Sevendust:

I recall Jonny got a bit of flack last year for doing something similar in May.

To be fair to Jonny the MetO do much of the groundwork for their winter forecast in May, and they have done well during recent years. So I'd have thought this is a decent and valid topic for discussion. FWIW, I'd not be surprised to see the MetO call a cold one this year, BUT (BUT..BUT..BUT) it's a huge gamble. They'll cover themselves with something along the lines of, "but we don't know whether the warming of recent years will have an impact". I think they did this in 2005/06. It's worth remembering that the MetO produced some research a couple of years ago suggesting that the years ahead bring an increased risk of -NAO conditions.

DEW:

brogdale:

DEW:

sriram:

We are well overdue a cold and snowy winter 

But years (or days for that matter) are not independent events. Therefore we are more likely to see a re-run of the previous day/week/year than to see a break in the pattern, in general terms; and only if there is specific evidence (NAOs or change in course of jet or whatever) for a break in the pattern is that prediction likely to change

but surely Sriram was just making the fairly straightforward point that if sustained severe (winter) weather (1962/3) has a statistical recurrence time period, say 200 years (), the each year we go without such events must surely 'shorten the odds' on a recurrence?

If indeed he and you are making that point, then you are (I regret to say) statistically speaking quite wrong.

Consider tossing a coin. By your argument, a sequence of, say, 10 heads makes  the next toss virtually certain to be a tail. Alas, the penny doesn't remember what it's been doing and the next toss is still equally likely to be heads or tails. In fact, you might well argue that the next toss is actually more likely to be heads, as someone might be trying to wind you up with a double-headed penny

My argument is that the situation as regards weather is worse than that of the penny. The weather may well 'remember'  what it has been doing, but only in the sense that a pattern once established tends to persist. So repetition is more likely than variation. In some respects, that's what global warming predicts.

Thanks for that

The crux of our diagreement would appear to be whether or not one subscribes to the notion of any form of cyclical behaviour within the atmosphere. I do happen to think that the atmosphere behaves in cyclical patterns, and that we obviously are at a very early stage in our appreciation of such patterns, their causes and potential for inter-relatedness. So, for me, you analogy with the coin tossing does not appear totally convincing; clearly you are arguing about the probability of a sequence of independent and unrelated events (each one with a 50:50 chance). If you do think that such an analogy is fit, it would seem that you are discounting any form of cyclical pattern in the weather

Most on here would surely recognise that the chances of any one year seeing an ENSO event would increase with each additional year following the last event? Or am I just showing up the limitations of my Mathematical ability? If so I can only offer my apologies

Brian Gaze:

Sevendust:

I recall Jonny got a bit of flack last year for doing something similar in May.

To be fair to Jonny the MetO do much of the groundwork for their winter forecast in May, and they have done well during recent years. So I'd have thought this is a decent and valid topic for discussion. FWIW, I'd not be surprised to see the MetO call a cold one this year, BUT (BUT..BUT..BUT) it's a huge gamble. They'll cover themselves with something along the lines of, "but we don't know whether the warming of recent years will have an impact". I think they did this in 2005/06. It's worth remembering that the MetO produced some research a couple of years ago suggesting that the years ahead bring an increased risk of -NAO conditions.

 

This is a very interesting topic Brian.

 I think the MetO are getting wise to the massive media over-reaction that accompanies even three days of northerly winds these days. To be honest I think that even if they could genuinely see another 47,63 or 79 on the cards I don,t think they would put it out there in September or October for public consumption. They would probably go for some thing like '' considerably colder than average and then ratchet it up with each monthly update.  One only has to look at the c**p that was printed in the media ahead of 2005/6 to see what would happen if the MetO publicly went the whole hog for a genuinely hard winter.

Having said that I,m sure they would let their commercial clients know their private thoughts well ahead of time if they really did see a hard winter on the cards. 

brogdale:

We are just a couple of weeks short of May when the MetO will be starting to work on their LRF for the winter 2008/9 NAO index. One of their key indicators will be the spatial pattern of N. Atlantic SST anomalies and as we approach May I thought it would be worth looking at the seasonal pattern emerging in the N. Atlantic to see if we can pre-empt the MetO's NAO call this year.

Here is the latest seasonal pattern:-

 

and this can be compared with the MetO's own predictor pattern for a +ive winter NAO based upon May SST anomalies.

Ummm.....some evidence of a negative image there

Game on...it's looking like a cold one for sure...remember you heard it here first

I did mention over a week ago that the met office where lilkley to go for a colder than average winter!

But someone decied to delete my post.

 

I did mention over a week ago that the met office where lilkley to go for a colder than average winter!

But someone decied to delete my post.

Quote

Oh dear....that's a shame

but at least you can now post in this thread. Were you basing your prediction on SST anomaly patterns as well

Well to me our current SST pattern from the map above seems to be  the complete opposite to the one that the MET compile there "negative" NAO LRF from. 

If Warm/Cold/Warm = negative NAO for winter then surely the current Cold/Warm/Cold pattern will mean the opposite, i.e positive NAO for next winter? 

Thought I would bump this one back up because I think it is a well worth discussion by those who are interested.

We are now obviously well into May and the analysis of the May SST's will no doubt be in full swing now and to be honest it continues to be quite interesting if you take the following images;

http://weather.unisys.com/surface/sst_anom.html

http://www.metoffice.gov.uk/research/seasonal/regional/nao/images/svd_patterns.gif

Given the current SST and previous weeks patterns you would have to say that in general the current setup is opposite to that of what the UKMO suggest is required for a +ve NAO winter.  We may well be quietly surprised by what is initially published this year, as long as none of the other big players (La Nina, El Nino, QBO etc) become significantly dominant there may well be some hope for this coming winter.

Brogdale et al...current thoughts?

Cheers, Matt.

I'm keeping on an eye on this every day now. Very quietly, day by day, I think the pattern thats evolving is taking us further and further towards a negative NAO pattern.

I still have a few concerns;

1. Temperatures in the tropical Atlantic still need to pick up

2. I'd like to see warming taking place in that north-eastern corner of the Pacific.

3. Just a general concern about La Nina. I wouldn't rule out La Nina to start re-strengthening again around September/October and having another go at us through next winter.

All thoise caveats said, I think the Atlantic is heading towards being pretty well set up for a negative NAO call from the Met Office!

I have to agree and May SST's do show a negative NAO trend for Winter. Again there will have to be neutral ENSO conditions during this period for a lengthy cold Winter. Otherwise another La Nina will easily limit the Northern blocking during this period. 

Not concerned about tropical Atlantic SST's needing to pick up because in a negative PDO phase this normally doesn't happen.

There is still this perception that -ve NAO = cold winter. It doesnt We saw plenty of -ve NAO charts last winter where it was dry and average temp wise in the UK due to the euro high

JoeShmoe99:

There is still this perception that -ve NAO = cold winter. It doesnt We saw plenty of -ve NAO charts last winter where it was dry and average temp wise in the UK due to the euro high

 

Bit it increases the risk of a colder winter Joe. 

JoeShmoe99:

There is still this perception that -ve NAO = cold winter. It doesnt We saw plenty of -ve NAO charts last winter where it was dry and average temp wise in the UK due to the euro high

 

Show me a cold Winter in the UK with a +ve NAO.

We know the sign of the -ve NAO can cause mild as well as cold conditions. (takes a rare synoptic for this to happen though) Say if these persisted all/most of Winter it would be cold overall.

Must be getting confused between 850mb temperatures and surface. 

Plenty of -ve NAO last Winter, where?

Notice the negative phase occured during the cold period in December, which ended up below average for England and Wales.

Charmhills:

JoeShmoe99:

There is still this perception that -ve NAO = cold winter. It doesnt We saw plenty of -ve NAO charts last winter where it was dry and average temp wise in the UK due to the euro high

 

Bit it increases the risk of a colder winter Joe. 

Yes, I agree the chances are better but I think using a single teleconnection index is foolish to base winter forecasts on...espeically in May! All the index does is reflect a pressure pattern in the western atlantic. What about AO, ENSO, PDO etc etc etc. I know lets throw stratospheric warming and solar cycles in too since they seem to be in vogue!

Even if the May signals were hugely -ve the MetO would still call an 'average' winter with the possibilty of a few cold spells. i.e. like any other winter. I just dont see a) why people care what the meto say because its so granular it doesnt matter and its worded so its more or less never wrong whatever happens and b)calling a winter forecast the previous may is like calling the lottery. We cant even predict next week with any accuracy

JoeShmoe99:

Charmhills:

JoeShmoe99:

There is still this perception that -ve NAO = cold winter. It doesnt We saw plenty of -ve NAO charts last winter where it was dry and average temp wise in the UK due to the euro high

 

Bit it increases the risk of a colder winter Joe. 

Yes, I agree the chances are better but I think using a single teleconnection index is foolish to base winter forecasts on...espeically in May! All the index does is reflect a pressure pattern in the western atlantic. What about AO, ENSO, PDO etc etc etc. I know lets throw stratospheric warming and solar cycles in too since they seem to be in vogue!

Even if the May signals were hugely -ve the MetO would still call an 'average' winter with the possibilty of a few cold spells. i.e. like any other winter. I just dont see a) why people care what the meto say because its so granular it doesnt matter and its worded so its more or less never wrong whatever happens and b)calling a winter forecast the previous may is like calling the lottery. We cant even predict next week with any accuracy

 

Yes I agree. However, its called sods law in that we sit under the wrong side of the block, while the rest of Europe is bitterly cold and has snow upto their necks!

JoeShmoe99:

Charmhills:

JoeShmoe99:

There is still this perception that -ve NAO = cold winter. It doesnt We saw plenty of -ve NAO charts last winter where it was dry and average temp wise in the UK due to the euro high

 

Bit it increases the risk of a colder winter Joe. 

Yes, I agree the chances are better but I think using a single teleconnection index is foolish to base winter forecasts on...espeically in May! All the index does is reflect a pressure pattern in the western atlantic. What about AO, ENSO, PDO etc etc etc. I know lets throw stratospheric warming and solar cycles in too since they seem to be in vogue!

Even if the May signals were hugely -ve the MetO would still call an 'average' winter with the possibilty of a few cold spells. i.e. like any other winter. I just dont see a) why people care what the meto say because its so granular it doesnt matter and its worded so its more or less never wrong whatever happens and b)calling a winter forecast the previous may is like calling the lottery. We cant even predict next week with any accuracy

Joe, the chances aren't only better, they are the only chance for the UK.

The MetO called a colder Winter not average last time and I'm sure would not just go on this. I would agree with bold highlight for example with a weak/moderate La Nina or El Nino during the positive PDO and less so during the current negative PDO.