Model Output Discussion 1st January 2014-06z onwards.

[That ECM]

http://images.meteociel.fr/im/128/gfsnh-1-102_oft9.png

Look at that cold air to our ne.

[fergieweather]

 

Low not taking as southerly a course as it did on the 12z http://www.wetterzentrale.de/pics/Rtavn901.png!!

All very knife-edge, but that's always been expected... could go either way, as per varied ENS outcomes.

[Continental Climate]

 All very knife-edge, but that's always been expected... could go either way, as per varied ENS outcomes.

Yep I have to agree this aint a done deal yet, lets all remain cautious until we have our easterly at T72

[Cheshire Freeze]

Heights still gaining a foothold to the N though + vast majority of energy heading SE

 

[Allseasons-Si]

Over a 1000 users now at the moment,where are thow

 

very cold temps in scandi,will they make it

 

12z@ 108hrs18z@ 102hrs

 

 

[Purga]

Good job this is after the 9.00pm watershed

 

[tight isobar]

Yes slap on the wrist for me, one frame and I overhyped expectations. Much more progressive 18z thus far.

[Joe Levy]

I think it was always going to be fairly knife edge, and this chart is a very good one as far as I am concerned! In fact is shows that we can still get energy south-eastwards, even if the low is further north. However, not a done deal so let's hope this pattern is maintained/improved upon

[Cheshire Freeze]

Could be much better long term actually. Look where centre of block is....forcing more disruption SE of lows rather than heading E or NE

 

 

And it stops attempted interference from Atlantic high at bay.....which is a plus.

Edited January 8, 2014 by CreweCold

[Ice Day]

OK, may not be quite as good as earlier runs, but this is still far better than anything else this winter.  Could still get there in the end as well!?

 

[Snowman.]

I think it was always going to be fairly knife edge, and this chart is a very good one as far as I am concerned! In fact is shows that we can still get energy south-eastwards, even if the low is further north. However, not a done deal so let's hope this pattern is maintained/improved upon

Remember the bias of the runs.

 

0z likely to be closer to the mark.

[Geordiesnow]

Think this run looks more like the ECM than the GFS 12Z run is respect of any blocking, looks to have more potential too me, whether enough energy is sliding under the block to show an easterly flow remains to be seen but I do suspect as per usual with the GFS, it will all look rather messy and disorganised but the signs are increasing that we may tap into some of the colder air to the NE but still many more runs needed before the detail gets nailed down. 

[snowmadchrisuk]

High pressure much stronger and further into Greenland , sending the low pressures in a much better SE direction, will undercut the High much better on this run IMO. Also should drag Cold in earlier than the ECM

[Purga]

I hope the pub run won't turn out to be late night horror ----  'Nightmare on Netweather Street' !

 

Nick Sussex must be a nervous wreck!

[Cloud 10]

It will be interesting to see where that front is on the 96 hrs fax chart when it comes out shortly.

 

[Fred Sykes]

+1

 

Also the alignment of the small scandi shortwave is as the ECM- funnelling cold SW as opposed to blocking it-

 

Upgrades........

 

The train is coming.- 90% but the 18z doesn't want it to leave the stn

 

S[

And according to Ian F, the train may never reach us, so best not to get excited yet.

If these runs are similar on Sunday I will be the first to welcome the train, but until then, I remain cautious.

[Cheshire Freeze]

Could be an epic 144 hours chart coming up

[Continental Climate]

At 126 it looks very different from the 12Z http://www.wetterzentrale.de/pics/Rtavn1261.png!! The high is less robust and not as large but centred more toward Iceland Greenland. So am not sure which I prefer really haha over to the experts on that one

 

At 138 the high looks very weak http://www.wetterzentrale.de/pics/Rtavn1381.png! It looks like it could just dissolve into nothingness!!

Edited January 8, 2014 by Continental Climate

[Cheshire Freeze]

At 126 it looks very different from the 12Z http://www.wetterzentrale.de/pics/Rtavn1261.png!! The high is less robust and not as large but centred more toward Iceland Greenland. So am not sure which I prefer really haha over to the experts on that one

 

I'll take the 18z please....copious amounts of snow somewhere with this collision

 

 

Weaker block, yes, but better placed and much more energy underneath across the pond

Edited January 8, 2014 by CreweCold

[BlueHedgehog074]

Even though there is no 100% guarantee the cold South-Easterly/Easterly/North-Easterly flow will come off, going to rate each model out of 100 in regards to the quality and potential of their cold outlooks. I will also give an overal percentage rating at the end of each model. 12Z runs only.

 

 

12Z GEM

 

Northern blocking development potential: Quite a clean transition with Lows out in the Atlantic sending some trough disruption to the South-East along with a strengthening block to the North-East forcing the Lows/shortwaves to slide underneath the block - 87/100

Easterly flow quality: Quite a long drawn flow from the East with shortwaves and/or troughs circulating in the flow. The source of the Easterly flow does eventually orginate more from the South-East within time - 87/100

850 hPa temperature coldness: -1*C or colder 850 hPa temperatures become established across the whole of the UK as early as 126 hours with increasingly colder 850mb temperatures spilling in from the East. Many areas of the UK become entrenched in -8*C to -10*C 850 hPa's for a time. The cold 850 hPa temperatures do eventually start becoming mixed out from the South-East - 90/100

Block strength: A sturdy looking 1035mb High Pressure system establishing from Iceland through to Scandinavia, which holds quite well. However, some of the Lows and the pieces of the Vortex to the North and to the West of the High do try to force the thing to back a little bit further East/South-East within time (probably also thanks to the fact that the Azores High tries to link up with the block to our North with Lows finding it harder to some some enegry South-Eastwards), although with the UK still in a cold flow from the East or South-East - 88/100

Longetivity: The cold weather seems to last right to the end of the run with that cold flow from our East or South-East. Some risks that the pattern could start to colapse to the West or North-West, although with those trough of Lows to our South and South-East, this could help to cotinue to prop the block to our North for a further few days - 93/100

Snow potential: The Easterly flow looks rather unstable with some of those chilly 850mb temperatures and Low heights with wintry showers likely to be quite frequent over to the East. Shortwave troughs embedded in the flow could provide some longer spells of sleet and snow at times. Some of the wintry weather could easily make it all the way to the Western UK with that Cyclonic Easterly flow. A possible 'battleground' rain, sleet and snow event for the 13th January, too, as Atlantic fronts try to bump up against the colder air to the East/North-East - 90/100

 

Overal score: 92%

 

 

12Z GFS

 

Northern blocking development pontential: Not quite as clean looking in comparison to the GEM. Some members mention the trouble of one or two of the shortwaves around the Iceland area hindering the transition of the Lows trying to slide underneath the block properly. The High Pressure system to the North and North-East of the UK does get its revenge and the Easterly flow establishes for the whole of the UK, albiet a little later than on some of the other models - 76/100

Easterly flow quality: - Very similar to the high quality Easterly flow of the GEM's. Fairly slack(ish) at times (altough this could help aid frost development during periods where the skies clear), and also unstable. Becomes more North-Easterly within time. Near the end of the run, developments to the West and North-West cut-off the UK North-Easterly flow - 85/100

850 hPa temperature coldness: Due to some hindered developments near the bgeinning of the run, those cold 850 hPa temperatures from the East don't make any real impact until around Wednesday/Thursday next week. 850 hPa's varying around -7*C to -11*C become more widespread from the East for a time, but subside somehat from the South-East. Near the end of the run, milder 850mb temperatures spill in from the West to affect much of the UK - 85/100

Block strength: Takes a little while to make an influence for the UK, but does become more suasage-shaped to our North. Starts off more like a 1020mb High, but goes on to become a 1030mb monster later. It eventually looses the battle against the advancing Lows to the West knocking the block to our East - 90/100

Longetivity: Lasts for a good few days. But the Azores High starts to cause trouble and ends up linking up with the High Pressure system to our North cutting off the supply of Low Pressure systems sliding underneath our block. With the Polar Vortex coming back to life over Greenland, Low Pressure systems to our West blast the blocking away and the Westerly winds return. (This is, however, in deep FI and the GFS can have a habit of flattening the pattern out a little too prematurely) - 84/100

Snow pontential: Probably start as high-ground events only, especially on Monday, as that trough pokes its way Eastwards and brings spells of rain sleet and snow - the sleet and snow likely to be restricted for the hills. Snow, via wintry showers, or longer spells of wintry precipitation, later on next week should reach increasingly low levels, and probably likely to become widespread at times from the East. The unstable showery Easterly airflow does get eradicated eventually, and any showers, mostly in the South-East could turn to rain, or sleet, as those milder uppers from the South try to get into the Easterly flow - 82/100

 

Overal score: 84%

 

 

12Z ECMWF

 

Northern blocking development pontential: Seems to get their without too much hassle. Quite similar to the clean transition of the GEM with Lows sliding under the establishing block to our North/North-East. The development of it does look a bit too fragile for Monday with the ECMWF almost tricking you into thinking that the pattern will end up being a little bit too far North. But... the block soon gets its act together and gets 'em Lows tracking far enough South with the Easterly flow saying hello to the UK a day afterwards - 83/100

Easterly flow quality: Another decent-looking Easterly flow, which becomes long-drawn all the way from Scandinavia. However, this soon turns into a milder South-Easterly flow - 84/100

850 hPa temperature coldness: - Despite the Easterly flow establishing next Tuesday, the -5*C or colder 850 hPa's don't become influential until the day after. 850 hPa temperatures around -5*C to -10*C become more widespread with Scotland seeing those chilly -10*C or colder 850 hPa's, but these do quickly get knocked away as milder 850mb temperatures get sucked up from the South and South-East - 77/100

Block strength: Doesn't seem to hold on quite as well as the GEM and the GFS at around 240 hours. Lows tracking East through Greenland smack it South-East, although it does not get knocked away completely with it clinging on like blu-tack our North-East. The block does develop a centre of around 1025/1030mb to our North - 80/100

Longetivity: Again, we see a High Pressure system to the West or South-West which links up with the Icelandic and Scandinavian block to our North. But with the Polar Vortex wanting to return to the North-West, it puts pressure on the pattern and the block starts to sink quickly South-Eastwards with our cold flow cut off. The Low Pressure to our South-West may help, however, to stop that High to our North-East to collapse entirely - 80/100

Snow pontential: Maybe a chance for some wintry precipitation over high-ground late on Sunday and into Monday. Potential for wintry showers again to flood in from the East as the Easterly flow becomes more unstable, although some North-Western spots could stay quite dry. The unstable Easterly flow does get cut-off fairly quickly, so any showers that may still occur will turn into rain - 79/100

 

Overal score: 80%

 

 

12Z JMA

 

Northern blocking development pontential: Does that usual idea that the other models do with some negative tilting of the troughing out in the Atlantic helping to draw High Pressure to our East further Northwards with that block forming to our North and North-East. Its evolution to get us to the Easterly flow is a bit of a long one, and a bit messy like the GFS. The Lows that approach from the West that try to slide underneath the block are more ball-shaped and don't seem to disrupt as much, or get quite as squashed in relation to the 12Z GEM run. The Easterly flow doesn't set in until Thursday next week, where the Lows start sliding underneath the block more effectively - 74/100

Easterly flow quality: Is more of a South-Easterly flow at first, although quite a chilly looking one. It looks as though the more direct Easterly following on after could become rather potent as those -10*C 850 hPa temperatures to our North-East look eager to flood Westwards over the UK - 80/100

850 hPa temperature coldness: Despite the varied flow during the first part of next week, some pockets of -5*C 850 hPa temperatures become embedded over the UK at times. But I think the JMA does overdo the coldness of the 850 hPa's at times. -5*C, and potentially much colder 850 hPa temperatures, attempt to spill in from the East later on - 85/100

Block strength: It's big. It's bad. It's strong... and it looks in no hurry to move from its Scandinavian spot. But can it back any of its ridging towards Greenland before the Polar Vortex gets their first? Probably.

High Pressure center - 1035mb! - 92/100

Longetivity: With the run only going out to 192 hours, it's kind of hard to tell, although no mild weather looks evident for the UK. That mighty Scandinavian High Pressure system could hang about to our North and North-East for a good while. And may even last longer than the likes of the GEM and GFS - 94/100

Snow pontential: Possibility for various pieces of wintry weather to affect some parts of the UK for the first part of next week, though it may be mostly concentrated over the hills and mountains, but some of it could extend to lower levels at times - what with the 850 hPa's looking quite cold. Wintry showers could then start piling in from the East towards the end of the run - 85/100

 

Overal score: 87%

 

 

12Z UKMO

 

Northern blocking development pontential: Quite a clean transition with the block to the North trying to force the approaching Lows out West to track South-East, while some troughing goes over the top of the block to the North to try and keep the High steady. May need to watch out for the sphere-shaped Low coming in from our West next Tuesday (should it verify). It looks quite possible, though, that the block to our North could force it to disrupt some energy South-East. (Edit: Just having birefly stumbled across one of Nick Sussex's model paint jobs, the potential for Low undercutting seems even better than I realised). Was 82/100, but now bumped it to 85/100

Easterly flow quality: Probably too early to say, but as longs as that Low to our West on Tuesday slides underneath the block smoothly, then we could be seeing something similar to what the other models show. Some sort of Easterly flow does, at least, occur for Tuesday, though looks mostly concentrated towards the Northern UK. Maybe anywhere between 80 to 90/100 depending how those Lows out to the West behave on future runs. 

850 hPa temperature coldness: Probably will leave this one out. The Meteciel model viewer does, however, show the -4*C 850 hPa temperature line over the far North-East on this run at 144 hours. But could easily see colder 850 hPa temperatures spilling in from the East. ?/100

Block strength: Quite a tough looking thing to our North with a High Pressure centre of around 1030mb. Those approaching Lows to our West should help to support it in some way to our North along with the existing Low heights to our South, and it doesn't seem to be in any real danger of sinking like a boat - 85/100

Longetivity: I think it will depend how well that block to our North can disrupt those Lows out to our West. But agian, their doesn't seem to be any real danger of too much 'energy' piling over the block, or the Polar Vortex trying to unleash its power back to our North-West. So maybe a rating around 85/100 or higher.

Snow pontential: If things go according to plan, then we could see the wintry shower setup from the East, with maybe some high-ground snow events earlier on in the run. (Maybe FergieWeather could clarify on some of the detail here - only if he's okay with it). ?/100

 

Overal score: 86% (but with some bias towards some of my guesswork. And it probably does also seem unfair to rate it considering the run goes out to 144 hours)

 

The Winner: 12Z GEM. Congratulations, you win an oscar for the best-looking cold run of the night...

Edited January 8, 2014 by DiagonalRedLine

[Captain Shortwave]

Interesting this is, marginal snow event across the UK, look north, the high will move west and watch the low over Svalbard move south.

[Severe Siberian icy blast]

So many frantic posts , I understand given the short wave drama I suppose !

One thing that strikes me today is the significant shift west with the what was scandi high , it's now Iceland , toward Greenland , but we know for long lasting trough disruption it's best to see a classic murr sausage !

[Allseasons-Si]

@At 144hrs...........

 

potential reload from the north

 

 

not there on the 12z @150

 

 

this could be good with the hights going into greenland(retogresion)

 

EDIT:CS beat me to it

Edited January 8, 2014 by allseasons-si

[Cecil Hogmanay Melchett]

I'll take the 18z please....copious amounts of snow somewhere with this collision

 

 

Weaker block, yes, but better placed and much more energy underneath across the pond

Dont want to be a party pooper CC but thats RAIN for the majority.By Tue night we're still above freezing..

[Cheshire Freeze]

Interesting this is, marginal snow event across the UK, look north, the high will move west and watch the low over Svalbard move south.

 

Yes! Less pressure on the block too with vortex energy draped around it rather than passing over the top of it....