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MattHugo

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About MattHugo

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  1. End of the week post...apologies if any typo's/grammar issues, been a long week and an early work start this morning...a cold beer awaits! So, where are we now? Without sounding like a stuck record, the significant MJO development from a week or two back most certainly aided in producing a significant WWB and of which aided in reversing the AAM at the mid-lats than compared with late April and into early May. This was well predicted in advance, pretty much 2 weeks back, at the end of April, that a shift away from the more changeable pattern (for the UK) would mean a much greater risk of blocking patterns, once again, and amplification to the pattern. The overall AAM plots haven't changed a great deal within the last week, but the transition to an increased amount of E'ly momentum through the mid-lats is in evidence, while clearly there's plenty of W'ly momentum through the tropics, the overall Nino pattern remains. The anom plot covering the 12th to the 15th of May really does highlight well the transition to significant amplification and a more blocked regime across NW Europe and this, yet again, continues to link up towards the extensive high pressure that remains dominant over polar regions in relation to the continued influences from the final warming of the strat vortex, now a number of weeks ago. What is quite impressive with the last month or so is how dynamic and 'active' this downwelling has been and certainly more influential and of significance than what followed the SSW in early January. Equally, just starting to look ahead but the CFS continues to highlight a potential return to a heightened risk of a convective atmosphere through the I/O and perhaps into the Pacific again through the first half of June, this exampled on the NCICS plot. Note as well, the significant MJO activity from late April and into early May too which continues to link well with the above transition of the AAM Where do we go from here? Well, to be honest, through the final 10 to 14 days of May, I'm not entirely sure. NWP has been all over the place this week with regards to the UK and the patterns across the N Atlantic. At times, finally showing a breakdown of the blocking regimes at more polar regions, perhaps signaling an end to the downwelling event. However, that signal soon reversed and northern blocking at latitudes where you don't really want it at this time of year does look set to continue. While the recent links between the MJO/WWB event and transition to increased E'ly momentum at higher latitudes have definitely had an effect on the patterns to date, I'm not entirely sure whether this influence will now wane through the rest of the month, it seems like it to me now, with blocking patterns becoming less likely at say 45-60N. The other important signal now is increased consistency for a more cyclonic pattern to evolve across the N Atlantic and into NW Europe looking ahead, this all coming 'underneath' yet further blocking over Greenland. I have a feeling that until this unwanted blocking clears off, then we won't default into a more typical 'summertime pattern'. The 00Z ECMWF highlights this well, amongst other models too; The persistence of this block really is painful to see and watch, from a cold/winter fans point of view. We've had an alternating Scandinavian-Greenland blocking pattern now for what feels like weeks, it probably has been weeks and, again, until this blocking regime breaks down then the outlook is particularly uncertain. However, what is somewhat confusing is the ability to still get fairly mobile and W'ly weather across the N Atlantic under this blocking looking ahead, despite what has been a clear transition to a heightened E'ly momentum at higher latitudes. Given some guidance from Tamara regarding the below image, the CFS outlook has and continues to signal a marked rise in AAM through towards the middle of June and, in fact, the last few model runs has taken this signal to >2sd from the main 4 members. The obvious question here is: Is the CFS just simply over doing this signal or, is it correctly picking up on yet further MJO activity running through the I/O and into the Pacific to reinforce the westerly momentum and keep the overall Nino pattern going looking ahead and this increasing the changes of heightened E'ly momentum through the mid-lats? Another final piece to the puzzle is regarding some tweets I have seen with regards to the actual fall in SST anoms across more central and eastern areas of the Pacific in recent days, despite the recent significant WWB/CCKW activity. Some are now suggesting a possible trend away from a more Nino type, to perhaps La Nina looking ahead, no doubt this is unlikely to be of any great significance within the short term, but could perhaps have greater influences on the longer term, through the latter stages of the summer. However, there seems to be uncertainty and discussion regarding this with various posts and graphics showing both sides of the coin and I also recently spotted this tweet from Paul Roundy; So, in summary.... 1)The blocking regimes of present can clearly be connected back to the MJO activity of past weeks and the increased W'ly momentum through the sub-tropics and a reverse through the mid-lats. 2) Northern (Greenland) blocking continues to be a troublesome feature and despite the recent developments still seems to be a feature looking ahead and this may well maintain a more cyclonic pattern to the N Atlantic, beneath the blocking through the rest of May. 3) All eyes on the potential for further MJO activity through the I/O into early June and this possible signal from the CFS to increase AAM as the opening summer month progresses as this could well then have sig impacts for summer weather down the line. Cheers and have a good weekend, Matt.
  2. Just a quick post, further to the above, but below is the most recent EC Monthly plots and what seems a little concerning here is the lack of a 'reload' moving forward to me. There seems to be some correlation to the above EC ENS image, which you would expect, but just running back through the last few weeks of updates of these graphics and there is no clear evidence for another reload to get the MJO back in the Indian Ocean and more western areas of the Maritimes before early June. The other curious thing as well is how, for some reason, the AAM and GWO plots have shifted/changed suddenly over the last week or so. Just referencing my own post, prior to Tamara's above, of which included AAM and GWO plots dated the 7th of May, I highlighted the significant progression of the GWO through into phase 4 along with a significant spike in tendency. The prediction at that point was for a potential progression through phases 5-6-7 but with perhaps relatively low amplitude. However, and again, curiously, that data seems to have changed suddenly. Gone has that spike, the latest plot from the 11th of May, has the 5th, 6th and 7th data into the COD, nowhere near phase 4 really, or not like was in evidence back on the 7th. Equally, gone has the so-called +4sd tendency plot. If anyone can provide further insight on to why this would occur I would be interested to hear. I thought this wasn't model data as such, more actual data being observed? Clearly, if this is more model data then like any model output it can change, but that shift and change within the space of 3 or 4 days seems significant to me and doesn't provide as much support to say that more amplification will appear long term. The other concern, to me, more from a meteorological NWP perspective seeing I've been on shift for 4 days now is the lack of ability to get MSLP to rise long term, through the latter stages of May. As much as I have been taking AAM developments on board, while forecasting, it is just near impossible not to predict a changeable and, overall, more cyclonic than anticyclonic outlook now for the final third of May, with the current anticyclonic spell obviously coming to end rather quickly, by Friday. While the GFS may well have something of a 'negative' bias, I've been following the likes of the EC clusters and other model data closely and even there, there's little evidence for any pronounced recovery in GPH looking forward. I dropped the below graphic on to Twitter yesterday which really does highlight nicely how the AAM can be connected to anomalies and broader synoptic pattern changes over the last month or two. However, and again, what is a little concerning is the longer term. While the significant MJO event and WWB from early May has, without question, helped to reduce W'ly momentum at higher lats, even bringing about that reversal to more of an E'ly component, that event is clearly waning now and the obvious question is, where do we go from here? - Tamara's reply above seems to provide additional insight into that, for the early summer period, which does provide some positivity but, overall, there just seems to be something 'a miss' here now looking ahead and, to me, especially from an NWP perspective, the outlook doesn't scream out an anticyclonic end to spring/start to summer, but we shall see. All eyes on the potential MJO developments I presume looking forward... Kind regards, Matt.
  3. Just a quick reply, but thanks for the additional review and analysis, Tamara. Some interesting pieces of information in there that I can take away to advance on, or at least 'bookmark' for referencing further down the line. One question I do have, is, where do you still get the archived AAM plots? - Are these simply something you've saved on your PC or is there an archive somewhere?. I can't seem to find them on the usual GSDM website and I've often wanted to look back on certain years/situations to help the learning process. Clearly, comparing with what has been to what may well be occurring now is certainly highly useful, as you've done above with regards to that of 2012 v 2019 and the differences in evidence re; Nino and Nina differences. Will hope to keep firing out some posts as and when possible in the coming weeks to keep this thread going, no doubt it'll gain more interest, as usual, towards the end of the year but there's still use in thoughts and analysis through the summer. If you've got the time to keep replying/responding then I look forward to your further insight. Regards, Matt.
  4. Hi. Some general thoughts and analysis below... The transition to a greater amount of W'ly momentum through the mid-lats during the middle and latter half of April has now played through the system nicely, clearly aiding in producing a more unsettled and changeable period of weather through the opening week of May, reanalysis of that is shown below. However, as was discussed within the last update, the development of a significant MJO event through the Indian Ocean and into the Maritimes was set to change the AAM, decreasing the W'ly momentum through the mid-lats and aiding to promote an increasing amount of amplification. That evolution is continuing to take place and we are now clearly set to progress towards a far more anticyclonic period of weather looking ahead. The significant MJO event over the last 7 to 10 days has now begun to influence the AAM. As can be seen on the total AAM plot above, the W'ly momentum through late April has now eased as we've progressed into early May. The medium-term will now, clearly, be dominated by a pronounced rise in atmospheric pressure from this weekend onwards. This transition away from the unsettled and changeable weather of the opening week of May is most certainly related to the influences of the MJO on the AAM budget, reducing the W'ly momentum and once again creating more of a Nino atmospheric profile. With the large upper trough within the N Atlantic aiding the process of amplification through WAA, the atmosphere is now pre-conditioned for amplification and that is what will take place through the next 5 to 7 days. Just to reference the previous post from above as well, the prediction from the 30th of April was as follows; The GWO, as mentioned before, will likely continue to rise into higher phases (how high is uncertain), so +AAM and that, in turn, will likely mean between the 10th and the 14th of May we see a developing signal for high pressure. Clearly where and how any anticyclone will develop is unknown, but I still fully expect a much greater risk of blocking patterns to dominate the further we progress into May and clearly, that may well mean a marked rise in temperature too. What is nice to see is that on this occasion the links and 'jigsaw pieces' of how the AAM and the MJO can indeed influence the atmosphere have come together nicely and that time frame of the 10th to the 14th is pretty much-looking spot on now. So, where do we go from here? - It is likely that we will continue to see the GWO in relatively high Nino phases. This is exampled well below from the latest plot, it's about to rise once again through phase 5. The prediction was for the GWO to remain in higher phases and we have once again had another massive (+4 sd) spike in the tendency of the AAM, despite a recent brief fall. This will, without question, continue to promote higher phases of the GWO looking ahead and that does mean a greater risk of further blocking patterns with a higher than average likelihood of E'ly momentum at mid-lats (~40N to 60N). What NWP output is signaling, however, is a possible fall in pressure by the 18th and 19th. What should be stressed here, however, is that this fall in pressure isn't directly related to an increase in W'ly momentum through the mid-lats like we have just recently had. This fall in pressure seems to arise due to the fact that the main anticyclonic is 'pulled' to the N and NW of the UK in association with yet further northern blocking patterns and a natural fall in pressure results, especially after potentially getting atmospheric pressure near 1040mb by the 12th and 13th. Clearly, if this had been the middle of winter we would be in the grip of some major cold synoptics, at this time of year it is a nuisance! If we take a look at the ECM, GFS and CMC anom plots, this does tell the story well looking ahead. The initial high pressure of this weekend and into next week does look as though it will end up at higher latitudes, again, this is directly related to developments within the strat and the final warming. What is very difficult to gauge here is how much of a negative tilt there will be to the trough pattern within the N Atlantic. In my opinion, the models (especially GFS!) are being too aggressive with that trough which, therefore, means low pressure moves into the UK from the S and SW. Don't forget, referencing the above, the atmosphere will remain in a Nino state with a greater likelihood of E'ly momentum at high latitudes. This doesn't promote low pressures systems from moving into NW Europe and, to me, means low-pressure systems will dig further down into France and Iberia, remaining, primarily, more to the S and SW of the UK, as per EC and CMC plots below, rather than the GFS which has the more cyclonic pattern nearer to the UK. The problem here, however, is obvious and it is a very fine line/margins. As was exampled perfectly during the "summer" of 2012, getting higher pressure at more northern latitudes at this time of year does mean that an E or NE'ly flow is possible given lower pressure to the S or SW of the British Isles and higher pressure to the N etc. So, we should expect some significant regional variation in temperatures looking ahead with a bias for more N and W areas of the British Isles to see the higher temperatures. Equally, to what extent the blocking regimes to the north dominate will determine whether low-pressure systems do influence at least parts of the S and SW of the British Isles. Despite the fall in pressure I still fully expect higher pressure to be a feature longer term, towards the latter half of May and into early June with no full-on cyclonic pattern dominating as we have had over this past week. However, what we really need to do is lose this northern blocking at higher latitudes. The problem here, however, is there is no obvious 'ingredient' at this time of year available to remove it and that is certainly the wild card for the time being and looking ahead. SUMMARY: The major WWB in association with the active MJO event over the last 7 to 10 days has now played through the system, increasingly W'ly momentum through the sub-tropics and reducing the W'ly momentum at higher lats. This, therefore, has increased the risk of amplification, which was predicted in late April. We are now seeing a far more anticyclonic outlook looking ahead. I fully expect northern blocking to continue, I don't expect a full-on transition back towards cyclonic weather during the second half of May even though lower pressure may well influence the southern half of the British Isles for a time. It is, however, the blocking patterns over the polar region that needs to be monitored closely as we move into early summer, as this is seemingly dictating the location and development of higher pressure at the moment and if anticyclones continue to build to the N or NW of the UK looking ahead than E or NE'ly flows remain a risk, while low pressure may try and move into the UK creating a difficult period of forecasting for details. Regards, Matt.
  5. Forecast model data is continuing to support more of a signal for a cyclonic spell through the opening week of May, once we get beyond this colder regime for the BH Weekend. This continues to be associated with the recent and on-going increase of W'ly momentum through the mid-lats given the recent fall in AAMl. However, longer term, so further into May and the outlook and prediction remains similar and that is for high pressure to eventually return. Usual 2-day lag applies, but what can be seen well now is the E'ly, negative values between 30N and 40N, while there has been a clear increase in W'ly moment between approximately 50N and 60N. The Greenland block is, without question, a direct result of the recent split of the strat vortex. The following link ( http://users.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwf100f24.gif ) highlights well where the opportunity for height rises over Greenland would be. Note the two separate vortices left over after the final breakdown of the strat vortex, it is between these features where tropospheric impacts have resulted and clearly will influence the UK's weather this BH Weekend. Note as well how the surface pattern almost mirrors the 100hpa pattern to the E and NE, with a pronounced low and trough, clearly, that is also a variable, when combined with the Greenland block, in bringing the colder N'ly flow later this week. Back to the AAM and the fall in AAM to phase 8 is directly related to the transition to a greater amount of W'ly momentum through the mid-lats. I still expect this transition to be relatively temporary, perhaps a case of influencing the N Atlantic pattern for the opening 7 to 10 days of May. The prediction, however, is still for the GWO to rise through phase 5 and 6 in association with a reversal of this pattern the further we progress into May. I would hope, if the science is correct, that the plot on the left will, eventually, revert back to that of early April with a greater amount of E'ly moment returning to higher latitudes. One to keep a close track on in coming weeks... The 00Z EC, GFS, and CMC mean plots below highlight the N Hem and N Atlantic pattern very well through the first week or more of May. What stands out is the clear signal for northern blocking over polar regions, again that is directly related to the breakdown of the strat vortex as discussed above. However, note across the N Atlantic domain between the 30th and the 9th all three models have lower than average heights and what is overall, a fairly zonal, W'ly type. This links in perfectly with the recent AAM change as highlighted above. Does this mean that we will be locked into a cyclonic pattern through May for weeks on end?...I still believe the answer to that is, no. If we take a look at the on-going MJO activity this has both implications on the short term, but also the long term which I alluded to in the last email at the end of last week. The MJO emerged strongly through the Indian Ocean over the last few days and is now moving through into the Maritimes before likely weakening into the Western Pacific. Just using a reanalysis chart for an MJO phase 3 in April you can clearly see this, at least initially, supports a more cyclonic outlook across the British Isles and NW Europe. This ties in well with NWP output for this more unsettled period of weather beyond the Bank Holiday weekend, perhaps getting through to the weekend of the 11th and 12th of May. However, I would suggest that this MJO activity will, overall, be aiding to increase W'ly momentum through the sub-tropics, so while it may well be aiding and supporting more of a zonal 'push' within the short term I still expect that this MJO development will aid in reversing the AAM trend longer term, of course with the help of mountain and frictional torque events as northern hemispheric MSLP patterns change. The GWO, as mentioned before, will likely continue to rise into higher phases (how high is uncertain), so +AAM and that, in turn, will likely mean between the 10th and the 14th of May we see a developing signal for high pressure. Clearly where and how any anticyclone will develop is unknown, but I still fully expect a much greater risk of blocking patterns to dominate the further we progress into May and clearly, that may well mean a marked rise in temperature too.
  6. Just a quick post but the above discussions seem to be almost reversing, again that comes back to the question that I was asking (still awaiting a reply) with regards to how can one better understand how the AAM may well evolve. As I mentioned days ago, this is no doubt a very complex question, but there must surely be some 'ground rules' as with regards to what can be looked at to gauge how the AAM may trend, whether +ve or -ve. From what @Singularitymentioned regarding the likely lack of progression of the trough into the UK and NW Europe, potentially related to the AAM quickly 'bouncing back', that now seems to be going the other way. The graphic I put above (crudely!) looks increasingly unlikely, or so as I see it. The tendency of the AAM, while very briefly 'jumping back' has again gone negative, this potentially related to mountain torque activity and the below charts highlight this, despite the usual 48hr lag... The AAM now seems to be as low as it was (obviously not that low on the grand scheme of things) since early March. The MT activity of potential influence the tendency chart clearly, again, is more similar to that period around late Feb and into early Mar. There continues to be a distinct lack of any trend towards a more W'ly biased signal through the sub-tropics, potentially meaning blocking would return to the N Atlantic domain rather quickly. Again, it seems to be going the other way for some reason. The GWO has also done a "360" to an extent, strangely coming back towards phase 8 or even phase 1, again this just highlighting the trend away from a possible rise in GWO. I do, however, remember someone mentioning that the GWO doesn't take into affect earth AAM, just relative or the other way around (?). Either way, NWP output is certainly far more bullish for a more sustained cyclonic period of weather for the N Atlantic domain now and into NW Europe looking ahead. It'll be interesting to see where we go from there; will this general trend continue, will the weak El Nino force things back to promote a return to blocking, or will, perhaps, the influence of the strat vortex pull through as well. Interestingly, there is evidence in some NWP output for northern blocking into early May with perhaps some highly unwanted cool N or NE'ly flows...
  7. When you say "further positive AAM cycles" I presume you mean through the sub-tropical regions, as we have had over the last couple of weeks, so roughly 10N to 30N, as opposed to +ve AAM regimes like back in early March at more northern lats? If this is what you're implying then I can see how the -ve AAM regime may well continue then at more northern latitudes as per the last couple of weeks, meaning that further blocking episodes are likely. I would imagine with the breakdown of the strat vortex too over the next few days this will only reinforce the lack of any W'ly momentum at more northern latitudes; Clearly May is often the driest month of the year across the UK, on average, for a reason(s), this certainly being one each year no doubt. The latest GWO plot seems to have done just that, from a few days ago it has suddenly 'jumped' back around to phase 5 so a relatively high/+AAM state still which ties in with what you mention as well... The charts are now 72hrs old, so hopefully should update today, but even back on the 15th the relative AAM tendency has quickly bounced back up, perhaps related to some mountain torque activity. Again, tying this in with what you've mentioned, could this well be the sign that +AAM will return through the sub-tropical regions, while more northern lats maintain more of a -ve regime. Apologies for the crude colouring (on the right image) but perhaps the prediction then, in terms of a total AAM through the next week would be something like below, this mirroring or at least being similar to that of the first half of April as we approach late April and early May. The end result, or prediction, is a continued risk or a greater propensity for blocking regimes within the N Atlantic/N Europe domain (?) Regards, Matt.
  8. As an addition to the above, find below a few extra graphics and plots. This seems to tie in nicely and is seemingly a good example of how the AAM and 500mb anoms can clearly be connected with regards to either +AAM through the mid-lats, say 40-60N, as what occurred during the first half of March or more. This N Hem pattern is clearly a distinctly +NAO regime too and, as I highlighted yesterday, brought a particularly unsettled and disturbed period of weather to the British Isles. The opposite has seemingly been occurring since early April mind, with -AAM through a similar latitude range, but clearly note the completely different N Hem pattern and especially so across the N Atlantic domain. This has, essentially meant that the first half of March compared with the first half of April, for the UK and NW Europe are completely opposite and this seems to be a superb example and connection to me. I think the main question of interest, which no doubt has a very complicated answer is; how can one predict the likely evolution of the AAM, whether +ve or -ve looking forward, especially so within than 40-60N latitude range?...As we found out this winter mind, this link isn't always clear cut and can vary, but still.
  9. Just thought I'd drop a quick message in here, it's a shame discussion have fallen away. While winter is over there's still be some interesting connections and links with how the weather so far this spring has progressed, or so it seems from over here in the UK. Apologies if this is brief and with some rather 'rusty comments' perhaps, it's been a good few months since I've sat down and properly looked at any AAM/GWO stuff and linked it to current/recent synoptics and how things may evolve... What seems to have been of particular interest here in the UK is how, finally, some more significant blocking patterns have materialized over the last 2 weeks, or essentially the first half of April even though the strat vortex has been in a particularly strong late-winter phase, so no help from there I would suggest and the MJO has been particularly 'quiet' too. March was, overall, noticeably cyclonic and wet, very wet for some areas of the UK, but this transition to blocking patterns at more northern latitudes is what was clearly hoped for during most of the winter. While we all know that the blocking regimes were there, at times, the lack of ability, if that's the right word, to set up at more northern latitudes was clearly a major failure, with the NAO in particular very reluctant to get -ve in any shape or form. However, I would surmise that the -ve values of total AAM since late March and through into April above 40N initially and then above 50N is surely related to the large and dominant Scandinavian blocking pattern, with a very much reduced W'ly component to the atmosphere at these latitudes. Indeed, if this had been 2 or 3 months back then much of N Europe would have been in the freezer, it has been quite cold here in association with the block anyway, but clearly not to the same extremes that would have been possible back in the winter months. However, does that pattern now look set to change?...It does to me, there has clearly been a progression towards the tendency to fall more negatively in recent days, nearing the values of late February. 500mb anom plots from the EC, GFS and the CMC all signal quite an abrupt change and removal of the blocking pattern through next week, not before however bringing a very pleasant Easter weekend to the UK with rising temperatures as a much warmer air mass becomes entrained into the overall block. However, could this be a good example of the links and connections between the AAM and blocking patterns or, indeed, more cyclonic weather at times. Perhaps one for one of the more knowledgeable to answer... Mountain torque has trended negative of late and while the GWO has been loitering in P5, 6, 7 and 8 it hasn't really been on the move or with any significant amplification. But could that be about to change, in association with this more pronounced trend away from such a strong blocking pattern across Scandinavia? There may well be someone out there who may be able to make a more distinct prediction of how the AAM may evolve over the next few weeks, perhaps drifting into phase 8, so more of neutral or even La Nina regime, but I would suggest that after the last 2 weeks of -ve anoms at 40, 50 and 60N, with a much reduced W'ly momentum, that pattern may well reverse with the more N Lats seeing an injection of W'ly momentum looking forward. Regards to all, Matt.
  10. Can someone advance on this at some point... I've seen this highlighted a number of times now, but without clear discussion as to why. Given the combination of a slow downwelling SSW, but also with an atmosphere that, at times, was conducive to blocking patterns, why and, more importantly, how, would this year's SSW be a counterbalance and essentially stop the likes of the MJO imprinting itself onto the N Hem pattern? - Surely, no matter the speed of a downwell after a SSW, if you've got a favourable tropical evolution, in terms of +AAM and say MJO in phases 6-7-8, then these would "connect" to the -ve E'ly regime downwelling into the trop to help promote northern blocking regimes and tank the AO and NAO (?). At the beginning of the winter, there was a clear link between a transitional QBO from E'ly to W'ly essentially being another piece of the puzzle that would support a possible SSW further down the line. One analogy I remember seeing was "building a house on dodgy foundations" - While we are indeed transitioning to a W'ly QBO, because the lower levels would still be primarily E'ly then this could well promote a breakdown of the SPV, the SSW prediction this year was as good as I remember it. However, what seems to be a new one to me, is, again, how did this year's SSW, as some have mentioned, essentially spoil the party when, at times, the AAM and the MJO were both singing from the same hymn sheet. There's a clear disconnect this winter between the tropics and that of the higher lats, but further info on the above would be very interesting to read by those who have any answers/suggestions. Kind regards, Matt.
  11. It's a quick one but I really do look forward to reviewing this winter and picking out some of the primary reasons why predictions have gone so wrong, overall, especially from a UK and European perspective, especially with regards to the teleconnections etc. The last two weeks or so have been the quietest in here all winter and no surprise! Following on from my post last week, of course this just highlighting the AAM and MJO situation, then yet again the outlook just doesnt match what these "indicators" are/were showing; this perhaps the 3rd time now this winter, if not more, has there been a clear picture and guide, but for the outcome to fall short. It's been a long time since a winter promised a lot, but overall delivered very little from a UK but even European wide basis, there was a good tweet on that with a temp graphic from Ventrice yesteday. Not only has the likes of the MJO and AAM/GSDM been a 'swing and a miss', as a predictor/guide, but the likes of the EC Monthly have been incredibly 'way off' through much of the winter too, including seasonal models. These highly respected models (primarily of ECMWF origin, as usual), for whatever reason, equally falling short and there must be some analysis and review on this to learn and advance. Even the likes of the UKMO back in early January and for a number of weeks after were consistently highlighting a heightened risk of colder synoptics and weather, for nothing to really materialise. Did they follow the SSW "rule book" too literally as well, I wonder... One things for sure it is certainly a winter which shows that no matter the promise and analysis but many individuals, either on here, or else where the weather will always do what it wants to do; a good thing mind as otherwise I'd be out of a job! A frustrating, long, tedious winter is, thankfully, coming to a close and I've certainly learnt a lesson or two, or should I say had a few "revision lessons" on what to belive and what not to be belive perhaps too directly, and that includes the likes of GSDM/AAM. It's been quite the winter of disconnections and surprise really IMO more than anything. Kind regards, Matt.
  12. So, here we are again, some very interesting information coming from the GSDM site and also the MJO too. Won't ramble on too much as I've just noticed Zac has posted something while I've been typing this up, which no doubt correlates to the below. However, hopefully, the 'interference' that has been in evidence this winter is waning, the SSW has played through the system and hopefully, the MJO, especially given the predicted amplitude of the P7-P8 transition can be maintained. Granted the GFS has been 'off the scale' which does look unlikely but that aside it still looks a reasonable amplitude. The AAM remains very +ve indeed, the tendency of significance too and, in association (perhaps) with the S Am +MT the GWO plot has swung back towards P5 and will then, likely, transition towards P6-7 looking ahead. The MJO plots and composites below... IMO, the result of all of this is a continued prediction of the risk of significant blocking patterns now through the final third of winter and, most likely, through into early March as well. March, in recent years, really has become an extension of winter (speaking from a UK perspective in particular) and I expect that to be the same this year as well. The MJO composites for P7 and P8 for February are significant, note the P7 does tally reasonably well with the outlook into next week with a Scandinavian block, or at least a block to the east. However, the combination of the AAM plus an MJO moving through into P8 could well support (finally!) a Greenland blocking scenario. This has clearly been missing this winter, despite predictions and one could argue, this will not play out again, it may well not, but, compared with the winter to date, we are now on a different playing field, for a number of reasons and, finally, the Canadian vortex is not running the show over the W and NW Atlantic either. So, keep a close eye on model output for possible retrogression towards Greenland over the next 7 to 14 days and beyond. The late February and early March period could well be very interesting indeed. Granted, it is a time when the suns 'strength' is increasing and a more potent air mass is required for any significant cold weather and snow, but that, I believe remains a sound possibility and March, or at least the first half of it, is highly unlikely to deliver an early spring weather and may well be in keeping with some of the previous March's over the last few years. I look forward to those with a greater understanding of the connections and links between the 'system' to hopefully review the winter into early March and certainly place more emphasis on why, perhaps, there may well have been some sort of 'stalemate'. Perhaps the wQBO dampened the SSW, allowing the main TPV to remain solid in certain parts of the upper latitudes. The tropical forcing (MJO etc ) didn't possess the 'energy', if that's the right word, to breach the TPV structure, the slow downwelling not helping either perhaps, but the disconnect this winter has certainly been there for all to see compared to what many thought and predicted was a possibility back in Dec and into early Jan. However, and finally, there can be some late winter connection and link-up between the MJO, AAM and the mid-lats looking ahead... Kind regards to all, Matt.
  13. As ever, some great posts in here and thanks to the usual few, especially @Isotherm for some more detailed information on what may have been the cause for some of the failings so far this winter. For now, I'll remain quietly optimistic, despite a sense of 'time is running out'. What this winter has shown, especially from a UK perspective is that, once again, even beyond day 5 and 6 there can often be significant changes to the forecast. That is one of the reasons being a meteorologist in the UK is both equally exciting and frustrating at the same time, it doesn't take a lot to change the conditions across the UK and NW Europe very quickly, as compared with a Continental climate, for example. Yes, it has been a frustrating winter and I still stand by the post I made a few weeks back regarding the likes of the AAM and the MJO and how they haven't come to fruition this winter, especially when compared to what was predicted at times, this needs close review, especially by those more experienced in that area. The residual vortex left over by the SSW over N Canada has, IMO, certainly been one of the biggest 'players' to bugger up the N Atlantic pattern, predicting where any vortices would end up after a split SSW is surely impossible at any lead time. The AAM remains significantly +ve and the GWO is currently in the highest amplitude phase 5 and 6 as it has been all winter, FT does, however, remain -ve. The MJO has certainly been a frustrating variable as well this winter, as highlighted by a set few, phase 6 for January could lead to the below pattern, the allusive Greenland high. The GWO in phase 6 would also support a significant blocking regime over the N Atlantic and Greenland, again the allusive -NAO that has been searched for all winter. Many could 'throw the towel in' now given what has evolved this winter but, again, if 7 days is, at times, long range then who really knows what will develop through the rest of February and perhaps even into early March as well. IMO, there's no evidence to support a full-on zonal regime across the N Atlantic to end winter, meaning NW Europe will be dogged by a mild, wet and windy end. While the E'ly late last Feb and into early Mar was clearly an extreme for the UK it does highlight that cold synoptics can still deliver winter weather even in the UK later in the winter period, March 2013 was another example. Clearly, the SSW evolution different this year, another 'wildcard' IMO as well this has been, especially regarding the downwelling saga! It'll be interesting to read everyone's thoughts and reviews on this winter come March and beyond. It is definitely a winter a lot can be learned, sometimes when forecasts and predictions go array it can actually be a good thing moving forward, but, at times, the weather most certainly has given everyone the middle finger this winter, perhaps more so than was thought possible. Mother Nature hey, despite the science, the technology and the understanding, it still does what it wants to do no matter what...but that's both the exciting and frustrating aspect of meteorology and forecasting. Kind regards, best wishes, Matt.
  14. Are we 'struggling' for amplification once again?... Just one piece of the 'puzzle', I know, but yet again we seem to be struggling to get the AAM into a higher phase... The tendency seems to be on the way down as well, despite AAM remaining near +2SD. Clearly many pieces to the puzzle here, but what does stand out this winter, is the inability to be able to fully know what kind of downwelling will occur from an SSW to start with. Quick response or slow response, from my experience the latter, as we have now, is usually more associated with a displacement of the vortex, while a split, as we have had this winter more often than not leads to a quicker response, clearly not the case this year. A crude analogy but it's sort of like waiting for a late train, you know it'll arrive eventually, but knowing exactly when can lead to a frustrating and uncertain wait. Getting an SSW is one thing, but the slow downwelling this season has been noteworthy and important IMO. Equally, while not completely teleconnection related, but what myself and many others in met acknowledge as a primary 'stone in the shoe' for the UK winter is the Canadian vortex left over by the split. As usual, where any residual vortices end up is near impossible to predict, but without question that feature maintains low heights, deep cold and continues to provide a pronounced baroclinic environment within the W and NW Atlantic, ripe for cyclogenesis and this is surely not helping to get a -NAO regime. Just as the UK found out last week, the lack of amplification within the N Atlantic scuppered what looked to be a darn good chance of an E or NE'ly evolution. This remains a persist aspect of the short, medium and longer term forecasts at the moment IMO. The EC Monthly(Weeklies) has been very poor, especially regarding the signal for Greenland blocking and, overall, a -NAO regime, the cause is unknown really, but there are many aspects to this winter which are an unknown now. It'll be interesting to see if there is a rapid increase in MSLP towards the Greenland region with a more pronounced -NAO regime, especially given some recent pieces of info in this thread. -AO is one thing, but the NAO is certainly another. I'm now to be convinced this season, but time will tell as ever, and, like many aspects of meteorology and the weather despite the best minds, the weather can often do as it pleases, whether that matches predictions from a multitude of sources. Great posts of late, by the way, thanks for those continuing to take the time to post... Regards.
  15. Just quickly drop this in here, I used it on Twitter, RE: AAM developments and GWO, hopefully, the amplification finally makes an appearance this time around...
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