Winter Model Discussion - The Hunt For Cold -12z 14/12/12

[LomondSnowstorm]

The Gfs 12z op run looks like a mild outlier to me, i'm sticking it in the shredder with the polar vortex. The ukmo 12z looks more realistic and i'm sure the ecm 12z will be better.

It's not so much the temperatures as the December 2011/ January 1993 level strength of the vortex it builds. Looks a wee bit suspect to say the least...

[Frosty.]

It's not so much the temperatures as the December 2011/ January 1993 level strength of the vortex it builds. Looks a wee bit suspect to say the least...

Yes it's very suspect and doesn't fit with the background signals, it's just one of those rabid zonal nonsense runs the gfs is famous for. I still believe there will be trough disruption next week and cold air will make some sort of comeback but the T+96 to 120 range is still to be sorted, will be pivotal to where we go from there..my hunch is cold.

Edited December 14, 2012 by Frosty039

[chris55]

This mornings ECM vs the GFS 12z could not be more differant for the 22nd!!!!!!!!!

[bluearmy]

there is a norwegian shortwave on the ecm 12z (version was also on the 00z) just so we feel 'at home'.

[Summer Sun]

GFS 12z ensembles

[Gavin Hannah]

This mornings ECM vs the GFS 12z could not be more differant for the 22nd!!!!!!!!!

GFS loves to really wind it up. ECM much more attractive.

[Harsh Climate]

ECM looking decent at 144h

[Matty M]

ECM not bad. move that shortwave east of Scotland southwards and we are in a cold flow.

[phil nw.]

ECM like the other models continue to tease with that cold air edging so close to our north east around T120-144hrs..

again the energy from the west just too much and holds us in the Atlantic pattern.

There are just too many fragments of energy breaking off the main vortex to our north which precludes any solid westwards extension of those Russian heights.

Edited December 14, 2012 by phil n.warks.

[Gavin Hannah]

ECM like the other models continue to tease with that cold air edging so close to our north east around T120-144hrs..

again the energy from the west just too much and holds us in the Atlantic pattern.

There are just many fragments of energy breaking off the main vortex to our north which precludes any solid westwards extension of those Russian heights.

Looking good for the North. And the South isn't exactly tropical. I'm seeing tiny wee upgrades from the ECM over the last few runs.

Edited December 14, 2012 by IBringTheHammer

[TEITS]

So a slight difference between the GFS & ECM!

http://www.wetterzentrale.de/pics/Recm1681.gif

http://www.wetterzentrale.de/pics/Rtavn1681.png

[Methuselah]

Surely, if the block to the East was sufficiently dominant, any 'shortwaves' wouldn't matter a jot?

[Panayiotis]

So a slight difference between the GFS & ECM!

http://www.wetterzen...cs/Recm1681.gif

http://www.wetterzen...s/Rtavn1681.png

Just a tad! Not looking bad at 216hrs can we get a ridge into Greenland once the low moves east? http://www.meteociel...ype=0&archive=0 Edited December 14, 2012 by panayiotis

[phil nw.]

Looking good for the North. And the South isn't exactly tropical. I'm seeing tiny wee upgrades from the ECM over the last few runs.

Yes we are so close to a proper incursion of cold -the ECM way better on this as shown by TEITS but not quite there on this run.

Things are still finely balanced but i have seen these setups before where the block to the east holds the pattern up for a while as we remain on the edge of things.

We are not yet seeing enough heights building to our north.

[Gavin Hannah]

Yes we are so close to a proper incursion of cold -the ECM way better on this as shown by TEITS but not quite there on this run.

Things are still finely balanced but i have seen these setups before where the block to the east holds the pattern up for a while as we remain on the edge of things.

We are not yet seeing enough heights building to our north.

Well, on the 00Z, the -5 was east of scotland, on the chart you posted, it's over Scotland. If i'm reading correctly. So, small but significant steps in the right direction.

[swfc]

Well no doubt a downgrade on ECM . Guess its a suck and see job !

Edited December 14, 2012 by swfc

[Zakos]

The positive trend continues, There is definitely the possibility of a cold spell around the xmas period.

It is too far out to tell, but on balance the Atlantic is slightly more likely to win the battle. This could change at any time, the cold air is very close to our shores, a small westward shift is all it takes. Knife edge at the moment.

According to posters on here, some professionals are writing off cold until the new year.

This is foolish in my opinion. There is little indication of a raging easterly just yet, but with a stubborn and very powerful Russian high, and a cold pool just to our east, there is no way anyone can rule out cold for the rest of the month.

[TEITS]

Well good luck to anyone forecasting the xmas period.

Very bizzare set up really because the ECM continues to keep the jet displaced further S than the norm but we don't have the N blocking that you associate with a jet tracking S like this. As a result only slight differences can mean either mild or cold and to be honest I have no idea which. In this set up you would assume Scotland has the greatest chance of being on the cold side.

Until +96 to +168 is resolved then I won't analyze the model output too much. I did hear Peter Gibbs on BBC at lunchtime say the mild, unsettled pattern will continue into xmas! Well I for one wouldn't be so confident on any forecast.

[joggs]

Cmon all you big guns, gp,jh,chio,bftp,teits etc. Its friday eve im opening a nice bot o red and praying for some undercutting showing soon. Taking everything into account how do you guys feel(with all your experience) these next 2 wks or so will evolve to what the models are showing? Think of yourselfs in the smoky met room in the 70s/80s about to go live with nothing but intuition and skill. Bit of fun to liven the mood!

[phil nw.]

Well, on the 00Z, the -5 was east of scotland, on the chart you posted, it's over Scotland. If i'm reading correctly. So, small but significant steps in the right direction.

Yes i take your point but i was commenting more on the pattern overall.

As i said the cold is very close to our north east and the boundary will ebb and flow slightly in the differing runs but essentially the deep cold is held at bay across the north sea.

[chris55]

Complex set up, ECM OK and sticks with the same theme. I still think we need the Barents sea Low to push east into North Eastern Russia to give our cut off Scandi high a chance to set up in the right place though. 12z has it forcing on the western side, hence not such a good run in FI. However these short-waves tend to be modelled better in the shorter timeframes.

[nick sussex]

Overall a disappointing evening in the models. The trend has been to take the jet further north, even the ECM is going the wrong way, a long train of lows moving east quickly with nothing to stop them.

The problems really start early with shortwaves to the north east stopping an initial westwards ridge to at least edge the pattern a little further south and develop a more favourable tilt to troughing to the west.

There are some marked differences between the GFS and ECM/UKMO but even allowing for that its hard to be convinced that future outputs by the ECM wont continue to edge the pattern north.

The PV looks to be on the move with pieces flying all over the place but at the moment those seem to be landing in all the wrong places.

The Xmas Miracle boat has now been torpedoed and is taking on water fast, an SOS has been sent out, we'll find out tomorrow whether that has been responded to or whether the ship finally sinks.

The ECM holds just enough interest but we need a big push south in the jet to deliver.

My optimism rating has now plummeted from 6 this morning to 5/10.

For those wondering why the rating isn't lower! A score lower than 5 means Code Red and entails lots of operatives being moved into all exits from net weather, this costs alot of money and I already spent most of the budget on the Xmas shopping!

Edited December 14, 2012 by nick sussex

[swfc]

Overall a disappointing evening in the models. The trend has been to take the jet further north, even the ECM is going the wrong way, a long train of lows moving east quickly with nothing to stop them.

The problems really start early with shortwaves to the north east stopping an initial westwards ridge to at least edge the pattern a little further south and develop a more favourable tilt to troughing to the west.

There are some marked differences between the GFS and ECM/UKMO but even allowing for that its hard to be convinced that future outputs by the ECM wont continue to edge the pattern north.

The PV looks to be on the move with pieces flying all over the place but at the moment those seem to be landing in all the wrong places.

The Xmas Miracle boat has now been torpedoed and is taking on water fast, an SOS has been sent out, we'll find out tomorrow whether that has been responded to or whether the ship finally sinks.

The ECM holds just enough interest but we need a big push south in the jet to deliver.

My optimism rating has now plummeted from 6 this morning to 5/10.

fair call there looking at today's runs.nice to see a post without any

background signalsete ete .refreshing and to the point !!! Can feel a "dido"moment coming on Tom nick hahaha

Edited December 14, 2012 by swfc

[J10]

http://forum.netweat...-december-2012/

The latest Alps forecast has now been released, and the synoptic extract from it has been shown below.

Daily Synoptic Summaries

Starting with today's actual synoptic charts -

Temp guide at 850HPa sub -10c very cold, -5c cold, 0-5c cool, 0 to +5c mild, above +5c very mild

Sat 15 December - There is a large area of High Pressure (1056mb) centred over Russia, with south to South Easterly winds over Eastern Europe, and Northern Scandinavia, very cold here. There is low pressure covering much of the Atlantic, lowest pressure around 970mb to the west of the UK. This is feeding in mild SW winds over the UK and much of Northern and Central Europe, including Southern Scandinavia and the Alps. Further South there is High Pressure over Southern Europe as the Azores High ridges eastwards, bringing mild or very mild weather here.

Sun 16 December - The general pattern very similar, however the air mixing out over Northern and Eastern Europe, turning less cold over much of Scandinavia, and less mild over other parts of North Eastern Europe, this fringing the Alps, so not quite so mild here. The low pressure over Atlantic, weakening, but still rather unsettled and mild over the UK. Further South there is still High Pressure over Southern Europe, bringing mild or very mild weather here.

Mon 17 December - Synoptically again similar, but the low pressure now over the UK (99mb) and continuing to weaken. Cool over the UK, much of Northern mainland Europe, cold over Scandinavia and over Russia with the High Pressure still strong (1048mb). Still mild over Southern Europe. The Alps in between the cool weather to the North and mild weather to the south, with 850HPA around 0c.

Tue 18 December - High Pressure continues to dominate over Russia, Eastern Europe and into Scandinavia, so cold or very cold here. Cool over much of Europe with weak low pressure over the low countries. Still mild over Southern Europe, low pressure further east, the Azores high keeping things more settled over Iberia, Pressure also starting to rise over Western parts of the UK, cool in the east, mild in the west.

Wed 19 December - High Pressure (1052mb) continues to dominate over Russia, Eastern Europe and into Scandinavia, so cold or very cold here. A deep area develops over the Atlantic bringing unsettled conditions and very mild air into Southern parts of the UK. Also turning milder over western parts of mainland Europe, but still cool over Eastern Europe, this divide splitting the Alps in Half.

Towards Weekend - The High Pressure Over Russia remains a constant, so very cold here and into Scandinavia, cool also over Eastern Europe. The Azores High staring to ridge back into Southern parts of the UK, and cooler again after the mild weather of midweek. As has been often the case this week, the Alps very much in between weather systems.

[Frosty.]

Next week shows major uncertainty, the cold block is close and is ready to pounce although the latest ecm run would be coldest in the far north, the changes begin as early as monday and tuesday with cyclonic conditions and temps a bit lower than the weekend, nearer 6-8c on mon/tues following the 8-10c on sat/sun. We really need to see the troughing modelled to slip further southeast to enable the cold block more chance to dig further south and west so it wouldn't just be scotland that turns colder, but it keeps things interesting for coldies.

Edited December 14, 2012 by Frosty039