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Catacol

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  1. And more importantly NAO, EPO, PNA and all the other alphabet agency style descriptors are simply index reflections of the pattern. They are not drivers in the true sense of the word - they are more effect than cause. The bigger question I think is the extent to which drivers interact and the relative weight of each. Hence GSDM, but with big emphasis on the adjective “dynamic”. This is probably the crux of the forecasting conundrum. If we could accurately assess the relative weighting of global drivers then forecasting would simplify enormously. However the system is rarely in predictable balance because the elements of the system ebb and flow, and predictability at longer time scales is tough precisely because each element is dynamic. And then there is ongoing vortex science, arctic research, solar research, snow index research, ENSO prediction etc etc. Multiple significant factors that complicate the picture, and relative weighting that can confound models and humans alike. 2018/19 taught us that. So much still to learn...
  2. Thanks Eric. I wondered in our previous exchange as to the ability of a major +EAMT to shift the pattern. An example of state dependent noise acting like a huge hammer? If this is indicative of a more aggressive Nino style shift, with vp200 charts suggesting a move towards a more dominant phase 6 MJO - might we also see renewed wave 2 hits in an already relatively unhappy vortex? Interesting watching. You guys can drool over a west Pacific ridge and downstream trough. For me I want wall to wall blocking from Greenland to Scandinavia with the jet pushed underneath. Ha - little chance of that....but a - NAO would be a first step.
  3. Seems an eminently sensible methodology. Some disagreement would appear to be ongoing over the tropospheric impacts of the rather fixed current IO pattern, and in that context I will also be following the reality of MJO impacts carefully. Eric Webb’s contention that RMM plots will not pick up the true impacts of a fairly substantial static IO phase 2 wave have me wondering, Will GLAAM continue to rise? Can the vortex be perturbed further? Much to be decided. Can we get the MJO to the more advantageous phase 6? I bow to your knowledge on last season’s GLAAM levels. I’ve lost my GSDM access and so am working off memory. I do remember it was high in November. I’m still uncertain why it was as high as it was for much of winter 2018/19 but perhaps it is time I let that go now and focus on the weeks ahead. Can’t dwell in the past too long. An interesting December ahead for sure. I have a nagging feeling we are going to see Greenland heights be a repeating element through the season, and hence short lived cold opportunities at least will be in the mix. Even the most solid 3 month + NAO average seasonal can comfortably contain a couple of significant sliders against residual heights. Seasonal 3 month average charts are near pointless. Don’t know why the MetO bother with them.
  4. Thanks Eric/Zac - I appreciate the replies. I suspect I'm coming across as trying to box up a formula for atmospheric interpretation - in truth I'm not so naïve as to think that we can do this effectively (forecasting would be very easy if we could) but trying to draw a few straight lines helps make sense of the mish mash of wavy ones. Eric - would "state dependent noise forcing" be a techno speak way of effectively saying that random chance based variables still apply? The analysis of our ENSO/atmospheric base state still strikes me as complex. I understand that a strong +IOD can often be a precursor to a forthcoming Nina ENSO as the ocean transitions out of Nino....so maybe 2020/21 will see a change of state - but for the season that started today I'm still trying to work out whether we can expect GLAAM to rise as per Nino, bottom out as per the year long Nina curve (until October when it recovered) or confuse us all in terms of expected trajectory. I guess we are back to the starting point of "there's more to it than one simple chart" and this is why the best supercomputers in the world cannot consistently and accurately get a seasonal forecast correct....and this is before we even consider the impact of vertical flux on the strat vortex and the frictional downwelling potential for all kinds of mischief as per 2018. Perhaps the passage of the MJO through the latter half of December will give us a clue as to the potential impact of any ENSO forcing later in the season given that the conditions in the Indian Ocean have sparked a lot of debate and may possibly interfere with the expected passage of that wave. UKMet seasonal would appear to be siding with a much muted signal and a Nina-esque forcing returning to dominate January, combined with a failed SSW. We shall see.
  5. Powerful recent debate Eric - as a Brit I have no innate interest in a warm or cold US so I can claim neutral ground!! However I want to learn. Your VP charts here are clear. However until November GLAAM has been falling. I’ve been posting around the place fairly aggressively recently trying to get my head around oceanic/atmospheric disconnects and the extent to which we can therefore get the majority of our answers from GSDM theory. I am very much an interested amateur with no clients. If we have a Nino in operation why has GLAAM been falling through the year? Recently, however, it has picked up - are we seeing a Nino signature emerging in terms of GWO response? Is the strongly positive IOD actually going to help drive this Nino development rather than retard it? (I understand your MJO argument in the face of standing wave preconditions but am less clear on whether a standing wave has the same impact on momentum transfer as a more common propagating W to E MJO signal). Finally we look to be about to see a major +EAMT with the usual consequent significant jet extension across the Pacific and through to the Atlantic (and my Brit interests kick in here...) Is a significant torque event like this able to impact on the static ENSO progress pattern you are seeing? I’m pushing the boundaries of my understanding and might be barking up completely the wrong conceptual tree here, but the only way to learn when the head is in contact with the ceiling is to ask for input.... Genuine questions - any thoughts appreciated.
  6. Thanks - an excellent post. I think many of us were caught out by the QBO state that created such a delay in propagation. I would concur broadly with all here, and especially the neutralisation of Nino forcings by the timing of the +AO impacts of slow propagation. This in itself shows that GSDM modelling is subject to moderation, and polar patterns can play a trump card. It doesn’t quite explain the high state of GLAAM though. I don’t have the charts you’ve got there - so am operating on memory - but my memory is that GLAAM was high well before the effects of strong MJO cycles hit the season, and this at a time of weak ENSO. Again from memory total GLAAM actually fell away a bit during the course of the 2 major MJO winter progressions...and so I’m still left considering the effects of disconnected states. I guess this is a little separate to a reanalysing of last winter. For my part I also learned to lay more attention to Atlantic SSTs. These were also not aligned to high lat blocking. They are better this year. I’ll be very interested to see how GLAAM progresses through December. I’ve read differing opinions, and I’m assuming that seasonal modelling isn’t expecting much of a spike or upwards trajectory. Having said that I have no idea whether seasonal models have algorithms that are sensitive to global wind flows - I’m not sure I understand how seasonal models function at all - and one of the great interests of the coming winter is to see how this output fares against analog forecasting and human interpretation. The scientist in me (not a strong aspect!) wants the modelling to improve and become a better tool. The forecaster and interpreter in me wants the computers to fail and human minds maintain a toehold on 21st century progress. There is a lot of talk about the power of AI and algorithms...and I’d rather not see Skynet take over... What’s your take on the season ahead?
  7. Thanks for engaging. A lot of sense in all your analysis, but it leads me to another question - last winter we still had that semi-Modoki profile to the ENSO with heat concentrated close to the maritimes and colder water further east. The same discussion over the MJO’s potential inability to push through to the central Pacific was had. The current +IOD clearly complicates things further for MJO predictability this year. But last year GLAAM was through the roof. In fact it sat at its highest level for many years, and I remember asking the question within the knowledgeable community as to why this was. There were next to no answers. In other words - we spoke again of a disconnect of a different type - a weak Nino ocean profile producing a GLAAM profile that was more like a strong Nino. This season weak Nino produces a year long fall in GLAAM and an early winter Nina echo. Something in all this doesn’t sit right. Other factors are clearly at work, and while wind flows and GSDM relationships explain distribution of momentum and tropospheric response the background state driving momentum flows are themselves out of kilter. All of this is indicative of imperfect understanding on my part, but my training as a historian has given me a preference to learn by observation as much as by scientific analysis, hence the overall conclusion above that forecasting remains an art - at least for now. I’m enjoying this current winter run up a great deal, and learning all the time. That is probably all that counts in the end, whether it snows or it doesn’t!
  8. This brings us back to the issue of ocean/atmosphere disconnect. The ocean is acting in a weak Nino state, but the atmosphere chooses a different path. Explanation uncertain - purely a by product of observation? I wouldn't disagree that things may pull back towards a Nina profile, but getting my first look at a GSDM chart for a good while via a tweet put out by Matt Hugo I also wonder whether a spike in torque, and a consequent spike in GLAAM, might jar the atmosphere out of its disconnected state? In the end we will see what we will see, and perhaps the trades will fire back up...but then again perhaps by then the atmosphere will be in a positive GLAAM trajectory. I think what I'm trying to say (in a not very clear fashion), is that we can make all the connections between the relevant aspects of GSDM but still not fully grasp the pattern because aspects of the dynamic model can be disconnected. And by hook or by crook i'm back to the head scratcher of the disconnect. And while disconnected states are observed and possible, the art of weather forecasting will remain an art as much as a science.
  9. At what level is this area measured? Really interesting angle on vortex influence. While it may indicate an approaching more positive +NAM does it also reflect a more southerly polar jet - perhaps low solar influence? And if it spreads wider does it also therefore weaken in intensity? Lots of questions - but never seen an area measurement of the vortex before. Intriguing.
  10. An interesting debate if we take out the honesty jibes and earlier references, once again, to bias. The automatic alignment of interpretations of colder outlooks with biased science I find irritating. I haven’t seen a forecast put out there arguing for wall to wall cold, and the majority see cold phases interspersed with mild. Is it the emphasis that some people put on the cold moments that appears to grate with some of you? My own forecast for the UK has picked out a 4 week spell out of 12 in total that might end up”very cold” though I present dual pathways based upon potential vortex impacts, and one pathway argues for no cold at all. And yet my own discussion earlier this season also had a response loaded with phrases linked to bias attached to it. If we all accepted that human motivation is rooted in subjective attitude, and that therefore an accusation of bias is no more than a relative comparison between two different starting points then we’d all make better progress. The fact that one poster might be on the lookout for cold and another warm and another neither warm nor cold but just the most likely outcome doesn’t make any one starting point better than another nor more worthy than another. And in the context of a community a desire for a position of absolutely objective neutrality should never be used as a stick to beat others with, any more than those hoping to see cold outcomes appear should strike the other way. Of far greater relevance - I’d really like to dig into the Nina atmospheric response to a Nino oceanic base state. I completely concur with the macro scale forcings of net easterlies at the tropics with consequent boosting of the sub tropical high pressure belt with active westerlies over the top. My very average grasp of physics has expanded enough for an understanding of angular momentum relationships. But I continue to struggle, as I posted in another thread, with the idea that GSDM products are recording a generally low GLAAM state at a time when other data can be produced that shows an overall Nino oceanic pattern. I have considered lag effect - but an examination of the 2019 ENSO profile when matched against GLAAM on its slowly declining trajectory across the calendar year doesn’t suggest lag. Torques? Surely too transitory. The truth of the yearly progression is that momentum has been falling while the oceanic base state has remained neutral to weak Nino for a good while. So the “disconnect” as we call it has become a long term product.....and I don’t understand why this is the case. As I have questioned before - why was GLAAM so high last winter when again the oceanic base state didn’t suggest it should be? How long can we continue to talk about a “disconnect” before actually we have to question our understanding of the ocean/atmosphere relationship and it’s impact on GLAAM? If I am being very naive in this then genuinely I’d love someone with a better understanding than mine to explain the dynamic. My own interpretation of the season ahead has a similar shape to yours in that I also see greater opportunities for cold weather outbreaks towards the back end of the season, and this is based on the idea that the Pacific signal will eventually produce a net injection of westerly momentum that might work effectively to support northern blocking when the tropospheric vortex is past its strongest phase and seasonal wavelengths have an enhanced potential to shorten. But if the atmosphere is going to continue to sit in an oppositite state then I begin to question my own assumptions. Last winter high res modelling along with a good number of interpretative forecasters thought northern blocking would kick in over the North Atlantic...but it didn’t. And it hasn’t been convincingly explained in post-facto analysis (in my opinion) and I have a nagging thought that won’t go away that wonders whether the high GLAAM base state represented an exaggerated response to the weak Nino that left the atmosphere in a position not conducive to the expected response. But I can’t clearly conceptualise what this might be in hard science. This post is too long. In essence - further thoughts on ocean/atmosphere relationship from all knowledgeable posters would be good!
  11. Thanks Zac. Agree totally on complex nature of momentum budgets - broad sweeping analysis only gets us so far. I find the ongoing reality of ocean/atmosphere disconnect perplexing. I haven’t logged exactly how often the states have been disconnected over the last few years, but it is certainly frequent enough to be memorable. If the atmosphere fails to connect and respond to the ENSO base state then this strongly suggests that other drivers are creating an alternative relationship....and in this case what are these drivers? And if we cannot “trust” the atmosphere to respond as expected to ENSO forcing then it suggests an unpredictable nature to the pattern that verges on chaos. Except we know that chaos is inaccurate as a descriptor. Flow patterns hemispherically can be predicted to an extent by high res models, and observation and experience can begin to make sense of likely developments. Which takes me back to the regular(ish) nature of disconnect. We see a Nino....the post above that I responded to posts vp200 charts that show a clear Nino imprint, and yet GLAAM is in a generally falling pattern. Last year we had very high GLAAM values for much of the winter season, more than could be explained easily by the near neutral ENSO. So what are we missing here? Or more specifically what am I missing here? Essentially I’m at a knowledge ceiling that leaves me puzzled, because if the atmosphere won’t respond as expected to the ENSO then it feels as though the ENSO becomes highly questionable as a source of forecasted patterns. I’ll keep reading and musing and learning from others such as you - there are connections and relationships I’m not in control of here conceptually yet. Thanks for the reply. The fact that you use the word “opinion” as an end point is comforting - I’ve never subscribed to absolutes as a concept, even in a field effectively contained within an envelope of science.
  12. Really enjoy reading your posts - thanks. GLAAM has been falling (on average) for months....with an elastic recovery phase in the last few weeks. Do we have a disconnected ocean/atmosphere at work here? Or are you expecting GLAAM to hold steady now rather than fall away again in the context of the Nino forcing you are seeing? I'm a bit frustrated at having lost access to GSDM products, but regardless of this I'm intrigued by the impact of the ENSO on this coming winter as opinions seem to be so divided. In the last 3 days alone I have read assessments from posters I have come to respect stating differing views - one that ENSO is so neutral it wont really impact at all, one that we will drop back towards a more Nina atmospheric state with consequent increased momentum at 65N and now your post here which I'm taking to mean sees ongoing impacts of an MJO that is likely going to remain active in phases 6-7-8 approx. as it cycles towards the maritimes. Always learning, interested to probe sharper heads than mine....
  13. Bit of a cry for help - all my links to GSDM products have failed this season. Free products always preferable, but in the end if payment is what is needed to get the data then so be it. What's the best access point to GLAAM/GWO and GSDM products as a whole? I can see from some posts and twitter in particular that these plots are still being drawn somewhere on the net.... Apologies if I'm asking a question that has been answered elsewhere.
  14. OK – here’s my winter forecast for 2019/20. It has a clear UK focus so apologies to the majority on here who are probably less than interested in the unbelievably complex micro conditions that can cause the UK to be so variable and probably explain the national fascination with the weather. My rationale is simple – I want it to be accessible in plain speak but technical enough to tweak some interest. I’m a snow hunter so have written it largely from a snowfall perspective (and make no apologies for that purpose). Finally I do see 2 quite clear possible routes, with the potential direction of travel hinging on the extent of vortex disruption in early January. I am not using any analogs. I have become less and less convinced by the relevance of analogs, though acknowledge they make for interesting reading and pattern matching. Drivers Both via observation and technical paper reading there are clearly core drivers that impact the pattern over the UK. In some kind of approximate hierarchy these are: 1. ENSO forcing that impacts global momentum budgets and, as a result, likely pressure patterns. Central to this in winter is the extent to which the sub tropical high pressure belt is supported in a northerly direction by circulation at the pacific equator (including convection patterns mapped via the MJO), but also the extent to which surges in momentum can create blocking at higher latitude. The UK sits right on the boundary between the sub tropical (Azores) High and the polar jet, and torque events either over North America or East Asia can have a significant downstream impact on the ridge/trough pattern that leaves us either on the warm or cold side of the flow. 2. Vortex strength from the top down, but also the extent to which impacts from the bottom up can either disrupt the vortex or alternatively encourage a coupling of the upper and lower layers. Once coupled the vortex is a tough beast to break. The tropospheric vortex naturally strengthens through November and into December before beginning a slow decline through January and more especially through February, and this is an important precondition to keep in mind. 3. Sea Surface temperature anomalies in the North Atlantic and the extent to which the jet can be affected by this. 4. Snow cover, ice extent and the issue of arctic variability which can impact on the Siberian High in particular. Perhaps also impacts the vortex in terms of tropospheric ridges in the arctic causing disruption. 5. Solar variability. Much disagreement here amongst forecasters and interpreters, but the balance of the argument suggests that times of low solar activity encourage higher than average ozone levels in the stratosphere with a greater chance of vortex disruption, but also reduces the overall strength of the jet, encouraging more “wobble”, often described as a more meridional pattern. 6. Finally its worth acknowledging the natural waxing and waning of the wave pattern, and therefore shifts of wavelength and movements in the peak/trough pattern are inevitable. Observationally I have come to see these as working in thirds of months, with occasionally a standing wave situation creating less movement. We are in one such standing wave situation now with the trough fixed over the UK for, I would think, two thirds of the month. With such a neutral ENSO background state I wouldn't be surprised to see static periods of wave activity repeat. The Driver Context in 2019/20 1. ENSO impacts are expected to be minimal this season, with an essentially neutral position currently. The MetOffice forecast sees the weak Nino focused in the central pacific but a context further to the west of a very positive IOD and cooler waters which, in theory, promotes more of a Nina pattern. Much further to the east the pacific is cool, once again suggestive of Nina impacts. This “Nino Sandwich” is a tricky one to call, but the signature is so close to neutral that impacts will probably not be substantive. However – and this is important – the global atmospheric momentum signature is rising and has been rising for several weeks. This is indicative of Nino forcing in the pattern (as well as nature's desire to try and return momentum budgets to zero....), and so it looks possible that the tropical cycle through the winter may become more of a factor later on, particularly if GLAAM hits positive values as it rebounds. Given the elastic nature of GLAAM the upwards trend looks likely to continue for at least a few more weeks with a likely peak in January. Whether the upwards trend continues beyond that is a tough call – but more Nino style impacts increase the chances for stronger late winter blocking patterns. More commentary later on this in the monthly descriptors. 2. The stratospheric vortex is currently strong, but just beginning to feel the impacts of a well known tropospheric combination of low pressure over the Aleutians and High Pressure over Eastern Europe and Scandinavia which encourages warm to be fired into the upper vortex from opposite sides of the globe. This is providing early stress on the vortex, helping prevent the upper and lower layers from properly coupling, and this is a process that may be being enhanced by the background low solar context. Given expected lag times, the impact of this wave 2 attack may take up to 4 weeks to see real tropospheric change given any stretch/split/displacement needs to work its way through the layers (assuming the atmosphere is receptive to frictional downwelling…and we all know that last year it wasn’t…) meaning end of December or early January for maximum downwelling effect. This may be enhanced by the predicted passage of the descending eQBO below 30hpa as January progresses. As we move towards December the signs of vortex stress in the modelling are increasing, though these values vary a bit from day to day and model to model. There is broad agreement, however, on an unusual trend towards a weak vortex by end of November and probably beyond. 3. Sea Surface anomalies currently favour a slightly south of normal jet projection. Warmer than average water around Greenland, if maintained, may help to further support any anomalous ridging in that area, and a jet firing beneath weak heights to the north, and over cooler waters, is a tendency we have already seen this season and one which ocean temperatures suggest may continue. Low solar may also strengthen this signal. The CFS forecast going forward for the season sees warmer waters to the north of the UK, and cooler to the west. To me this strengthens the possible atlantic undercut signature with favourable conditions, especially late season, for continental high pressure to nudge west. 4. Snow cover is high, and ice regrowth on the atlantic and Siberian side has been robust, much more so than around Alaska in the pacific sector. This may well help create a very strong Siberian anomaly for this coming season, and this is a consideration for the second half of winter when atlantic firepower starts to drain away. 5. The sun is quiet, and looks set to remain quiet. No pepping up of a flat jet is a decent bet for the coming season, and indeed already I think the seasonal models have been blindsided by the angle of the jet as encouraged by the more meridional flow than expected. This is a context that will be with us all season. Monthly specifics December Current patterns have demonstrated a very resilient Scandy/East Euro block that has acted as a solid barrier that any amount of atlantic fury has failed to crack. Watching the first 2 weeks of November carefully has been instructive in this, and for snow lovers the sight of atlantic lows hitting this block is mana from heaven in terms of adding weight to vortex disruption. The MJO pattern through late November is also supportive of blocks at higher latitude. As a result a trough has remained as a semi permanent feature over western Europe, unable to move, dropping copious amounts of rain in England (less so Scotland with the southerly displaced jet) and temperatures have undercut model predictions. However, this pattern looks set to fade. The MJO will reenter the Indian Ocean shortly. In addition, the tropospheric vortex continues to be on an upwards curve seasonally, reinforced in all probability by growing cyclogenesis caused by currently colder than average temperatures in the mid/eastern US, and into early December a flatter pattern looks likely. A neutral ENSO signature overall is not going to significantly disrupt this seasonal trend. In this scenario the vortex disconnect will remain in force, as tropospheric impacts on the stratosphere disrupt the stratosphere while at the same time the atlantic becomes more dominant tropospherically. +NAO setup will be the end product for the first two thirds with an increasingly +AO in attendance. However, by month’s end downwelling impacts of vortex distress, and possibly even vortex disintegration, will begin to be felt, and the next ENSO cycle will bring the MJO back close to phase 7-8-1 and more support for blocking. A wet first two thirds, with temperatures average to slightly above average will be replaced by a drier final third, greater presence of frost and a pattern shifting towards less mobility. January Timings tough to pin down here, but two possibilities broadly. Possibility No 1 rests on major vortex distress and a downwelling that impacts significantly. If GLAAM continues in an upwards direction, elastically turning positive on the current upwards curve, then torque events may enhance this phase. Lag time, and likely MJO cycle and associated torque increases, suggests mid month for any potential reversal pattern as the AO drops swiftly, and much will depend on where residual shards of the vortex may land. With the axis of attack sitting between Alaska and Siberia we may expect energy displaced to east Asia and Canada, so a burst of atlantic energy initially via a +NAO followed by a swift reduction and a reversed pattern with a -NAO taking over. Best guess here therefore is for greatest cold impacts mid month, maybe final third. Blocked, cold and snow potential at that point. Possibility No 2 rests on the vortex resisting the predicted assault, stretching and reforming. This may be assisted by a transition back to a lower GWO orbit (low GLAAM state) as the ENSO signature fades and the MJO returns again to the Indian Ocean. In this circumstance again a stormy first third to January, perhaps with a Scandy High in attendance due to vortex stretch, and a slight relaxation into a default westerly regime by mid to late month. A close but no cigar event for snow hunters. Southerly jet predisposition may keep temperatures around average, perhaps marginally below, with rainfall above average. The angle of the jet wont totally rule out snow at times, but widespread and durable cover difficult in this scenario. February Being honest, if the vortex collapses in January then I think February could turn out very cold. Shortening seasonal wavelengths, as the tropospheric vortex continues its slow decline, encourages retrogression of the wave pattern, and the generally cold and blocked January could lead to a period of significant continental influence as the Siberian High edges west. It is beyond my gift to predict with any reasonable accuracy the likely progress of the month from start to end, but years of observation would suggest that, as the month ends, any cold pattern would begin to relax. First two thirds very cold, final third relaxation as inevitably a degree of late season vortex reforming returns. However the likely passage of the MJO later in the month may help to sustain the blocking throughout, and any relaxation would be relative. Dry overall, with temperatures below average. If the vortex reforms its shape in January then a second opportunity for cold blocking arrives in the latter half of February as the troposphere makes one final stab at vortex stability. January mobility will produce more wave breaking and another assault on a much weakened vortex, and the knock out blow may arrive with the final ENSO pacific cycle of the season towards the end of February. Chance of late season cold in this scenario – but no guarantee. A non descript first two thirds, certainly drier than January, with temperatures perhaps above average as the Azores High makes an appearance initially, before a colder final third as blocking appears to the north, and intrusion of further cold into March. Temperatures overall around average as the cold end cancels out the relatively mild beginning. So – there it is. I’m going to plump optimistically for possibility No 1 through January (though possibility 2 definitely remains on the table), and summarise my overall spread as: December: Broadly +NAO, wet, average temperatures but more blocked final third. January: Stormy first third under renewed +NAO, then strongly negative -NAO mid to end of month and continental influence. Widespread snow potential. Temperatures overall slightly below average, rainfall overall average. February: Largely -NAO regime, especially first two thirds. Temperatures below average throughout, relatively dry. I hope this reads coherently. Bear in mind we all have limits to skill levels, and the truth behind most forecasts is that they are as much hopecasts and guesses as anything else. However I'm interested to see how the season works out in relation to the level of understanding that has created this moment of crystal ball gazing, and ultimately I post for enjoyment more than anything in looking for cold weather patterns. If we get a cold December with snow, and a mild January/February with no ice in sight I won't mind one bit - a cold December would cancel out any disappointment at inaccuracy and, in any case, we are all learning all the time. I'll do a review in Mid March once the winter has lost its edge.
  15. Thanks for the detailed analysis David. I think this is a good call - I have been reading a technical paper from 2017 that focuses on the Indian Ocean dipole, and its conclusions are that a positive dipole following a Nino is a convincing precursor to an approaching Nina. Last winter we had a curious pattern - very high GLAAM indicative of a Nino sitting alongside what was not obviously a strong Nino forcing in terms of the temperature profile, and virtually all seasonal forecasts bust. Still not found or read any convincing analysis as to why. But anyway - Nino relaxed its grip on GLAAM throughout 2019 and the trend has been downwards for months until a degree of elastic bounce back in the last 6 weeks. This may serve to give us some comparatively higher GWO orbit movement as we approach January before perhaps moving back down towards what may be the truth of 2020 - a transition to a Nina profile. Lots of water to flow under the bridge before then, all part of the enjoyable learning curve. Good luck with the business...
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