Model Output Discussion 01/09/17

[Guest]

Not much time today - so just a quick update on my post (on page 250) regarding the UKMO. I still disagree with quite a few comments regarding how different it is at T+144. In fact it looks almost identical to the GEFS ens control run:

               UKMO 0z T+144                                    GEFS 0z T+144                               GEFS 0z T+228                                 GEFS 0z T+264

           

The concern raised by some is that small LP cell in the mid Atlantic due west of the UK. If you look at the charts earlier in the runs (not shown) it has been around for several days more or less in situ and with a similar central pressure. So not a problem at this stage. Following on, the concern raised is with the LP moving over the top of the HP and dragging in much milder air. The GEFS do move it north and then north-east and by T+228 have it just south-west of Iceland but without any deepening. At the same time there has been another rapid build of heights into Greenland. The LP then merges with the "semi-permanent" LPs stretching from north of Svalbard through Scandinavia and into northern Europe. Only then does it intensify as in T+264. It then moves south-east towards north-west Europe pulling in an even more potent northerly behind it. Whether the UKMO follow this pattern is not at all certain. The main point is the constant Arctic re-loads and all the model runs get there in the end but with rather different routes to get there. With the Atlantic so blocked and Arctic heights repeatedly rebuilding (reflected in the strongly negative AO) I do not see the general pattern changing a great deal over the next few weeks (out to mid-December). There may be a few less cold blips but it's looking predominantly cold and, possibly very cold at times. I still favour an eventual evolution to an easterly with the Russian and Arctic HPs linking through Scandinavia but that's a long way off and the models will continue the explore how the blocked patterns evolve.

Edited November 27, 2017 by Guest
Correct typos

[Had Worse]

I note that the high between Iceland and Scotland is trying to ridge with the Russian one.  Unfortunately the fingers are just too short.

[karlos1983]

Can the GFS do it...

Having a damn good go!!

The good news is the GFS and ECM are pretty similar at 144. 

Edited November 27, 2017 by karlos1983

[frosty ground]

4 minutes ago, karlos1983 said:

Can the GFS do it...

Having a damn good go!!

It's starting to move now and with the high being slightl further north it' probably going to be a better run than the 0z.

[northwestsnow]

well 6z shows the cold persisting with frosts widely now inc Friday night- its a far cry from last December so i think we ought to bear that in mind while we look towards where the next pattern will take us..

[Dennis]

yes we can (or not)  it seems OK by this run

Edited November 27, 2017 by Dennis

[swfc]

34 minutes ago, frosty ground said:

I think there is a problem I think everything is moving away from cold to just around average. Even if we get the artic air to come south via a block this morning ECM is showing energy getting through the high if that interacts with the artic air it could deepen into a full blown depresion  and cut of the air and send it to the Atlantic 

 

I wouldn' be surprised if this cold spell beyond the weekend is dead by the 12z runs

Really???6z looks ok imo leading into winter!!!

[northwestsnow]

6z brings very cold arctic air southwards with snow showers pushing inland -its not trended to ukmo so for now that will do thankyou very much  FI tho in fairness ..

[Scandinavian High.]

Can’t believe some folks are saying we moving way from cold 

[karlos1983]

4 minutes ago, northwestsnow said:

6z brings very cold arctic air southwards with snow showers pushing inland -its not trended to ukmo so for now that will do thankyou very much  FI tho in fairness ..

It's very good news in my opinion, actually the GFS at +192 is better than the ECM. so the usually progressive GFS more amplified than the usually over amplified ECM. 

12z are going to be a nail biter!

Look how mild the Eastern US and Canada is! they must be spitting feathers 

Edited November 27, 2017 by karlos1983

[frosty ground]

10 minutes ago, swfc said:

Really???6z looks ok imo leading into winter!!!

My comment was regarding the 0z runs

 

The 06z looks okay but that low moving through the block could be a spanner grown in the machine. Could also generate snow.... 

Edited November 27, 2017 by frosty ground

[feb1991blizzard]

Now we are heading towards the genuine proper cold territory with some runs, the GFS 6z being a good example, look what's coming down to from the North around 200 hours, there is no gaps in between the cold uppers, -8c widely, -10c, that's what I mean when I bang the drum for what we require regarding uppers, there is no marginality, its guaranteed snow if there is precipitation, of course there is still hurdles, we need some sort of wave to develop otherwise inland will get no precipitation and it will just be coastal areas, plus we need features to not drag in mild uppers with them, then we need the high not to just move in like the end of this week, but all in all, the 6z GFS is very interesting.

[swfc]

I think people need to lower there expectations slightly esp after last nights 18z which I hope some of the new members bookmarked.easy to forget were actually an island and not in mainland europe.6z can't be called bad esp when the atlantic is in isolation. Also look at the esb on the 6z blocking a plenty moving out towards the atlantic! !!

Btw wheres the pv!!!!*

Edited November 27, 2017 by swfc

[northwestsnow]

6z just looks cold to me- if that comes off we'll be happy campers

[Tim Bland]

Looks like our worst case scenario is a dream come true compared to the last few years.  potentially less cold period over the weekend before the ridge builds back in - then back to snow showers early next week before a front makes inroads from the west bringing more widespread snow for a time.  Worst case scenario is the Atlantic breaks through and we get a short period of milder weather - looking at the Pv and it being shunted over the other side of the NH and the anomalous mild over NE U.S then it will only be a matter of time before we see another block develop!

[swfc]

Fantastic fi.great 850s into uk and Europe. Bank!!!

[northwestsnow]

Classic stuff from GFS- lets hope and pray UKMisery stops its sillyness on the 12zs...no move towards ukmo on the 6z...

[bluearmy]

Looking through the eps clusters and I would suggest taking nothing for granted - 6 clusters in the 5/8 day period with the op in one of the lowest percentage groups.  Strong confidence in mid Atlantic upper ridge of some description but how far n/e/s/w remains unclear. 

[northwestsnow]

1 minute ago, bluearmy said:

Looking through the eps clusters and I would suggest taking nothing for granted - 6 clusters in the 5/8 day period with the op in one of the lowest percentage groups.  Strong confidence in mid Atlantic upper ridge of some description but how far n/e/s/w remains unclear. 

Yes, i think the only thing we can say at the moment is the picture is a little more complex this morning- maybe the colder solutions will win out, but the ukmo model still is a concern, quite a large concern from where i'm sat.

Anyway, frost watch begins tonight

[Derecho]

Morning here is my interpretation of the 06z GFS, 00z ECM and 00z UKMO

Only interpretations upto T240 are made. PS not sure why but Sundays and Saturdays runs appear on some of the pictures!

Upto T120 the models still look uncertain about the low in the Central North Atlantic.

At T144 its difficult to know what will happen next though a quick sinking of the high to our west looks less likely now (hopefully!). The UKMO would probably be quite anticyclonic in later frames.

GFS                                                           UKMO                                                    ECM

So the next big source of uncertainty is retrogression, two key things need to happen:

- The low in the central Atlantic needs to remain rooted
- Pressure to our south needs to be sucked up to Greenland like a vacuum

These two things are difficult to achieve but both the GFS and ECM do pretty well. What I really like is the warm air being directed to the NW Atlantic. That is going to have a serious knock on effect and prevent the jet off NE Canada from firing up.

GFS                                                          ECM

Therefore both the GFS and ECM build strong heights over Greenland and we get a cold northerly on both at varying stages. High pressure to the south is a minor annoyance on the GFS as it stops the really cold uppers spreading all the way south but it is still a really good run!

ECM sees the low in the central Atlantic cut through the block stopping a classic run, but salvages a northerly in the end and sends the UK into a good cold spell

GFS                                                          ECM

Overall its good to see the UKMO tone down on the Central N Atlantic energy somewhat but it could be better. Issues with retrogression are emerging but we should expect that. Interesting output and warmth being sent where we want it most on ECM and GFS! Lets hope pressure doesn’t stay high to our south.

Here are the ratings

UKMO 6.5/10 snowflakes – Can only go to T144 here but it looks a bit better
GFS     8.5/10 snowflakes – A great run especially for Scotland, so close to something even better
ECM  8/10 snowflakes – Gets to a sharp northerly in the end in spite of shortwave issues

Edited November 27, 2017 by Quicksilver1989

[northwestsnow]

 

While we wait for the GEFS to update the BBC monthly outlook sounds generally cold until Mid month- but as Blue posted above the jury is out as to how cold and for how long, certainly as far as the EC eps are concerned.

 

[bluearmy]

4 minutes ago, northwestsnow said:

 

While we wait for the GEFS to update the BBC monthly outlook sounds generally cold until Mid month- but as Blue posted above the jury is out as to how cold and for how long, certainly as far as the EC eps are concerned.

 

Whilst the London eps continue to look cold, from my perspective, the 00z suite moves the outlook away from cyclonic cold closer to anticyclonic cold. Still between the two and it remains within the swinging pendulum, back and forth. 

In the medium term, if the halfway house solution of the Atlantic cut off low escaping and running around the top of the amplifying ridge is correct then this could well run into the base of the developing trough as per the 06z gfs. The ec control did this - whilst it cuts off the northerly it does provide for a big potential snow event somewhere across the uk  

[stodge]

Morning all

Well, as the cloud breaks and the cold air arrives in London Town, I'm taking a rare glance at the early winter models.

Unlike some, I'm not too concerned about the UKMO at this point - it has the cold air locked in for most until Thursday (Friday in the SE) and we then have the transition to next week's Northerly to get past. Signs on the GFS 06Z of a less direct hit than previously but ECM solid this morning - the blast next week hinges on the HP easing away W or WNW while the LP develops to the north of Iceland and swings ESE across the northern isles and into southern Scandinavia opening the door to the Arctic air.

We need that sequence of events to occur in the right way at the right time for cold blast 2 to happen.  As I say, GFS 06Z OP offers a glancing NNW rather than a direct N'ly while Control looks very similar.

To depress some, and it may simply be GFS struggling and reverting to type, I do wonder if come mid December we'll be looking at a more normal pattern. The Aleutian HP moves up over the Pole and it may be that will serve to lower heights over Greenland but that's a very long way off.  

[snowblizzard]

52 minutes ago, karlos1983 said:

It's very good news in my opinion, actually the GFS at +192 is better than the ECM. so the usually progressive GFS more amplified than the usually over amplified ECM. 

12z are going to be a nail biter!

Look how mild the Eastern US and Canada is! they must be spitting feathers 

Unlike coldie's in UK many Canadians probably enjoy the prospect of a milder winter!

[Guest]

23 minutes ago, northwestsnow said:

Yes, i think the only thing we can say at the moment is the picture is a little more complex this morning- maybe the colder solutions will win out, but the ukmo model still is a concern, quite a large concern from where i'm sat.

Anyway, frost watch begins tonight

Hello, I never like to contradict anyone directly on this thread but I continue to feel that you (and many others) are doing the UKMO rather an injustice. Their 0z T +120 and T+144 are actually almost identical to the GEFS 0z (and now the GFS 6z) at these times! My posts on pages 250 and 253 explain this with the relevant charts. The UKMO has the major disadvantage in not going past T+144. Summer Sun's posts with the T+168 UKMO charts are a little misleading as we cannot see the eastern Atlantic and full UK view - even more important with the current set up. We cannot assume that the UKMO will not find the path to another northerly reload - in fact I firmly believe that they will. The GEFS 0z took that small LP over the top of the Atlantic HP and the GFS 6z takes it underneath. Both models end up with the Arctic reloads. So, we all need to be patient and not make assumptions which are really not yet shown! Give the UKMO a chance and I feel that it will all be resolved during the next few runs. All paths lead to cold LOL!

I do hope that you take this in the right spirit as I have no intention of upsetting you and I respect everyone's opinions.

Edited November 27, 2017 by Guest
Correct typos