Catacol

One gentle addition to this phrase - I would be interested to see if anyone can find a cold spell from the modern archives we have access to that was not aligned with background forcings. I would agree that such forcings do not always come up trumps. But I am not aware of a spell we have had, when we have data we can look at, where that spell came out of nowhere and in contradiction to what the drivers were indicating. In other words...snow doesn't always lead to the building of a snowman. But without snow there can be no snowman.....

It's definitely a factor and the one factor that I think was pointing in clearly the wrong direction going into the winter. As I have come to see it, high solar activity whips up the jet. Low solar leads to a less active jet. There are papers on it now, and I remember way back in the early days when it was rubbished by many including (from memory) the MetO and then, lo and behold, some proper research conducted and the above conclusion very broadly reached. We are not at solar minimum, but the hope is that one signal on its own will not drown out all the others. When we get to the end of the season I wonder where we will be on our ENSO analysis. Strong at the start of the season, predicted to wane to moderate by season's end. Part of the back loaded call was linked to ENSO. If Nino stays strong under a similarly strong solar umbrella than the outcome could be grim!

"Sometimes"? Hehe - I'd turn that to "often" or maybe "usually." Even when the macro patterns are nailed, we are such a small island that tiny alterations can make a big difference. And at the eastern edge of the north atlantic those micro patterns can be a nightmare to pin down. I do not know the data, but I rather suspect that weather forecasting in the UK is one of the hardest parts of the globe to pin down with certainty. The potential for dominant long draw south westerlies because of the Hadley Cell and our position in latitude is always there - but at the same time a burst of momentum and a significant wave eddy can create an easterly draw that suddenly pulls in bitter continental air. We truly have a variable package. I think I'd like to say at this point that, for all the problems in getting a pattern accurate, we shouldn't stop trying. This is a model watching thread so all forms of model related output are fair game but I also hope that, no matter how frustrating it can be, there will continue to be a place for those who try to anticipate what may appear in the models, predict when perhaps the models are barking up the wrong tree, and provide some kind of analysis of that. It is true that, over the years, this site/thread has had favourite topics to explain failure or misery. We had a season when all the talk was of the IOD. We have had multiple seasons where solar has been a focus - interestingly very little about this in 2023 so far. But in the end these are all chapters in a growing book of knowledge, a book albeit undermined by CC and significant climate challenges both now and in the future, but a knowledge compendium nonetheless. And for nearly everyone on this site it is a hobby. A few have gone on to make a living out of it - GP did and I think Matt also these days...but as a hobby people need to know that time is finite and we cannot be experts. If I could put as much time into my winter weather passion every day as I have to put into my real job then maybe expertise might follow....but at best we are amateur to semi pro in status. Anyway....it does look as though Xmas now will be fairly unremarkable. There is a hint still that things may change in the run up to New Year. Beyond that we have events in the strat followed by the next passage of the pacific wave to look forward to. And if 2023/24 goes into the bin then there is always 2024/25. A never ending diet of mouth watering excitement. And for all the frustration at not actually landing a proper, frigid, minimum one week belter of a snow context much of the fun is in the foreplay.

Both ECM and GFS are seeing something shifting just after Xmas. Heights emerging to the north. This is our best case scenario as the reality of the pacific wave combined with expected momentum increase creates a context more conducive to blocking. More time needed to see whether there is sufficient oomph in the signal to force a change but some grounds for optimism tonight, on the back of a bullish CPC report. Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4979836

Curse my wobbly moment earlier today, data updating in style this evening. Always stick to your instinctive guns. Significantly increased amplitude of MJO passage on the ECM tonight - a short dip into low amplitude, but a really quite strong progression out into phase 1. If this forecast is right then my punt earlier will be correct - actual passage somewhere between the very weak early ECM and the very bullish BOM. GEFS following suit GLAAM meanwhile on the rise as expected and total AAM approaching as high as it got in November with more to come. US daytime updates have really come good tonight UK time. No surprise at all that NWP is flirting with alternative solutions in just over a week. I think this will continue and upgrades are on the way. Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4979863

Curse my wobbly moment earlier today, data updating in style this evening. Always stick to your instinctive guns. Significantly increased amplitude of MJO passage on the ECM tonight - a short dip into low amplitude, but a really quite strong progression out into phase 1. If this forecast is right then my punt earlier will be correct - actual passage somewhere between the very weak early ECM and the very bullish BOM. GEFS following suit GLAAM meanwhile on the rise as expected and total AAM approaching as high as it got in November with more to come. US daytime updates have really come good tonight UK time. No surprise at all that NWP is flirting with alternative solutions in just over a week. I think this will continue and upgrades are on the way.

Well - I'll put the towel away for now. The hope that we would see an active MJO progression remains - experts at the CPC have concluded that "• The MJO remains active, with the enhanced convective phase now over the Pacific, where it is constructively interfering with the El Niño base state. • A strong westerly wind burst event is developing over the equatorial Pacific near the Date Line in response to the MJO-related enhancement. • Easterly (westerly) anomalies propagated across the Pacific (Western Hemisphere and the Indian Ocean), consistent with MJO activity. • A strong Pacific jet is consistent with the El Niño response." There is enough here for me to maintain my optimistic sense that the models have not been spotting MJO activity accurately at all. It may be, in time, we find that the true amplitude sits somewhere between the pessimistic ECM and optimistic BOM solutions, but time will tell on that. The same report sees a very swift next cycle ahead, the wave back in the IO by New Year. Even if we don't get a block out of the current pattern around New Year, enhanced by a predicted spike in momentum, this offers the possibility of a swifter than average return to the Pacific in time to hope that January can see a renewed opportunity before month's end separate to anything happening in the strat. So - things are tough at the moment in terms of op and ensemble model watching, but I guess we keep the faith a little longer! And since when was snow hunting ever easy. We will fail far more times than we succeed given our location at the wrong end of a large, warm ocean - but hope springs eternal, evidenced by infrequent events of significance. Ding ding....round 3. Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4979736

Both ECM and GFS are seeing something shifting just after Xmas. Heights emerging to the north. This is our best case scenario as the reality of the pacific wave combined with expected momentum increase creates a context more conducive to blocking. More time needed to see whether there is sufficient oomph in the signal to force a change but some grounds for optimism tonight, on the back of a bullish CPC report.

Ah!! - awesome. BOM to the rescue. Thanks Sebastiaan.

Well - I'll put the towel away for now. The hope that we would see an active MJO progression remains - experts at the CPC have concluded that "• The MJO remains active, with the enhanced convective phase now over the Pacific, where it is constructively interfering with the El Niño base state. • A strong westerly wind burst event is developing over the equatorial Pacific near the Date Line in response to the MJO-related enhancement. • Easterly (westerly) anomalies propagated across the Pacific (Western Hemisphere and the Indian Ocean), consistent with MJO activity. • A strong Pacific jet is consistent with the El Niño response." There is enough here for me to maintain my optimistic sense that the models have not been spotting MJO activity accurately at all. It may be, in time, we find that the true amplitude sits somewhere between the pessimistic ECM and optimistic BOM solutions, but time will tell on that. The same report sees a very swift next cycle ahead, the wave back in the IO by New Year. Even if we don't get a block out of the current pattern around New Year, enhanced by a predicted spike in momentum, this offers the possibility of a swifter than average return to the Pacific in time to hope that January can see a renewed opportunity before month's end separate to anything happening in the strat. So - things are tough at the moment in terms of op and ensemble model watching, but I guess we keep the faith a little longer! And since when was snow hunting ever easy. We will fail far more times than we succeed given our location at the wrong end of a large, warm ocean - but hope springs eternal, evidenced by infrequent events of significance. Ding ding....round 3.

Try here - JMA gathered some overall data.... but composites across months with variable amplitude and different background factors eg ENSO are certainly not gospel! MJO DS.DATA.JMA.GO.JP

Except it didn't in November when the IOD was even stronger. There are layers within layers going on here that I think are not understood. I messaged Eric Webb recently to get his thoughts on the MJO passage and pacific situation and he didn't come back. Why would he? 2 reasons. He couldn't be bothered to reply to one of many turgid requests. No issue with that tbh. We all get too many messages. Or...and I put my request relatively cogently I think, he is not prepared to take a stab at what impacts on such a variable forecast of pacific conditions, so important for sub tropical windflows and patterns, because even he is vague on it. I note he works a lot off ensembles. I wish there was a coherent archive of pacific patterns going back as many years as we now have synoptic charts. Does anyone know of an MJO archive anywhere? I'd love to see whether my sense of failed cycles at crucial points of the core winter season has any basis in fact or whether I'm seeing things. I'd also love to get some statistical data on the link between phases and blocking or westerly patterns. I know we have the composite charts, but they are averages. And without the MJO data it is difficult to get setups to analyse. I want to be able to pull up a Hovmoller, RMM or something similar and sit it against a northern hemisphere synoptic chart at 1, 2 and 3 week lags and do some old fashioned police work!

I can't think of much that can theoretically override a high amplitude MJO signal in all honesty - a strong, coupled vortex working top down would see it off....that's not what we have at the moment. Vortex is weakening. Phases 2 - 5 are poor for us, so if the MJO progresses as fast as ECM has it progressing today towards phase 2 then our goose is cooked. I am awaiting today's CPC assessment on the MJO before making any rash calls, but I have to admit that the white towel is sat on my lap. Even with a spike in momentum which I do think we will get shortly, a COD phase of 7/8/1 as poor as ECM is modelling it - and BOM has pretty much come into line on amplitude also - would spell the end of any hope of the kick we need to get a block at higher latitude. This would leave us with a mid lat context at best, preventing any flux from stabbing towards the arctic to disrupt things there and also reducing the chances of anything like a significant wave break to provide that block. Sadly I have spent the last few years fighting against my instincts, namely that the only way for the UK to see sustained and bitter cold in a warming world is for us to get a significant SSW, and probably a split SSW for maximum impacts. Over the last few years I have said this many times but decided to go into this year with a renewed sense of what the trop on its own could offer us. I remember swapping some messages with GP in the aftermath of the Dec 2012 fiasco and the failed torpedo: he was certainly beginning to reflect on the fact that the modern global setup was mitigating against patterns that were once more predictable in terms of response. The theory of pattern creation is increasingly being challenged by the observed reality. Any evidence for my instincts? The one that sticks is the increasing number of times that our coldest patterns are dropping into March, when impacts of a late winter strat warming are at their greatest. Increasingly, prior to March, how often are we seeing vortex-inspired westerly dominance with a northerly shunted Hadley Cell dominate Jan and Feb? Pretty much every year. We get the occasional coldish spell at the start of the season - indeed twice in 2 years now we have fallen lucky there....but once the core of "winter" arrives the pattern defaults to flat. If the CPC do not throw us a bone later then, for me, the trop impacts of the current wave become a fail, and that will mean the end of the first half of winter. We wont see a high lat block on the back of phase 2-5 progression. All eyes will literally turn to the stratosphere and the hope that we can get some joy from a proper warming. Chances there are still good. And we may also be lucky enough to be able to time the effects of this (2-4 week lag) with the next pacific wave....and that means February or late Jan at the absolute earliest. Perhaps the seasonal models were sniffing exactly this kind of potential when they were looking at a colder Feb - though, to be honest, my mind boggles as to how seasonal NWP runs in terms of a mathematical model. If we cant get NWP accurate at 7-10 days then how on earth does a seasonal model do it at lead times of 8-12 weeks....and surely if month 1 busts then all subsequent months bust!!! Anyway, sobering times. I am hoping my 3cm of snow at the start of the month that lasted half a day is not the last I see this season....but we may well be on the cusp of having to look way into the future at lagged impacts of a SSW. On the positive side, let no one forget the awesomeness that was Feb/Mar 2018. My favourite weather in the UK probably ever. That is what a SSW can do. Roll on the next example. Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4979253

I can't think of much that can theoretically override a high amplitude MJO signal in all honesty - a strong, coupled vortex working top down would see it off....that's not what we have at the moment. Vortex is weakening. Phases 2 - 5 are poor for us, so if the MJO progresses as fast as ECM has it progressing today towards phase 2 then our goose is cooked. I am awaiting today's CPC assessment on the MJO before making any rash calls, but I have to admit that the white towel is sat on my lap. Even with a spike in momentum which I do think we will get shortly, a COD phase of 7/8/1 as poor as ECM is modelling it - and BOM has pretty much come into line on amplitude also - would spell the end of any hope of the kick we need to get a block at higher latitude. This would leave us with a mid lat context at best, preventing any flux from stabbing towards the arctic to disrupt things there and also reducing the chances of anything like a significant wave break to provide that block. Sadly I have spent the last few years fighting against my instincts, namely that the only way for the UK to see sustained and bitter cold in a warming world is for us to get a significant SSW, and probably a split SSW for maximum impacts. Over the last few years I have said this many times but decided to go into this year with a renewed sense of what the trop on its own could offer us. I remember swapping some messages with GP in the aftermath of the Dec 2012 fiasco and the failed torpedo: he was certainly beginning to reflect on the fact that the modern global setup was mitigating against patterns that were once more predictable in terms of response. The theory of pattern creation is increasingly being challenged by the observed reality. Any evidence for my instincts? The one that sticks is the increasing number of times that our coldest patterns are dropping into March, when impacts of a late winter strat warming are at their greatest. Increasingly, prior to March, how often are we seeing vortex-inspired westerly dominance with a northerly shunted Hadley Cell dominate Jan and Feb? Pretty much every year. We get the occasional coldish spell at the start of the season - indeed twice in 2 years now we have fallen lucky there....but once the core of "winter" arrives the pattern defaults to flat. If the CPC do not throw us a bone later then, for me, the trop impacts of the current wave become a fail, and that will mean the end of the first half of winter. We wont see a high lat block on the back of phase 2-5 progression. All eyes will literally turn to the stratosphere and the hope that we can get some joy from a proper warming. Chances there are still good. And we may also be lucky enough to be able to time the effects of this (2-4 week lag) with the next pacific wave....and that means February or late Jan at the absolute earliest. Perhaps the seasonal models were sniffing exactly this kind of potential when they were looking at a colder Feb - though, to be honest, my mind boggles as to how seasonal NWP runs in terms of a mathematical model. If we cant get NWP accurate at 7-10 days then how on earth does a seasonal model do it at lead times of 8-12 weeks....and surely if month 1 busts then all subsequent months bust!!! Anyway, sobering times. I am hoping my 3cm of snow at the start of the month that lasted half a day is not the last I see this season....but we may well be on the cusp of having to look way into the future at lagged impacts of a SSW. On the positive side, let no one forget the awesomeness that was Feb/Mar 2018. My favourite weather in the UK probably ever. That is what a SSW can do. Roll on the next example.

ECM for the 22nd. 00z 13th 00z 14th 00z 15th 00z 16th 00z 17th I think to give this 9/10 is generous. The amplification within the atlantic sector is quite variable, and the latitude of the trough dropping towards the UK is also quite variable. Doing the same for the GFS reveals a similar inaccuracy/variability. Not 2/10 to 9/10 for sure.

An additional interpretation using vorticity charts. While the Canadian trough does indeed drop south it is not the instigator of the change - it is a consequence of it. What we have is a burst of momentum through the Atlantic and its peak strength on this chart is heading through the mid Atlantic - and such is the strength of that burst of energy that it starts to throw an eddy up ahead of it. That eddy is a ridge that then gathers strength thanks to energy to its south, and that same ridge is what then forces troughs to move. This is how ridges are thrown up to high latitude - they don’t just happen. It would be better if I could build a movie of these slides but I haven’t learned how. But you can run the sequence on tropical tidbits just by sliding the slider…. Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4978166

An additional interpretation using vorticity charts. While the Canadian trough does indeed drop south it is not the instigator of the change - it is a consequence of it. What we have is a burst of momentum through the Atlantic and its peak strength on this chart is heading through the mid Atlantic - and such is the strength of that burst of energy that it starts to throw an eddy up ahead of it. That eddy is a ridge that then gathers strength thanks to energy to its south, and that same ridge is what then forces troughs to move. This is how ridges are thrown up to high latitude - they don’t just happen. It would be better if I could build a movie of these slides but I haven’t learned how. But you can run the sequence on tropical tidbits just by sliding the slider….

Depends on how one sees patterns created. A lobe over Greenland will have no relevance at all if the long wave pattern is impacted by a spike in momentum enhanced by a significant torque/jet event. It’s one of those chicken and egg conversations - which is cause and which is effect….but for me the big drivers shift the pattern and everything else dances to that tune. Given the predicted huge spike in the pacific jet in the coming week a lag of around 1 week to see impacts in the Atlantic feels about right. The ECM 240h chart fits the bill as does GFS at around 192h though it then rather loses the plot I think. Will be interesting to see if this is picked up again in coming runs. If the MJO reorganises more completely than some NWP has suggested then this kind of development will be enhanced. I’m genuinely fascinated to see which of the models have this crucial 7/8/1 passage modelled most accurately.

Oooo now this is interesting. Signs of amplification at last?

Lots of fizz in here around Xmas charts - very tough call. I think, given the delay in forcings, if we end up with a snowy Xmas it will be 2 from 2 in the "best case scenario from marginal driver conditions". Happy days. Looking a little further over the horizon, good news this morning. Mountain torque that has been mentioned a few times recently is now on the up. ...and this will climb further when a substantial element of +EAMT arrives shortly. This is helping support a rising tendency in momentum, hoped/expected at around this time given Nino and decent MJO amplitude. GLAAM has now broken into positive territory as a result. It's a marginal breakthrough - but a breakthrough that fits the analysis and moves things in the right direction. At long last this is enabling the GWO to climb into the 5-8 Nino orbit, more conducive for cold blocking patterns in our part of the world. So....where next? Well - there has been some arguing on here about MJO orbit and amplitude. We will watch and wait....but I remain on the positive side of this debate particularly as the CPC - who are the real experts on this - are projecting a reorganisation of the pacific signal over the forthcoming period. With windflows now turning more Nino rather than Nina in shape, and a projected 7/8/1 MJO orbit we can continue to be optimistic about a block establishing itself in the right kind of place to pull cold air in. Timing uncertain as ever, but I'll stick with where I was before....namely that things have been delayed and therefore peak interest is now more on the New Year period rather than Xmas. If a cold NW can pull a short term blizzard over the UK in the meantime then so much the better (though bitter experience suggests to me it is likely to be so marginal, even if the synoptics line up, that most will not open their curtains to a white out! - hoping to be wrong of course....) Plenty going on. Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4977554

Lots of fizz in here around Xmas charts - very tough call. I think, given the delay in forcings, if we end up with a snowy Xmas it will be 2 from 2 in the "best case scenario from marginal driver conditions". Happy days. Looking a little further over the horizon, good news this morning. Mountain torque that has been mentioned a few times recently is now on the up. ...and this will climb further when a substantial element of +EAMT arrives shortly. This is helping support a rising tendency in momentum, hoped/expected at around this time given Nino and decent MJO amplitude. GLAAM has now broken into positive territory as a result. It's a marginal breakthrough - but a breakthrough that fits the analysis and moves things in the right direction. At long last this is enabling the GWO to climb into the 5-8 Nino orbit, more conducive for cold blocking patterns in our part of the world. So....where next? Well - there has been some arguing on here about MJO orbit and amplitude. We will watch and wait....but I remain on the positive side of this debate particularly as the CPC - who are the real experts on this - are projecting a reorganisation of the pacific signal over the forthcoming period. With windflows now turning more Nino rather than Nina in shape, and a projected 7/8/1 MJO orbit we can continue to be optimistic about a block establishing itself in the right kind of place to pull cold air in. Timing uncertain as ever, but I'll stick with where I was before....namely that things have been delayed and therefore peak interest is now more on the New Year period rather than Xmas. If a cold NW can pull a short term blizzard over the UK in the meantime then so much the better (though bitter experience suggests to me it is likely to be so marginal, even if the synoptics line up, that most will not open their curtains to a white out! - hoping to be wrong of course....) Plenty going on.

From publicly available sources: ECMWF budget for 2022/23 = £54.7m (member states) + £43.7m (Externals) + £12.9m (Data sales). Total = £111.3m Key facts and figures | ECMWF WWW.ECMWF.INT An overview of who we are can be found in the Who we are section. Below, we offer a breakdown of some of the essential facts relating to our work (as of August 2023). Bureau of Meterology (Australia) budget for 2022/23 = $345.5m (Govt funding) + $98.8m (Source income). Total = $443.3 Aus. Transparency Portal WWW.TRANSPARENCY.GOV.AU Transparency portal Now - this doesn't quite tell the whole story because ECMWF is purely focusing on computer modelling while the BOM is an agency with a much broader remit. There is nothing in public data to ascertain what % of their $443.3m is spent on modelling as opposed to other projects they undertake, but still it is a misrepresentation to claim that BOM is a small scale local operation compared to the giant that is ECMWF. And to deny the relevance of location is to deny the human condition. We are all more concerned with what is at our back door. BOM runs their MJO forecast twice daily. ECM once daily. Evidence, should you need it. Finally - the evidence on accuracy was carefully laid out in a previous post. I don't think anyone said BOM "will be more accurate" - instead the evidence shows that BOM comes second to ECM. In modelling the recent MJO phase 4 - 5 transition BOM outperformed ECM in forecasts provided at the end of November.

Really? I assume you are referring to the predicted. Through phases 4 and 5 BOM was more accurate than the others. Let's wait and see whether the phase 7/8/1 ends up being COD as ECM had it or more amplified as BOM predicted. Jury is still out there. What's odd to my eye at the moment is that the bias corrected ECM is reducing the amplitude of the op runs. That is weird. Reading up on this, the bias corrected is designed to try and cope with the inaccuracy of modelling through the MC where often the models under read the signal. To have ECM bias going down runs against that. By contrast BOM bias corrected is going the other way. An interesting mini case study while we wait for this holding period to end.

I think we are seeing the beginnings of a process that will end with an SSW. Statistically these things are almost impossible to forecast until within a 14 day window, and the outer edges of that 14 day window are looking significant. A stretched vortex impacted by wave 2 forcing looks to me like grounds for optimism for a split. Exciting times. Top down SSW impacts alongside ongoing possible pacific trop led impacts might serve up a tasty mid winter diet...

Wow - things must really be bad if you are throwing in the towel! Too much reliance in here on NWP output at 7 days plus. We have just hit phase 7. The interest in the current wave is therefore only just beginning and it is 14 December. +EAMT and AAM increase around the corner. Strat vortex shifting to Scandy or Russian side. Agree with the general conclusion in here that cold pre Xmas is now distant. Has been clear for a few days. But after that there is plenty of interest before we have to rebait the line with a fresh worm and cast out as far as the next cycle in February. Watch the MJO carefully. Watch AAM response to +torque. Follow strat vortex location, windspeeds and shape. Add on lag. Stay focused on the truth that the weather is not a random collection of swirls - it produces patterns that are the product of identifiable forcings. Timing remains the bugger. Responses appear to be slipping back…but that’s ok so long as those forcings remain in play.