coldwinter

The issue is at days 4/5/6, the low coming through the states is fast and the low in the atlantic stays in situ, meaning they phase, and when they phase its game over for the Greenland high that time. ECM and the 00z kept them separate

No proper split flow however, you want part of the jet going through the Labrador sea through Baffin bay and then back down the other side of Greenland, with the other part going under, that's when we get the super Greenland highs. Let's see if we can squeeze out this pattern enough to get the proper cold to the UK

He's right you know, it was only a little chilly

Yep, be interesting to see if they continue to show that, higher chance of unsetlled early Dec, but then possible downwelling in time for Christmas. Interesting stuff, so many things going on this winter!

Of interest

Its going to be another stonker in FI. Its fine margins getting the shortwaves to behave and ensuring enough amplification to link the siberian high with the Atlantic high

Absolute stonker of an ECM so far

Might be of interest......

Worth pointing out though that 09 had a very warm strat through Nov with very low zonal winds, but yes, crucial to see the blocking in the trop continuing to stop the strong strat PV from ruling the pattern, that's what we are all watching!

It really isnt uncommon to have blocking around the arctic towards the end of October. Long way off winter yet, what happens in the next 6 weeks in the strat is what we want to watch, amongst everything else.

Well i would say SST's are pointing to a weak -VE NAO but you have to remember that SST's are one piece of one very big and complex puzzle, it's never as simple as A=B, and the seasonals may well of been reacting to what is a very cold strat at the moment i believe. We are still a long way off

The issue is people take them too literally, banking on a cold winter based off weak blocking to the north isnt wise, anyway as Steve says, still far too early to issue proper outlooks, another 3 weeks at least before we can start wondering what early winter may bring, let's hope we arent staring down the barrel of a rampant PV.....

People keep saying the GLOSEA was completely wrong last winter and it just isnt true. Here was the Nov update A *weak* blocking signal to the north and troughing into eastern europe. Here is what actually happened A *weak* area of blocking to the north and troughing in eastern europe, it did miss the strong azores high coming through spain into the UK, but to say it was completely wrong isnt true. The anomalies for this year are VERY strong for what looks like a strong PV, looking at current modelling our high pressure over Taymyr and northern siberia is being replaced by low pressure, if that hold for the rest of this month that would favour a +ve AO, which could be what the model is reacting too. So, through this month into the all important November, we look for all of the usual stratospheric disturbances that will cause the vortex to weaken and promote blocking as we go into winter. It is simply too early to say what is going to happen in the next month and a half which lays the blocks for early winter at least. In our current QBO state any SSW is more likely to be later than earlier in the winter. So strap in and enjoy the ride Ryan.

Latest GLOSEA output makes for grim viewing for winter fans. Mild and wet

Not much point reading, as its just pseudo-scientific The Ural blocking in November is definitely interesting to watch, we had an anomaly there last year, which helped disrupt the PV, not quite giving the cold here that a lot of people wanted, but close and then eventually culminating in the SSW. Everything is linked and the atmosphere gives us clues, it's never as simple as A+B=C which i think people keep getting confused with

Plenty of papers on the subject as @interitus said in the other thread Error - Cookies Turned Off RMETS.ONLINELIBRARY.WILEY.COM

It's not "so tenuous as to be undetectable" All part of the puzzle, and putting the puzzle together through Autumn into winter is what many enjoy on here

The wintertime AO? Not linked soley, but this is the time of year the PV is spinning up, so of course we start the feedback loops etc etc, again, nothing in isolation and things CAN change quickly, it's all part of the puzzle!

Not a bad anomaly here with strong high pressure over the Taymyr region on the GEFS mean this morning, this is what we want to watch over the course of this month, maybe looks for an Aluetian low developing too?

I really don't understand why people feel it is so far fetched to see a link between the October pressure patterns and wintertime AO, nothing is ever 100% and i don't know how many times I have to say that! The pressure patterns link in with Cohens SAI theory, it is all linked, so then come the end of October we can start to build up a picture for winter, but of course what happens through November is crucial. So for now we watch and wait to see what happens through this October, the winter madness is approaching at break-neck speed

Just to back up the idea of the link between October pressure patterns and winter AO/NAO, a nice exercise here by Ant Masiello, again we see the higher pressure over the Taymyr region during October going into negative AO/NAO winters, so it certainly seems like a link there, Aluetian low possibly too? So as said before, the SAI and the OPI are quite closely linked, it's all about starting those feedback loops going into the winter season, ie weaker PV, stronger Siberian high, PV more prone to 'Attacks' etc. Again, nothing to be taken in isolation but it's all linked.

As i replied in the other thread, I'm sure there is a link between October pressure patterns and the winter AO, it links in with the snowcover advance index. These are some of the top negative OPI years, and top snowcover advance years i believe too, you can see the theme is higher pressure over northern siberian, the Taymyr peninsula, and the trough underneath, i havent been through all the years but it seems this synoptic definitely favours a negative wintertime AO. As we know, 2014 was a bust, so of course it isnt perfect, but there is something in it. Obviously the AO being negative is only one part of trying to get cold to our shores, but the AO/NAO correlation is about 0.7 if i recall correctly, so again we can start to build a picture of winter based off the October pressure patterns, the key thing is, and a lot of people forget this, is to never use one thing in isolation. October is the month where winter chasing really begins for many, going to be another interesting year, last year came so close to delivering, and an extremely weak PV going into winter, will we see the same this time, could it be the norm now with low sea ice and perhaps solar taking effect? As ever, time will tell! Regards

The OPI was linked in with the snow cover advance theory, as well as pressure patterns across the hemisphere, a predictor of the winter time AO. But people took it as a gospel for a cold winter, i feel it still has some merit wrt strength of the Siberian high, strength of the PV going into October, and possibly further 'attacks' on the PV through November into December. I certainly don't think its amazing, but there does definitely seem to be a link between October pressure patterns and the wintertime AO.

Hmm the GLOSEA actually picked out the blocking signal for winter from September 09, as with any model, pinch of salt on its output, especially at longer lead times, Octobers and of course Novembers update should have more weighting , the winter madness starts so early!

Could be worse, could have this guy at your front door