I see by 240 the GFS is completely different again to its 0z run.

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Thanks Steve 

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I am surprised nobody else has taken issue with this statement.

You assert your opinion as fact, even although the majority in the scientific community would disagree.

The debate basically boils down to 'Free will' versus 'determinism'.

If I am asked to 'freely choose' to raise one of my arms in the air I will certainly appear to have a free choice and free will. If I raise my right arm however, was I preordained to 'choose' to raise my right arm? So then I might think well I will demonstrate my 'free will' and actually raise my left arm. Again though, was I preordained to choose to raise my left arm in that exact scenario?

There is not outright consensus within the scientific community but the majority these days are weighted towards a deterministic model.

So basically, just because there is the illusion of free will and choice does not epirically prove in any shape or fashion that there is indeed free will and choice.


Now that is debating 'Free will' versus 'determinism' in human beings with consciousness and at least the illusion of free will.

The weather is reactionary to synoptics, it does not have a 'mind' or 'free will'. There weather WILL act in a determined manner to given synoptics. I.E. If the dew points, temperature, precipitation amounts etc are a certain way then it will snow and if it is 50°C with no precipitation then it most certainly will not snow. The weather is a reactionary result of hard synoptics and science.

In that light if a shortwave emerges that was not shown in output several days before and completely alters the forecast, the weather did not 'decide' to throw a shortwave up, it was always going to happen in the given synoptics, the computational power just failed to pick it up. There are so many variables to account for in weather forecasting that the models have trouble exactly resolving what will happen and this causes a ripple effect further down the line that can result in massive swings in model output. This does not for a second mean the weather decided to change what it would do from one day to the next, it means the variables were not effectively taken into account in the first place, what was going to happen indeed happened in a completely determined manner.

If the weather was not deterministic then weather forecasters and governments would not be throwing money at computers with ever increasing processing capacity, if future weather was not determined then this would be an insane waste of money.

Another avenue of enquiry which completely refutes your assertation that the weather is not determined is that over the decades weather forecasting has improved it's accuracy, if the weather was not determined and what was going to happen changed from day to day then this would not be possible.

In summary, whether all human existence is determined is a point for debate although opinion is leaning towards it being determined. The weather has far less variables than the sum of human existence and is almost certainly pre determined, to suggest otherwise would be to suggest the weather has a 'mind' and even then it would probably still be determined. Just because there are a miriad of variables that can be nearly impossible at times for us to predict, and the model's handle on it flips from day to day, does not mean the outcome is not pre determined.

 

I wont quote all of this - but well written, marky1... Chaos Theory in a nutshell that is and spot on!

 

 

I disagree that it is spot on. The whole point of chaotic systems like the weather is that they CANNOT be predicted from a given starting point. We can't say what will happen in a couple of weeks because if, say, an aircraft is diverted from one airport to another in two days' time, its exhaust will be heating a different part of the atmosphere than it would otherwise have done, and it might leave a vapour trail in a different place which will affect solar heating, and these tiny changes will cause other small changes and so on and so on, and significantly alter the course of the weather once you get several days down the line

In chaotic systems, tiny changes at the start point turn into massive changes. In deterministic systems, tiny changes at the start will only lead to tiny changes down the line.

 

In summary - very accurate forecasting beyond a few days will NEVER be possible.

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No, no it's God that decides what sort of weather to give us, dependent on what sort of mood he's in that particular day!

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Of the theories I posted yesterday (or was it Sunday), the one about the stratosphere forcing the return to a +ve AO has risen to become the most likely explanation for the changes being observed beyond around +144 hours on ECM in particular. Essentially, as some strong wave breaking begins to propagate in from the mid-latitudes, the vortex is focused into a more intense feature for a time. Only after that do we see the SSW land a heavy blow... assuming we do manage one, that is.

It makes a lot of sense for the proposed +ve AO to combine with the SST pattern in the Atlantic to bring a return of the Euro High, however it is quite common for the models to bring about these large scale trop. responses too quickly and end up adjusting to a slower progression.

 

ECM has toned down the rise of the AO on the 00z compared to the past few op runs from the model, and with this comes a slight reduction in the support for the northern arm of the jet (extending NE/E from the split in the western Atlantic, west of the mid-Atlantic ridge) to dominate proceedings. This has resulted in a +144 hour chart that looks less convincing with respect to the Atlantic storms powering through afterward. If the southern arm of the jet is increased in strength relative to the northern one, and/or the upstream jet strength is toned down much further, the balance should tip in favour of the blocking high holding its ground across the UK beyond the weekend.

GFS is also displaying a similar trend, but it's bias for favouring the northern jet arm out of a split is not helping with seeing the results. Just the subtlest hints from the 06z in that weak trough disruption on Monday's chart.

UKMO has been our shining star lately in consistently giving the southern jet arm more of a say in matters. The heart-shaped high at +144 is a classic signature of a blocking high that's keen to gain a little latitude.

 

It's too close to call really. We could see something like in Jan 2013 in which the UKMO nailed a jet split at +144 while ECM took until as short a range as +96 and GFS wasn't up to speed until inside +72 hours. It really was bonkers! Or it could be one of a number of cases in recent times where UKMO has gone off on one for a number of runs only to back down. It is notable, though, that the current period of divergence from the pack is the longest I can recall in the past year or so. Very interesting times indeed.

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Amen

Interesting!

The contrast of deterministic vs free will is - as you say - irrelevant.

It may be more instructive to view systems as existing on a spectrum from chaotic (let's say next weeks lottery balls) to deterministic (let's say the movement of the planets during the next week). Weather exists in the space between the two and is perhaps best described as probabilistic. Clearly there are patterns, there are actions and reactions driven by synoptics etc as you say. NWP models are based on these and are incredible human achievements. But to make an argument that all weather for ever is pre-determined and could be calculated given enough data and computing power looks like an uphill struggle to me. Volcanoes erupt, chunks of ice slide into the sea.These are usually defined as exogenous events as far as weather forecasting is concerned - you have to have limits to the system you are describing somewhere!

My point is only that we should remember that there are random/chaotic factors that influence the weather. These factors can and do exert influence in the gap between forecast and realisation. So sometimes the NWP forecasts will be wrong not because of design or implementation error, but simply because something not modellable has happened somewhere.

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IF you can calculate EVERY detail of the system, then you can predict the outcome.  The problem, is that we cant capture every detail of the starting point - we dont even know what every detail of the system is...  that doesnt mean that its not deterministic...  a Chaotic system doesnt mean that it behaves randomly, but one that is highly sensitive to the starting conditions

Why is this page not updating? It only updates when I post! -is it the page or my browser settings? -The last updated is thus:

Gooner
#781 Posted : 11 January 2016 23:22:01

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But it isnt a spectrum... its one and the same.  as per my post above, a Chaotic System isnt random... its still very much deterministic, but one that is very highly sensitive to its starting conditions 

http://www.weerplaza.nl/15daagseverwachting/?type=eps_pluim

De Bilt from the ECM 00z

i can't remember the previous one but it looks like a better cluster going for continued cold.

more twisting and turning!

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GEFS6z offers a lot of support for a milder outlook next week. Could be wrong! Here's the control run: 

http://www.theweatheroutlook.com/twodata/chart.aspx?chart=/charts/gefs/0_180_500mb.png?cb=379

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The aircraft's exhaust vapour trail is simply another variable.

The vapour trail will have a wholely determined impact upon it's enviroment, I.E. If the amount of exhaust fumes are enough to mean a change occurs then that change will occur.

The amount of variables that would need to be taken into account are utterly mind boggling, a grain of sand moving in a different direction on another continent could influence the weather down the line. That doesn't for a second mean it is not determined. It simply means it is unbelievably hard to take every variable into account and have a completely accurate forecast, it doesn't for a second mean it is not determined, it means it is extremely hard.

The grain of sand or exhaust fumes are going to have the effect on the weather that they will in line with science.

Now you could say that the pilot altered his course so he chose to alter from his 'plan' so it could not be predicted. That is why I said in my original post that it ultimately boils down to free will versus determinism. The weight of academic opinion would argue that the pilots change was determined and thus just becomes another variable that would have to be taken into account.

I do not think for a second that in the near future the weather will be forecast with complete accuracy, the variables are as I said mind boggling, that doesn't mean it cannot be done and it certainly doesn't mean it is not pre determined.

In a 'determined' system there are no 'changes'. The statement is paradoxical, if it can be 'changed' then it wasn't determined.

Have you tried F5 for a refresh?

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But it is not only sensitive to the starting conditions, it is also sensitive to external influences which will alter the future starting conditions. Even if you knew exactly what every molecule in the atmosphere was doing right now, if I ran outside and waved a leaf-blower around, or lit a bonfire in my garden, I would change what the weather will do in a month's time.

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Well as that chart is completely different to the one produced for the same day just 6 hours ago,I think I might discount it.

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The balls drawn 'can' be viewed as deterministic too. There would be an unimaginable amount of variables to account for to begin to work out what balls would be drawn. Enough variables to mean that attempting to predict this could be regarded as a futile exercise, that doesn't mean that it CANNOT be done and it doesn't mean that it empirically cannot be done, it just means it would be immensly difficult. Therefore the 'spectrum' you mention isn't a spectrum.

 

Again because something is immensely difficult doesn't mean that it CANNOT be done and doesn't mean it is or is not determined, it simply means it is difficult.

 They are still simply variables, extremely hard ones to predict but variables none the less.

Not if you consider infinity, if we infinite knowledge and infinite computer processing power then it would be possible to predict the weather with complete certainty long into the future. It would take the mystique away for sure, and the computational power and knowledge needed is far beyond my comprehension but it is certainly 'possible' as what will happen with the weather down the line is basically a monumental equation which could be calculated.




That is just adding another variable. I don't think anyone would argue that the amount of variables are immense to put it mildly. It doesn't mean that your actions or that of the weather are not determined.

I think UKMO will back down tonight. I wish Steve Murr is right, but all the other output points to the jet powering over and not under.

Latest GEFS are even worse. I think its time to call time on this. UKMO has led us up the garden path

 

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Quantum Mechanics might have something to say about this!

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Yes - that's the point of a deterministic system.  if you can calculate the starting conditions, you can calculate the effect of you lighting a bonfire or waving your leaf blower...

 

Just because we dont have the ability to currently do that, doesn't stop the system being deterministic - just makes it very hard for us to calculate the eventualities

Of topic - but surely infinity means "not finite" i.e. not determinable ?

All the variables will never be able to be measuared as they are all changing all the time (i.e. at an atomic level and space/time level and beyond)

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Not quite sure why a few are bashing GFS for its different outcomes. The UKMO would have the same issues if it went beyond 144. ECM ENS and GEFS are showing many possible outcomes (which is very normal) but IMO, the trend is growing for an Atlantic breakthrough... at least temporarily.

I still think UKMO will begin cracking this evening with the High slowly being eroded and nudged ESE.

 

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Thats a flooding chart for the NW.  One has to hope it doesn't turn out that way.  Sod's law and all that....😔

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