Well to say it's been a poor day for model watching ( if its cold you're looking for ) would be an understatement.The only consolation would be there's still lots of uncertainty beyond 7 days, however we all know deep down that this will be another missed opportunity as dark forces conspire against us and halt the cold before we become all giddy.

Yes it has. Initially the mean went down to -7C or so quite quickly and stayed there from about Tuesday. Now the -5C air doesn't arrive down here till Thursday and is gone by Saturday. What was a stiff northerly or even northeasterly has become a slack west-northwesterly.

its the idea that you view the individual ensemble members and arrange them in a continuum from the mildest to the coldest solution.  The one or 2 in the middle (to my earlier study of the GEFS at 168) was the solution as I have described it and illustrated here (ptb 9) Confidence in any solution is low. But there was a cluster of runs of this ilk between extremes.

That would work if you wanted to find the median in terms of temperatures for a given location. But how do you find a "median chart" for the whole of the North Atlantic like that? Surely that is impossible and it must just be the MEAN value for each point on the chart?

GEFS12z a big spread as discussed but more runs at a glance appear to be going mild.

That's exactly right, I calculate this from the perspective of SE England. 

Here is the Chinese perspective in a week's time:

Agreement up to the 15th which is 168h away.

Can't deny they're trending in the wrong direction in terms of prolonging cold. Let's hope by the time we reach next week we are gaining more support for a continuation for cold.

I'll be more worried when ECM and UKMO come more on board 

In any case at least it's still in FI and subject to change (again) 

Navgem at 180.  Cold holding on.

I thought that would be a real benefit for us, just goes to show

Wasn't the NAO forecast almost going off the chart a couple of days ago? Now look...

Like the strat forecasts, like the jet forecasts, like SLP model forecasts, they are all just predictions and susceptible to the same oscillations, its important that we recognise this. 

ECM12z 144 looks messy.

The 00z ECM had high pressure over Spain, too?

Granted, to t96 ECM and GFS are similar, although thereafter the Azores low is modelled differently on ECM at t120. Nervous to see how it evolves from there! 

Yes, I think messy describes the picture nicely.

Edit: Yes I was also going to comment that pressure was high over Spain on the 00z ECM too! 

I thought this was an interesting post.

It is perhaps a viewpoint underpinned by an implicit (& apparently widespread!) assumption that the weather is a deterministic system. A deterministic system is one in which no randomness is involved in the development of future states. A deterministic model will thus always produce the same output from a given starting condition or initial state. In this context, the poster proposes that if we had the data and the computing power we could calculate what the weather would be at a future point.

But I think that we all understand innately that weather is far from deterministic. There are chaotic elements - the proverbial flap of a butterfly's wings etc. - which influence outcomes. As forecast horizons extend the scope for these to have an impact increases. Given a specific set of starting conditions, multiple outcomes are possible. The weather that we get is one realisation, but there may have been other equally plausible outcomes at the point the forecast was made.

Criticism of NWP outputs on this board (and others!) often follows a pattern. Posters will say that the models are "struggling to tie down" a feature, or that the models are "always poor in this type of setup". With the benefit of 20/20 hindsight, posters will say the model was "wrong because it failed to pick up ... [height rises over the Azores?]".  Any verification gap is thus attributed to modelling weakness/failure, overlooking the possibility that something (chaotic) happened between the point at which the forecast was made and its realisation.

What is the point of all of this? I guess it's a plea for acceptance that the models aren't "searching for a solution". We shouldn't criticise them when they "flip-flop" from one outcome to another, especially where longer time periods are involved. There simply isn't one path that the models have to "lock-on" to. Weather has chaotic elements. If the models this afternoon don't show the extended cold spell they were showing yesterday it might not be because they are inaccurate. Something might well have changed!

NWP models are wonderful tools for forecasters. I'm sure that they have massively improved forecasting accuracy in recent years, and that these improvements will continue. But we should always remember that weather is not a deterministic system, and modulate our expectations and responses accordingly.

ECM 144 looks messy.

I've certainly learnt a lesson , all the models were showing a stunning output and with all the talk of a negative NAO and reading Tweets I got sucked in a bit, even this morning I thought that GFS was in the wrong field barking up the wrong tree.

Back to where I was a week ago hoping for a cold Feb

Slightly milder than the 00z? Milder air being dragged up quite sharply from the Azores low. Like you say though, very messy chart 

How can the Atlantic still when even though the building blocks for a cold spell are in place

AO and NAO going -ve

Likely SSW event

Heights rising over Greenland and Scandinavia

Cold air over Europe

It seems that the Atlantic will win regardless of any favourable factors

Big snow event M4 North at day 6. 

http://www.wetterzentrale.de/pics/Recm1442.html