Model Output Discussion

[SP1986]

How can you give the GFS FI any credibility? It's clearly just a symptom of what's happening over Russia, but personally I find it very very unlikely. I'm very sorry that's not what everyone wants to hear but credibility has it's place, unfortunately that's not within FI runs like that

[pyrotech]

Read the posts tonight and thought i had slept for a few months, talk is like we have got to 3rd of March not December.

Winter has far to go and coldest temps more likely in 2010 Jan , feb.

Yes its teasing us with fi but its becoming a trend, GFS constantly playing with cold air and Ecm very similar in same time frame.

After a very mild period, which the models handled above average in my opinion even in to fi, we now have a chance of real cold heading in to Europe.

Its a upgrade for cold considering last couple of weeks. Heading to the UK is also well into fi and alot more can go wrong so its likely to fail. BUT if it does fail then a cold europe is a head in the right direction.

Its very 70s / 80s style and too me this setup will eventually bear fruit, just hope some on here have enough prozac to ensure they get to see it.

Enjoy the charts in fi but don't get sucked in , you know they will never be 100% right, upgrade or downgrade possible.

For the record GFS showed a cooling for this week with snow on some hills in FI last week, it happened.

[nick sussex]

A decent gfs 18hrs run to end the evening, as for FI lets leave that aside, i think when you're trying to plot a route out of one pattern to a possible colder spell the best route is the simplest, this means theres less that can go wrong and in the UK thats especially important.

As we've seen over the last few days some subtle changes in the model output with now the euro high coming into play,whether this can help deliver a change only time will tell but if you take a look at the archives on wetter from the 23rd of December 2005 and follow this through for a few days to see how a euro high can help deliver something altogether more interesting, the key then was pressure rises to the ne and not the typical euro high with low heights to the north and ne that we often see.

The way to cold with the current pattern if its going to happen will probably need the euro high as a first step. If we don't quite make it lets at least hope it can get far enough north to deliver some drier weather for the UK and even some inversion cold.

[swilliam]

A very entertaining 18z! And now a look at the ensembles:

http://www.netweathe...ensviewer;sess=

Karyo

Yes and interesting to look at the Reykjavik pressure. One thing is clear we are almost certainly going to lose the low pressure in that vicinity after 11th December - so something is certainly going to change - the question is what to. I like the 18Z tonight as that is definitely a repeat of Jan 87 - it just shows that that scenario is plausible in the current set up.

Cheers

Stewart

[TEITS]

How can you give the GFS FI any credibility? It's clearly just a symptom of what's happening over Russia, but personally I find it very very unlikely. I'm very sorry that's not what everyone wants to hear but credibility has it's place, unfortunately that's not within FI runs like that

I think you need to check Jan 1985 and look how that E,ly developed and then you will see the 18Z is perfectly plausible.

Here are the charts for Jan 1985.

http://www.wetterzentrale.de/archive/ra/1985/Rrea00119850101.gif

http://www.wetterzentrale.de/archive/ra/1985/Rrea00119850102.gif

http://www.wetterzentrale.de/archive/ra/1985/Rrea00119850104.gif

http://www.wetterzentrale.de/archive/ra/1985/Rrea00119850105.gif

When you consider I said last week there is a chance of an E,ly followed by a N,ly around mid month and thats exactly what the 18Z is showing. Now im not 100% certain this will actually happen but it remains a possibility.

The problem with this thread is many have the attitude of "it will never happen because of our previous bad luck". However this isn't really scientific and the models couldn't give a monkeys about our past disappointments. If it wasn't possible then it wouldn't be modelled by the GFS!

Now im not saying we should always believe the GFS F.I charts. However it does become tiresome that they are so easily dismissed. I wonder at times why some bother following the models!

[SP1986]

Looking back at certain patterns won't make this one happen. They're easily dismissed because these amazing scenarios havent actually come off, despite being shown at times over the last few years, I think people are forever in hope (I'm not saying there can't be hope ). If it comes off I'll be the first to hold my hands up and say I was wrong but in all fairness I don't think it's going to happen, if I did then I'd say so... there's no scientific reasoning for it other than experience, and it's not pessimism because I wouldn't gain or lose anything if it occurred or not.

However it's equally as unscientific to assume that is going to happen because it's in FI and has occurred previous runs surely - I guess were all playing the same game really?

But fair enough, afterall who am I to tell anyone something isn't going to happen when it's clearly engrained in people's expectations, enjoy it (the model runs that is)!

By the way I've previously stated my reasons for watching the models, but people don't remember I don't think so there's little point in repeating.

[weather eater]

A decent gfs 18hrs run to end the evening, as for FI lets leave that aside, i think when you're trying to plot a route out of one pattern to a possible colder spell the best route is the simplest, this means theres less that can go wrong and in the UK thats especially important.

As we've seen over the last few days some subtle changes in the model output with now the euro high coming into play,whether this can help deliver a change only time will tell but if you take a look at the archives on wetter from the 23rd of December 2005 and follow this through for a few days to see how a euro high can help deliver something altogether more interesting, the key then was pressure rises to the ne and not the typical euro high with low heights to the north and ne that we often see.

The way to cold with the current pattern if its going to happen will probably need the euro high as a first step. If we don't quite make it lets at least hope it can get far enough north to deliver some drier weather for the UK and even some inversion cold.

One other thing to note, the 18z is not far out of kilter with the ECM 12z at 240hrs, not identical but not bad.

[swilliam]

How can you give the GFS FI any credibility? It's clearly just a symptom of what's happening over Russia, but personally I find it very very unlikely. I'm very sorry that's not what everyone wants to hear but credibility has it's place, unfortunately that's not within FI runs like that

Why is it not credible - it is happened before so it can happen again. As has been alluded to before this evolution is similar to Jan 87.

Then we went from this

To this

and finished with this

Fairly similar I would say with a Euro low ridging North and connecting with an Arctic high to deliver a very cold Easterly.

That of course is not to say it is likely but neither is it incredible.

Whoops TIETS beat me to it.

Edited December 4, 2009 by swilliam

[TEITS]

Looking back at certain patterns won't make this one happen.

Fair enough, afterall who am I to tell anyone something isn't going to happen when it's clearly engrained in people's expectations, enjoy it!

I don't mean to be rude but since I joined this forum you often dismiss any model output that suggests a cold spell. Remember back in Dec 2005 when you were adamant an E,ly wouldn't occur and look what happened.

All im saying is all members should keep an open mind. At the moment im focussing on +240 because its this timeframe where the developments are allowing an E,ly to develop.

Just add that 1987 is another very good example.

Edited December 4, 2009 by THE EYE IN THE SKY

[SP1986]

and I'm pretty sure I held my hands up for that to admit I was wrong.

I hope you don't see me as a mild ramper/wind up because that's not my intention..

I'd love to say this easterly will come roaring down but in reality whilst I may be more popular with my views, it just doesn't scream out realism, which is what I'd prefer.

I want you to remember this anyway and if this does not come off I can at least get a little lee way on what I am thinking, if however it turns out the way many expect, then I will have to rethink my strategy when it comes to FI

[kold weather]

Well firstly I just would like to see high pressure over the UK, the models are actually underdoing the low pressure cells recently and so we could quite easily see the 18z set-up being over-run by a flat zonal jet. The thing that would argue against that is the split vortex and that would rather suggest a more amplified flow again and thus as long as low pressure doesn't end up being shifted further east as time goes along (which is quite possible still...) then we have as good as chance as anything else to get a high to develop close enough to the UK to bring cold inversions into play. From then on just about anything can happen but in the last few winters any easterly spell has come through some variation of that synoptic set-up.

[swilliam]

and I'm pretty sure I held my hands up for that to admit I was wrong.

I hope you don't see me as a mild ramper/wind up because that's not my intention..

I'd love to say this easterly will come roaring down but in reality whilst I may be more popular with my views, it just doesn't scream out realism, which is what I'd prefer.

I want you to remember this anyway and if this does not come off I can at least get a little lee way on what I am thinking, if however it turns out the way many expect, then I will have to rethink my strategy when it comes to FI

I think you are correct in that the charts shown are very unlikely to be real as the chances of them occurring are pretty low ( my guess would be about (10-20% - in line with the number of very cold ensemble members)). The problem arises with the dismissive language which implies zero chance and gets people going.

Cheers

Stewart

Edited December 4, 2009 by swilliam

[john mac]

I don't mean to be rude but since I joined this forum you often dismiss any model output that suggests a cold spell. Remember back in Dec 2005 when you were adamant an E,ly wouldn't occur and look what happened.

All im saying is all members should keep an open mind. At the moment im focussing on +240 because its this timeframe where the developments are allowing an E,ly to develop.

Just add that 1987 is another very good example.

I totally agree with you teits, people do need to keep more of an open mind, and i think we would have even better discussions on here

[TEITS]

I hope you don't see me as a mild ramper/wind up because that's not my intention..

No not at all mate.

What im trying to suggest to all members is we should keep an open mind and not instantly dismiss F.I charts. Like i've said many times the GFS predicts many outcomes and the trick of following the models is knowing which one is right.

Personally I feel model watching is going to become very exciting over the next few days and I wouldn't be surprised if the ECM starts showing some interesting synoptics!.

[pyrotech]

and I'm pretty sure I held my hands up for that to admit I was wrong.

I hope you don't see me as a mild ramper/wind up because that's not my intention..

I'd love to say this easterly will come roaring down but in reality whilst I may be more popular with my views, it just doesn't scream out realism, which is what I'd prefer.

I want you to remember this anyway and if this does not come off I can at least get a little lee way on what I am thinking, if however it turns out the way many expect, then I will have to rethink my strategy when it comes to FI

I think the cold air will effect many European states, excessive cold for some. For us in UK probably see a downgrade as something does not sit right for me.

We all moan about fi but lets be honest, if it was 100% set in stone what would their be to discuss?

Its a start for cold lovers, and will be interesting to see what GFS does over the weekend.

No point arguing about it as will make no diffrence to result, I TOLD YOU SO may be in order between users can be fun.

My take is this ........... Something in between, vry cold for Europe, close but not quite for uk, to me that will be an upgrad from what we had so far, and sets up a good base for something special in the medium term.

Good night all

[swilliam]

No not at all mate.

What im trying to suggest to all members is we should keep an open mind and not instantly dismiss F.I charts. Like i've said many times the GFS predicts many outcomes and the trick of following the models is knowing which one is right.

Personally I feel model watching is going to become very exciting over the next few days and I wouldn't be surprised if the ECM starts showing some interesting synoptics!.

I would also add about cold lovers dismissing runs that don't show their favoured synoptics. Often we read that one run or another is being 'binned' for some reason or other and usually as far as I can see it is because it does show them what they want to see. As far as I am concerned all runs are equally valuable in making an assessment of what is likely to happen.

[Geordiesnow]

Now before we dismiss the pub run's latest drunken antics, this easterly is at the same time as was suggested the other day. We are always told to pick trends from FI after all...

True but you still can't say the easterly itself is a trend because not all runs have shown this however most models runs have shown height rises of some sort. How they affect us is one thing is not certain.

I'm glad the 18Z FI has lifted in the mood in this thread(for the time-bean!), hopefully it can be a bit of a wake up call to those who wants to dismiss December despite being only a few days in December.

Won't surprise me if the 00Z brings us back down to earth but if it does, hopefully people will see that an cold set up is still possible.

[Thundery wintry showers]

Personally I think Stephen Prudence has a good point. Yes, it isn't an implausible setup by any means, but the number of variables that have to come into place for an easterly to develop around mid-December are very large. And even if we do get one, it could end up like mid December 1997 (another El Nino winter!) with 36 hours of snow flurries for southern England and nothing but stratocumulus and 5C for most of northern England and Scotland. Or, even worse, an easterly spell like 5-15 December 2002 (at least the 1997 one brought a fairly widespread snow cover in the south- not so in 2002!).

I am confident that very cold continental air will head towards the British Isles around mid-December associated with a build of pressure to the E/NE but it's quite a tall order to get it as far west as Britain itself. That's not saying that it's impossible- just an outside chance rather than a high probability.

Cold/snow lovers will just have to be patient in the meantime- it's no good getting excited over one FI run only to be dashed by the next. GFS FI is merely showing the range of possibilities that this synoptic setup holds, which range from the mild & moist to the cold & bright with heavy snow showers.

[Duane S.]

So many are so quick to dismiss charts that show cold purely and simply because we don't normally get proper cold here in the UK. Fair enough but it is a bit of a rubbish way of looking at it. Often the only basis of rebuffing a particular chart run is as simplistic as that. We are all pragmatic enough (I would hope) to understand that the FI scenario the 18z is far more likely not to happen than to happen.

But... IMO the scenario being painted here is VERY plausable. As some have already alluded to, possibly our best route in is with the Euro high building at the same time as the Atlantic tails off and heights build to our N / NE. A classic dogleg movement of VERY VERY cold air COULD (if we got lucky) be sent steaming down from the arctic towards us, aka the 18z.

The prospect that for once the timings could be on our side is what interests me the most at the moment.

Edited December 4, 2009 by s4lancia

[SP1986]

I think at the moment we can be fairly confident that eastern Europe will see some deep cold, and I'm really looking forward to seeing how that effects those areas. To see temperatures of -20C or lower in some countries like Ukraine and Bulgaria would be very interesting.. if that came over here that would be a bonus for sure, but looking at the pattern my own personal take is that we will get the low pressure much as we are now.

If I am to be open minded I do think that if low pressure comes over us and the High is held at that position with it's western extent over eastern France/Western Germany, then snow over the UK is a possibility as the low pushes up against the high.

I don't hold much hope of it unravelling like the GFS FI shows, but if the possibilities must be discussed then there's a potentially cold one in two scenarios

The main problem perhaps with the 18z is the fact that this scenario is near the end of FI, and we have to go through 3 defined patterns to get there - also s4lancia altough you say very very cold arctic air would follow in that setup, the GFS does suggest it would be riddled with warm sectors - just going by what the charts are showing for this particular scenario

[Stu_London]

An interesting read of this thread, which personifies the winter period on NW with it's mood swings.

The reality is that not a lot has really changed over the last 36 hours. We have maintained 4 or 5 cold runs on each of the 6 hourly GFS outputs - and a high proportion of these have manifested themselves on the operational runs.

The euros don't go out that far and show a fairly mild pattern for the most part (but then again so does the GFS in the same timeframe)

Based on a combination of ensemble probability and our experience of how FI has performed in past situations, a cold, potentially severe spell around mid month has been consistently a 5-10% chance.

On that basis, the huge levels of excitement and depression (about equal in measure)we are witnessing are beginning to enter the realm of tedium.

[john mac]

Well it will be very interesting to see what tomorrows models have in store for us, Although the weather is not great at the moment its been a while since we've had such an interesting start to winter with models showing these cold synoptics early on. One thing is for sure, if the cold keeps showing itself more people will take notice and the excitment will grow, and this forum will be buzzing. I wait in anticipation

[ScottSnow]

When you consider I said last week there is a chance of an E,ly followed by a N,ly around mid month and thats exactly what the 18Z is showing. Now im not 100% certain this will actually happen but it remains a possibility.

The problem with this thread is many have the attitude of "it will never happen because of our previous bad luck". However this isn't really scientific and the models couldn't give a monkeys about our past disappointments. If it wasn't possible then it wouldn't be modelled by the GFS!

Now im not saying we should always believe the GFS F.I charts. However it does become tiresome that they are so easily dismissed. I wonder at times why some bother following the models!

[osmposm]

....Like i've said many times the GFS predicts many outcomes and the trick of following the models is knowing which one is right.

Well, on a light-hearted note, TEITS, that's stating the bleeding obvious ...unfortunately nobody on this planet has yet managed to perform that particular trick!

So we look as well - or some of us do - at what the tendency in recent years has been, which is to continue to offer the theoretical possibility (which there certainly still is), but never really to deliver it in practice...that is to say, in profound and/or prolonged cold terms, of a sort which used to come along from time to time. It was always the exception, the probability was never high; but as you would expect in an even statistical playing field, now and again it came off. And inevitably that begs the question of why it has been so long - much longer than ever before in the CET record, as I set out here: .

In another post, TEITS, you talked of "our previous bad luck", and suggested that assuming that it will continue "isn't really scientific". I would gently suggest that ignoring the current run of 'bad luck' is also not very scientific, since its unprecedented length suggests that there has been, in fact, more than just 'bad luck' going on here.

Edited December 4, 2009 by osmposm

[Iceberg]

Good agreement from the models for a more settled spell 11-13th of December as the Atlantic finally takes a breather.

It then looks like starting up again, the big question is whether or not the Jet will have a better orintation on it, the GFS and ECM cold scenario's take the Jet down to Africa due to it's direction leaving the US. This allows us to tap into the cold.

The warmer GFS and ECM runs pretty much take us back to square 1.

This is only a slight oppotunity IMO, but is the first of winter and worth looking out for, maybe 25%.

The key for the above is the Jet leaving the US at the 210-288 time frame. its moving closer to the realistic 144Z but we've will have to wait until the begining of next week IMO.