Model Output Discussion 17th Dec.2013-12z onwards.

[Blizzardof82]

What a beautiful set of charts this evening. Popped out of nowhere really.well at least we have the ecm to bring us back down to reality!!its been doing that over the past few days.

Even if that's the case IMO the ecm has been out performed by gfs so far this winter.

[Purga]

Well a decent FI from GFS 12z with a split vortex and some good warm uppers piling into the Arctic from the Aleutian side of the Globe.

This is exactly the sort of chart we want to see if there is to be chance of any proper cold weather developing for us here in GB.

Problem is it's far FI and won't verify like this but let's hope a - ENS shows some supprot & b - so does ECM when we get within range.

Edited December 19, 2013 by Purga

[Duane S.]

Interesting is the just-post-Xmas period. Over the past few days there has been increasing support for lower pressure over the Alps area.

 

 

The jet may well bounce back North a bit shortly afterwards but I could well see it digging down again 1st week of January, possibly with more gusto and followed by more sustained low(er) pressure in that area. Certainly a more likely outcome to my mind than a slug high over the continent by week 2 of Jan. Height rises from the other side of the NH are going to need to play a role here so hopefully we will see this refelcted over the coming days in the AO forecast.

[Ali1977]

PV still strong in the ens unfortunately , not following the Op!!!

[Cheshire Freeze]

PV still strong in the ens unfortunately , not following the Op!!!

 

I'm not sure how well the ens model the strat, if at all, so if indeed it is going to be a strat led pattern establishing, the GEFS may not latch on until much later.

 

I remember GP saying something along these lines last year.

Edited December 19, 2013 by CreweCold

[Ali1977]

Actually now at 336 there is some support showing...

[howmuchsnow]

Forecasts last week showing the path of the oscillating jet stream moving across the Atlantic are now paying dividends with colder air digging further south bringing us some wintriness to lower levels in the run up to Christmas. With the cool down in Eastern Europe and the continued dissipation of depressions hitting Scandinavia, the forecast pressure rise over Europe is going to be interesting!

[West is Best]

Well I've been watching and waiting on these runs, like most of you probably have, for days now. Not simply because of the symbolic time of year but this has been intriguing. Some of the oddest runs I've seen in a long while. On the one hand there's a massive PV shift itching to unleash from the north: you can see it with almost every run. On the other far to our south or south-west a bloody great Bartlett High that is desperately trying to hold on, with the jet piling through the middle, but switching south of us to bring us on the northern side of the polar jet front.

 

What's going to happen next? I hope I'm not ramping it but I think things could turn very very interesting. The week between 25th Dec and 01st January could see a massive shift to cold.

[Cheshire Freeze]

Loose support for something wintry from control run at same timeframe

 

Edited December 19, 2013 by CreweCold

[Gael_Force]

A perfect chart for VERY cold surface air over any snow covered areas in Scotland- ( if we can get this area detached from the jet)

 

http://modeles.meteociel.fr/modeles/gfs/runs/2013121912/gfs-0-186.png?12

 

&

 

http://modeles2.meteociel.fr/modeles_gfs/runs/2013121912/180-778UK.GIF?19-12  Approaching -15c  would be a good bet.......

 

 

Also 12z GFS

http://modeles.meteociel.fr/modeles/gfs/runs/2013121912/gfsnh-10-372.png?12 a spot of -16 over RUSSIA !! Same as last winter!!!!

 

 

S

 

I've already mentioned the very cold outliers (for W Scotland) appearing on the last few runs of the ECM 32 - It will be interesting to see if that signal strengthens in tomorrows update.

 

[Purga]

I'm not sure how well the ens model the strat, if at all, so if indeed it is going to be a strat led pattern establishing, the GEFS may not latch on until much later.

 

I remember GP saying something along these lines last year.

Yes agree with this CC & the Det run of the GFS in FI, although much slated, can be good at picking up distant trends. at least we can hope so in this case!

[Joe Levy]

At the end of the GFS 12z, the stratospheric warming over Asia is much more pronounced than I have seen on previous runs. If it verified, it would be the most significant warming of the season so far at that latitude

[nick sussex]

At last some interest in the models, the UKMO looks okay at T144hrs, the GFS in the higher resolution and also the GEM has a decent trend. I think part of the reason for this is that the models have made less of that low crossing the USA and move it further south.

 

The high pressure lobe in the Arctic now looks a key player to help at least deliver something a bit more wintry more UK wide, it would be great if we could see an undercut upstream.

 

I really hope the ECM has its Santa hat on and doesn't harpoon  tonights more positive trend.

Edited December 19, 2013 by nick sussex

[fergieweather]

 

I've already mentioned the very cold outliers (for W Scotland) appearing on the last few runs of the ECM 32 - It will be interesting to see if that signal strengthens in tomorrows update.

 

Ditto the colder ones further S (e.g. Reading) that I cited in my previous EC32 update note. Very much the minority on the last 2-3 runs (i.e., those where uppers dropped to circa -10) but tonight's output might be instructive regarding this being bolstered... or not.

[MR EXTREMES]

I think to be honest the ecm is gonna dampen the spirits but the ukmo gem and gfs all wanting to get into the new year party spirit will the ecm stand alone and come out smelling of roses or will the ukmo and gfs continue to rock the new year party certainly not boring.

[MR EXTREMES]

so far so good from the ecm at t96 slacker flow over Greenland couple of low pressure systems vortex swinging round could be a gradual slide southeast.

fingers crossed but the ukmo and gfs have been throwing out pattern change for few days now.

[Stuie]

Blimey, the PV has fallen apart. Not such a happy home now.

[swfc]

pretty good ecm at 144 hrs

[shaky]

pretty good ecm at 144 hrs

and so it begiins!!!!!!another potential cold spell!!

[gottolovethisweather]

Well the ECM 12z is rolling rolling rolling.

 

At t+72 hours we have this and just where does the resulting development want to present itself over the UK at such a timeframe.

 

 

Due NW of the British Isles and a very deep depression at that is the answer by t+96 hours.

 

 

Eyes down to the Christmas period and the H500s and SLPs of the ECM 12z suggest this for Christmas Eve.

 

 

A plain nasty depression over parts of Scotland and Ireland by Christmas Eve with a potential wave depression rearing its head in the Atlantic for Christmas Day itself? The T850s aren't stunning by this juncture but...... best watch this space judging by the view from over the Eastern seaboard, better offerings down the line perhaps? So now time to reveal Christmas Day and Boxing Day's expectations from today's ECM 12z.

 

The anticipated wave depression is situated over SW England by the big day itself, although we are predicted marginal T850s so clearly some hope of wintriness, especially those honoured with metres of elevation.

 

 

 

Come Boxing Day, the H500 and SLP pattern looks as follows by t+168 hours.

 

 

 

 

All in all, an unrelenting Atlantic driven flow is my projection of things over the coming seven days. Often windy/stormy, lashings of rain and some heavy snowfall thrown in to varying degrees, more especially away from Southern England would be my broad brush statement. The various ensembles are going to be very revealing over the coming days that's for sure.

Edited December 19, 2013 by gottolovethisweather

[nick sussex]

Bah humbug to the ECM! As soon as it blew up that low near Newfoundland at 144hrs it was going to phase that with the low near the UK, sum total this throws the energy ne!

 

Horrid, get with the festive spirit ECM! I'm off to see whether NOAA trash its view of the ne USA.

 

The ECM eventually looks less horrific and really isn't that far from the GFS, at least it hasn't replicated this mornings phasing at T240hrs, after my initial tirade the ECM at least is a little bit better than this morning, going forward the T240hrs will either make or break the early part of January, more amplification upstream and a stronger ridge from the Arctic high and you could manage an undercut.

Edited December 19, 2013 by nick sussex

[nick sussex]

If we get to a set up shown like that in both the ECM and GFS at T240hrs then it will be the pivotal moment of the winter so far, either you get the undercut or the energy phases with low pressure over the UK. No middle ground solutions, winner takes all! for newbies you need to see the ridge a little further southwest and low pressure over the UK more favourably aligned, if you get the undercut shown with the arrow the energy heads se and supports the ridge to the north and at last some wintry weather for the UK and not chasing a few hours of slush:

 

 

It's for this reason that the earlier timeframe is crucial, its hard going from the ECM T240hrs because its already thrown alot of energy ne, we need to see the low further south and digging more into mainland Europe.

Edited December 19, 2013 by nick sussex

[The Northern Ramper]

If we get to a set up shown like that in both the ECM and GFS at T240hrs then it will be the pivotal moment of the winter so far, either you get the undercut or the energy phases with low pressure over the UK. No middle ground solutions, winner takes all! for newbies you need to see the ridge a little further southwest and low pressure over the UK more favourably aligned, if you get the undercut shown with the arrow the energy heads se and supports the ridge to the north and at last some wintry weather for the UK and not chasing a few hours of slush:

 

ECH1-240.gif

 

It's for this reason that the earlier timeframe is crucial, its hard going from the ECM T240hrs because its already thrown alot of energy ne, we need to see the low further south and digging more into mainland Europe.

Previous winters you would back the ECM in this position, but it's had a mare this last month to be fair.

[liam300]

To be honest we have the major effects coming into place, although there isn't much cold air to dig into at the moment at 850hpa.

[cooling climate]

I certainly would not put much faith in the GFS 12z op run.

Nothing really changed this evening from what I can see apart from

tentative signs of something more promising as we go into 2014

although as I said the GFS run this afternoon is way, way over the

top with regards to northern blocking.