precursor gravity waves (explained the other day) and primed a very substantial +ve EAMT event to in turn imply a reconfiguring of the zonal wind anomalies within the stratosphere heading through February. That much can be said with reasonable confidence. And to be blunt, it is all that should matter at the moment based on the timescales involved. My guess is that these tropospheric drivers are vigorous enough to overcome the strength of the SPV and, as a minimum, result in a de-coupling, if not major SSW (quite conceivable). But again, that is subject to watching the evolution over the timescales involved A whole process measured over a few weeks at a time. Staring at a computer screen every 3 to 6 hours 24/7 is not going to provide the instant gratification that this thread persistently seeks. It is a pity b/c there is so much going on right now both in respect of current weather patterns and, looking ahead, what is being programmed within the atmospheric circulation itself. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5024662
  8. Grateful to be immune to mood swings over the (emotionless) depictions of computer models. Enjoyment and great interest is derived from seeing how the diagnostic processes related to the atmospheric circulation play out in real time. Admittedly lucky for sure, related to where I live, to be fully indulged by a remarkable (record breaking) spell of weather down here in Portugal, but that doesn't detract from being immersed in February outcomes, whatever they may be, and are two quite separate and different things. What is unfolding at the moment is a huge drive of planetary rossby waves. Amplitude intra-seasonal tropical convection (propagating across the tropics and to head right through the Pacific), which the velocity potential anomalies identify much better than the RMM plots..... .....which has already triggered precursor gravity waves (explained the other day) and primed a very substantial +ve EAMT event to in turn imply a reconfiguring of the zonal wind anomalies within the stratosphere heading through February. That much can be said with reasonable confidence. And to be blunt, it is all that should matter at the moment based on the timescales involved. My guess is that these tropospheric drivers are vigorous enough to overcome the strength of the SPV and, as a minimum, result in a de-coupling, if not major SSW (quite conceivable). But again, that is subject to watching the evolution over the timescales involved A whole process measured over a few weeks at a time. Staring at a computer screen every 3 to 6 hours 24/7 is not going to provide the instant gratification that this thread persistently seeks. It is a pity b/c there is so much going on right now both in respect of current weather patterns and, looking ahead, what is being programmed within the atmospheric circulation itself.
  9. Another way of looking at the potential perturbing effects of rossby wave transport at high levels of the atmosphere is to look at this gravity wave drag plot. In simple terms this refers to the strength of upward propagating waves that are created through torque deflection of wind-flows against very tall mountain ranges (e.g Himalayas and Rockies) and indeed wind shear c/o tropical convection (whose inflection point(s) of convergence zone(s) creates the eddies which propagate into the extra tropics in the first place) Gravity waves at high amplitude induce high turbulence proportionate to the ever higher levels of the atmosphere they propagate into. The trend on the latest GSDM GWD plot shows the torque friction effects occurring at the latitudes of the East Asian mountain ranges. There is quite the whiplash effect of global wind-flow in progress here. Recent deeply inverted reflective fluxing spilling from the stratosphere into the troposphere - now being sharply reversed by equally very strong +ve gravity wave propagation into the stratosphere. Strongly +ve AO to potentially robust -ve AO? Based on the lag time of the +EAMT. In that respect, the poleward amplification mechanism has already undergone starters orders and is embedding within the global circulation - and this needs to be taken into account when pondering the eventualities of the MJO progression through the Pacific. Yet again to say, the MJO, might be a catalyst for future wind-flow changes set in motion within the tropics - but in isolation it is not the be all and end all. @RainAllNight This post may help answer your question in another way Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5023753
  10. Another way of looking at the potential perturbing effects of rossby wave transport at high levels of the atmosphere is to look at this gravity wave drag plot. In simple terms this refers to the strength of upward propagating waves that are created through torque deflection of wind-flows against very tall mountain ranges (e.g Himalayas and Rockies) and indeed wind shear c/o tropical convection (whose inflection point(s) of convergence zone(s) creates the eddies which propagate into the extra tropics in the first place) Gravity waves at high amplitude induce high turbulence proportionate to the ever higher levels of the atmosphere they propagate into. The trend on the latest GSDM GWD plot shows the torque friction effects occurring at the latitudes of the East Asian mountain ranges. There is quite the whiplash effect of global wind-flow in progress here. Recent deeply inverted reflective fluxing spilling from the stratosphere into the troposphere - now being sharply reversed by equally very strong +ve gravity wave propagation into the stratosphere. Strongly +ve AO to potentially robust -ve AO? Based on the lag time of the +EAMT. In that respect, the poleward amplification mechanism has already undergone starters orders and is embedding within the global circulation - and this needs to be taken into account when pondering the eventualities of the MJO progression through the Pacific. Yet again to say, the MJO, might be a catalyst for future wind-flow changes set in motion within the tropics - but in isolation it is not the be all and end all. @RainAllNight This post may help answer your question in another way
  11. @Met4Cast You are correct. The equatorward fluxing is very much related to the strongly +AO and vigorous polar jet. It is also true that the longevity of this has been uncertain. But there are now clear signs of quite a potent momentum surge on the GSDM MT plots and a poleward directional +EAMT springboard and stratospheric pathway. Those fine lines of synoptic outcome under recent discussion look set to swing a pendulum back again. I have no skin in the game, or interest at all, in respect of favoured weather type across NW Europe, especially living in Portugal, but there looks to be a good match to support extended modelling that migrates high pressure NW'ward beyond (approx) the second week of February. How that fully manifests at this time, cannot be gleaned by anyone at this time. However the likely repercussions of the momentum transport, based on the updated evidence, looks set for the largest diminution within the stratosphere this season. On the way towards 22C today. Amazing. Previsão - Temperaturas podem bater recordes entre Quarta, 23, e Sábado 27 em Portugal - Calor em Janeiro WWW.LUSOMETEO.COM Previsão de tempo quente em Janeiro, com possibilidade de temperaturas recorde localmente - a Serra da Estrela pode chegar a 15ºC Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5023710
  12. @Met4Cast You are correct. The equatorward fluxing is very much related to the strongly +AO and vigorous polar jet. It is also true that the longevity of this has been uncertain. But there are now clear signs of quite a potent momentum surge on the GSDM MT plots and a poleward directional +EAMT springboard and stratospheric pathway. Those fine lines of synoptic outcome under recent discussion look set to swing a pendulum back again. I have no skin in the game, or interest at all, in respect of favoured weather type across NW Europe, especially living in Portugal, but there looks to be a good match to support extended modelling that migrates high pressure NW'ward beyond (approx) the second week of February. How that fully manifests at this time, cannot be gleaned by anyone at this time. However the likely repercussions of the momentum transport, based on the updated evidence, looks set for the largest diminution within the stratosphere this season. On the way towards 22C today. Amazing. Previsão - Temperaturas podem bater recordes entre Quarta, 23, e Sábado 27 em Portugal - Calor em Janeiro WWW.LUSOMETEO.COM Previsão de tempo quente em Janeiro, com possibilidade de temperaturas recorde localmente - a Serra da Estrela pode chegar a 15ºC
  13. My post profile does not now go back far enough to quote the relevant excerpts - but sometime around the festive period or early January, I made one particular summary which outlined the fine lines between +ve momentum transport pathway synoptic outcomes according to whether fluxing was poleward (and under unstable stratospheric conditions), or, equatorward (under stable stratospheric conditions or where a reflective warming event occurs). It is perfectly possible to have a compelling signal from a tropospheric diagnostic, but to have an unforeseen and quite unforecastable event within the stratosphere which either mitigates the tropospheric signal or completely reverses it. This make predictive skill harder in winter when the stratospheric and tropospheric relationship is much more volatile and dynamic when the polar vortex is present. The latter equatorward fluxing is related to recent developments with a further boost to the Hadley cell which is already stronger than average based on climate trends. Believe me, the talk in Portuguese meteorological circles is the impact that these persistent amplified African/ Iberian ridges are having, not just in respect of the intense heatwaves of summer but also negating the rains which the south of the country depends. With that said, and as it is, a quite glorious period of weather has embarked in this neck of the woods with local afternoon values between 21C to maybe even 25C this coming week which is quite astonishing ( and not normal) for the last week of January. It is important to understand that the Hadley cell drives the degree of stability of the anticyclonic response and while the HC is undoubtedly in greater ascendancy and more frequently dominating, it still ebbs and flows according to the wider diagnostic forcing changes - and so when that wider scale forcing changes, the High pressure will respond accordingly, There are no experiments whatsoever. To reiterate, these diagnostic tools are not intended to be fitted to one particular season and one particular weather type. The atmospheric circulation doesn't stand still, after all, between March/April and November/December. Naysayers who persist with a 1+1=3 approach to applying these diagnostic are the ones that will keep hoping in vain for a different outcome (a HLB outcome) by continuing to try to fit those diagnostic elements to that desired outcome and hoping they shake the double six next time. Better to try and ascertain whether such an outcome is feasible within the range of ALL probabilistic outcomes. Even then, unforeseen events will occur - but if the reaction is simply to say there is no point in trying to delve into such departures, then every weather bureau globally may as well give up the study of meteorology tomorrow and leave populations at the mercy of trying to guess what might happen from one morning to the next. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5023010
  14. My post profile does not now go back far enough to quote the relevant excerpts - but sometime around the festive period or early January, I made one particular summary which outlined the fine lines between +ve momentum transport pathway synoptic outcomes according to whether fluxing was poleward (and under unstable stratospheric conditions), or, equatorward (under stable stratospheric conditions or where a reflective warming event occurs). It is perfectly possible to have a compelling signal from a tropospheric diagnostic, but to have an unforeseen and quite unforecastable event within the stratosphere which either mitigates the tropospheric signal or completely reverses it. This make predictive skill harder in winter when the stratospheric and tropospheric relationship is much more volatile and dynamic when the polar vortex is present. The latter equatorward fluxing is related to recent developments with a further boost to the Hadley cell which is already stronger than average based on climate trends. Believe me, the talk in Portuguese meteorological circles is the impact that these persistent amplified African/ Iberian ridges are having, not just in respect of the intense heatwaves of summer but also negating the rains which the south of the country depends. With that said, and as it is, a quite glorious period of weather has embarked in this neck of the woods with local afternoon values between 21C to maybe even 25C this coming week which is quite astonishing ( and not normal) for the last week of January. It is important to understand that the Hadley cell drives the degree of stability of the anticyclonic response and while the HC is undoubtedly in greater ascendancy and more frequently dominating, it still ebbs and flows according to the wider diagnostic forcing changes - and so when that wider scale forcing changes, the High pressure will respond accordingly, There are no experiments whatsoever. To reiterate, these diagnostic tools are not intended to be fitted to one particular season and one particular weather type. The atmospheric circulation doesn't stand still, after all, between March/April and November/December. Naysayers who persist with a 1+1=3 approach to applying these diagnostic are the ones that will keep hoping in vain for a different outcome (a HLB outcome) by continuing to try to fit those diagnostic elements to that desired outcome and hoping they shake the double six next time. Better to try and ascertain whether such an outcome is feasible within the range of ALL probabilistic outcomes. Even then, unforeseen events will occur - but if the reaction is simply to say there is no point in trying to delve into such departures, then every weather bureau globally may as well give up the study of meteorology tomorrow and leave populations at the mercy of trying to guess what might happen from one morning to the next.
  15. Just a response to this before vanishing into the background again. Musings based on the best information available at the time. Which matched the diagnostic evidence available at the time. The SSW blip have been quite unusual with the incredibly powerful reflective nature of the wavebreaking. Equatorward fluxing, strong Hadley cell, and very strong polar jet. As posted a while back - in these situations +AAM momentum transport between the tropics and extra tropics to in turn perturb the polar field through +EAMT - will be negated by equatorward fluxing. Instead of poleward momentum higher latitude blocking, the downstream blocking resides instead across Europe. Sometimes these events hedge along fine lines which makes starkly different outcomes to the Annular Mode. The science of the stratosphere has come a very long way in the past 15 yrs and the likes of @chionomaniacpioneered a lot of that for this site back at the time. However, and also in respect of the continued skewing of climate change effects - so much more is yet still to be unravelled. On a personal note, following some very useful rain in the past week or so - the coming 10 days looks delightful down here. Blue skies, winter sunshine....and temperatures during afternoons into the low 20s across parts of the country. Portuguese weather bloggers are looking out for the 25C marker to be breached somewhere. Which even for this part of Europe would be quite something extraordinary in the last week of January. Not what this thread is interested in, but best wishes to UK weather watchers despite their frustration. Original post: https://community.netweather.tv/topic/99793-model-output-discussion-cold-spell-ending-what-next/?do=findComment&comment=5020335
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