Winter 2023/24 - A Post Mortem

[Metwatch]

 Derecho

Perhaps it would be better to compare the MJO analogues with ENSO state taken into consideration as well? i've linked them below:

Tabelle MJO - MeteoNetwork

WWW.METEONETWORK.IT

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Tabelle MJO

 

[Derecho]

 Metwatch I have to some extent, the years in which there was an El Nino I showed the El Nino composite (January 1987 for example)

[Nick F]

 Tamara i haven't debunked GDSM and I have no issue of you and others passion and in depth explanantions of how it may affect weather patterns, but I do think it's used too much in isolation to make predictions at the expense of the caveats that other drivers are also driving the patterns.

I'm sure the reactions from some of the more defensive replies I've seen on this forum would be different if we met face to face rather than online in front of a screen. Spent many a joyous time with Chinomaniac and Lorenzo sharing stuff on storm forecasting and listening to them with their knowledge of the strat face to face on storm chases and other meet ups, plenty of constructive debate. Also Thundery Wintry Showers, Blessed Weather plus others I've met in real life and had some great conversations. 

The web makes too many invincible, confrontational, rude, aloof, defensive and generally behave differently when challenged than if they talked face to face.

 

 

Edited February 10 by Paul

[Catacol]

3 hours ago, Nick F said:

I don't doubt that GDSM has It's place, but many of your posts seem mostly centred on the evolution of AAM to make predictions and not talking about other drivers and persuading the reader to disregard model guidance. Then when patterns do not evolve how you suggest, there is no admittance by you why it didn't play out how you predicted.

I'm not sure that's accurate Nick. Most of us look at the broad spectrum of drivers, as much as it is possible to make sense of the unique combinations that arrive every year and try and untangle them. GDSM is a representation of more than just one element - I still count myself a novice in its use, but it certainly includes the progression of the MJO, spikes or crashes in mountain torque (especially the impact of EAMT on the pacific jet and how that affects us downstream), frictional torque and its impact on the overall budget and the gradient of progression itself. You have been around long enough to remember GP using some of this in his forecasting methodology before he disappeared. And then, more recently, many of us talk about the stratosphere....still a riddle all of its own to be sorted out, and we discuss ocean temperatures and the role of the QBO, ozone transport via the B-D circulation (though we havent mentioned ozone much this year) and often solar stimulation of the jet, especially at maximum and the reverse at minimum. I think your suggestion that those using GSDM factors in their prognosis are ignoring all the others is a stretch.

Model guidance is an interesting one. We follow it. We watch it change frequently. We watch Glosea be correct and then incorrect. We watch the EC weeklies lead us up and down the garden path. I dont think anyone would argue we should ignore it - but I think old hands know it can often be wrong, and it is in itself a physics calculation that is taking on board all (?? - I often wonder if it is "all") the factors that get discussed by us. Does NWP factor in solar impacts? Hmmm. Many of us remember Dec 2012 with horror. I believe in the end it was decided that NWP went completely upside down at very short range back then because of a sudden increase in solar activity. So....if that is the case then are we wrong to argue that NWP does not have the perfect crystal ball? I dont think so. Surely a huge part of the fun is to try and out-interpret the physics based modelling, not least because we know it is often wrong!! And how far in advance did NWP spot the strat split and BFTE in 2018? I think many of us were a step ahead of the modelling back then and we watched it fall gradually into line. I have no problem stating that NWP is not the be all and end all - precisely because it isnt.

Do we admit failures? I guess it depends who you are pointing the finger at here, and probably best not to get into that. I think there are more figures on the mod thread that make unreasoned assertions as to what is going to happen who - when they are off target - just disappear...than there are those who set out a reasoned analysis who then do tend to come back and account for what has turned turtle. 

There's a lot of frustration right now - hardly surprising. Let's not bin any of the science though - and let's not get into a witch hunt. We like to think that CC might not be the biggest teleconnective driver of all and that we can hark back with optimism to 1947 and 1963 and 1979 and 1985 etc etc - but in truth we probably cant....and the pattern matchers will fall foul of this more than any others and we just have to accept that it is going to get harder and harder for the UK to get a properly frigid cold spell than it ever was 40 years ago. But let's not believe that we lack the tools to predict the next great cold spell. We are sharpening them nicely I think, and someone in the future using a particular predictive combination (including GSDM analysis) is set for cult status at some point! 

Edited February 10 by Catacol

[Catacol]

19 minutes ago, Nick F said:

The web makes too many invincible, confrontational, rude, aloof, defensive and generally behave differently when challenged than if they talked face to face.

On that we can agree! I'd happily bin aspects of internet comms - I think for all the benefits in communication it has made the quality of our lives much worse overall. When I retire, whenever that will be, I swear I will check my inbox no more than once a week.

Face to face always best. Never ever manage by email, message, text or platform. I was advised that way many years ago by a wise sage, and they were spot on.

[johncam]

Not being an expert but have followed the weather for 50 years. fFor all the latest science it's still an inexact art and probably will always be no matter what the latest super computer says. Still enjoy reading all the different view points. I don't believe anyone is right or wrong as the weather will always do its own thing no mater what we want. Have a great weekend everyone.

[stodge]

Evening all

I yield to the greater knowledge of many on here. 

Early musings - I’m not a fan of Wave 1 warmings from Siberia as they serve only to knock the PV over to NE Canada/Greenland. Once the stratosphere and troposphere couple we have to wait for there to be enough strength to completely disrupt the PV and hope the tropospheric response is both quick and favourable.

I suspect the recent tendency toward early and later cold spells while the traditional midwinter is Atlantic dominated is part of this. Could it be the Hadley Cell expanding north? I don’t rule it out but that would mitigate against hotter summers if we are looking in July for the trough to dip to the Azores and pull up a Plume?

On a complete tangent, the long term evolution of the European climate, in my view, is toward something like the present day Indian Sub Continent.

Back to this winter, we have also once again learned the lesson eye candy is nice to look at but too much of it makes you sick. How often in truth have the nirvana winter charts got to T+96 or T+120 which is where “reliable” kicks in. I suspect if we only had charts, models and forecasts which went, pace UKM, to T+144 we’d have been less emotionally invested in cold spells which proved to be a chimera.

I also want to mention the demise of fog - how many foggy days have there been this winter? A warmer atmosphere would suggest more energy, more movement and more volatility and in time more cloud. The synoptic evolutions toward cold require the atmosphere to slow down and lose energy - even if we can get the right synoptics they don’t last. What we call “cold zonality” where PM air dominates is a more sustainable winter pattern nowadays than getting an anticyclone to sit over us for days creating inversion.

[raz.org.rain]

33 minutes ago, Nick F said:

The web makes too many invincible, confrontational, rude, aloof, defensive and generally behave differently when challenged than if they talked face to face.

 

Very true, sadly... for the entire community. I won't act like a saint as I've not always behaved in the best of ways, but I like to think I learn from those mistakes rather than continue to be rude and will apologise when asked to. I find it just detracts from the overall enjoyment of engaging with the community to continue to be antagonistic when not necessary.

 

I wasn't too keen on partaking with the model thread at the height of its prime for a variety of reasons. Part of the reason was that my insight wasn't even close to being on the level of those who clearly did a lot of research with their findings, their commitment is great. My methods of analysis just don't compare.
 

I think it's good to remember that we're all here with a shared enthusiasm for the weather, whether or not it's the same kind of weather. For every unexpected outcome, we can learn and enhance our method with the next approach.

[WYorksWeather]

Probably a bit early at least for me for a true post-mortem of this winter. I am using a cut-off of meteorological winter for this - if we do get a cold spell in March I'd consider it out of scope.

But a quick contribution from me on the subject of forecasting. My general view is that the teleconnections, MJO / wind flows, past analogues and other such things are useful, but only up to a point. They should be viewed as a probabilistic adjustment to longer range output. In other words, an MJO favourable to blocking probably increases the chance of significant cold spells in the UK, but this should be considered in the context of the background chance.

In other words, in the past, we might expect say in the 80s and earlier maybe one in every three to five winters to bring a memorable cold spell. Favourable patterns might have raised that significantly, to more like a 50-50 chance. However, the background chance is ever falling due to CC, so probably the background chance is now around 10% perhaps, maybe lower, so even favourable patterns mean that you'd still bet against significant cold.

One of the notable factors about this winter is that even if you ignore the synoptic effects of CC (Iberian heights etc.), just by fractionally changing temperatures you would change a lot. If we lowered the temperature of our cold spells by 1-2C this winter, that would have given me a fair bit of lying snow in early December, a very notable deep freeze in January (albeit snowless), and probably have meant that the Thursday just gone would have been quite a significant event instead of marginality and slush that only lasted a few hours. So at least for Northern England I think absent CC this would have been at least an adequate winter for cold and snow if not a particularly brilliant one.

I think the default for winters is increasingly an extended autumn / early spring type pattern. Decembers have warmed significantly, and Februaries are just ridiculous, with my favourite fun fact being that if you take the last 10 Februaries, they average 5.7C, which is equal to the 1961-1990 CET average... for March. In all but name, February is part of spring now as much as March was in the 60s, 70s and 80s, and December is heading the same way in terms of being part of autumn. Of course, there are limits as to how long January will remain immune from these trends - we're overdue a very mild one at this stage.

In short, I think CC can throw an enormous spanner in the works these days, and that any predictions of cold have to be seen in terms of how tough a barrier it is to get any significant and prolonged cold in. The last prolonged cold spell the like of those in the past (say a two week spell significantly below 1961-1990 averages) was the first half of December 2022. They're becoming rare beasts.

I have no doubt that even in an increasingly mild context for UK winters we will still see the occasional exception that brings widespread cold and snow, just as Scandinavia has seen this winter with one of their coldest winters for many years. However, autumnal Decembers and spring-like Februaries will become much more common, and we will see many more mild records broken in the years ahead.

Probably better to leave a full post-mortem for exactly what happened this winter until it's over, or nearly over (probably when day 7-10 takes us to the end of February).

[Weather-history]

 MattH

Matt, thanks for your contributions, they are much welcomed.

Are you though disappointed given what the signals were suggesting, how it has turned out? Its mid February now and yes we can still have wintry weather in March but the meteorological winter is drawing to a close.

[carinthian]

Morning all. Yes, its been hard going this winter. Even as I speak its raining at 1450m. Our Central European Forecasting Agency have been frustrated about how the longer range signals have failed to deliver any meaningful cold to much of Europe so far. Has been an easy forecast for them for the past 6 weeks ( just relentless Sub - Tropical Air flows ) feed around the persistent high ridging from the SW. This appears to be one of the reasons why it has been curtains for any real cold air to last across much of Europe ( apart from Northern Scotland and Nordic Countries ). Currently in many parts of Austria there is no snow lying at below 1000m. I think most high level resorts are still relying on the heavy snowfall base from early in the season but even here the freezing levels are struggling at 2000m. We need snow soon or winter season will be busted. Again, the longer term models this morning provide a bit of hope to rescue winter. Another false dawn ?

C

[Weather-history]

Look at this chart from 9th January 1977, the winter up to then had been cold.

 

The SSW strikes  around this date and the winter then goes belly-up for the UK and turns into a mild,  wet affair.  It was the mildest February for 10 years for the CET and one of the wettest on record for the EWP

 

Did the stratospheric warming in January stitch this winter up?

[North-Easterly Blast]

 Weather-history The winter of 1976-77 in some ways followed a similar pattern to 1981-82, a cold December (though less so than in 1981), and a cold first half of January (though in 1977 it was cold up to about the 20th), then a milder rest of the winter.  Though you are not quite correct about February 1977 being the mildest for the CET for ten years at the time, as it was slightly cooler than Feb 1974.

You are correct in that a SSW does not guarantee cold for the UK, as our luck is then if the northern blocking sets up favourably to influence the UK with airflows from a cold source, as the dice still has to land favourably for us in the UK.  In the same way that a SSW does not guarantee cold for the UK, it does not guarantee not bumping the UK out of a cold spell either, as blocking may then reassert itself in an unfavourable position for us.  One recent example is that we did get a potent cold spell in early February 2021 (and it looked promising for a cold month), but it went belly up after the 14th and turned the UK very mild (February 2021 then did the same as Feb 2009, 2012, in seeing a very mild second half after a notable cold spell earlier in the month).

[jules216]

 Nick F Its actually quite simple. Its easy to follow GSDM on Victor Gensini website and it takes about a week to realize that even the GLAAM/GWO forecasts are as prone to get IT wrong as numerical models like GFS day 16 lol. When I followed the GWO graph it went from high AMP. Phase 7 to almost COD in a space of few days. So here you are, you Can be expert user im torques etc. but it requires also fórecasting accurately the Global winds/precipitation etc. If we cant forecast weather over 6 days ahead in general how come some think that tropical weather forecast post day 14 will be accurate. If people understand this that IT would be so múch more easier. i Remember post by Tamara in January where She was quite bullish about more favorable blocking in high lats. Taken look at Gensini GWO samé day and it was indeed showing big amplitude Nino atractor Phase 5-7, but in 2 days time IT vahished in amplitude and barely did 4-6 low amp. So there you are. And here lies the difference when using the right analogs, because they did show you what route did the MJO etc. took the same time in dáte and you seen that IT struggles and collapsed ať Phase 7 etc. Look example od analóg 2006/07 then MJO collapsed near Phase 7 in January. Look at the outcome in February vs this year. amazing isnt it?  Very good east based EL Nino analog. I Can name many occasions this worked very much flawless and with no need to get a degree or doctorate in understanding GSDM as its a tool usefull when forecast turns out already 15+ days, and when does it happen?

[Met4Cast]

36 minutes ago, jules216 said:

ts actually quite simple. Its easy to follow GSDM on Victor Gensini website and it takes about a week to realize that even the GLAAM/GWO forecasts are as prone to get IT wrong as numerical models like GFS day 16 lol. When I followed the GWO graph it went from high AMP. Phase 7 to almost COD in a space of few days.

Those CFS forecasts are completely useless, I can't say I ever look at them beyond mild curiosity, I certainly don't factor what they show into my predictions within the GSDM space. 

The (almost) real time plots produced by David Gold are more useful in determining the broader direction of travel, there's typically a 14-20 lag between initiation & pattern changes so it's often more useful to see what's happening *now* vs what might happen in the future re: AAM. For example, we have seen and are continuing to see subtle equatorward fluxing of both +ve and -ve AAM anomalies, this generally favours stronger Iberian/S European heights and indeed that's what we're seeing represented quite well within broader NWP modelling, despite on the face of it a favourable MJO for blocking and despite the fact we remain in a high GWO orbit. This is the reverse of what we saw through December with anomalies instead fluxing poleward reaching the realisation with the blocking early-mid January.

Worth noting though that the polar field is very important to factor in as well, the stratosphere can dominate or disrupt expected patterns at relatively short notice that no amount of applying the GSDM or various other teleconnections can help with, the mid-late January period was a good example of this, that SSW reshuffled the trop pattern and sent energy from the Canadian vortex eastwards across the Atlantic sector, instead of the blocking that had been expected we saw the pattern flatten & a stormier, milder period of weather ensue, as Tamara said "expect the unexpected".

Indeed the opposite was true for the December cold spell, broadly the GSDM was not in favour of blocking but the jet stream hitting road blocks as it crossed the Atlantic allowed for blocking to amplify, so, it’s not perfect by any sense of the imagination but it can and absolutely does provide context to NWP modelling and give a much broader picture of what’s driving our weather.

More often than not, the direction of travel re: AAM tendency is more important than the aggregated total AAM in the atmosphere. But, perhaps this isn't the right thread for this kind of discussion re: future forecasts and is better left in the Mod thread, just wanted to perhaps add some context for those reading the thread and wish to learn. 

This isn't some "elitist cult" and I'd be more than happy to help anyone wishing to learn more about this, just as @Tamara has often very kindly and patiently helped me, though admittedly I'm still very much a novice.

Edited February 11 by Met4Cast

[jules216]

  Met4Cast you have just said what I echoed too,broascale changes in polar field, SSW etc. How come I didnt need to be expert in GSDM field yet I managed to see in advance a SSW that would re-shuffle the good synoptics. I even mentioned it in models thread way in advance. Very similar f.ucked up SSW happened in January 2007,2015 etc. How come All the tools/people/mets/UKMo hot it wrong big time even though they scrutinize GSDM or incorporate it in their algoritm? Magic

[jules216]

 Met4Cast look at this from 15.1 referencing 2006/07 etc. It was ať tíme all were very bullish about February. I knew way before then how will it Evolve, how is IT a coincidence? This is not first time believe me, I occasionaly post when I see it being suitable in models over the past 1-2 years. Dont Remember when was I really wrong. i Can look All Up but dont know its necessary to bother.

[daz_4]

February so far is tracking 7-8C above average here in Central Europe. Instead of backloaded winter we have April. Min. temp today was 11C which is quite crazy. Maybe we will have a cooldown later in the month but the damage is already done as the warm weather will continue for at least another week. Few warm days in March and the trees will start to bloom for sure only to be scorched by frost later in the spring. The script remains the same no matter the state of ENSO, QBO and who knows what else.

[Derecho]

It looks like we are heading for a Feb 1998 / 2019 type month where instead of the usual backloaded El Nino winter we are getting a blocked pattern that we are stuck on the wrong side of. Looking at the anomalies this week indicates there is blocking around in the NH but Europe is acting as a road block. Interestingly Feb 1998 also saw a cold NE Europe. The problem this time is that high pressure is nowhere near as expansive so whilst still mild it is unsettled instead.

Looking at the Feb CET as it stands it is a remarkable 7.9C to the 10th despite that brief colder interlude in the middle of last week. Based on the 06z GFS it could be at 8.0C so the 1779 record may be under threat...

[North-Easterly Blast]

March can have its wintry moments as well - even last year it did turn cold at times during the first half of March, after there had been limited cold in February and even January had not a lot of cold in it either.  Having said that, March last year still ended up above average for the CET.

 

  Derecho  I am not sure what you mean by backloaded El Nino winters?  Apart from 1982-83, I cannot think of any other backloaded winter in an El Nino year - although the second half of winter 2015-16 was nowhere near as mild as the early part of that winter but it still was not cold.  

 

Edited February 11 by North-Easterly Blast

[northwestsnow]

Imagine if we forward 50 years ( I for one won't be here ) and people talk about this current winter as frigid !!

Scary ..

[Derecho]

 North-Easterly Blast There have been some in the past but it's not a clear link. Past observations suggest that Decembers have a distinct +NAO whilst Januaries and Februaries are often more blocked. So Januaries and Februaries tend to fare better. Looking at all the El Nino's since 1870 using the Multivariate ENSO index: 

 

Over half appear to be backloaded whilst the others are mixed. The NAO in a December is often more positive (see table above) in an El Nino which is where the notion of 'backloaded' comes from. Often the worst synoptics of an El Nino winter come in December.

The reverse is true for La Nina's. December 2010 and 2022 are good examples of cold Decembers followed by mild February's. So there is some link but other factors are of course at play. 

  

Edited February 11 by Derecho

[jules216]

 Derecho yes I mentioned 1998 as good analóg too. I have forward referenced it to possibly interesting analóg blend fór next winter 1998/99 and 2007/08 or 2016/17 here in central Europe. The provisional idea is for very little drought worry spring/summer then dry pattern setting Up in autumn. And later the cold building from the east/western Russia next winter. This is general idea going forward this year and Beyond. May looks particullary wet here in central Europe.

[North-Easterly Blast]

 Derecho If you or anyone says that La Nina winters are front loaded, then apart from 2010-11 and to a lesser extent 2022-23 (the latter was also a weak one), I cannot think of any other clear front loaded La Nina UK winters, though that said in 1999-2000 the February was milder than the earlier part of the winter, although even then the early part of that winter was actually not that cold.

 

Edited February 11 by North-Easterly Blast

[Derecho]

 North-Easterly Blast Disagree, in fact the NAO signal during La Nina phases is actually stronger. According to the multivariate ENSO index the La Nina of 2022 was also pretty strong.

As I said it's not fully clear but you'd expect that given Europe is far away from the ENSO region but ENSO does affect wider atmospheric circulation patterns and this has been in the scientific literature for some time now.

What is also worth adding that isn't considered in this list is the type of La Nina ENSO event that takes place. El Nino Modoki events and eastern based La Nina's tend to be best.

Edited February 11 by Derecho