General Model Output Discussion

[Bristawl Si]

Not being funny my friend- But whats the point of that post?- Like we dont know the detail will change- What value is that Adding-

This is about discussing the models & what they actually show- not discussing what they dont show-

Maybe an educated post of what could go wrong--

nah I guess not eh.....

Perhaps you would care to reference this-

http://www.meteogrou...e_forecast.html

Which is infact the ensemble data for the model that the UK MET use in conjunction with their own model-the fact that for London the mean doesnt get about 2/3c for 10 days

Or how about the panel map from the 18z- at T114

http://www.meteociel...&mode=1&ech=114

850's

http://www.meteociel...&mode=0&ech=114

& a little further at 150

http://www.meteociel...&mode=1&ech=150

Or how about from top down-

http://www.hpc.ncep....HEM_f120wbg.gif

http://www.meteogrou...thgt850_144.png

Ensemble Mean- is very consistent as well-

Infact Why do a fax chart for 120--- So much shortwave detail will change?........

Instead of telling me what to post or when or whenever to get excited- how about adding some value...

BTW the SW thread is here -

http://forum.netweat...ell-discussion/

S

Blimey! That's a bit of a strong post isn't it?

Ian's a pro, so he's entitled to his opinion and has been giving us excellent posts in the SW thread.

There's many of us on here who believe the models are decent enough 5/6 days out for showing a 'general' trend, but for giving detail more than 2 days in future they're distinctly ropey. New Year's Eve/Day was a most recent example. Around Xmas day the models wre showing snow for large swathes of the South, but a few days later it had gone. Same for this weekend if i remember rightly.

So i think Ian is right to exercise caution - he knows in these cold set-ups for the UK detail beyond 2 days is pretty pointless. Rant over.

[Nick L]

Errrr.... and chill (pardon the seasonally-relevant pun).

Who is doubting the prolonged cold spell? Who is doubting the consensus reflected by ensembles? No-one.

Doubting the snow threat, day-to-day; region-to-region, is another matter, and that's what I alluded to.

I'm well accustomed to the SW thread - thanks nonetheless for the helpful link.

I fully agree with you Ian, it was about time somebody injected some realism in here.

I thought this was the model thread, not rampers corner. Some of the charts being banded about are in the early reaches of FI, and to get hysterical about them at that range is frankly ridiculous. Looking at them and discussing them is fine, but going into ramp mode over them is daft. Concentrate on the nearer timeframes first, we have some fantastic synoptics to drool over in the near timeframe, let's not rush to get to the end. I mean, in winters past we would have given anything to get this at +72, but guess what, that's what we have!

http://charts.netwea.../72/h500slp.png

Edited January 2, 2010 by nick2702

[SMU]

Errrr.... and chill (pardon the seasonally-relevant pun).

Who is doubting the prolonged cold spell? Who is doubting the consensus reflected by ensembles? No-one.

Doubting the snow threat, day-to-day; region-to-region, is another matter, and that's what I alluded to.

I'm well accustomed to the SW thread - thanks nonetheless for the helpul link.

Yes & No-- The model consensus shows the East / NE & South East will take the brunt of the snow- There is likely to be MINIMAL movement of that area being effected- Why>?

Because a small shortwave isnt driving the pattern- the longwave pattern is

Ensemble mean shows < 2 m/b at day 4-

http://91.121.94.83/modeles/gens/run/gens-22-1-90.png?18

All I was saying is that someone in your position could make a considerably better contribution to the thread than telling us something that was not really that accurate in the first place-

S

Edited January 2, 2010 by Steve Murr

[PB22]

Savour these London ECM ensembles, save them in fact, as it could be many many many years before we see the likes of them again:

http://www.meteogroup.co.uk/uk/home/weather/services/ensemble_forecast.html

For much of this week, the average doesn't get above 0C!

[Optimus Prime]

Well, no. If you've read my posts it is easy to allude to the notion that my analysis of the models is a very dry one, and that snow will be very sporadic. It is my reading of this thread that widespread snow is a given. I do not think that is so, although I think snow will happen for the lucky few.

That I mention the radar is for those lucky few. I do not feel that this is a widespread snow event. Indeed, I've said so, in either a technical, or otherwise fashion for a few days now. Nothing has changed to modify my view ... yet.

No-ones saying a widespread snow is a given but all I seem to read is Village Plank vs the rest of the world on this one. We all know, as is the nature of these easterly snow can be confined in one rather wide area with other very close areas by missing out.

But to say a 'lucky few' is all you can come up with, I'm finding it rather baffling and that really doesn't help other members that are relying on us to give them an idea how widespread the snow will fall.

Looking at the models, IMO snow will become showery at first but then more widespread and much futher inland. Most parts of England, especially more towards the east and south/south west will get a good covering of snow. Marginality towards the coast will always be an issue.

Edited January 2, 2010 by Optimus Prime

[Bottesford]

Lets leave the pecking each other out of this thread thanks - back to the models please!

[Liam J]

exceptionally cold outlook, and i for one cannot remember any outlook like it, all the models are singing from the same sheet right now, no doubt there will be minor changes but i feel its nailed quite well at least the next 5-7 days we can be sure.

i feel many people will get a shock, to the severity of the cold and very large snow falls which are just bound to happen...

the first major event i think at this stage will tuesday with a band of ppn moving down from the north as is being shown nicely by the models, some large accumulations likely as it passes north to south, on a cold front reinforcing the cold air, ahead we have -7 to -8 850's so i would like to think even coasts will see the white stuff.

and it gets colder still through the week with gfs predicting -10 to -12 850's and further snowfall, villages will be cut off and places will see crazy amounts of snowfall, its radar watching on the day.

extreme frosts will cause problems with frozen water mains/burst pipe etc with temps maybe touching -20 or less in favoured places, cumbria for me has got ice days for the next week, with some daytime highs at -5c

astounding outlook, and we are on the verge of a special, and at times scary spell of weather...

hoping the models varify and give us what many of us will not have seen

[Ian Fergusson]

I fully agree with you Ian, it was about time somebody injected some realism in here.

I thought this was the model thread, not rampers corner. Some of the charts being banded about are in the early reaches of FI, and to get hysterical about them at that range is frankly ridiculous. Looking at them and discussing them is fine, but going into ramp mode over them is daft. Concentrate on the nearer timeframes first, we have some fantastic synoptics to drool over in the near timeframe, let's not rush to get to the end. I mean, in winters past we would have given anything to get this at +72, but guess what, that's what we have!

http://charts.netwea.../72/h500slp.png

It's a fascinating winter thus-far in any case; let's return to the model discussion on this thread without the caustic stuff. Who needs it.

[Paul]

Hi guys, I know we're all passionate about the weather, but let's try not to fall out over differing opinions please. We wouldn't learn much and these threads would be pretty tedious if everyone had the same view on things.

[SMU]

Savour these London ECM ensembles, save them in fact, as it could be many many many years before we see the likes of them again:

http://www.meteogroup.co.uk/uk/home/weather/services/ensemble_forecast.html

For much of this week, the average doesn't get above 0C!

Just seen these from the updated 12z ( had the 00z up until 10 mins ago)

If people cannot view these with a modicum of excitement then were there in the wrong game- as they depict something like a 1/25 event....

So have I got cause to ramp it- yes certainly- because just for once things are actually in place for a brilliant cold spell-

S

Edited January 2, 2010 by Steve Murr

[Jason M]

I concur Nick,

Those air temps progged on 18z for sunday next week just look plain wrong to me.It's FI though so probably irelevant.

What a memorable spell of weather we have before us.The really colder stuff being dragged down from Norway is just about to spread across the UK.

Hi All

First post here, so be kind

There is little doubt IMO that most will see snow over the next week, but i can't help but feel that we are starting to see the likely breakdown emerge. I've noticed recent runs have started playing up this Low over France. GFS tends to be pretty good at picking up on these features and i suspect its onto something. I think we need to look south east for the breakdown. This will give lots of snow in the areas highlighted by 'North Sea' but might not be so good for Kent and Essex (Essex being MBY) as milder air may turn the snow back to rain more quickly here.

Its only my view based on experience, but i expect GFS to develop this further over coming runs.

Still a good week of cold weather to enjoy first though!

Jason

[NorthNorfolkWeather]

It never gets above 70% - and to increase 70% to 85% requires a lot of energy - and the jet-stream is 300 miles south - so where is the energy, or insolation (cloud cover looks extensive) going to come from?

For sure the North Sea will modify this value upwards - but will it be enough? Will it get to the magic figure? Yes, in places it will, but those places will be sporadic and ill-defined. I am sure those who get lucky will get a good dumping.

Hi VP,

I'm constantly being told that the North Sea is like a 'warm bath', and with many North Sea SST temperatures, at the moment being between 8 and 10 C, I'd expect it to hit your magic figure reasonably widely, as long as the flow is greater than about 15mph in th easterly component. Less than that and what happens? Showers may be heavy near the coast, but are rain/sleet or wet snow, but they don't get anywhere before they die out

[VillagePlank]

No-ones saying a widespread snow is a given but all I seem to read is Village Plank vs the rest of the world on this one. We all know, as is the nature of these easterly snow can be confined in one rather wide area with other very close areas by missing out.

But to say a 'lucky few' is all you can come up with, I'm finding it rather baffling and that really doesn't help other members that are relying on us to give them an idea how widespread the snow will fall.

Looking at the models, IMO snow will become showery at first but then more widespread and much futher inland. Most parts of England, especially more towards the east and south/south west will get a good covering of snow. Marginality towards the coast will always be an issue.

I've posted charts that support my position.

The cut-to-the-chase point is: will the North Sea modify the air mass enough to give snow? That's the issue - everything else seems to be in place for the next week. For sure, everything else leaves marginal behind!

It is not VP vs ROW, either. Other people have said the same the thing, but have been lost in midsts of excitment, I think. Such excitment is warranted - such synoptics are rare, dare I say it, even before the christmas pudding, and I allude to a 1979 analogue elsewhere.

If I may, I am just trying to dispell the assumption of snowfall. That's all. No one has mentioned the dry airmass yet, so I thought it would be nice for balance. Indeed, I have even ramped for a northerly which changes the airmass type to Am which would yield vast quantities of the white stuff!

That's all. I can go away if you want me to.

[NorthNorfolkWeather]

Its only my view based on experience, but i expect GFS to develop this further over coming runs.

Still a good week of cold weather to enjoy first though!

Jason

Hi Jason,

Welcome to the bear pit

The North Sea is MBY and, if the breakdown comes from there, I'll get rain early in the breakdown. Somehow, I don't think that it will come from that direction, and I think it will take a little longer than we currently expect. ( Having said that, I've probably jinxed the cold spell)

[VillagePlank]

I'm constantly being told that the North Sea is like a 'warm bath', and with many North Sea SST temperatures, at the moment being between 8 and 10 C, I'd expect it to hit your magic figure reasonably widely, as long as the flow is greater than about 15mph in th easterly component. Less than that and what happens? Showers may be heavy near the coast, but are rain/sleet or wet snow, but they don't get anywhere before they die out

Superb point - the flow over the North Sea will become an integral component and will stop showers being a 'on the day random event' NetWeather has a 'streams' chart and if you look for lines with arrows pointing in a direction and converging then that, in my opinion, is the place where convection, and hence showers will kick off. The tighter and more acute the anlge - the more snow!

[Cecil Hogmanay Melchett]

Just a quickie regarding DAM/Thicknesses this coming week.Would it be fair to assume there will be less marginality this week when the showers/troughs etc roll in?I ask this because today,even though i saw around 7cm of snow it did become extremely borderline at times,and im at 650ft elevation on the pennines,are the relly cold uppers getting established now expected to persist through the week?

cheers.

[VillagePlank]

Just a quickie regarding DAM/Thicknesses this coming week.Would it be fair to assume there will be less marginality this week when the showers/troughs etc roll in?I ask this because today,even though i saw around 7cm of snow it did become extremely borderline at times,and im at 650ft elevation on the pennines,are the relly cold uppers getting established now expected to persist through the week?

cheers.

It is probably safe to say that for the next 3-7 days (less certain as time goes on) that marginality has disappeared. The only argument left, in my opinion, is precipitation.

In more detail. 850hPa's hover around -10C (need -5C or lower), 500hPa heights lower than 528dm (need 528dm for 50/50 chance of rain/snow) and Theta-W charts are well on the right side of marginal - ie, there would need to be a huge model turnaround for this to reverse.

[East Herts Snow]

Just seen these from the updated 12z ( had the 00z up until 10 mins ago)

If people cannot view these with a modicum of excitement then were there in the wrong game- as they depict something like a 1/25 event....

So have I got cause to ramp it- yes certainly- because just for once things are actually in place for a brilliant cold spell-

S

Very true Steve and at the very least the country should be alerted to the 'low/medium possibility' of a sustained very cold period is very near. People should at least be prepared for the negative impact that severe weather can bring.

This is surely the whole point of having medium to long term weather charts that show possible outcomes on a sliding probability scale!

This cold spell may turn out to be very expensive for the Government in cold winter payments......

Edited January 2, 2010 by North Londoner

[NorthNorfolkWeather]

Just seen these from the updated 12z ( had the 00z up until 10 mins ago)

If people cannot view these with a modicum of excitement then were there in the wrong game- as they depict something like a 1/25 event....

So have I got cause to ramp it- yes certainly- because just for once things are actually in place for a brilliant cold spell-

S

only consistently getting above zero after the tenth, that in itself must be unusual in the time since the internet made it much more accessible ( is that the "modern age"? )

[Jason M]

Hi Jason,

Welcome to the bear pit

The North Sea is MBY and, if the breakdown comes from there, I'll get rain early in the breakdown. Somehow, I don't think that it will come from that direction, and I think it will take a little longer than we currently expect. ( Having said that, I've probably jinxed the cold spell)

Hi, cheers for that

I've picked my moment, looking at the thread over the last twenty mins

My thinking is that warm air will get dragged up by the low pressure as it moves SW towards Portugal. Typical really as in reality it's the reverse effect of the low that ran through the channell a few days ago. I think it was the 87 cold spell that ended in a similar way with a warm front from the East. This would result in more snow than that (drizzly affair from memory) but the eventual outcome would be similar.

I will be very happy to be proved wrong though!

Jason

[LomondSnowstorm]

Very true Steve and at the very least the country should be alerted to the 'low/medium possibility' of sustained very cold weather is very near. People should at least be prepared for the negative impact that severe weather can bring.

This is surely the whole point of having medium to long term weather charts that show possible outcomes on a sliding probability scale!

This cold spell maqy turn out to be very expensive for the Government in cold winter payments......

Sustained cold has been here for roughly 3 weeks already. The charts are amazing, with very little marginality anywhere in the British Isles, with the chance of some huge snowfalls, particularly in eastern and southeastern areas. This winter so far has been the coldest and snowiest overall since the 80s here, with more snow and intense cold to come.

Incredible stuff

LS

[Optimus Prime]

That's all. I can go away if you want me to.

Certainly not. We know the airmass is going to be dry..it's from the East, a alarge expanse of earth (and concrete) without any a large scale water source. What I'm trying to say is if in the 80s where much of the south got heavy and disruptive snow on a large scale from, easterlys like shown on the models and the sea temperatures were probably lower, wouldnt that put us in a better position then even back then? With the increased Convective available potential energy on the warmer north sea?

Edited January 2, 2010 by Optimus Prime

[Bristawl Si]

Sustained cold has been here for roughly 3 weeks already. The charts are amazing, with very little marginality anywhere in the British Isles, with the chance of some huge snowfalls, particularly in eastern and southeastern areas. This winter so far has been the coldest and snowiest overall since the 80s here, with more snow and intense cold to come.

Incredible stuff

LS

Amazingly though the charts are saying one thing, members are saying "the most memorable synoptics in years" and yet the latest weather forecast right up to and incl. Tuesday on the Beeb is saying v.little snow - i'm confused! And that forecast is a downgrade on the one given a few hours ago!

[NorthNorfolkWeather]

My thinking is that warm air will get dragged up by the low pressure as it moves SW towards Portugal. Typical really as in reality it's the reverse effect of the low that ran through the channell a few days ago. I think it was the 87 cold spell that ended in a similar way with a warm front from the East. This would result in more snow than that (drizzly affair from memory) but the eventual outcome would be similar.

Jason

I remember it well, I was snowed in for a week, I live in the back of beyond, and was more than a little disappointed to see a south easterly bring warmer air in. I hope you are proven wrong, but we'll see. Plenty of time for evolution yet.

I was going to attach the chart for the 17th Jan 1987, but it seems to be kaput

Edited January 2, 2010 by NorthNorfolkWeather

[VillagePlank]

Certainly not. We know the airmass is going to be dry..it's from the East, a alarge expanse of earth (and concrete) without any a large scale water source. What I'm trying to say is if in the 80s where much of the south got heavy and disruptive snow on a large scale from, easterlys like shown on the models and the sea temperatures were probably lower, wouldnt that put us in a better position then even back then? With the increased Convective available potential energy on the warmer north sea?

There's some marginal CAPE around off the coast of Norfolk mid-week for a smidgen of a time (Tuesday night into Wednesday morning) and 700hPa vertical velocity does rear it's head from time to time, but it's not organised even though negative LI is present. One for the skew-t charts the day before, I think.

However, GFS, as has already been said, can do badly at this. I expect some small areas of 'surprise' very small areas of low pressure to form such that it will give favoured locations a dumping. I think I've already alluded to this, but, I think, the trick is to look 'beneath' the GFS grid.

Someone said that local experience is the key. I agree with that, wholeheartedly, but the underlying fundamentals must be good too. And, generally, they are - that is to say, that precipitation is the only variable left to play with.

Edited January 3, 2010 by VillagePlank