MattH
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TillyS This post in itself is misdirection... One failed evolution linked to previous discussions regarding the teleconnections and the likes of the GSDM and people then suggest they are not reliable, rubbish. There have been a handful of cases throughout the winter when the connections between these and the sensible weather on the surface have played out well. There's a saved post of mine from weeks back, highlighting the connections between the evolution of the GSDM and the waxing and waning of the AO through Dec and Jan, when we experienced both very good examples of +ve AO and -ve AO events. This last 'failure' is seemingly linked to a highly complex setup due to stratospheric interference and reflections - https://climateimpactcompany.com/daily-feature-introducing-a-new-index-to-help-forecast-polar-vortex-arctic-air-episodesstratospheric-downward-wave-reflection-events-2-2/ possibly, amongst other things too, but aren't worth bothering discussing. You can't win them all... You're right about the models mind and that includes the full suite of NWP, not just those three models, if you're looking at the short-term, then everyone should be looking at the ECM, UKMO et al. Regards, Matt. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5042443
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Model Output Discussion - Spring Has Sprung
MattH replied to Community Team's topic in Forecast Model Discussion
TillyS This post in itself is misdirection... One failed evolution linked to previous discussions regarding the teleconnections and the likes of the GSDM and people then suggest they are not reliable, rubbish. There have been a handful of cases throughout the winter when the connections between these and the sensible weather on the surface have played out well. There's a saved post of mine from weeks back, highlighting the connections between the evolution of the GSDM and the waxing and waning of the AO through Dec and Jan, when we experienced both very good examples of +ve AO and -ve AO events. This last 'failure' is seemingly linked to a highly complex setup due to stratospheric interference and reflections - https://climateimpactcompany.com/daily-feature-introducing-a-new-index-to-help-forecast-polar-vortex-arctic-air-episodesstratospheric-downward-wave-reflection-events-2-2/ possibly, amongst other things too, but aren't worth bothering discussing. You can't win them all... You're right about the models mind and that includes the full suite of NWP, not just those three models, if you're looking at the short-term, then everyone should be looking at the ECM, UKMO et al. Regards, Matt. -
Teleconnections - Interactions and Impact
MattH replied to Blessed Weather's topic in Forecast Model Discussion
Met4Cast Just a quick one, but some caution here...If you're after amplification to the pattern and a more buckled jet stream then you don't want +ve AAM anomalies propagating to higher latitudes, you want -ve E'ly AAM anomalies. This is where some of the GSDM plots can be misleading, on the MT plot you're statement is "correct" but in the grand scheme of things, if you look at the AAM transport plots, along with the Total AAM plot, relative AAM plot then it is the other way around. +AAM through the mid-latitudes would help to reinforce a westerly flow. I recommend cross-checking the following - https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/hgt.ao.cdas.png with the likes of relative AAM transports plot and you'll see the key links as to when the AO became both -ve and +ve based on the poleward propagation of E'ly AAM anoms and W'ly AAM anoms. Matt. -
Let's start with the AAM - If the number of posts over the years from Tamara et al haven't highlighted the importance and usefulness of the GSDM and the AAM, then I don't know what more can be done, so for those who feel that way, then, yeah, move on, but to take a quick look at the forum and see phrases like 'Snake Oil Sales' is just pathetic. In addition to the AAM - The charts that a set few posts are from a source that is run by the IBM Chief Met in the USA, David Gold. Nearly a year ago now the login for these was leaked and, as a result, his server was overloaded and it went down, for months. Those that use these and despite what some have recently said, even in the USA, where they are used, individuals were heavily disappointed they were down. Therefore, anyone after access to these needs to get in touch with him directly, as another burst of logins would cause further problems once again. There is no 'secret club' or anything like that, just a ridiculous statement, there is a reason, it's not a widely known source and I certainly won't be sharing login details when told not to. I've been using and studying the GSDM for the best part of 4 or 5 years now and within that time the amount of examples where it has helped to pre-empt NWP and also help to reinforce it are numerous. This area of meteorology has crept into forecasting more and without providing details is a foundation for some of my long-range forecasts for work and clients, especially in the energy sector. Meteorology and weather forecasting is a fluid process, things change, adapt and have to be modified. When an outcome doesn't happen as some expected then it is the comments, previously, that make an appearance, but shouldn't. As Tamara has stated many a time it isn't A+B=C and that includes the teleconnections and the GSDM, but it is how it is used and adapted that is key. I can't add much more, to be honest. We all have our opinions, but despite months and years of some trying to educate and discuss the likes of the GSDM to then swiftly knock it all back, including teleconnections too is ridiculous and I apologise for the off-topic post, but this needed to be said. Regards, Matt. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5035436
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I see the ill-considered posts are doing the rounds once again on here, quite remarkable and, as usual, one of the key reasons this thread persistently becomes unappealing to many as the years come and go, myself included, but I oddly keep returning. It would be a superb platform if it weren't for a set few who wish to dismiss aspects of meteorology just because they don't properly understand them or wish to dismiss them for unfounded reasons, more of an opinion. Let's start with the AAM - If the number of posts over the years from Tamara et al haven't highlighted the importance and usefulness of the GSDM and the AAM, then I don't know what more can be done, so for those who feel that way, then, yeah, move on, but to take a quick look at the forum and see some of the comments is just pathetic. In addition to the AAM - The charts that a set few posts are from a source that is run by the IBM Chief Met in the USA, David Gold. Nearly a year ago now the login for these was leaked and, as a result, his server was overloaded and it went down, for months. Those that use these and despite what some have recently said, even in the USA, where they are used, individuals were heavily disappointed they were down. Therefore, anyone after access to these needs to get in touch with him directly, as another burst of logins would cause further problems once again. There is no 'secret club' or anything like that, just a ridiculous statement, there is a reason, it's not a widely known source and I certainly won't be sharing login details when told not to. I've been using and studying the GSDM for the best part of 4 or 5 years now and within that time the amount of examples where it has helped to pre-empt NWP and also help to reinforce it are numerous. This area of meteorology has crept into forecasting more and without providing details is a foundation for some of my long-range forecasts for work and clients, especially in the energy sector. Meteorology and weather forecasting is a fluid process, things change, adapt and have to be modified. When an outcome doesn't happen as some expected then it is the comments, previously, that make an appearance, but shouldn't. As Tamara has stated many a time it isn't A+B=C and that includes the teleconnections and the GSDM, but it is how it is used and adapted that is key. I can't add much more, to be honest. We all have our opinions, but despite months and years of some trying to educate and discuss the likes of the GSDM to then swiftly knock it all back, including teleconnections too is ridiculous and I apologise for the off-topic post, but this needed to be said. Regards, Matt.
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Hi. I just wanted to create a post from an educational perspective and also be a point of reference regarding the importance of the GSDM and the AAM on the medium and long term. Hopefully, anyone who questions this should change their mind after reading the below. The reason it is worth doing this is because there is no better, clearer, example of the importance and connections between those upstream, Pacific developments and the downstream influence. I'll attempt to highlight and stitch this together using some of the usual plots and charts which tell the story so very well indeed and it is this which, hopefully, helps people to at least better understand the influences of the GSDM and what to look for moving forward. OVERVIEW: Firstly, we have just endured a very wet December, this comes as no surprise given what happened to the AAM in late November. Interestingly, seasonal models all pointed towards December being a +ve NAO month, in keeping with the long-term teleconnections with regard El Nino and a +IOD in early winter. The late Nov and early Dec cold spell can be linked back to the behaviour of the GSDM too, while what followed through much of December certainly can and what is happening now and looking ahead, most certainly is. Despite a weakened stratospheric polar vortex, it is the troposphere that is 'leading the dance' rather than the stratosphere for the most part even though it is lending a hand. The late Nov/early Dec blocked pattern has links to the temporary rise in the AAM in mid-November, with the usual lag in place. We can see this first evolution in the below plots... The second and more obvious evolution was then the more pronounced fall in AAM through late Nov as the MJO returned to the W Hem and westerly inertia was removed from the GSDM budget and, as usual, AAM fell along with a -FT (Frictional Torque) and -MT (Mountain Torque) event. The result was, as ever, propagation through the extra-tropics and then into the mid-latitudes of more westerly momentum, propped up by easterly momentum at circa 30-40N - Remember the inflated Azores high in the run-up to Christmas? - We can see how the +AAM anomalies, in particular, were distributed through the atmosphere within the usual window of approximately 14 days. No surprise we then saw an enhanced period of +AO and +NAO conditions just before mid-December onwards. Lastly, comes the 'big event' within the last week or so in terms of the pronounced rise in AAM. Once again, in complete contrast to what happened through mid-November, with a lag of course, we can see how the marked rise in AAM has allowed the propagation through the sub-tropics and into the mid-latitudes of more easterly inertia (-AAM) very well indeed, this is particularly obvious on the relative AAM transports plot, as highlighted below. Once again, no surprises at all and of which has been documented by the usual few on the group we are now seeing a complete reversal of that +AO and +NAO period with an array of mid-latitude and, eventually, high latitude blocking patterns. We can also see this visually on the zonal wind plots at 100hPa (top of the trop/bottom of the strat) too. While like in many areas of meteorology, there is never often a usual "a+b=c evolution", but this is about as close to that as you can get. We have certainly had help from the stratosphere here mind because a robust stratospheric polar vortex that is downwelling westerly winds into the troposphere can often be the dominant player, overriding what has occurred over the last month. There is likely to be some 'help' here from the El Nino and eQBO combination this winter as the sPV continues to remain disorganised and far weaker than it can be at this point in the winter with far less influence on the troposphere too. When it comes to the AAM it is crucial to be able to accept and acknowledge when there are other overriding influences and counterbalances. Tamara et al often talk about not taking the MJO at 'face value', it is similar with the AAM, but when you combine the usefulness of the GSDM and all it incorporates then, as I have perfectly examined here, nobody can ever say the likes of the GSDM and the AAM is "flawed or useless" when it comes to pre-empting NWP, at times, and also gauging how the broader patterns may evolve and shift. As I mentioned at the start of the post, I wanted to put this one together because there is no better example of the usefulness of the GSDM than what has occurred over the last month or so. The evolution and 'story' of the atmosphere have been well played out in these plots. For those who want some winter weather after the last few weeks of very wet conditions then 'this is your time'. We approach mid-winter with such solid footing for cold synoptics that it should be a pleasure to watch the more unusual patterns being modelled in NWP and, interestingly, this continues to link in well with the majority if not all of the seasonal models with regards to how Jan and Feb and perhaps even Mar should progress. Winter is about to start... With regards, Matt. Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4994387
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Evening. I scanned across a post earlier today, which discussed the AAM and how this is now unfavourable looking ahead, also referencing early Dec as being the onset of where the current blocking patterns and propagation of AAM anomalies to the mid-lats started - This is not correct. I did a detailed post, using three separate examples which got pinned on how the last month or more, in terms of the AAM evolved and influenced the pattern. To use the current (20th Jan) GSDM data to write off the outlook into the first half of February, at least, is a mistake. The MJO has progressed into phase 5 and there are now increasing -ve OLR anomalies throughout the Maritimes all linked to the expected eastward push of the MJO. Don't forget some of the key important phases, in terms of the MJO and the GSDM are phases 4-5-6. People often hope for phases 7-8 of the MJO. The current evolution can be seen well on the below...The higher latitude -ve E'ly AAM anomalies have been replaced by a zonal push, won't repeat the reasons why that has happened, but, once again, the current and upcoming +AAM event and rise in GWO cannot be simply dismissed as an influence within the next 14 to 21 days because expectation is for the zonal higher latitude flow to persist, unabated. To say that we are missing a poleward propagation of +AAM anomalies is also incorrect, it is E'ly AAM anomalies that are looked for. This is the complicating area of the GSDM that needs to think about, as +ve AAM regimes through the tropics promote -ve AAM anomalies at higher latitudes and vice versa. What I have been musing over is whether the more zonal, westerly type at higher latitudes will now remain dominant and acting to keep a lid on the potential for northern blocking, but IMO I don't think it will. We are now only just starting to see the usual GSDM responses to the ongoing MJO progression and the re-development of westerly inertia into the tropics, in the areas of interest. This remains a watching brief, but it is way (way!) to early to say that we won't see any influence through the mid-latitudes into early February onwards. Don't forget we maintain a robust eQBO regime too. My expectation and prediction is that the current dominant zonal +NAO regime will, essentially, burn itself out within the opening week of February (approx), with a far greater risk of amplification to the pattern, this is perhaps particularly relevant if the sPV declines more towards Russia once again. In terms of colder synoptics and February is very much a lot to play for, despite how some may be analysing the situation. Regards, Matt. Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5022710
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Model Output Discussion - Spring Has Sprung
MattH replied to Community Team's topic in Forecast Model Discussion
Evening. I scanned across a post earlier today, which discussed the AAM and how this is now unfavourable looking ahead, also referencing early Dec as being the onset of where the current blocking patterns and propagation of AAM anomalies to the mid-lats started - This is not correct. I did a detailed post, using three separate examples which got pinned on how the last month or more, in terms of the AAM evolved and influenced the pattern. To use the current (20th Jan) GSDM data to write off the outlook into the first half of February, at least, is a mistake. The MJO has progressed into phase 5 and there are now increasing -ve OLR anomalies throughout the Maritimes all linked to the expected eastward push of the MJO. Don't forget some of the key important phases, in terms of the MJO and the GSDM are phases 4-5-6. People often hope for phases 7-8 of the MJO. The current evolution can be seen well on the below...The higher latitude -ve E'ly AAM anomalies have been replaced by a zonal push, won't repeat the reasons why that has happened, but, once again, the current and upcoming +AAM event and rise in GWO cannot be simply dismissed as an influence within the next 14 to 21 days because expectation is for the zonal higher latitude flow to persist, unabated. To say that we are missing a poleward propagation of +AAM anomalies is also incorrect, it is E'ly AAM anomalies that are looked for. This is the complicating area of the GSDM that needs to think about, as +ve AAM regimes through the tropics promote -ve AAM anomalies at higher latitudes and vice versa. What I have been musing over is whether the more zonal, westerly type at higher latitudes will now remain dominant and acting to keep a lid on the potential for northern blocking, but IMO I don't think it will. We are now only just starting to see the usual GSDM responses to the ongoing MJO progression and the re-development of westerly inertia into the tropics, in the areas of interest. This remains a watching brief, but it is way (way!) to early to say that we won't see any influence through the mid-latitudes into early February onwards. Don't forget we maintain a robust eQBO regime too. My expectation and prediction is that the current dominant zonal +NAO regime will, essentially, burn itself out within the opening week of February (approx), with a far greater risk of amplification to the pattern, this is perhaps particularly relevant if the sPV declines more towards Russia once again. In terms of colder synoptics and February is very much a lot to play for, despite how some may be analysing the situation. Regards, Matt.
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It is highly likely that the rest of January, beyond the end of this week of course, will 'come and go' with no significant cold synoptics in play. We look towards February then for the renewed risk, which still hasn't changed. January, overall, mind is likely to be something of a disappointment, as the change to colder synoptics now most certainly wasn't expected to be removed as quickly nor as easily as is now on the way from this forthcoming weekend onwards. The ebb and flow of the processes behind the GSDM certainly have some influence here, despite clearly the AAM not falling anywhere near the same levels as we started off the winter, back in the first half of December. As I mentioned the other day though it is the strat developments, especially within the lower levels of the strat, that will primarily aid in changing the pattern. The recent pushing and pulling of the vortex, with a low-level split (circa 100-150mb) an evolution that could not have been foreseen some weeks ago. We can see this again on the PV plots and the standard 500mb height charts...Note the split and separate lobe over N America, ejected eastwards and boom, a return to a solid vortex in its usual locale. It is this, without question that is the key driver for the rapid change to a more +ve NAO regime looking ahead - Ironically, it has been the troposphere that has 'led the winter dance' so far, with the stratosphere having little influence, but the recent weakening and split of the vortex, again ironically, actually helping now to end the current cold spell and bring us back to a more 'usual' winter time pattern. If the split hadn't occurred or occurred differently, then the outlook may well have been different, but that's all 'if, but and maybe'. Looking further ahead there is still no reason to write off the rest of winter, in any shape or form - The MJO remains active, another +GLAAM is on the way and just as happened in late Dec/early Jan this will be another interesting "test" of the processes at play within the GSDM to help alter the up-coming +NAO pattern. There are likely to be a lot of hard-going synoptics to get through first and, again, by the looks that will take us now to the end of January at the earliest. Cheers, Matt. Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5014150
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It is highly likely that the rest of January, beyond the end of this week of course, will 'come and go' with no significant cold synoptics in play. We look towards February then for the renewed risk, which still hasn't changed. January, overall, mind is likely to be something of a disappointment, as the change to colder synoptics now most certainly wasn't expected to be removed as quickly nor as easily as is now on the way from this forthcoming weekend onwards. The ebb and flow of the processes behind the GSDM certainly have some influence here, despite clearly the AAM not falling anywhere near the same levels as we started off the winter, back in the first half of December. As I mentioned the other day though it is the strat developments, especially within the lower levels of the strat, that will primarily aid in changing the pattern. The recent pushing and pulling of the vortex, with a low-level split (circa 100-150mb) an evolution that could not have been foreseen some weeks ago. We can see this again on the PV plots and the standard 500mb height charts...Note the split and separate lobe over N America, ejected eastwards and boom, a return to a solid vortex in its usual locale. It is this, without question that is the key driver for the rapid change to a more +ve NAO regime looking ahead - Ironically, it has been the troposphere that has 'led the winter dance' so far, with the stratosphere having little influence, but the recent weakening and split of the vortex, again ironically, actually helping now to end the current cold spell and bring us back to a more 'usual' winter time pattern. If the split hadn't occurred or occurred differently, then the outlook may well have been different, but that's all 'if, but and maybe'. Looking further ahead there is still no reason to write off the rest of winter, in any shape or form - The MJO remains active, another +GLAAM is on the way and just as happened in late Dec/early Jan this will be another interesting "test" of the processes at play within the GSDM to help alter the up-coming +NAO pattern. There are likely to be a lot of hard-going synoptics to get through first and, again, by the looks that will take us now to the end of January at the earliest. Cheers, Matt.
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Just a quick post but the reason for the quick transition to the westerly type is, in my opinion, linked to the recent weakening of the strat vortex and how, within the lower layers of the strat/top of the trop are likely to behave following the consolidation of the vortex in the coming days. We can see this very well in the below four plots... The lobe of the vortex that has been bringing the extreme cold to N America is ejected eastwards over the N Atlantic and clearly to a locale where it then helps to drive the charts and patterns we are seeing for next weekend onwards, as the PV plots highlight very well and the vortex is then a more uniform system. Personally, the MJO through recent phases may also be helping the westerly push, but it is the above which is the key driver for the rapid breakdown of any HLB. Does this signal the end of winter after just a week of cold? - does it heck and don't let anyone tell you otherwise in this instance. The reasons for the potential/expected/likely return of blocking have been well documented by Tamara, Catacol et al in recent posts and it is likely to be a relatively short wait before further winter synoptics return by late Jan or early Feb onwards. All that aside as I mentioned the other day, for those who like the cold enjoy the week ahead. Kind regards. Matt. Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5011627
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Just a quick post but the reason for the quick transition to the westerly type is, in my opinion, linked to the recent weakening of the strat vortex and how, within the lower layers of the strat/top of the trop are likely to behave following the consolidation of the vortex in the coming days. We can see this very well in the below four plots... The lobe of the vortex that has been bringing the extreme cold to N America is ejected eastwards over the N Atlantic and clearly to a locale where it then helps to drive the charts and patterns we are seeing for next weekend onwards, as the PV plots highlight very well and the vortex is then a more uniform system. Personally, the MJO through recent phases may also be helping the westerly push, but it is the above which is the key driver for the rapid breakdown of any HLB. Does this signal the end of winter after just a week of cold? - does it heck and don't let anyone tell you otherwise in this instance. The reasons for the potential/expected/likely return of blocking have been well documented by Tamara, Catacol et al in recent posts and it is likely to be a relatively short wait before further winter synoptics return by late Jan or early Feb onwards. All that aside as I mentioned the other day, for those who like the cold enjoy the week ahead. Kind regards. Matt.
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Apologies for the 'one liner'...but this holds a lot of truth. Just like those that look for the heat and summer synoptics, those that like the winter synoptics just stop now, simply enjoy the week ahead. Don't "worry" about next weekend and what may follow, simply focus on the here and now and what is on the way next week. It'll be a great week of winter weather. With the longer term variables in play then I'm sure this will not be the only week with this kind of blocked pattern before the end of February. Tempus Fugit - Sit back and enjoy some winter weather. Cheers. Matt.
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All valid points here and just replying to this so I can post some GWO analogs as requested by @Met4Cast about this expected rise in the GWO once again during the second half of January. As per the MJO plots mind, don't take a face value, but as you can see the overall likely outcome is obvious and supports all other ideas and information... No time at the moment for anything further, but yes, as per usual, be extremely cautious (everyone!) about individual model runs and variability, especially at longer lead times. The above quick set of bullet points is exactly what highlights the next 4 to 6 weeks and there is simply no reason to change all long-range thoughts, plus also the consistent signal from the Seasonal Models, for months, for the second half of the winter to be significant in terms of colder synoptics etc. Cheers, Matt. Original post: https://community.netweather.tv/topic/99760-model-output-discussion-colder-but-how-cold-and-for-how-long/?do=findComment&comment=5005845
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All valid points here and just replying to this so I can post some GWO analogs as requested by @Met4Cast about this expected rise in the GWO once again during the second half of January. As per the MJO plots mind, don't take a face value, but as you can see the overall likely outcome is obvious and supports all other ideas and information... No time at the moment for anything further, but yes, as per usual, be extremely cautious (everyone!) about individual model runs and variability, especially at longer lead times. The above quick set of bullet points is exactly what highlights the next 4 to 6 weeks and there is simply no reason to change all long-range thoughts, plus also the consistent signal from the Seasonal Models, for months, for the second half of the winter to be significant in terms of colder synoptics etc. Cheers, Matt.
