Thanks, Andy J. Shows how difficult it is to get a pattern match. There's always some crucial factor which doesn't fit! But an interesting read.

I liked Retron's graphs for Manston winters. It's funny - I looked at those plots, and my first thought was how little variation there actually has been in terms of weather over the last 70 years. Despite the obvious cycle of the AMO in the bottom line, the only real standouts for me were just how abnormally cold 1963 was, and how unyielding was the ice down there in 1985. Other than that, if you weren't actually living there and getting frustrated by the absence of the specific, Siberian easterly you crave, then you'd glance at those lines and say, what's the big deal? They just go up and down from start to finish. (Admittedly it doesn't help that the CET had the same value 70 years ago at the start of the graph as it did last year! Coincidence, I know.)

Going back to the figures on the previous page, for Manston winter temperatures, again I was surprised at how little the mean has actually varied from start to finish. Especially if you were to strip out the extremes of 1963, 1985, Dec. 2010 and Dec. 2015.

On the other hand, I suppose the latter actually supports your point in a way: of the four events which really do stand out from the norm, the three cold ones were in the past, while the mild one was in the present.

But extraordinary events aside, I'm still sceptical about whether the overall, year-in, year-out, 70-year data actually do illustrate any fundamental change.

I think the best summary was the one in your last post - that memorable cold events are so marginal in a maritime climate, that any deviation from the norm renders them suddenly impossible to achieve. So what on the ground, to someone living in Leysdown-on Sea, manifests itself as frustratingly boring weather and a real change in the winter experience, might equally appear utterly unremarkable to me, who's never lived there and still can't get over the once-in-several-lifetimes glory of the December we experienced here in 2010.

The daily CET stats are interesting in that respect

If you just look at the winter months and the Maximum Daily CET ( better than the Mean or Min for judging the likelihood of prolonged snow) you can get a list of every one of the 91 possible date records for December (31) January (31) and February (29) going back to 1878

If you then plot the date records for highest and lowest CET Maxima on that date you get :

The increase in date records nearer the current date and decrease in cold date records is very clear

In fact there have only been 3 years ince 1987 with cold date records (2010, 1995, 1987) contributing 9 date records out of 91 possibles. On the other hand there have been 17 years with warm date records in that 30 years consisting of 52 of the possible 91 dates

 

 

We've had frigid and snow-bearing easterlies in recent years, though.

In Jan 2010 we had one from around the 8th/9th lasting several days (we had snow lying on the ground for about 3/4 weeks)

 

That was a pathetic one, Saint. Brought nowhere near the snow amounts first predicted and infact initiated a very slow thaw.

Late January 1996

 

That was a pathetic one, Saint. Brought nowhere near the snow amounts first predicted and infact initiated a very slow thaw.

 

Late January 1996

As 'nippy' as the winter of 2009/2010 & the period Nov/Dec 2010 were, I don't recall any 'true' easterly occurring. Perhaps in the UK they did, but they failed to reach here.

The last authentic easterly I can recall occurred for a couple of days back in Jan 2008.

 

That was a pathetic one, Saint. Brought nowhere near the snow amounts first predicted and infact initiated a very slow thaw.

 

Late January 1996

I'd still put Jan 2010 as the best winter episode here, based on the depth of snow received (17cm) and longevity of it lying (3-4 weeks).

I'm sure there've been many much better easterlies, but I was just using the event as an example of easterlies that I could remember.

Late Jan 96 didn't deliver anything memorable here... else I'd have remembered it  I'm not that concerned with weather stats for the sake of them, just what it was like 'on the ground'. And cold without snow always seems like a waste to me (and doubly-annoying as cold easterlies generally bring snow to parts that are a long way from MBY)

 

The point was that we don't get midwinter easterlies any more, for whatever reason. Some parts of the UK, such as where I am, rely on them for severe cold.

I would like nothing more than to see the 21-year drought ended, but as ever it's impossible to predict when it'll end. What I will say, though, is going back 100 years there's never been such a prolonged absense of them.

Of course, if you live somewhere that can get similar conditions without requiring an easterly, you'd not have noticed!

Late January 1996

What a lovely chart - and of course, 1996 wasn't even an especially cold easterly episode in the scheme of things. As mentioned several times, it's the depth of cold air aloft that we've been lacking.

In that late January case, 850s didn't even reach -10C down here, yet the wodge of cold air aloft was very thick, having been sourced east of the Urals a few days earlier. The whole frigid mass moved across us like a lump of ice and although the North Sea did warm it significantly (note the -7C over the Netherlands), there was such a depth of cold air and it was moving so fast that it simply couldn't be mixed out in time. Result? Powder snow, icicles, a penetrating ice day and so forth.

It's not just midwinter easterlies which have been severely lacking since 1997 - whenever we've had an easterly waft, it's been just that: a waft, not the screaming "lazy wind" sort of easterly.

When we do get a sniff of an easterly (see the very end of November 2010 down here), the block seems invariably to collapse before it's managed to whizz that deep upper cold air over us, allowing it time to mix out (as in the very begining of December 2010 here). Or it's simply too late, such as that February 2005 example (which saw -14C at 850 here and a decent "reloading" pattern).

Thanks Lanky, astonishing statistics, I just wonder what sort of numbers we will be looking at in 10 years time.

 

What a lovely chart - and of course, 1996 wasn't even an especially cold easterly episode in the scheme of things. As mentioned several times, it's the depth of cold air aloft that we've been lacking.

In that late January case, 850s didn't even reach -10C down here, yet the wodge of cold air aloft was very thick, having been sourced east of the Urals a few days earlier. The whole frigid mass moved across us like a lump of ice and although the North Sea did warm it significantly (note the -7C over the Netherlands), there was such a depth of cold air and it was moving so fast that it simply couldn't be mixed out in time. Result? Powder snow, icicles, a penetrating ice day and so forth.

It's not just midwinter easterlies which have been severely lacking since 1997 - whenever we've had an easterly waft, it's been just that: a waft, not the screaming "lazy wind" sort of easterly.

When we do get a sniff of an easterly (see the very end of November 2010 down here), the block seems invariably to collapse before it's managed to whizz that deep upper cold air over us, allowing it time to mix out (as in the very begining of December 2010 here). Or it's simply too late, such as that February 2005 example (which saw -14C at 850 here and a decent "reloading" pattern).

 

Those 1996 charts show the classic double block: high pressure near Greenland and over Scandinavia.  It has often been highlighted that you need that pattern to prevent the block coming under too much pressure and either retreating or being squeezed south/south-east.

In fact there have only been 3 years ince 1987 with cold date records (2010, 1995, 1987) contributing 9 date records out of 91 possibles. On the other hand there have been 17 years with warm date records in that 30 years consisting of 52 of the possible 91 dates

That really is a remarkable bit of data. I know many of us on here will have had a "gut feeling" that things have swung in favour of mild versus cold in the last couple of decades, but as that graph shows it goes back all the way to the 80s.

Those 1996 charts show the classic double block: high pressure near Greenland and over Scandinavia.  It has often been highlighted that you need that pattern to prevent the block coming under too much pressure and either retreating or being squeezed south/south-east.

Yup, for a sustained spell a Scandi/Greenland block, extending over Iceland, is pretty much required. 2010 was the last time we came close to it, but that was more biased towards Greenland than Scandi. Before that? Feb 2005 again - that one went on for a couple of weeks.

(It'd be interesting to see how the jet pattern has changed since the 90s, too. My gut feeling is that given a "will the energy go north or south  when it splits" scenario, it'd be more biased to "go north and collapse the high" rather than "go south and prolong the block". Not sure how to quantify that one though!)

 

As 'nippy' as the winter of 2009/2010 & the period Nov/Dec 2010 were, I don't recall any 'true' easterly occurring. Perhaps in the UK they did, but they failed to reach here.

The last authentic easterly I can recall occurred for a couple of days back in Jan 2008.

Nov 30 2010:

Not a long lived easterly & not so good down south, but dumped over 30cm of snow in my neck of the woods in 12 hours thanks to a persistent trough/occlusion:

 

Yup, for a sustained spell a Scandi/Greenland block, extending over Iceland, is pretty much required. 2010 was the last time we came close to it, but that was more biased towards Greenland than Scandi. Before that? Feb 2005 again - that one went on for a couple of weeks.

(It'd be interesting to see how the jet pattern has changed since the 90s, too. My gut feeling is that given a "will the energy go north or south  when it splits" scenario, it'd be more biased to "go north and collapse the high" rather than "go south and prolong the block". Not sure how to quantify that one though!)

Yes that would be my view too.

 

Nov 30 2010:

Not a long lived easterly & not so good down south, but dumped over 30cm of snow in my neck of the woods in 12 hours thanks to a persistent trough/occlusion:

That night it got down to below -20°C in parts of the Highlands and we had about 10” of snow lying here. Not much has really come close since. The next night it dropped to -17°C at Aberdeen airport.

 

The daily CET stats are interesting in that respect

If you just look at the winter months and the Maximum Daily CET ( better than the Mean or Min for judging the likelihood of prolonged snow) you can get a list of every one of the 91 possible date records for December (31) January (31) and February (29) going back to 1878

If you then plot the date records for highest and lowest CET Maxima on that date you get :

The increase in date records nearer the current date and decrease in cold date records is very clear

In fact there have only been 3 years ince 1987 with cold date records (2010, 1995, 1987) contributing 9 date records out of 91 possibles. On the other hand there have been 17 years with warm date records in that 30 years consisting of 52 of the possible 91 dates

 

Thanks for that. It's definitely food for thought. But I still have the problem that 10% of the cold date records have nevertheless occurred in the last 3 decades. That's 10% of the records appearing in the most recent 22% of the series. 

Obviously I'm not disputing that there is a bias towards higher maxima, which, as you say, is what precludes lasting snow (and icicles, of course). But to me that is not evidence of any fundamental change since Darren's legendary 1985 easterly. Quite the opposite, if 10% of winter dates then went on to produce maxima which were lower than any previously recorded since 1878.

The point Darren makes about the jet annoyingly tending to sink the block these days rather than support it is a good one. Even last winter, which we all moaned about, was incredibly blocky. It's just that the jet insured that the block was parked to our immediate east, rather than further north over Scandinavia.

So anti-cyclonic winters are still easily possible, as last year demonstrated. The question is whether the fact that those anti-cyclones have recently tended to appear further south than previously is evidence of fundamental change, or whether that's just a roll of the dice which hasn't worked out for us as often as it used to. 

I'm tending to the view that it's just one of those things - pot luck, and the blocks are still there, and one day it'll all turn out the way we want it again. 

But I do sympathize with the view that a shift in jet patterns does imply that there is something different going on.

 

Thanks for that. It's definitely food for thought. But I still have the problem that 10% of the cold date records have nevertheless occurred in the last 3 decades. That's 10% of the records appearing in the most recent 22% of the series. 

Obviously I'm not disputing that there is a bias towards higher maxima, which, as you say, is what precludes lasting snow (and icicles, of course). But to me that is not evidence of any fundamental change since Darren's legendary 1985 easterly. Quite the opposite, if 10% of winter dates then went on to produce maxima which were lower than any previously recorded since 1878.

The point Darren makes about the jet annoyingly tending to sink the block these days rather than support it is a good one. Even last winter, which we all moaned about, was incredibly blocky. It's just that the jet insured that the block was parked to our immediate east, rather than further north over Scandinavia.

So anti-cyclonic winters are still easily possible, as last year demonstrated. The question is whether the fact that those anti-cyclones have recently tended to appear further south than previously is evidence of fundamental change, or whether that's just a roll of the dice which hasn't worked out for us as often as it used to. 

I'm tending to the view that it's just one of those things - pot luck, and the blocks are still there, and one day it'll all turn out the way we want it again. 

But I do sympathize with the view that a shift in jet patterns does imply that there is something different going on.

I think it's worth stressing here that there's a difference between 'high pressure' and a block.  By definition a block deflects the prevailing jet stream and to do that it has to be positioned in relatively high latitudes.  High pressure too far south isn't a block - mid latitude blocks invariably come with energy riding over the top.  

IMO end of Oct and early Nov seems the best window of opportunity for some blocking, but even if it happens ir'd still be more likely to be to the east of us making it difficult for to tap into cold air.

Late Nov and Dec more likely to be zonal, but Q1 should be more fun!

Nobody knows anyway 

 

I think it's worth stressing here that there's a difference between 'high pressure' and a block.  By definition a block deflects the prevailing jet stream and to do that it has to be positioned in relatively high latitudes.  High pressure too far south isn't a block - mid latitude blocks invariably come with energy riding over the top.  

Yes. A block is high pressure, but high pressure isn't a block if the jet simply pushes it south. Which it seemed to do for most of last winter.

A lesson learned. If a poster (i.e. me) wants to think straight, then he needs to get the terminology right in these sorts of discussion.

 

Yes. A block is high pressure, but high pressure isn't a block if the jet simply pushes it south. Which it seemed to do for most of last winter.

A lesson learned. If a poster (i.e. me) wants to think straight, then he needs to get the terminology right in these sorts of discussion.

The latest CFSv2 models seem to be suggesting a chance of a Scandi high in December, and northern blocking in February. and high pressure to our east in March (albeit that could just bring warm air like this March).

However if I recall correctly, this time last year it was showing northern blocking for the whole winter.