General Model Output Discussion Thursday December 24Th:

[nick sussex]

Sorry I was being sarky

Yes i know! Do you think i would have been that nice in reply if i had thought otherwise! Must be great up there in Edinburgh at the moment. Happy Xmas by the way and enjoy the snow.

[Cloud 10]

IMO all systems go! shovel watch early warning for lucky people on the northern flank of the low. I suspect the gfs still has the low too far north and complicates things with that secondary feature but overall a great run so far.

Shovel watch indeed!

I swear i will go blind if i have to view runs like the gfs 12z every day.!

[kold weather]

All aboard the polar express...choo..choo

A mega wintry GFS 12z run from the middle of next week until the end with a N'ly which just goes on and on and on. I just don't see how a N'ly can last so long though, surely it would topple after 3-5 days max.

We keep a split PV on this run right to the end and as long as we keep a Scandi PV lobe present then any LP that comes up against the block is going to be forced northwards and induce another Greenland block. The 12z actually shows 3 seperate highs develop between 144-384hrs and so its a series of reloads.

This pattern has HUGE risk however, esp if we don't have much of a southerly jet stream as on the 12z run...IF the Candian vortex becomes stronger the whole thing will sink faster then the titanic.

Its certainly an amazing run, but the set-up has very large pitfulls and reminds me rather a lot of other failed cold spells on that run looked like on the models before they imploded...

[JoeShmoe]

Yes i know! Do you think i would have been that nice in reply if i had thought otherwise! Must be great up there in Edinburgh at the moment. Happy Xmas by the way and enjoy the snow.

LOL - you too Nick and here's hoping Santa brings everyone a good snow fall (or thaw depending on what you want in your stocking)

seasonal cheers all from a snowy Edinburgh

[loopydreamer]

i might not be that good at model reading so i dont normally post here. i just read all the posts but im gradually beginning to understand model reading a bit more now and i have to say, this is looking great for the new year! we need that low in the right place tho!

[cooling climate]

the gfs model for the past 2-3 days has being giving us early christmas presents outstanding charts.this time round it may give us a winter like the late 70s early 80s again lets all hope it doesnt go tits up

IF the 12z GFS run verified it would surpass most winters in the 70s and 80s for prolonged cold and wintry conditions

apart from the most severest IE 79, 85,86 and 87.

Lets hope the Euro's agree.

[nick sussex]

The GEM is excellent this evening and has the low much further south, the ukmo has the low the furthest north so far with the gfs in between, all the major models so far agree on the general pattern. Almost there folks but we need another day here to be relatively sure of things but overall a great start to the evenings model output.

[doublebarrel]

The GEM is excellent this evening and has the low much further south, the ukmo has the low the furthest north so far with the gfs in between, all the major models so far agree on the general pattern. Almost there folks but we need another day here to be relatively sure of things but overall a great start to the evenings model output.

Hi Nick, Merry xmas to you all, Does this mean then that our local radio will stop saying 6C for next week then

[Frosty.]

We keep a split PV on this run right to the end and as long as we keep a Scandi PV lobe present then any LP that comes up against the block is going to be forced northwards and induce another Greenland block. The 12z actually shows 3 seperate highs develop between 144-384hrs and so its a series of reloads.

This pattern has HUGE risk however, esp if we don't have much of a southerly jet stream as on the 12z run...IF the Candian vortex becomes stronger the whole thing will sink faster then the titanic.

Its certainly an amazing run, but the set-up has very large pitfulls and reminds me rather a lot of other failed cold spells on that run looked like on the models before they imploded...

Theres no doubt the GFS 12z is an EPIC run for coldies but as you say kold, it could sink without trace rapidly and I reckon that, whilst on the surface it's incredible to look at, it could be built on sand. I still think we will get a very cold snap developing next week, but nowhere near on the scale this run shows.

Edited December 24, 2009 by Frosty039

[nick sussex]

Hi Nick, Merry xmas to you all, Does this mean then that our local radio will stop saying 6C for next week then

At the moment there is uncertainty with how far north the low gets, there is milder air to the south of this so we won't be sure of who gets the initial rain changing to snow until much closer in. What we want for the moment is for model agreement across the board in terms of the pattern. So far this evening we have this but are waiting for the ecm to come out. In terms of the route to cold its easier if the low tracks further south,this gives a little insurance which is nice to have. And Merry Xmas and hopefully a snowy New Year.

Edited December 24, 2009 by nick sussex

[cooling climate]

No one care to comment on the UKMO run tonight.

T144 is a excellent chart regardless of whether the low to the sw is further north.

The run is more progressive in retrograding the vortex over to Canada so the much

colder air should start to affect the country sooner.

[yamkin]

Will Hand is going with the ECM model and is going for a severe cold period

Here's the link: http://groups.google.com/group/uk.sci.weather/browse_thread/thread/e6b6f29e9182bd87?pli=1

Edited December 24, 2009 by yamkin

[doublebarrel]

At the moment there is uncertainty with how far north the low gets, there is milder air to the south of this so we won't be sure of who gets the initial rain changing to snow until much closer in. What we want for the moment is for model agreement across the board in terms of the pattern. So far this evening we have this but are waiting for the ecm to come out.

Thanks for reply Nick

[kold weather]

Theres no doubt the GFS 12z is an EPIC run for coldies but as you say kold, it could sink without trace rapidly and I reckon that, whilst on the surface it's incredible to look at, it could be built on sand. I still think we will get a very cold snap developing next week, but nowhere near on the scale this run shows.

Well I'd say thats actually one of the least likely options at the moment and I'd be willing to bet the high would sink right over the UK.

The global pattern is very condusive for repated northerly shots here it has to be said and reloads to the general -ve NAO pattern. I'd suggest we've not seen this pattern since 95-96 being sustained for more then 10-15 days, so this is starting to become quite impressive. The AO shouldn't be too keen to head up either if we can keep that split in place...

[nick sussex]

Thanks for reply Nick

You're welcome , i do understand that many members will look at this from their own location but we should bear in mind theres less that can go wrong if the low tracks further south, this might mean that some initially aren't favoured with the rain to snow scenario but this will be better longer term in terms of keeping the cold and with it further wintry chances.

[mushymanrob]

Cant see any one with an ounce of sense complaining at the moment.Great output and runs.The devils in the detail as ever but the trends are amazing

erm, i have alot of sense thank you very much and ill moan at the output...because i dont like cold!

its pretty certain that some sort of cold spell will return next week, the cold will win out so even if an initial blizzard is missed there should be plenty of snow for many people... and this is only the start of winter with the coldest time to come.

[kold weather]

Ensembles are in general very good, super agreement on at least the intial NE/N shot for the New year but there are some ensemble members that highlight my worries very nicely indeed which sink towards the Midatlantic and we end up getting a cool anti-cyclonic flow which isn't all that cold at all.

As I said on TWO, if I was going to use a scale, P12 from the GFES would be 10% of the potenial of the charts:

http://www.meteociel.fr/modeles/gefs_cartes.php?ech=192&code=12&mode=0&runpara=0

The 12z op GFS is about 50%, the 0z ECM would be about 65% and 62-63 would be something like 95-100%....

[swilliam]

Control run is even better than the OP. It keeps the low further South and it then run along the channel ala 1978.

Then it runs through various Northerlies with regeneration of the HP Block to the NW. Then as a final present it gives us a beasterly in deep FI with <-12 uppers and extensive precipitation - dream on.

My only concern is as was pointed out by Geordiesnow if the low stalls out to our West or SW and the north easterly winds are in the Atlantic. What makes that low want to suddenly move East like that?Should we be concerned about this?

Edited December 24, 2009 by swilliam

[snowlover2009]

The GEM is excellent this evening and has the low much further south, the ukmo has the low the furthest north so far with the gfs in between, all the major models so far agree on the general pattern. Almost there folks but we need another day here to be relatively sure of things but overall a great start to the evenings model output.

its all nice discussing this snow potential and stuff, but you seem to forget if this low comes too far south many people in north england and parts of midlands will not get anything. yes we have had snow, but it would still be nice to have some more too and also if the low keeps being forecast too south it may well just hang onto the very south like it has done before. There is many other parts who want snow too and not just the people in the southwest and wales.

Fi on gfs would deliver bags of snow. lets hope its a trend too

Edited December 24, 2009 by snowlover2009

[rmc1987]

No one care to comment on the UKMO run tonight.

T144 is a excellent chart regardless of whether the low to the sw is further north.

The run is more progressive in retrograding the vortex over to Canada so the much

colder air should start to affect the country sooner.

Quite why is it so excellent? I'm a bit confused as to what all the excitement is about this early. Then I asked the question before and never got a reply.

Edited December 24, 2009 by rmc1987

[Guest North Sea Snow Convection]

You're welcome , i do understand that many members will look at this from their own location but we should bear in mind theres less that can go wrong if the low tracks further south, this might mean that some initially aren't favoured with the rain to snow scenario but this will be better longer term in terms of keeping the cold and with it further wintry chances.

Hi nick - a happy xmas to you

The GEM 12z is excellent and looks to me like everyone in the south would get snow from that - none of this M4 corridor nonsense lol! Then there is the NE'erly coming in behind so frost over the snowfilds as well as further snow showers coming in off the north sea. Purrfection for me!

The UKMO has the low furthest north as you say and is the worst output so far - no snow anywhere south of the Midlands there, plus I don't like the way the low appears to be slowing and preparing to drag its heels across the UK. This definitely would delay the cold air and I think if there was a t168 it might show areas still on the wrong SE side of the low. GFS as you say is inbetween, but still clears the low away eastwards with an epic prolonged northerly to follow..

Long way out to worry about the UKMO anyway - and it often doesn't verify too well at t144 anyway.

Edited December 24, 2009 by North Sea Snow Convection

[snowlover2009]

Well i for one living directly on the south coast have not had any lying snow at all.

am aware of people in the south without snow, but many parts in the north of england have only had a few flurries and been unlcuky to get much. it seems to me all everyone gos on about in here is the snow for the south and the low stalling to the south. so this is annoying me a little. hoping ecm keeps the snow up north in favour for us too

[azores92]

it looks some of us are paying too much attention to specifics once again. what we are discussing is still FI in reality, and so talking about details, like how long the greenland high can stick around for is just contemplation at the moment. given the chop and changing of the models at the moment, i dont think we can talk about the strength of the canadian vortex and the like, for a few days at least. a merry christmas one and all for tomorrow anyway

[Guest North Sea Snow Convection]

not trying to be rude, but lets hope for the low to be further north , as all you would here in the newspapers is 'blizzards blast southern britain' always seems to be about the south, we had a hell of streamer on sunday and nothing in the media at all. like the freezing rain in the south, that was in the media yesterday, yet in lincs it was freezing rain, honestly!

The reason being that as nick explained, having the low further south is better for a more sustained cold spell for everybody

It isn't just about who gets snow in their back garden because of the low - it is about the prospects for another cold spell following the low.

As azores 92 rightly has just said though, it is far too early to go into specifics/details about this anyway. It won't be till after xmas proper that there will be a better idea about these.

Edited December 24, 2009 by North Sea Snow Convection

[snowlover2009]

The reason being that as nick explained, having the low further south is better for a more sustained cold spell for everybody

It isn't just about who gets snow in their back garden because of the low - it is about the prospects for another cold spell following the low.

As azores 92 rightly has just said though, it is far too early to go into specifics/details about this anyway. It won't be till after xmas proper that there will be a better idea about these.

even if ukmo came off, it there would likely to be a sustained cold spell, quite a good greenland high on 144 hrs chart IMO. But one thing what annoys me about these situations is, that it is always you lot in the south who make such a fuss by closing airports, media attention, 'don't go out'. go to america with 5 ft snow and they get on with it. and i say you in the south because in the north we just have to get on with it becuse no one cares. Its not the uk who come to a standstill, it is the south, trying to make a big deal like its the day after tomorrow. what would you be like if it was a 63 or 47 or 78 situation, god only knows. it is the same everytime snow is forecast, same headlines, same old story, it is getting old and old now. people know the flaming drill.