Model Output Discussion - Sunday 20:35--->

[Bristawl Si]

This is just one run; things will evolve over the next few days. But how?

We'll either end up with a boring high that settles things down, cold days and nights, fog and frost, but what follows is a return to the atlantic eventually or the high will dig in, gradually pulling in colder and colder air, with pressure falling to our south and setting up dream synoptics. Here's hoping

It's good model watching this week that's for sure. It's only a week or so ago that there was a massive air of despondency on here, but what's developed over the last couple of days just shows how quickly things can change (well, hopefully there will be change! )

[SP1986]

Usually however the one situation where if anything the cold tends to get upgraded is on these HP set-ups, seen it countless times before and not always in inversion situations either, I think its because they don't handle low level cold very well full stop.

Inversions are often mistaken for cloud, I remember last year the GFS forecasted 5C and cloud, turned out to be foggy and 0C. I'm not sure whether the GFS figures inversions into the output.

[chionomaniac]

I suppose once you've had fillet steak this appears to be a bit of old rump but its impossible to judge exactly whats going to happen with the shortwave. On a positive note if we had not seen the FI output and were just hoping for something more seasonal then this would be a very good run. I sort of find it difficult to gripe too much about this gfs run as compared to the recent monsoon for the UK it's a welcome change.

Overall the shortwave looks like driving everyone mad but in the meantime at least we have some colder and frostier weather on the way.

I don't believe Nick that the short wave is the problem with the 18Z run. The Canadian segment of vortex was much further east and north and in a far more unfavourable position sitting alongside western Greenland. This prevented the height rises there as seen on the 12Z. I wouldn't be concerned from 1 run this far out though it does highlight how easily the door can get closed.

[SP1986]

Its on a knife edge ste.

Although you are probably in one of the worst places geographically speaking if the ecm for example were to come off.

The pennines would be the spoiler for you i suspect.

Well I'd get some of the coldest weather in the UK were it to come off, as it has a longer land fetch. Northeasterlies as subscribed on the 12z would probably give my area the coldest temperatures in the country, whereas 18z would probably give some of the coldest temperatures but not the coldest temperatures.

No snow though.

[kold weather]

Deep cold anyway Steve, however I think the models will still develop a cold high pressure cell, probably developing an inversion (and I know what Stephen said but eventually it will develop if that high holds for more then 5 days I'd have thought)

Besides, as much as people may moan about the 18z, it still gives us ice days!

[Andy_]

yeh the parralell run once again comes up with them dream sypnoptics i think this thread would be even busier than it is now if it had replaced the current GFS now,

quick question, could someone explain what an inversion is? oh and a shortwave? sorry am still learning haha

[Jason H]

Unlikely in one word.. I definitely think the 18z operational is the closest yet to what I would expect the outcome will be, realistically

Why is that the most likeliest outcome? It has has much chance as the previous operational. As you've been banging on in all your post tonight, we should ignore the FI charts. Does not compute!

[cooling climate]

The GFS model is doing its normal built in flaw with the shortwaves here's hoping that both

GFS and the ECM are more in line with the UKMO at t144 then we can rest much easier.

[johnny1972]

Id imagine Mr Murr would happily take this,

http://91.121.94.83/...nh-1-276.png?18

Something must be brewing this winter ! I dont recall a winter chart with such intense cold across the Northern Hemisphere for quite a number of years !!

[Cecil Hogmanay Melchett]

Well I'd get some of the coldest weather in the UK were it to come off, as it has a longer land fetch. Northeasterlies as subscribed on the 12z would probably give my area the coldest temperatures in the country, whereas 18z would probably give some of the coldest temperatures but not the coldest temperatures.

No snow though.

Yes,we need a good old North west wind.On the other hand i do quite well from easterlies,lets hope we get one.

[SP1986]

Why is that the most likeliest outcome? It has has much chance as the previous operational. As you've been banging on in all your post tonight, we should ignore the FI charts. Does not compute!

Evidently not, as of course you want the cold, of course my view isn't going to be popular, it's the likeliest outcome because it sides with the GFS ensembles, plus the ECM ensembles. All it means its there is unlikely to be a severe cold event at least not now. It doesn't mean it wouldn't be cold though, with I suppose potential inversions occurring.

I will keep banging on about until I see reason to change my opinion (if I have to)

[mountain shadow]

Deep cold anyway Steve, however I think the models will still develop a cold high pressure cell, probably developing an inversion (and I know what Stephen said but eventually it will develop if that high holds for more then 5 days I'd have thought)

Besides, as much as people may moan about the 18z, it still gives us ice days!

Exactly, worst case scenario is still cold and frosty.

As Steve Murr was saying above, it is still a knife edge situation and one that cannot be resolved in the models yet. I wonder if the teleconnection guys can give us a clue?

As a positive, the parallel is the new upgraded GFS, so perhaps Op run can be binned.

[pyrotech]

I seriously can not believe how quick people jump away on one run. The cold air is still near, and great pool over Europe.

Shortwaves that can not be accurately forecast at this timescale. Potential for a set up better than seen for years.

GFS did same yesterday, It is like a yo yo. Just looking at all possibilities and yet it still comes up with the cold air close.

This is not set in stone for us either way, nor will it tomorrow.

3 major models going for cold and severe cold over europe, Still well in fi, and huge potential ahead.

This could upgrade from the 12z by friday with prolonging of the cold right through chrismas. Yes we have seen this before for it to be snatched away.

3 models today show cold.

one slightly downgrades still in Fi

I put money on it before wednesday we are all on here watching a upgrade back to 12zgfs today. Then the rollrcoaster continues

[The Eagle]

Just goes to show how fickle the setup we are looking for is. Don't worry about it.

Personally I think the Russians have the right idea of what we can expect.

Edited December 6, 2009 by The Eagle

[nick sussex]

I don't believe Nick that the short wave is the problem with the 18Z run. The Canadian segment of vortex was much further east and north and in a far more unfavourable position sitting alongside western Greenland. This prevented the height rises there as seen on the 12Z. I wouldn't be concerned from 1 run this far out though it does highlight how easily the door can get closed.

Agreed C i thought it was just easier to use the shortwave as our punchbag! as people will most likely concentrate on it, of course one thing leads to another like a domino effect. I'll just be glad to see the back of this mild rain down here which is threatening to ruin a good start to the ski season, by the time the rain stops and the colder temps arrive i fear my snowcapped vista will be spot the snow patch!

I had a few nice pics of the view from my terrace but still cant work out how you attach these to your signature at the bottom so that they appear with every reply, Shuggee gave me some advice but i still cant work out how to do this. I know this has veered off topic so I don't mind the mods moving it but hopefully at the same time they can PM me with help here!

[mountain shadow]

Something must be brewing this winter ! I dont recall a winter chart with such intense cold across the Northern Hemisphere for quite a number of years !!

That's because we haven't seen such high latitude blocking for well, lots of numbers of years. As i mentioned previously, deep cold is about to spill from the Arctic and it;s about time we tapped into it.

[Jason H]

Evidently not, as of course you want the cold, of course my view isn't going to be popular, it's the likeliest outcome because it sides with the GFS ensembles, plus the ECM ensembles. All it means its there is unlikely to be a severe cold event at least not now. It doesn't mean it wouldn't be cold though, with I suppose potential inversions occurring.

I will keep banging on about until I see reason to change my opinion (if I have to)

I don't want anything, apart from reasonable balanced debate. For what its worth I agree that the only thing settled so far will be that High Pressure takes charge towards the end of the week. I don't understand how you can dismiss one set of charts because they show cold, then say it's the most likliest outcome 6 hours later when they charts in FI show less severe conditions?

Again, I'd agree that the ensembles do not show severe cold, but this was not what was stated in your post.

[winter watcher]

As a positive, the parallel is the new upgraded GFS, so perhaps Op run can be binned.

Just taken this peice and to add that i have been very very impressed with the parallel run for a while back now. It has been sticking with its guns since this potential cold spell was progged and still has tonight not backed down one bit.

[Sawel]

Just goes to show how fickle the setup we are looking for is. Don't worry about it.

Personally I think the Russians have the right idea of what we can expect.

lol can you imagine if the ECM, UKMO or GFS showed that at +96?

[David-kig]

Just goes to show how fickle the setup we are looking for is. Don't worry about it.

Personally I think the Russians have the right idea of what we can expect.

THIs is what most people expect if this dont happen then everyone moans lmao that is woooo.

who bets on it ending up just high pressure over the uk???? as the final outcome

[NorthantsSnow]

Evidently not, as of course you want the cold, of course my view isn't going to be popular, it's the likeliest outcome because it sides with the GFS ensembles, plus the ECM ensembles. All it means its there is unlikely to be a severe cold event at least not now. It doesn't mean it wouldn't be cold though, with I suppose potential inversions occurring.

I will keep banging on about until I see reason to change my opinion (if I have to)

I wouldn't describe it as "unlikely" personally when we have 3 major models forecasting significant cold either near or directly over the British Isles in around 10-14 days time. That to me suggests it is very much possible, and that it's a waiting game to see if these synoptics can enter the reliable timeframe and whether or not the real cold will back far enough west to affect us.

The extent of the cold will not be nailed until much closer and the ensembles are liable to change dramatically if the cold operationals persist.

Overall, very pleased with today's output.

[Cloud 10]

just had a look through the 18z ensembles for +240,not much agreement to say the least!

[SP1986]

I don't want anything, apart from reasonable balanced debate. For what its worth I agree that the only thing settled so far will be that High Pressure takes charge towards the end of the week. I don't understand how you can dismiss one set of charts because they show cold, then say it's the most likliest outcome 6 hours later when they charts in FI show less severe conditions?

Again, I'd agree that the ensembles do not show severe cold, but this was not what was stated in your post.

I basically look for a pattern that I think is likely, not a particular model. If the GFS showed a severe easterly tomorrow, I would disagree with it if it showed a similar lead up event, if it showed high pressure over the UK the next day I would probably agree with it, depending on the pattern in the realistic timeframe. Plus I'm not really looking at FI per se, I'm looking at the build up to FI, and what leads up to it and weighing up whether FI is likely or unlikely based on experience and good old forum posters intuition.

Yes FI should really be ignored, but the reason I have said that is because ocassionally people may look at FI at face value without taking into account the lead up to it.

[snowlover2009]

how long has the paralell been running for? someone above said its the new upgraded gfs. Has it only just been created?

just had a look through the 18z ensembles for +240,not much agreement to say the least!

i don't think they are too bad tbh.

[patneve]

how long has the paralell been running for? someone above said its the new upgraded gfs. Has it only just been created?

the GFS parallel will substitute the operational (I don't have the date though)