Model Output Discussion 29th December - Into mid-Winter.

[Singularity]

1 minute ago, karyo said:

The 12z ECM say No to any quick road to cold! In fact, even the 240 hour chart is underwhelming.

Not when looking forward; it's doing well with digging the trough down to our east and lining up a shortwave to engage with cold our while crossing the UK... but of course that's how some will find it uninspiring; it's a much slower process than GFS has come up with.

Seems to me it's a good fit for the 00z EPS based on BA's descriptions...?

[Stuie]

5 minutes ago, January Snowstorm said:

Every year attention is given to Northern blocking. Perhaps it's more important to try find out why these euro slug highs keep happening of late.

Just the way our climate is, HP loaded South and lower heights North, you can`t change that.

[knocker]

And with the ecm post T168, just to be awkward, has a major upper trough coming out of the eastern seaboard and our old friend the upper low to the south still playing a key role. One thing one can say is there is a lot of cold air around to the W.NW

Edited January 1, 2017 by knocker

[karyo]

2 minutes ago, Singularity said:

Not when looking forward; it's doing well with digging the trough down to our east and lining up a shortwave to engage with cold our while crossing the UK... but of course that's how some will find it uninspiring; it's a much slower process than GFS has come up with.

Seems to me it's a good fit for the 00z EPS based on BA's descriptions...?

How much more forward are we supposed to look? It is just imagination after the 240 chart.

[Dennis]

28 minutes ago, ArHu3 said:

you must not have seen the latest ecmwf yet, it's bad, really bad

 

i trust not only one run in weather- model-land

[bobbydog]

11 minutes ago, karyo said:

How much more forward are we supposed to look? It is just imagination after the 240 chart.

Well, on the GEFS, perturbations 8 and 19 have similar-ish atlantic profiles at 240 to the ECM. Going forward to +300, this is what they look like-

Obviously the overall profiles are very different but for the Atlantic sector, it gives a rough idea as to what might happen next.

[bluearmy]

19 minutes ago, Singularity said:

Not when looking forward; it's doing well with digging the trough down to our east and lining up a shortwave to engage with cold our while crossing the UK... but of course that's how some will find it uninspiring; it's a much slower process than GFS has come up with.

Seems to me it's a good fit for the 00z EPS based on BA's descriptions...?

Looks that way. Certainly a slower evolution to back the trough west than the GEFS but headed in the same direction. Will the new eps become a bit more progressive?

Btw, the GEFS members are quite a spread of solutions though the clusters look a decent set through week 2. Expect even more clusters evident on the eps with the extra 30 members! 

 

[booferking]

14 minutes ago, knocker said:

And with the ecm post T168, just to be awkward, has a major upper trough coming out of the eastern seaboard and our old friend the upper low to the south still playing a key role. One thing one can say is there is a lot of cold air around to the W.NW

Is this the low you talk about Knocks circled on both ecm and gfs charts i can see how the low is more west on gfs which helps build heights into a more favourable location also a smaller low on portuguese coast on gfs.

[Captain Shortwave]

Well I must admit this is probably the chart that sums up my feeling about the cold chase so far.

   

So close but yet so far. A few GEFs do bring 850s as low as -10C into the south east briefly offering a few light snow showers.

All the hard work of that deep cold pool getting into most of Europe is undone by an absolutely dire upstream pattern which blows up another mid-latitude high just south west of the UK. Anyway moving onwards, The GEFs

      

Still consistent on a Euro trough and Atlantic ridge, it could be cold zonal with a general polar maritime flow or something more substantial. Going by the 850s the end of week 2 the prognosis is definitely cold (4C below normal)

  

[Cheshire Freeze]

2 minutes ago, Captain Shortwave said:

Well I must admit this is probably the chart that sums up my feeling about the cold chase so far.

   

So close but yet so far. A few GEFs do bring 850s as low as -10C into the south east briefly offering a few light snow showers.

All the hard work of that deep cold pool getting into most of Europe is undone by an absolutely dire upstream pattern which blows up another mid-latitude high just south west of the UK. Anyway moving onwards, The GEFs

      

Still consistent on a Euro trough and Atlantic ridge, it could be cold zonal with a general polar maritime flow or something more substantial. Going by the 850s the end of week 2 the prognosis is definitely cold (4C below normal)

  

I get the feeling, looking at the farther range output tonight, that a cold zonal end game can be the minimum expectation. Suits me because it looks fairly likely at the minute that at some point we'll see a cold PM northwesterly....good for this location and something that I haven't seen for years.

[knocker]

17 minutes ago, booferking said:

Is this the low you talk about Knocks circled on both ecm and gfs charts i can see how the low is more west on gfs which helps build heights into a more favourable location also a smaller low on portuguese coast on gfs.

Yes that's the one as seen easier here. Don't get too hung up on it's exact position on one chart as it tends to move around during the run as it gets topped up with energy, first from the NW and then the south

[I remember Atlantic 252]

Shame this will be watered down because this is a proper snowy NW'ly

[booferking]

Just now, knocker said:

Yes that's the one as seen easier here. Don't get too hung up on it's exact position on one chart as it tends to move around during the run as it gets topped up with energy, first from the NW and then the south

Cheers got it.

[feb1991blizzard]

Just now, I remember Atlantic 252 said:

Shame this will be watered down because this is a proper snowy NW'ly

It might not even be watered down, it might verify as a SWerly!!!

[snowbunting]

2 hours ago, johnholmes said:

I rarely, if ever, look beyond 240h on GFS. So sticking to that.

So far no one seems to have made comment on the ridge building out of N America, from about 168h. If you look at the output for that side of the pond you can see how and why it has developed. A mobile feature but I suggest it is the reason that we have a bout of deep cold air predicted by GFS to swing over the UK from about 192h?

It has some support from the anomaly charts for that part of the world, although not very strongly. So maybe something for the cold lovers to watch on subsequent runs with GFS and to see if ECMWF and UK Met have it in their respective time frames down the line?

Just to note, several years ago, some of you will be able to quote I am sure, a similar even was the start of a longish deep cold spell into the UK-any ideas?

Not saying it is going to happen just suggesting it MIGHT be worth watching the 12z tomorrow to see if it still shows it 24 hours from 192 hours over the UK.

Was that March 2006 by any chance John?

[cyclonic happiness]

13 minutes ago, feb1991blizzard said:

It might not even be watered down, it might verify as a SWerly!!!

'might' is not an option.   Seems like anything cold gets overblown and ends up SW'ly.

Well, let's see what the 18z brings, our bad luck cannot go on forever.......can it?

[Daniel*]

19 minutes ago, I remember Atlantic 252 said:

Shame this will be watered down because this is a proper snowy NW'ly

The arctic oscillation is forecasted to go strongly negative to be honest I think it's been years since I've seen something familiar, or my memory is short, suggesting very cold arctic air bottled up north typically - is going to spill southwards to mid latitudes. Therefore I don't find the GFS 12z outlandish in the slightest, certainly a credible chart. 

 

Edited January 1, 2017 by Changing Skies

[Jonan92]

Well, if my memory is right the index is determined with the GEFS forecast, so it should be no surprise that it matches what the GFS shows

[Singularity]

21 minutes ago, Captain Shortwave said:

Well I must admit this is probably the chart that sums up my feeling about the cold chase so far.

   

So close but yet so far. A few GEFs do bring 850s as low as -10C into the south east briefly offering a few light snow showers.

All the hard work of that deep cold pool getting into most of Europe is undone by an absolutely dire upstream pattern which blows up another mid-latitude high just south west of the UK. Anyway moving onwards, The GEFs

It's confounding really, just how close we are to something we'd talk about for years to come.

What really gets me is that having a trough right down to the Azores at the same time is more often than not a great way to encourage such a high to retrogress to the northwest - no surprise the models were toying with it really. It just so happens that a trough passes north of the cut-off trough at exactly the right time to draw out one of the lows within and make use of it to pump up the jet at about the worst possible moment for our easterly chances.

So as much as some people will talk of climatology showing us that easterlies are always a long-shot, I believe we have genuinely been about as unlucky as it's possible to be when such potential is at play.

The thing with this potential cold spell was that most runs had a fairly vigorous westerly flow coming up against the Scandi Block once it was in place, but the behaviour of the Azores low had allowed the trough to replace the high across much of W Europe and provide a rock for the block to stand on, and so it held fast despite the strong pressure against it. Now that the means of setting down that rock has been lost, there is nothing to fight the mobile flow except the curiously persistent northward displacement of the subtropical ridge. The cold spell was very circumstantial in its nature - the type of situation that can have whole ensemble suites leaning in an ultimately erroneous direction for the time period in question.

So it is that we turn to the next round of upstream amplification, which due to typical wavelengths means any notable change from the +ve NAO setup is put back by 4-7 days which is from the missed opportunity in 4-5 days so some 8-12 days from this evening. At least we have plenty of signs that the amplification should come along. 

      

Looking at the +96 hour charts again I have to wonder how far people would have been prepared to test their nerves had the ECM 12z shown such a large adjustment west of the cold pool toward us. There has to be some chance this trend could evolve into something of note, because the 'switchback' of the jet stream around a strong ridge of high pressure is something the models have been known to underestimate in times past (I tracked a particularly strong case of this with the GFS in Nov 2010), but I'd not go betting anything on it to be honest!

[Ali1977]

With the NAO slightly negative and the AO extremely negative towards mid month surely this has a good chance of bringing us a really cold 2nd half of Jan. EPS out shortly might follow the GEFS days 10-15 showing us something colder.

[mountain shadow]

1 minute ago, Ali1977 said:

With the NAO slightly negative and the AO extremely negative towards mid month surely this has a good chance of bringing us a really cold 2nd half of Jan. EPS out shortly might follow the GEFS days 10-15 showing us something colder.

Slightly negative NAO results in what we are seeing in the model output, the bitter cold slipping by to the East of the UK, we need higher heights towards Greenland.

[Dancerwithwings]

19 minutes ago, I remember Atlantic 252 said:

Shame this will be watered down because this is a proper snowy NW'ly

 

18 minutes ago, feb1991blizzard said:

It might not even be watered down, it might verify as a SWerly!!!

Watered down, SWerly.....come on guys,  pessimism is not the word....in Mid Winter.. Agreed C'H our luck will change....but then again ' if we didn't have bad luck.....we wouldn't have any luck at all 

[nick sussex]

The UK's attempt at proper cold so far has been a case of several missed opportunities, open goals missed and penalties hoofed into the stands. You only have to look at CS's post to see how we fired another penalty into the stands,

To answer a previous post which wondered why the Euro slug has set up shop, its simply a response to the upstream pattern. These Euro highs of course can seem like immovable objects or entities in their own right but they're just like any other synoptic.

Anyway we are where are and as much as I'd like to have a good moan or have one of my tirades it's not going to change the outputs.

So we're now onto cold potential 237 of the winter so far! A word that is probably beginning to grate on coldies in here.

Rather than write a long post it's simply down to whether the high pressure displaces west/ nw wards and allows low heights further west. With no HLB's we're not looking at a big freeze but we might manage some decent PM air and some snow rather than the mind numbing tedium of the Euro high.

 

[bluearmy]

The eps slightly differnent with a flatter Atlantic so the upper ridge bit more to our sw than west and the surface just west. This attempts to retrogress to that ridge coming off Canada but hangs back a slightly high anomoly into nw Europe well into the 10/15 day period. This is certainly where it differs to the GEFS and gems. so again a variation on a theme and perhaps best to wait for the next suite before making any conclusions. heights hanging on for too long ?  Heard it before somewhere .............

the GEFS and gems 10/15 day charts

 

[bobbydog]

I was going to attempt to lighten the mood by posting a cracking CFS chart....

fortunately the CFS 9 month run is just seen as fantasy. However, just to avoid any nervous breakdowns, DO NOT look at the CFS....