Winter 2023/24 - A Post Mortem

[Snowyowl9]

 I remember Atlantic 252

Thats because childhood memories are the best,memory is a very strange thing..

Yes the 90s were good at times nothing exceptional only for unprecidendent wind storms and february 1991 for cold pooling..

We ve seen much more exceptional weather of all sorts since I joined this site back in july 2006..Many records broken cold deep snow heat floods the kitchen sink..

For me of course it would be the mid 80s..

As for the 70s those were hit and miss..I will say the 70s were not great..

Whatever happened here the cold dips so far to the west,I ve seen this many times but this is intense..

[Earthshine]

 Frigid Life in the UK really is relentless a winter supposedly posed to bring cold weather ended up almost seeing 20°C being reached in Scotland.  

[Met4Cast]

 Earthshine

I plan to go back through my own posts this winter & do a more in depth write up on what I said about the AAM/MJO & compare to what actually happened & then compare that with the weather outcomes when I get a bit of time. 

I’ll likely wait until winter is actually over though. 

[Penrith Snow]

It's probably down to higher SSTs but another negative aspect of recent winters are the luke warm northerlies which fail to deliver wintry conditions even in the North.

Look at this chart for February 1969, midday temperatures were below freezing from the Midlands North with -3c at Manchester airport and -7c at Aberdeen accompanied by a bitter North wind.

An area of heavy snow swept South on these bitter winds arriving in London during the early evening, by the following morning the whole of the UK was snow covered apart from a few areas near the south coast.

Such conditions now would have the media in melt down.

We can only dream.

Andy

[North-Easterly Blast]

 Penrith Snow January 2024 wasn't overly mild, it had a CET of 4.7, which is actually very close to the 1991-2020 average, although it would have been relatively mild by 1961-90 standards and earlier than that (51-80, 41-70 etc).

January 2024 wasn't in the 5*s club let alone the 6*s club, which would be notably mild for January, like 2020 was in recent years.

January 2024 looked promising for a colder month earlier on, especially with the fairly cold HP spell earlier on being followed by the cold northerly spell in mid-month, but it then all fell apart by the 20th and the chances of a below average month were then ruined by a very mild final third to the month, and the very mild final third of January has now just remained through the first half of February.

Any chances of this winter being cold were already ruined last September with how exceptionally warm it was.  It is a well known fact of the British weather patterns that anomalous warmth in September does not favour a colder winter to follow.  For a high September CET, it would mostly be the result of HP over Central Europe and largely stalling low pressure areas to the west of the UK.  This weather pattern in September does not favour the development of northern blocking, and northerly and easterly patterns over the UK during the following winter.

Another point about winter 2023-24 is that we are approaching solar maximum, so it is not a good solar match for cold.  Just after the last solar minimum, I feel that the UKs best opportunity since 2012-13 for a cold winter was in 2020-21, when we actually got close with the pattern to deliver a cold winter for the UK in 2020-21, as that winter had a good amount of northern blocking but unluckily, the low pressure in the Atlantic did not get far south enough to allow northerlies and easterlies from high latitudes to influence the UK for long periods of time, although in Scotland there were good cold spells at times.  At the last solar minimum, I always think of winter 2020-21 as being the year that the UK "missed the boat" for a cold winter.

It appears that for British winters, a strong ENSO anomaly either way, or a strong IOD anomaly, or anomalous warmth in the previous September, is a winter killer pattern for the devlopment of cold weather patterns in the UK.  Whenever any of these situations happen, I think that you can almost guarantee that colder winter weather is already "dead in the water" before the winter even starts.

If I were a betting man I would put money on the UK never again seeing a cold winter after an anomalously warm September, and that anomalous warmth in September are, and always will always be a winter killer pattern for the UK.

[Penrith Snow]

 North-Easterly Blast  Good analysis, despite its limitations I prefer historical pattern matching to MJO naval gazing but that's just my opinion.

Andy

[Tamara]

I echo the words of @MattH  And no, there is nothing unreasonable in he what said at all. 

I have lost count of the number of times that I have tried to implore that the MJO is only one part of the total components that make up the "global wind-flow budget". This sounds a fancy term no doubt to the naysayers piling into threads like this in a queue to use it as a scapegoat for their snow being stolen, but if the atmospheric circulation is considered as the vacuum that it is, then it is not difficult to envisage that to maintain its parity, wind-flow that decelerates in one part, has to be compensated in another.

And vice versa when acceleration occurs in one part, there has to be equal compensation in another to maintain parity.

Angular momentum refers to the turning force (torque) exhibited where convergence, or divergence meet as inflection points to create that turning force on the jet stream. When decelerating wind-flow exceeds +ve momentum, then there is a greater requirement for more and more flow to be sucked back into the void that is left. This is represented by a -ve torque mechanism.

The converse again holds true to produce a +ve torque mechanism

The MJO represents wind-flow & momentum changes in the tropics. As part of Mother Nature's natural vacuum, it is necessary to consider the rest of the atmospheric circulation system in the extra tropics and top layers when catalysts for change of wind-flow begins in the tropics c/o MJO related forcing.    In winter this means greater focus on not just interactions between the tropics and extra tropics in respect of +ve and -ve wind-flow interactions, but how both the troposphere itself as a whole further interacts with those "top layers".

Namely the stratosphere.

This is undoubtably the hardest task of all. And anyone who tries to relay context of the GSDM in respect of ultimate stratospheric evolutions and the subsequent tropospheric impacts is going to struggle and make errors. But that doesn't make the diagnostic wrong. It is simply the immense difficulty in making judgements set against complex and sometimes countervailing aspects.

There is so, so much more to this subject of the "global wind-flow budget". But it is the scientific essence of the Global Synoptic Diagnostic Model (or GSDM). I guess the title name itself makes it sound like it is the home for an elite echo chamber - but it is simply a title given by the late NOAA official Ed Berry in conjunction with others like David Gold. Who now has taken over fully its operation with others.

As @Met4Castsays, these are not untouchable gurus - and those of us who have been given access to the GSDM data plots are not a privileged elite, but people who have a genuine fascination & equally recognition of the insight into the atmospheric system that dictates wind-flow changes (aka the jet stream paths and strengths) and how convergence & divergence of wind-flows (torque mechanisms) change angular momentum tendency and in turn carve out the global synoptic patterns. Not just for UK postcodes.

Anyone else can choose to do this is they genuinely wish, by asking permission to the plots. The cautious issuing of permission rights over the years has been the late Ed Berry's wish for his pioneering work to be protected, as it developed more and more. In the same way as study of the stratosphere has come on leaps and bounds over the past couple of decades, this tropospheric diagnostic has slowly (more slowly) come forward as well. But somehow has contrived to be misrepresented as some kind of cultist elite movement. That is a big pity. Meteorology as a study as a whole loses out.

Other than incomplete over focus on the MJO in isolation of the rest of the wind-flow budget, the biggest factor for failure of messaging & understanding the value of these diagnostics is the emotional attachment to one desired synoptic outcome. Its one thing using an MJO composite in isolation (which increases likely error rate of probabilistic outcome anyway) but when these are also attempted to be fitted to bias outcomes as part of a bias confirmation process, then this further ups the error rate and ultimate disappointment when the bias outcome proves AWOL in reality.

The consequence?  "The workman blames his tools"

To be blunt if these "workmen" are going to do this, then it is quite reasonable that anyone who tries to genuinely understand the purpose of the diagnostic as an objective, neutral process to ascertain ALL probabilities (as one does with ensemble & ensemble cluster groupings as per @Mike Pooleetc) to express resentment at the discrediting of the methodology. The frank answer is to either express a desire to hook up to the data and try to study the diagnostic objectively, or not bother at all . It is possible of course to continue to rely on NWP to look for outcomes. But as with the GSDM, continue to be disillusioned when persistent attempts to skew model data information or expectations to a bias outcome founders more often than verifies.

Neither using NWP and/or GSDM are wrong, and both of course are wholly valid. But the GSDM is meant to compliment NWP as a diagnostic insight into how synoptic patterns might evolve over time . Not some magic silver bullet to give faux insight into how it might increase the chance of snow in a given post code.

The GSDM is a diagnostic process not just for analysing winter patterns, but for all year round. The atmospheric circulation doesn't stand still from around March to October/November. So viewing tropical convection patterns is not a toy to play with snow-making for a few months and putting away in a cupboard till the next time - it is one component, just one component, of aggregate global wind-flow which is in constant flux 24/7, 365 days a year.

We would all not be here if it wasn't...

It is always quite possible to give an overview of the GSDM as an update to the present synoptic outcomes. However, as emphasised, this is only possible within a neutral framework as discussed in this post. That neutral framework would not justify its effort & existence as no-one would show interest because it  would not be geared towards a favoured outcome. That is, if it was being used for the trur purpose it is geared towards & intended.

Sensible to leave it to one side based on the time it takes to put together analysis of the data. I can only say reasons have been given for why the disillusion itself is to blame and the "workmen" have to look at their own responsibility in inviting their own disillusion.

Melhores cumprimentos.

Edited February 10 by Paul

[johncam]

 Penrith Snow we just dont have that depth of cold to our nirth now and probably wont again in the near future. I do remember the 70's up here having a lot of PM weather and it was always cold enough for snow which would lie.Some of our best winter snowy weather 60's to 80"s was PM weather.

[Derecho]

 Frigid The MJO hasn't been in a favourable phase since the first half of January and some blocking did follow. It's being used as a bizarre scapegoat.

[Weather-history]

 North-Easterly Blast

"Another point about winter 2023-24 is that we are approaching solar maximum, so it is not a good solar match for cold."

 

 

...and yet  4 of the 6 coldest winters of the 20th century happened near solar maximum.  

 

[northwestsnow]

Again I will post the graph of European winters since 1850

It is absolutely pointless posting a chart from Feb 1922 saying look how mild it was on that particular day or week  ,the point is the milder days are becoming more frequent ,the trend is as unambiguous as you  could wish for and the warming trend since the late 1980s is clear for all to see...

[Weather-history]

Further to my point on solar activity and its influence 

One of the mildest winters on record for the CET, 1833-34 occurred at solar minimum

The famous Murphy's winter, 1837-38, a severe winter, occurred just after a large solar maximum. Infact, the peak of that solar maximum occurred during the coldest spring on record for the CET.

 

[North-Easterly Blast]

I am not sure about that - the severe winter of 1978-79 occurred shortly after the solar minimum in 1977, but solar activity was on the rise.  The severe winter of 1962-63 occurred close to a solar minimum.  1947 was I believe a bit like 1978-79, occurring shortly after a solar minimum when solar activity was on the rise.  I am not sure about the cold winters of the early 1940s on what solar position they occurred in.

That all said, solar minimums have often coincided with winters in the UK that did have notable cold spells - such as the mid 1950s, winters 1985, 1986, 1987, and winters 1995-96 and 2009-10, December 2010, and shortly after a solar minimum (but solar activity on the rise) winter 2012-13.  The solar minimum of 2019 failed to produce anything cold of note close to or shortly after it - the most we got was in 2020-21 when the pattern tried to deliver the UK a cold winter with a good amount of northern blocking, but I do not know why it happens but it just did not quite come together with the low pressure not getting far enough south for northerlies and easterlies to influence the UK for significant amounts of time.  I often regard winter 2020-21 as the "missed opportunity" for a cold winter in the UK close to the most recent solar minimum.

More often than not the solar cycle is more favourable for cold winter patterns in the UK close to or a just after a solar minimum.  That said I can think of occasional good cold spells near solar maximum; winter 1968-69 (especially February), winter 1981-82 (especially December and first half of January), but they have been few and far between.

[Weather-history]

 North-Easterly Blast

Solar maximum was around December 1979

Solar maximum was around May 1947 

 

[North-Easterly Blast]

 Weather-history I thought that there was a solar minimum in early 1977, and we actually did start to get some colder winters from then on, with 1976-77 and 1977-78 having their cold moments and then the big one was in 1978-79.  In many ways winters 1976-77 and 1977-78 could be seen as setting up the pattern for the big severe one to come.

Judging by your point the late 1970s must have been a rapid increase from solar minimum to maximum.

Edited February 10 by North-Easterly Blast

[Chris Smith]

I think it's pointless looking backwards because CC has, and is accelerating at such a rate now, history is meaningless - even history as recent as the 60s, 70s and 80s.

Watching the MOD threads over the winter, and one thing keeps popping up over and over - "Iberian heights". Persistent high pressure to our south has more or less removed any chance of deep cold reaching the UK, either from the North or the East.

If you want to experience winter weather in the UK, as your Christmas cards want to paint it, you need to visit Northern Scandinavia, or Northern Canada.

TL;DR @northwestsnow is right.

Edited February 10 by Chris Smith
TLDR

[Chesil View]

Lots of really thoughtful posts in this thread making it a really interesting read. 

I think the fact that there are just so many variables in the background signals that have to fall into place for the the UK to get deep cold and a winter worthy of the name has always been the problem to overcome (even back in the 60's 70's and 80's when decent winter spells were more common. )

Local records here tell the story snow wise. In the 60-80 s even lowland Dorset could expect a half decent covering in 7 winters on each of the decades. That is now down to three on average.  That's is the difference a small rise the mean  winter temps has made.

 

Edited February 10 by Chesil View

[Weather-history]

 North-Easterly Blast

It was a year early,  the new solar cycle of that time started  in the March of 1976

[Weather-history]

An interesting article by the Rev. Eric Robson from the end of February 1947, talking about sunspots. Activity actually peaked during 1947 not the following year as he suggested. 

Edited February 10 by Weather-history

[North-Easterly Blast]

Judging by when the most recent solar minimum occurred in 2019, and the sort of winters that the UK experienced, it makes one think that a winter like 2020-21 may be regarded as cold in the UK (and a winter like 2017-18 as well), and certainly raises fears that it is no longer realistically possible for the sort of cold spells like the UK experienced in 2009-10, December 2010 and 2012-13 to ever develop again, and it now looks very likely as though the cold spells of this time are well and truly consigned to the history books, and there is certainly fear that a winter like 2020-21 or 2017-18 may be the modern version of 2009-10, December 2010 or 2012-13.

Edited February 10 by North-Easterly Blast

[North-Easterly Blast]

 Chris Smith I think that if you want to experience winter cold in the UK, you do not want to see anomalous warmth in September or a strong ocean anomaly any way (ENSO, IOD), as all of these are winter killer patterns for the UK.

[North-Easterly Blast]

Looking at bad signals for colder winter weather in the UK, most past strong ENSO anomalies either way have co-incided with milder winter weather in the UK, and no strong ENSO anomaly has ever co-incided with a UK winter as a whole being cold.  The only exceptions to strong ENSO anomalies that I can think of are; one strong El Nino did co-incide with a cold winter month (February 1983), and one strong La Nina did co-incide with a very cold winter month (December 2010), but apart from that, there has been little in the way of cold weather to speak of in the UK during strong El Nino or La Nina winters.

I think if anything that the warm September = mild winter theory is even stronger still.  When you look at what anomalous September warmth is (the 1961-90 September average CET is 13.6, and the 1991-2020 September average CET is 14.2), you would certainly consider a September CET of 15.0 or more as warm, and a 15.5 CET or more could be regarded as a very warm September, and by 1961-90 standards or earlier than that a September CET of more than 14.5 would be considered warm. 

Looking at testing the warm September = mild winter theory, I cannot think of any September in the "very warm" category (CET 15.5 and above) that has led to a cold winter; most of the winters following all Septembers of 15.5 and above were mild or very mild, and very few Septembers above 15.0 CET have even led to a cold winter either (the only exceptions that I could possibly spring to mind is that September 1961 (15.2 CET), did go on to produce a winter that had a significant cold spell in December, and again from late February and through most of March (albeit not particularly cold through most of Jan and Feb), and September 1958 (15.1 CET) did go on to produce a winter that did have a cold January (albeit not particularly cold either side of this), and another could be September 1929 (15.3 CET) did go on to produce a pretty cold February (although it was generally mild before that).  Apart from that there has been little in the way of cold weather to speak of in any UK winter after a very warm September.

Looking at Septembers in the average or cool category, it appears that it is still possible to have a September that it just above average (1939, 1946, 1978, 2009 low 14s CET), and get a cold winter after it, and in fact among the warmest Septembers that I could think of that have gone on to produce notable cold spells in the following winter are 1981 and 1985 (14.5 - 14.6 CET).   

Edited February 10 by North-Easterly Blast

[Don]

It makes you wonder how mild a Billy Bartlett dominated winter, a la 1988/89 would be these days?!  

[Nick F]

 Tamara It's all very well and admirable learning about and explaining GDSM and how works in the bigger picture of the global atmosphere. Many of us, including me, appreciate this alternative and unconventional way of forecasting.

But it was the aggressiveness of the response from MattH when I dared questioned it's validity which was quite a shock to me and others. 

Because the subject is very technical to understand and explain it immediately puts a barrier to most questioning its validity because they aren't confident to put up a counter argument with lack of data access. 

If the GDSM is such a great tool, how come it's no longer available from NOAA. Or anywhere else. Met Office don't mention it publicly but do with all other drivers including MJO. There's no substantial evidence or papers that the theory is water tight and certainly with confidence can anyone attribute to AAM influencing weather patterns over N Atlantic.

We can't question those who make these predictions using GDSM because we don't have to hand archive charts, verification stats and any access to such data.

The thing that irks me is that predictions are made in MOD based on these GDSM / AAM plots but with little reference to other drivers, linked or not and we're told to ignore the model guidance. But, then there's never any follow up when these predictions don't come off as pescribed. 

 

Edited February 10 by Paul

[raz.org.rain]

Personally I still believe that teleconnections are a crucial detail in forecasting. It takes a lot of skill and knowledge to understand how they interact and what the implications can be further down the line. It's fair to say that the teleconnections aren't a guarantee of something happening, I don't believe any analysts would say that something is an absolute based on their observations. It just gives us a very good idea of how we should expect the weather to behave further down the line, or what pieces of the puzzle we'll be dealing with.

The elephant in the room is that the climate is growing increasingly erratic. I'd imagine that it's considerably more difficult to be confident in the findings. Teleconnections are a very nuanced and complex subject, certainly not something I could hope to master.