Yearly CET

[West is Best]

I mention this last point on the strength of the persistence of the meridional flow of late. We have been on the warm side for some time but it would seem, if not equally likely, at least possible that we could also fall on the cold side and if this were to be the case it could persist for some considerable time.

I do think this is a really important point to stress, even if obvious TM - you are very right to emphasise it. If we stick in this pattern and get the other side of the flow it could be sharply different. On the other hand, all this warmth pumping into the arctic circle isn't good news for residual temps 'up there' surely? If (A)GW is right then it's the poles which are disproportionatly warmer than the equator ... and that would be bad news. It might mean we start to see more of the northerlies without bite, and indeed even the occasional easterly that is more the fireside kitten than the roaring lion.

Edited October 19, 2006 by West is Best

[VillagePlank]

Do you think you could refrain from comments like this? Carping against one of the leading climate research institutes in the world makes you (and the rest of us) look a little below par.

Reread. Please.

Read as "This also includes the possibility of the last few years being a warm anomaly, with a correction to a higher base mean as predicted from people like the Hadley centre"

ie Correcting the temperature upwards on the basis of the research people like the Hadley centre are conducting.

Also known as agreeing with them.

Edited October 19, 2006 by Wilson

[SP1986]

Indeed WIB, I think what ive seen (not having lived at the times when the easterlies were roaring), is that the easterlies that form over Russia are a very fluid, and fragile medium in our weather patterns. It does not take much for easterlies to generate heat one minute, then cold the next. There's more to it than that obviously, but the general issue is that if a warming trend (I refrain to say global warming because im not convinced *everywhere* will warm to such a degree), continues, then easterlies will become warmer, and it doesn't take much on a continent with topography and form such as Europe.

[Stratos Ferric]

Sounds about right. Although, taking on board current GW stats, I'd lower the base mean to about 9.7 to include any rogue cold months (which, of course, are still entirely possible) This also includes the possibility of the last few years being a warm anomaly, with a correction to a higher base mean as expected from people like the Hadley centre.

That sounds too low to me at present. A 9.7 outturn requires a total of around 8.5C across the year compared to the last few. That's a majority of months cooler than current par (doesn't happen any more), or three or four months well down (doesn't happen) with the rest around par (doesn't happen). I am starting to suspect that it's very possible that our climatic norm has lurched upwards.

[Guest Mike W]

The current 76-05 average is too low really, which is why IMO the only baseline that relates best to our climate now is the decadal average i.e 96-05. Though 96 being massively different to following years especially for the annual CET. 96-05 Manley 10.29, Hadley: 10.30. A 5 year average would be the best representaion of now, but it may sound silly really. The problem i think witht he 30 year average now is that you still have at least 10 years of notably cooler regime that knock the average alot lower down than to what it would have been without the high previous emmisons of sulphates we emmited 20+ years ago. For example 71-00 average you have lets say 71-86 where the majority is 8's and 9's as annual CET's, the second half is totally different with majority being 10's and only a handful of 9's basically. Maybe the 1981-2010 series will rectify this, at the presen trate it's defiantely going to be a 9.9* and easily could be the first 10.** average.

Edited October 19, 2006 by Mike W

[Stratos Ferric]

The current 76-05 average is too low really, which is why IMO the only baseline that relates best to our climate now is the decadal average i.e 96-05. Though 96 being massively different to following years especially for the annual CET. 96-05 Manley 10.29, Hadley: 10.30. A 5 year average would be the best representaion of now, but it may sound silly really. The problem i think witht he 30 year average now is that you still have at least 10 years of notably cooler regime that knock the average alot lower down than to what it would have been without the high previous emmisons of sulphates we emmited 20+ years ago. For example 71-00 average you have lets say 71-86 where the majority is 8's and 9's as annual CET's, the second half is totally different with majority being 10's and only a handful of 9's basically. Maybe the 1981-2010 series will rectify this, at the presen trate it's defiantely going to be a 9.9* and easily could be the first 10.** average.

Mike, numerically you're absolutely right in one sense, but for the first time in the history of the CET the 30 year period is now much shorter than the wavelength of the event it is seeking to normalise, hence the start of the period is below average and the end above it quite consistently. A data set of thirty allows certain statistics to be run with confidence, though in a data set that is no longer behaving normally (in the statistical sense) some of that value is forsaken anyway.

[paul tall]

Going by the 1970-2000 data, deviations from average are as follows (Hadley CET)...

January: +0.1C

February: -0.5C

March: -1.4C

April: +0.5C

May: +1C

June: +1.8C

July: +3.2C

August: -0.1C

September: +3.1C

Looking at those figures, am I the only one here thinking "er yeah, that is exactly how the weather should be" (bar August, which should not have been allowed)

[Stratos Ferric]

Well, we're reaching the pitch at which all bets will be off for a continuing fall in in the recent trend of (very slight) yer to year drops in average CET.

Assuming October outturns at 12.6C, which is looking slightly conservative and certainly not excessively generous, then we will have 10.2 cumulative degrees in hand to avoid passing last year. Only 14 of the past 60 years have failed to reach this in Nov + Dec, which on the face of it still leaves reasonable odds, however:

- it last happened in 1996 (though, interestingly,also in 1995 and 93 before that);

- it has happened only 5 times int he last 37 years (in case you wonder at this apparently random cut-off, this marks the sudden end of a period when N+D were much cooler than today);

- within this 60 year set, 20 years (including the current one) have outturned >10C, 11 in the last 13 years - and with one very near miss in addition: of these 20 only two returned a N+D <10.2C.

I'd reckon there's now less than a 5% chance of this year being cooler than last. WHAT'S MORE, there's now a marginally better than evens chance of the annual record being broken.

[Snowly does it]

Well, we're reaching the pitch at which all bets will be off for a continuing fall in in the recent trend of (very slight) yer to year drops in average CET.

Assuming October outturns at 12.6C, which is looking slightly conservative and certainly not excessively generous, then we will have 10.2 cumulative degrees in hand to avoid passing last year. Only 14 of the past 60 years have failed to reach this in Nov + Dec, which on the face of it still leaves reasonable odds, however:

- it last happened in 1996 (though, interestingly,also in 1995 and 93 before that);

- it has happened only 5 times int he last 37 years (in case you wonder at this apparently random cut-off, this marks the sudden end of a period when N+D were much cooler than today);

- within this 60 year set, 20 years (including the current one) have outturned >10C, 11 in the last 13 years - and with one very near miss in addition: of these 20 only two returned a N+D <10.2C.

I'd reckon there's now less than a 5% chance of this year being cooler than last. WHAT'S MORE, there's now a marginally better than evens chance of the annual record being broken.

Yes, what looked an almost 'in the bank' drop prior to the astonishing July/Sept/likely October returns now looks doubtful. It would take a cold November and average December or vice versa. 'As you were' from last year plus an October 12.5 would equal it, 'As you were' for all months Oct/Nov/Dec would give us a 0.05 rise.

All in all another year within the 'margain of error' mentioned often in relation to the past 4 years? Unless a mild November and December push us over the top of course.

[Stratos Ferric]

Yes, what looked an almost 'in the bank' drop prior to the astonishing July/Sept/likely October returns now looks doubtful. It would take a cold November and average December or vice versa. 'As you were' from last year plus an October 12.5 would equal it, 'As you were' for all months Oct/Nov/Dec would give us a 0.05 rise.

All in all another year within the 'margain of error' mentioned often in relation to the past 4 years? Unless a mild November and December push us over the top of course.

Whichever way it turned out - whatever the excitement regarding another potential but very trivial fall - as we discussed recently, the movement was likely to be well within rounding error. Not sure I agree that a drop was ever "in the bag", though it was well in the zone of possibility. It matters not, though, because it's highly unlikely now.

[Snowly does it]

Whichever way it turned out - whatever the excitement regarding another potential but very trivial fall - as we discussed recently, the movement was likely to be well within rounding error. Not sure I agree that a drop was ever "in the bag", though it was well in the zone of possibility. It matters not, though, because it's highly unlikely now.

I agree, the likely outcome for this year is as per the past 3, much of the same except the margainal change this time will likely (more than likely) be upwards.

Don't fancy a record year.

It seemed in the bag prior to July - we were about 3 cumulative degrees behind 2005 at that time. OK, in the bag is excessive but in March I truly felt a sub 10 year was on the cards..

[Snowly does it]

In the interests of being balanced, a high 12s October would put us about a cumulative degree ahead of 1999's equal record year, but that featured above average November and December which we need to approach to take the record.

[Stratos Ferric]

In the interests of being balanced, a high 12s October would put us about a cumulative degree ahead of 1999's equal record year, but that featured above average November and December which we need to approach to take the record.

If this were the 1960s I'd agree with you, but seeing as three of the past four years have managed the level you suggest then achieving this and setting a new record would actually be anything but remarkable.

[Stratos Ferric]

I have only just seen TM post earlier regarding a 'flip-flop' scenario with our weather and xtra instability lurching between greater extremes. I think this hits the nail on the head. The sort of meridional pattern we have become used to, I think will continue and even become more manifest and will indeed invite this sort of scenario and we may all need to be circumpsect in our CET predictions and not make assumptions based on summer warmth meaning winter warmth.

Watch southerlies become northerlies in the weeks ahead with a winter pattern taking over from the current summer one. I'm not sure we can predict our weather on the prevailing atlantic basis that we used to. Perhaps our climate will become increasingly more continental and current assumptions regarding outcomes of the warming trend may have to be revised?

Tamara

Tamara,

Whether and how we need to be circumspect depends on whether we agree with the "flip-flop" scenario. You will agree with it because it provides a glimmer of hope, but some of the chatter this autumn really has perplexed me.

I'm sorry, but there are a few on here (you amongst them) whose ability to ignore the obvious trend and go looking in ever more desperate places for prospects of cold, as if the current general mildness isn't happening and is not the prevalent norm, is something that I find personally blinkered. I keep saying it: I like snow as much as anyone on here, but it doesn't make me blind to realities.

With a hemisphere that is generally warm, and more energy in the system; with high SSTs all around us; we are not going to get persistent blocks of the type required to bring intense and sustained cold our way. Anyone would think that the last two months have not been dominated by weather coming off the Atlantic.

I don't want this to seem harsh, I am just trying to be realistic, however unpalatable the meteorological outcomes of such thinking may seem to some people.

[West is Best]

I don't think meridionality is locked in though Tamara. The models are looking increasingly zonal in FI, with high pressure to the south of the UK and a very flat jet streaming in across the Atlantic. In due course this may encourage north-south meridionality, but it could take a fair while especially so if that high pressure locks in over southern Europe (aka 'Bartlett'). Either way, I can't see much sign of correction to the yearly CET being high just now. If the following type of charts come off, which isn't set in stone, then it's not going to bring much cold for a wee while:

At the moment I'd pigeon hole this as a 'trend to watch', so my main emphasis is not to assume that meridionality is necessarily here to stay.

Edited October 22, 2006 by West is Best

[Glacier Point]

With a hemisphere that is generally warm, and more energy in the system; with high SSTs all around us; we are not going to get persistent blocks of the type required to bring intense and sustained cold our way. Anyone would think that the last two months have not been dominated by weather coming off the Atlantic.

I don't want this to seem harsh, I am just trying to be realistic, however unpalatable the meteorological outcomes of such thinking may seem to some people.

Not entirely balanced here Stratos.

Rewind the tapes. 2005, one of the warmest hemishpheric and global years. Temperatures across northern and western Europe widely +1.5 to 2 C for the summer months, a highly diminshed cold polar pool in historical terms.

And yet.....

A significantly cold winter for central and SW Europe, in some cases 2.5 to 3 C below the 1968 - 96 average. True, the cold never really got to the UK's shores, but in a climatological sense, that is but a hair's breadth due to the prevelant synoptics as the origin our sustained winter cold episodes are essentially the same as the rest of western Europe.

We must ask why did such a turnaround take place given such positive forcing of hemishperic surface temperatures ? Was there a masking of a really harsh winter ?

The answer to the second challenge is one that neither you nor I can confidently respond to and it likely take many more years to be able to conclude either way.

This year in many respects poses a re-run of 2005. The Atlantic SSTAs are very similar. The summer warmth is greater, and yet I would conclude at this stage the prospects for another winter with an increased probability of cold synoptics is entirely feasible - this time perhaps more so during January.

Should be a fascinating few months though either way.

GP

[Stratos Ferric]

Hi SF

I agree with the flip-flop scenario because... I believe in it - that's all I don't need to 'hope' as you put it, nor am feeling uncomfortable about anything unpalatably warm Naturally I don't expect you or a few othes to agree with me - and that is fine, but I was also trying to throw some intended conjecture into the melting pot which I had hoped would have been perceived when read without being taken too literally as a definitive prediction. It wasn't intended to be

I would actually question how much true atlantic influence there has been in the last couple of months? A fair amount of continental blocking to me with us caught in a southerly sandwich - pretty much the story of the summer. And a far greater continental influence last winter too. The coldest air to the east may not have reached here but neither did much LP get past the meridian. How long since we last saw true zonality? January 05 I think.

Regarding SST's I see that others have aptly answered that one on the other thread so no need for me to do so (and go offtopic!) here

Tamara

Well, they responded, I'll grant you that. Answered? Matter of opinion.

I'm sure all you were doing was throwing something into the melting pot, which is all I was doing I think.

[Thundersquall]

My calculated guess would be a yearly CET of 11.25c (assuming November has an average of 10.0c

and December has an average of 7.1c).

[Stratos Ferric]

My calculated guess would be a yearly CET of 11.25c (assuming November has an average of 10.0c

and December has an average of 7.1c).

Which would actually give an outturn of about 11C, unless October gets up to 15. I know the outlook is mild, but surely not THAT mild!

[Thundersquall]

Which would actually give an outturn of about 11C, unless October gets up to 15. I know the outlook is mild, but surely not THAT mild!

Hmmm - but it could be a record-breakingly warm year on average.

What temperature was the hottest year on average and in which year did it occur?

[Snowly does it]

If this were the 1960s I'd agree with you, but seeing as three of the past four years have managed the level you suggest then achieving this and setting a new record would actually be anything but remarkable.

Didn't say it would SF, but they would need to be above average for the record to fall. I don't think they will be far enough above to take the record. We'll see.

[ukmoose]

I

Watch southerlies become northerlies in the weeks ahead with a winter pattern taking over from the current summer one. I'm not sure we can predict our weather on the prevailing atlantic basis that we used to. Perhaps our climate will become increasingly more continental and current assumptions regarding outcomes of the warming trend may have to be revised?

Tamara

T, I actually think the recent evidence points towards us becoming rather more 'mediterranean' than continental. Over the last 15 years or so, the increasingly mild, wet winters and increasingly hot, dry and sunny summers (all moderated by our more northerly latitdue) do point to a change, but not to a continental type in a climatic sense.

Moose

[Dawlish]

Not entirely balanced here Stratos.

Rewind the tapes. 2005, one of the warmest hemishpheric and global years. Temperatures across northern and western Europe widely +1.5 to 2 C for the summer months, a highly diminshed cold polar pool in historical terms.

And yet.....

A significantly cold winter for central and SW Europe, in some cases 2.5 to 3 C below the 1968 - 96 average. True, the cold never really got to the UK's shores, but in a climatological sense, that is but a hair's breadth due to the prevelant synoptics as the origin our sustained winter cold episodes are essentially the same as the rest of western Europe.

We must ask why did such a turnaround take place given such positive forcing of hemishperic surface temperatures ? Was there a masking of a really harsh winter ?

The answer to the second challenge is one that neither you nor I can confidently respond to and it likely take many more years to be able to conclude either way.

This year in many respects poses a re-run of 2005. The Atlantic SSTAs are very similar. The summer warmth is greater, and yet I would conclude at this stage the prospects for another winter with an increased probability of cold synoptics is entirely feasible - this time perhaps more so during January.

Should be a fascinating few months though either way.

GP

Hi GP,

Well argued. I may not agree that looking for analogues, or interpreting telecommunications is of proven practical use in in forecasting a winter to come, but it is well worth remembering that an average(ish) UK winter followed a very warm summer last year, which is a similar situation to this. Warm summers are not a precursor of a warm winter and never have been, statistically speaking.....but then again, a warm summer is not a precursor of a colder winter.

You are right about not being sure of what we saw in terms of a change in pattern, at least to more blocked, not being apparent for several years - though if the pattern changes back this winter, to more Atlantic/Bartletty weather, we can ignore last winter much more quickly, unless the next 3, or 4 years produce blocked conditions. Again, I think a real pattern change is unlikely, but your argument holds. The re-establishment of a pattern, after an anomaly, points towards a continuation of a pattern. A pattern change would take longer to establish.

I think you may be reading too much into similarities, GP. Similarities, to years past, have been well proven not to have a similar effect on that year's seasons to come. ie you can't forecast a season accurately using analogues, even if the analogue is the conditions in the previous year.

Paul

Edited October 22, 2006 by Dawlish

[Glacier Point]

Thanks Paul.

Yes a restablishment of a pattern following an anomaly would be suggestive of the trend for increased warming throughout the year. Two anomalies on the bounce, some inconvenient questions might be asked.

The problem comes if we get a highly average winter, but with the first widespread snowfall event in the last xx years. That wouldn't help us too much either way.

[Stratos Ferric]

Didn't say it would SF, but they would need to be above average for the record to fall. I don't think they will be far enough above to take the record. We'll see.

Above average over what period though? Given that the current trend for pretty much every month of the year is upwards taking an average of a long time series is not the most meaningful treatment of the data. The longer the series chosen, the more outlandish a warm-ish N+D appears, yet in the context of the even larger teapot it is starting to seem genuinely normal.