Model Output Discussion

[Stu_London]

'Ok' compared to the last 15 years?

yes it's interesting compared to the last 15 years, particularly in the context the a cold spell and some snow is in the bank for many already this winter.

however it was more interesting 24 hours ago and I suspect it will be less interesting in 24 hours time as we are in the process of a classic backtrack by the computers at present.

I'm very much open minded as to what the rest of winter will deliver.

[NorthNorfolkWeather]

So, if I can sum this up as I see it, perhaps the more knowledgeable here can correct me.

All the models show a low pressure running across the bottom of the UK or Northern France at around T+96. Where, and whether, we get rain, snow or a combination of both depends on the actual track of that LP system. For my area, North Norfolk, it will almost certainly be rain, whereas other, favoured, area's may well end with a real dumping of snow.

I'm amazed by the way that some people, again, have "It's the end of winter as we know it" Syndrome, we are not even out of 2009 yet, we've had more cold that anytime in the last, probably, 20 years and people are still not satisfied.

We have a very unusual High Pressure over Greenland that, as others have been saying, is 'nailed', the possibility of a warm breakdown keeps being moved to FI, and warm, or even mild weather with a Greenland high is very unusual.

Final point, models usually go walkabouts due to lack of data over Christmas Day +/-24 and people are still obsessing about small variations.

What will happen will happen, no point in obsessing, personally I look forward to a colder North sea later in teh winter which will increase my chances of snow.

[Stu_London]

Who's to say in another 24 hours it won't have prolonged the cold spell? It's far too early to write it off completely.

It's obviously a much better chart than any we've seen for a good few years.

see my post above - if I am wrong, I will publicly acknowledge it - lets hope those who are slating me now will do the same if I am proved right

So, if I can sum this up as I see it, perhaps the more knowledgeable here can correct me.

All the models show a low pressure running across the bottom of the UK or Northern France at around T+96. Where, and whether, we get rain, snow or a combination of both depends on the actual track of that LP system. For my area, North Norfolk, it will almost certainly be rain, whereas other, favoured, area's may well end with a real dumping of snow.

I'm amazed by the way that some people, again, have "It's the end of winter as we know it" Syndrome, we are not even out of 2009 yet, we've had more cold that anytime in the last, probably, 20 years and people are still not satisfied.

We have a very unusual High Pressure over Greenland that, as others have been saying, is 'nailed', the possibility of a warm breakdown keeps being moved to FI, and warm, or even mild weather with a Greenland high is very unusual.

Final point, models usually go walkabouts due to lack of data over Christmas Day +/-24 and people are still obsessing about small variations.

What will happen will happen, no point in obsessing, personally I look forward to a colder North sea later in teh winter which will increase my chances of snow.

Yes some areas look like having a period of severe weather (length, severity to be determined)

Pressure is high over greenland but this alone does not guarantee cold weather

The milder breakdown does not keep getting pushed back further into FI (there wasn't a breakdown at +384 yesterday, now it is in evidence at +162)

There is as much air traffic and flight data recorded on Christmas as any other in the calender.

[Optimus Prime]

think you must have mistaken me with someone else - i dont even comment on the models that much

No but you do when there is cold on the horizon. You constantly pulled down the cold spell we just had prior because you persistently looked at each run rather then the broader, long term picture.

It's clear from what I'm seeing is there's huge blocking setting itself up over the arctic region and effecting the key areas - American, Russia and Asia with Europe in the transient zone at the moment. Once these global pattern start shifting as the winter progresses I feel blocking will become more prevalent around our region.

[lukemc]

Hi,

I did read a comment on this forum by one poster that when we get a cold spell it normally lasts no longer than about a week or so but when we get a mild or very mild spell it can last for weeks on end really does anyone think that is true I would say that given the right synoptics a cold spell can easily last as long as a mild spell would.

Anyway back to the models is it true that the GFS 12z run is better for long term cold and snow than the 06z run? And why are people saying that this is poor and represents a backtrack? And would the UKMO run produce rain as opposed to snow even in Northern England and why? I know that the LP is further North but wouldn't that be better in terms of the chance for snowfall where I am in the NW(Liverpool)?

Luke

[Cecil Hogmanay Melchett]

Hi,

I did read a comment on this forum by one poster that when we get a cold spell it normally lasts no longer than about a week or so but when we get a mild or very mild spell it can last for weeks on end really does anyone think that is true I would say that given the right synoptics a cold spell can easily last as long as a mild spell would.

Anyway back to the models is it true that the GFS 12z run is better for long term cold and snow than the 06z run? And why are people saying that this is poor and represents a backtrack? And would the UKMO run produce rain as opposed to snow even in Northern England and why? I know that the LP is further North but wouldn't that be better in terms of the chance for snowfall where I am in the NW(Liverpool)?

Luke

The low will bring Atlantic air with it.To be honest liverpool is probably the most snowless place in the world.Hope that helps.

[NorthNorfolkWeather]

The milder breakdown does not keep getting pushed back further into FI (there wasn't a breakdown at +384 yesterday, now it is in evidence at +162)

When do you consider FI to begin? I rarely accept anything after T+144, and currently I don't believe anything over T+108 can have any degree of certainty. The models have been 'confused' for a while as they try to prog this setup. If you believe that T+162 i snot FI, that's your choice

GFS 168 here

ECM 168 here

And they are the same?? If we weren't in FI, at least they would be similar

[lukemc]

The low will bring Atlantic air with it.To be honest liverpool is probably the most snowless place in the world.Hope that helps.

:lol:

Talking of snowfall we did not do very badly for snowfall in the last week not as much as some other places but at least we can say that Liverpool did get some! Really do you think that we get less snow than say, the Caribbean, Hong Kong, Algeria etc. you must be joking LOL! At least we do better than some places on the planet!

Luke

[NorthNorfolkWeather]

So..any missing data is likely to come from lack of input and interpretation, not the fact it is not there.

It seems I've been reading too many other people's posts and assuming they were correct.

If the data's the same, I apologise, but the perception is that the models do vary a lot around Christmas day.

[Stu_London]

When do you consider FI to begin? I rarely accept anything after T+144, and currently I don't believe anything over T+108 can have any degree of certainty. The models have been 'confused' for a while as they try to prog this setup. If you believe that T+162 i snot FI, that's your choice

GFS 168 here

ECM 168 here

And they are the same?? If we weren't in FI, at least they would be similar

FI is a moveable feast - it can be +48 in a lot of circumstances and other times when there is good cross model and ensemble agreement, it is well worth looking at +240 and beyond - although not for any detail obviously.

Unfortunately it is a fact that there was solid model and ensemble support yesterday for a prolonged nationwide cold spell - whatever way you look at it, today the models are not showing the same thing, although I except that they do remain of great interest (particularly in the context of the model watching I have done over the last 7-8 years).

[Cecil Hogmanay Melchett]

The low will bring Atlantic air with it.To be honest liverpool is probably the most snowless place in the world.Hope that helps.

:lol:

Talking of snowfall we did not do very badly for snowfall in the last week not as much as some other places but at least we can say that Liverpool did get some! Really do you think that we get less snow than say, the Caribbean, Hong Kong, Algeria etc. you must be joking LOL! At least we do better than some places on the planet!

Luke

Yup i was only playing mate,liverpool isn't the best place in the UK though,the irish sea acts as a electric blanket,you did well to get some lying snow last week.:lol:

[03jtrickey]

ECM out to +144, looking better to me. (though could be wrong)

http://www.wzkarten.de/pics/Recm1441.gif

Seems to get rid of that nuisance shortwave over Scandinavia. Could be a better easterly this time? Or setting up for another battleground scenario if that low advances from the west?

Edited December 26, 2009 by 03jtrickey

[Snowstorm1]

ECM out to +144, looking better to me. (though could be wrong)

http://www.wzkarten....cs/Recm1441.gif

Seems to get rid of that nuisance shortwave over Scandinavia. Could be a better easterly this time? Or setting up for another battleground scenario if that low advances from the west?

Yes looks like the ecm is saving people from losing there minds hopefully ! North of the m4 especially midlands and northern england (were i live) are going to get pasted! A foot of snow is easily possible i am 14 and never seen that in my life :lol:

[Optimus Prime]

No real changes on the ECM run. There's a chance of northerly winds taking over later on.

It's a very good run overall. A somewhat better version of February 2005.

Edited December 26, 2009 by Optimus Prime

[Cloud 10]

Plenty of cold weather on offer on tonights ecm,although it comes out with a strange +192 chart.

[Cecil Hogmanay Melchett]

ECM goes rapidly downhill at T168.

4 to 5 day cold snap looks odds on,prolonged freeze looks very unlikely at the moment.

From a NIMBY perspective i look good for some snow tue/wed but id happily drop that for a 10 day to 2week freeze.

:lol:

[Harsh Climate]

ECM goes rapidly downhill at T168.

4 to 5 day cold snap looks odds on,prolonged freeze looks very unlikely at the moment.

From a NIMBY perspective i look good for some snow tue/wed but id happily drop that for a 10 day to 2week freeze.

I think I would take heavy snow on tue/wed over anything.

Its not often we have the chance of a classic snow even across central england/britain, anything after then is always guna be FI, especially as the exact track of the low means everything for what follows..

I think a return to mild south westerlies/bartlett high in the next couple of weeks is very unlikly.. The nao/ao is expected to go briefly less negative around 1-3rd january, that may be inclusive to slightly less cold conditions, but soon after it plunges negative again, id expect that to coincide with a strengthening greeny high :lol:

[snowray]

I would suggest that tonights ECM might be the run to bank, bit there for everyone, and lots for some lucky folk. If I was being realy fussy though, I'd shunt everything about 50/80 miles further South. :lol:

[Cecil Hogmanay Melchett]

I think I would take heavy snow on tue/wed over anything.

Its not often we have the chance of a classic snow even across central england/britain, anything after then is always guna be FI, especially as the exact track of the low means everything for what follows..

I think a return to mild south westerlies/bartlett high in the next couple of weeks is very unlikly.. The nao/ao is expected to go briefly less negative around 1-3rd january, that may be inclusive to slightly less cold conditions, but soon after it plunges negative again, id expect that to coincide with a strengthening greeny high :lol:

I Know what you mean mate but some people have not had a sniff.I feel really sorry for those in the SE who missed out last week.They dont even get all that cold looking at the ecm850's.Still,it could all change tomorrow so lets see how the low to the SW looks then!

[kold weather]

No real changes on the ECM run. There's a chance of northerly winds taking over later on.

It's a very good run overall. A somewhat better version of February 2005.

Not with that AO imploding on the charts around 168hrs, I'd advise with the way the models are going we need to look at a cold surface feed for the best chance of cold...ECM isn't far off but its not a terrible run...equally we've seen many many better runs just from the last few days, not sure I'd say its a very good run but its an ok run...

Remember these lows could quite easily trend southwards that see post 144hrs from the models and if you get that then you could get an interesting result, and also more chances at snow.

For my area, this cold snap/spell could well end up being a very wet and overall useless set-up but for the northern areas this pattern that may evolve is far more interesting...I think alot of southerners aren't going to be happy with the evolution whilst those closer to the snow/cold will be content...

[Frosty.]

I would suggest that tonights ECM might be the run to bank, bit there for everyone, and lots for some lucky folk. If I was being realy fussy though, I'd shunt everything about 50/80 miles further South. :lol:

Maybe the next run will shunt it 200 miles further south, a few strange charts in there lacking much detail...could it be the lack of data issues which also occured this time last year but were resolved by 27th dec, there are no excuses from tomorrow if the models still don't show what some are expecting.

[LomondSnowstorm]

Well any model output at the moment is suiting me - easterly winds turning northeasterly through the middle of next week with the -5 uppers line almost guaranteed to be south of the border, with a big orange greeny high! All models look good IMO at 120 hours:

http://www.wetterzentrale.de/pics/Recm1201.gif

http://www.wetterzentrale.de/pics/Rukm1201.gif

http://www.wetterzentrale.de/pics/Rtavn1201.png

LS

[Mark Parsons]

Don't be to down about all this, a lot can change in just a few days and these set ups that are border line if you like can be the ones that produce the snow, for example 1947 was not famous particularly for its cold but for the amount of snow, temps were on the whole quiet average, in my experiance the intense cold just brings cold dry weather to most and short lived deep snow in break down situations. I would prefer initially to see this low dive south and pull in and establish some good cold then have some attacks from the SW that produce wide spread snow but not a break down, be patiant is my advice!!

[Harsh Climate]

I Know what you mean mate but some people have not had a sniff.I feel really sorry for those in the SE who missed out last week.They dont even get all that cold looking at the ecm850's.Still,it could all change tomorrow so lets see how the low to the SW looks then!

Cant say im too bothered about the south east lol, they had plenty of snow last thu/fri , it would be nice for central southern england/south west to get some snow as they allways seem to get the short straw..

One thing about if we do get easterly winds next week, the continent isnt really that cold so I couldnt imagine too much snow to lower levels.. People in Leeds can vouch for me that in recent days we have learnt how much of an influence the north sea/irish sea can have on your snow chances.. without real cold goin over either sea or enough cold air allready established, the milder sectors/milder air they introduce often mean rain/sleet rather than snow to lower levels..

Edit: Yesterday evening I had rain at 0.1C, saturday night (last week) rain at 0.3C but xmas eve morning, settling snow at 0.3C as the wind was coming straight from the south across the land :lol:

Edited December 26, 2009 by Jed Bickerdike

[snowlover2009]

The low will bring Atlantic air with it.To be honest liverpool is probably the most snowless place in the world.Hope that helps.

Talking of snowfall we did not do very badly for snowfall in the last week not as much as some other places but at least we can say that Liverpool did get some! Really do you think that we get less snow than say, the Caribbean, Hong Kong, Algeria etc. you must be joking LOL! At least we do better than some places on the planet!

Luke

christ, even i know he was exagertaing about liverpool being the snowless place in the world. if anything one of the snowless places in the northern parts of uk or msot of the uk