Model Output Discussion 18th Nov.2013-12z onwards.

[bluearmy]

looking through the ecm ens mean and spreads this evening my thoughts at day 10 are definitely that its eyeing up a scandi ridge. most of the long range ens output from ecm recently has built an anomolous  scandi ridge at back end of week 2 but how far north it can get will be the question.  maybe a murr sausage will be our best hope to advect deep cold back west across us.  a great start to winter model watching for 2013/14.

[Methuselah]

CFS 1 is interesting for mid-December. "That CFS?"

 

Yeah, right!

[Catacol]

Early days... but this is as valid a model image as any other, even though this thread tends to focus on charts at 500 or 850.

 

Here is the Strat prediction for 1hPa - right at the top of the stratosphere - for 10 days time.

 

 

Note the warming that is forecast to develop over our part of the NH.

 

This is the strongest predicted warming so far this autumn/winter - we cant see beyond 10 days but quite possible it may build further. It takes a week or more for something like this to propagate downwards towards the troposphere... but it may suggest the beginning of some kind of assault on the vortex.

 

If it turns out as forecast then currently it supports the idea of blocking in our locale. We could do with any vortex distortion at lower levels dragging that high pressure to our east or west... but without trying to use our crystal ball too much this is generally a good sign overall. I'm not knowledgeable enough yet to say more than this - but if we can get blocking enhanced in the latter half of the month with some reduction in the zonal wind speed aloft then our chances increase for sustained rather than transient cold.

Edited November 29, 2013 by Catacol_Highlander

[Panayiotis]

As others have said there is support for the ECM Det 12z! Notice the snow depths for LONDON (bottom right) and mean temperatures remaining at/below 5C in the day after the cold blast. http://www.knmi.nl/exp/pluim/Data/pluim_06260_0_00_60.png?1385759123740

Edited November 29, 2013 by Panayiotis

[Snowman.]

 

 

 

 

 

Looks like someone beat me...

Edited November 29, 2013 by SN0WM4N

[The Northern Ramper]

erm, can you explain why you feel that will/may happen please. Both the 500mb charts show an upper trough over Scandinavia, and over the past few days there has been no sign of the upper high moving on them to where you suggest?honest question

Just my viewing of the 12z output and recent Ens have supported a ridge in this region, I'm sorry John but I haven't factored the 500mb into my post but it is Friday night and I was just offering my opinion.

[gottolovethisweather]

After a brief northerly toppler which will bring some welcome cooler weather neaxt weekend, the default mild pattern of High pressure over Europe and Low pressure strongly centred over Greenland looks the form horse.

 

 

At least the far end of FI shows the jet displaced south and has a bit of promise.

The ENS show the brief cool down before a strongly mild and zonal type regime exerts its grip in the run up to mid month.

 

I personally think your form horse is a right OUTSIDER but time will tell.   I must admit from the 4th/5th December the models don't appear to have a clue, so in my view, NO solid judgement can be made. I personally favour a good week of cold to very cold weather (more especially so given the lying snow likelihood) to come from the 3rd to the 10th December, but even then its conjecture. No form horses for me,  just a decent bout of non-mild air for a fair few days as shown by my other recent posting.

Edited November 29, 2013 by gottolovethisweather

[jam]

Apart from on 2 occasions - 1981 and 2010 - all very early cold-incursions have been transitory in nature; and, it didn't seem to have any deleterious effects on the following winters...Was it the last Saturday in November 1969, or the first in December, that produced blizzard-conditions in Tunbridge Wells - for one day? â€‹IMO, the short blast of Arctic air currently being predicted by some model-runs is nothing out of the ordinary...

If your team won 1-0 last December it doesn't stop you getting excited when they win again 1-0 this year

[Tim Bland]

As others have said there is support for the ECM Det 12z! Notice the snow depths for LONDON (bottom right) and mean temperatures remaining at/below 5C in the day after the cold blast. http://www.knmi.nl/exp/pluim/Data/pluim_06260_0_00_60.png?1385759123740

Is this Definately for London as it say Debilt?

[Skyraker]

I've got nothing to add, but I noticed this in the strat thread and I really hope this propogates straight down.

 

Something is brewing and I think the models are struggling somewhat.

 

 

Early days... but this is as valid a model image as any other, even though this thread tends to focus on charts at 500 or 850.

 

Here is the Strat prediction for 1hPa - right at the top of the troposphere - for 10 days time.

 

 

Note the warming that is forecast to develop over our part of the NH.

 

This is the strongest predicted warming so far this autumn/winter - we cant see beyond 10 days but quite possible it may build further. It takes a week or more for something like this to propagate downwards towards the troposphere... but it may suggest the beginning of some kind of assault on the vortex.

 

If it turns out as forecast then currently it supports the idea of blocking in our locale. We could do with any vortex distortion at lower levels dragging that high pressure to our east or west... but without trying to use our crystal ball too much this is generally a good sign overall. I'm not knowledgeable enough yet to say more than this - but if we can get blocking enhanced in the latter half of the month with some reduction in the zonal wind speed aloft then our chances increase for sustained rather than transient cold.

[nick sussex]

Further to BA 's post the Dutch ensembles, a cluster go for an an easterly with  zero/sub zero for that region, note also the low dew points and the wind direction.

 

As good as the NOAA maps are re anomalies they can be slow to pick up a change, if the chance of an easterly grows the models usually will go to it quickly, the ECM 240hrs is the first step, this might come to nothing if we don't see enough energy heading south into the mid Atlantic but certainly something to keep an eye out for. It might be a more continental flow easterly with centre not in the ideal location, a Euro/Scandi high rather than the 5 star one centred much further north but at least theres a chance we could see an extension to the cold.

 

 

 

 

 

 

[fergieweather]

 

Is this Definately for London as it say Debilt?

Yes, I pondered the same and was baffled - that's De Bilt in the Netherlands??! I'm just going to check the (real) London EC EPS for comparison (might be broadly similar in some broadscale set-ups, but rarely identical... there'll be varied nuance differences in the EPSGram output).

[SHM040519]

If it snows on 20th December so I can't get to Earls Court, I will cry! As much as I love snow, just not on the 20th! 

[Summer Sun]

ECM ensemble shows -5 850's covering all of the UK at t168 and t192 -10 850's just clip northern Scotland

 

 

By t192 the ensemble shows pressure slowly building over the UK with the 850's slowly recovering though it would remain cold at the surface

 

Edited November 29, 2013 by Summer Sun

[bluearmy]

Panyotis - those are the debilt 00z charts. The 12z dutch show that the control follows the op closely and thereafter into the freezer as the flow turns to the east (and not completely slack either). The drum beats quietly for an easterly flow to follow the northerly (in whatever form it takes)

[essexweather]

London/Essex ECM ensembles here: http://www.essexweather.com/outlook.html

 

Not too different, but about 1 or 2 degrees difference this side of North Sea.

 

There were 4 members (out of 50) that had snowcover, greater than 1CM in London at the next of next week.

 

Also worth pointing out, there were a couple of sub-zero (ice day) members too :-)

Edited November 29, 2013 by essexweather

[fergieweather]

 

London/Essex ECM ensembles here: http://www.essexweather.com/outlook.html Not too different, but about 1 or 2 degrees difference this side of North Sea. There were 4 members (out of 50) that had snowcover, greater than 1CM in London at the next of next week. Also worth pointing out, there were a couple of sub-zero (ice day) members too :-)

Yup - thanks. I was just checking the Reading ones. Broadly similar story.

[Frosty.]

The Ecm ens mean has improved from a wintry point of view, this is now looking much better than previous days and with power to add if the cold signal becomes even stronger which it could. As things stand, arctic air will surge down across the whole of the uk towards the end of next week with a strengthening Nw'ly veering Northerly airflow bringing a band of rain which could turn to snow on the back edge of the cold front as the arctic air piles in behind it with snow showers following to many areas, some heavy and merging at times with drifting in the gale force winds, high windchill factor and penetrating frosts setting in with at least a few ice days...not a bad start to winter in my book.

[tight isobar]

Yes, I pondered the same and was baffled - that's De Bilt in the Netherlands??! I'm just going to check the (real) London EC EPS for comparison (might be broadly similar in some broadscale set-ups, but rarely identical... there'll be varied nuance differences in the EPSGram output).

.plenty varied one would susspect.

[Mucka]

18z is a repeat of the 12z only a tad faster at 120h, certainly different to MetO and especially ECM.

[Cloud 10]

Wintry weather into northern Scotland at t120 on the 18z.

 

 

 

Slowly coming around to the Euro models,but not quite there yet.

[Cecil Hogmanay Melchett]

18Z Not going to look anything like ecm and looks flatter and faster with the secondary low.

We'll see how it pans out..

[Snowman.]

Better amplification so far.

[Mucka]

GFS ECM comparison for what is now just 138h

 

 

One of them is very wrong. 

[Frosty.]

Check this out guys..GEFS 12z perturbation 5........what a stunner and it has more staying power than the ecm 12z op run, there are some other crackers in there too, including the control run. This has been a much more positive day / night for coldies hopes of a sharp shock Arctic Blast in barely a weeks time.