Model Output Discussion 01/09/17

[No Balls Like Snow Balls]

 

 

Edited November 9, 2017 by No Balls Like Snow Balls

[Cheshire Freeze]

7 minutes ago, No Balls Like Snow Balls said:

 

 

To be honest, neither look particularly appetising RE UK.

First chart= extreme west based -NAO

Second chart= doesn't bear thinking about!

I'm assuming that is referring to height anomalies, as there is no legend!

Edited November 9, 2017 by CreweCold

[Daniel*]

18 minutes ago, CreweCold said:

To be honest, neither look particularly appetising RE UK.

First chart= extreme west based -NAO

Second chart= doesn't bear thinking about!

I'm assuming that is referring to height anomalies, as there is no legend!

Seems you're in a bit of a muddle neither are indeed, the first chart is CFSv2 week 3 the other week 6. No EC I know what model I would put my money on. 

[phil nw.]

A noticeable bout of Atlantic/Greenland ridging continues to show in the medium term and the GFS 06z is no different.

Just highlighting this one to show how we need luck on our side to get the cold here in spite of Greenland heights-a typical west based -NAO

As it is in that pattern we are mainly in the polar air so we are still rather cold.Now if we can see more amplification from the upstream ridging to sink that European trough then that would bring even colder air down from the Arctic.

 

 

[Cheshire Freeze]

3 minutes ago, Daniel* said:

Seems you're in a bit of a muddle neither are indeed, the first chart is CFSv2 week 3 the other week 6. No EC I know what model I would put my money on. 

Indeed...just dawned on me! (you'll have to forgive me, had about 1 hr sleep and been work on that)

Well the CFS is hellbent on a +NAO winter, so it comes as no surprise. However, I've posted over in Mod banter thread as to why the CFS could be suspect.

Edited November 9, 2017 by CreweCold

[mountain shadow]

38 minutes ago, phil nw. said:

A noticeable bout of Atlantic/Greenland ridging continues to show in the medium term and the GFS 06z is no different.

Just highlighting this one to show how we need luck on our side to get the cold here in spite of Greenland heights-a typical west based -NAO

As it is in that pattern we are mainly in the polar air so we are still rather cold.Now if we can see more amplification from the upstream ridging to sink that European trough then that would bring even colder air down from the Arctic.

 

 

Is that really a West based -NAO Nick, seem to be a core of height pushing just to the North of Iceland towards Svalbard although i get where you're coming from with the heights West of Greenland.

I think it's just the orientation of the low pressure which is scuppering the Northerly, is it just short wave drama!

[Snowy L]

19 minutes ago, mountain shadow said:

Is that really a West based -NAO Nick, seem to be a core of height pushing just to the North of Iceland towards Svalbard although i get where you're coming from with the heights West of Greenland.

I think it's just the orientation of the low pressure which is scuppering the Northerly, is it just short wave drama!

Iceland looks like its in the gradient between the pressure systems so I guess it could be west based? Though I think west based NAOs have been given a tough time on this forum. A lot of the time they can work as long as the Euro high is sufficiently displaced away from mid Europe and into the East Med, allowing low pressure to take the spot.

 

It looks like one of our coldest ever Decembers was west based, definitely more west based than the chart you have quouted

 

Edited November 9, 2017 by Snowy L

[cheshire snow]

In the more reliable time frame the GFS12z shows Snow Showers for the Hills of NW England/N Wales.and the North Midlands on Sunday Morning.

C.S

[Polar Maritime]

Only a very brief slack Easterly surface winds as the Low exits, But the flow is West to East. Ultimately from the N/W.

As per c.s post snow poss into Sunday.

 

 

 

Edited November 9, 2017 by Polar Maritime

[Cheshire Freeze]

The vertical advection Pacific side is cut off much earlier on this run as opposed to the 6z. This in turn has big effects on the trop vortex- AO not quite as negative and a bigger section of the vortex left on the Canadian side rather than the Siberian one. 

We'll see how it progresses through FI.

[Singularity]

What a strange period of model-tracking this is turning out to be. Big high-lat blocking versus a difficult Atlantic has long been the signal, but the former has come under some question today for the first time in about a week.

 

Anyway, the 12z GFS has seen a sizeable step toward the ECM runs of late in that the low off the Eastern Seaboard is slower and allowing a ridge to build ahead rather than behind it. With the trough ahead, however, the model remains relentlessly more progressive in moving the storm close to the UK.

UKMO has moved closer to GFS as of day 6 though in that the flow near-N of the UK remains flatter than ECM has been having it, so it's not out of the question that ECM could be the one left with egg on its face.

This outcome, with no quick feed from the E. Seaboard trough, spares most of the UK any particularly strong winds or large rain totals, and instead brings a chilly polar maritime feed with some showers, most in the west. Much more appealing than the previous few GFS runs.

[knocker]

The gfs is like a dog with a bone vis the explosive cyclogenesis albeit it has dropped the more bizarre interpretations. This could still bring blizzard conditions to Scotland if perchance it came to fruition

.

Edited November 9, 2017 by knocker

[Singularity]

 

Hmm so yes as CreweCold has pointed out, changes on the Pacific side have altered the balance of vortex distribution between the Canadian and Siberian sides - but this may have focused the high-lat blocking in a more useful location for us if it can persist long enough, which is still possible if the Canadian vortex segment stays far enough west and away from Greenland.

Watching with interest.

[Met4Cast]

The trend for a Greenland high seems pretty solid now, I'd be surprised if that didn't happen.

What is concerning is the trend for low pressure to become "stuck" over the UK and not really do anything, whilst it'll be chilly it wont be cold and snowy like many of us want. Ideally we want to see that ejected South and East as quickly as possible.

[Cheshire Freeze]

6 minutes ago, Singularity said:

 

Hmm so yes as CreweCold has pointed out, changes on the Pacific side have altered the balance of vortex distribution between the Canadian and Siberian sides - but this may have focused the high-lat blocking in a more useful location for us if it can persist long enough, which is still possible if the Canadian vortex segment stays far enough west and away from Greenland.

Watching with interest.

Trop vortex being pincered with intent. Always good to see. A long way away though

[SMU]

I doubt anyone will turn their nose up at that If it landed

1070 MB GH & multiple High pressures alligned into the pole-

[Singularity]

 

Well how about that - the Canadian segment has become a disorganised mess! Take from that what you will regarding the resolute nature of this blocking event.
With the blocking focused to the NE, deep cold has been moved closer to us than at this time on the previous few GFS runs.

At this stage the GFS solution is looking more effective for achieving a cold spell than the ECM 00z was, in which light the similarity of the UKMO 12z to this GFS run may be a good sign.

Time now to see whether GFS insists on ramming a broad trough across under the big ridge to the W/NW or tries the arguably more realistic feeding across of shortwave lows... or just stops everything getting across, which would also be fine by me.

[Cheshire Freeze]

5 minutes ago, Singularity said:

 

Well how about that - the Canadian segment has become a disorganised mess! Take from that what you will regarding the resolute nature of this blocking event.
With the blocking focused to the NE, deep cold has been moved closer to us than at this time on the previous few GFS runs.

At this stage the GFS solution is looking more effective for achieving a cold spell than the ECM 00z was, in which light the similarity of the UKMO 12z to this GFS run may be a good sign.

Time now to see whether GFS insists on ramming a broad trough across under the big ridge to the W/NW or tries the arguably more realistic feeding across of shortwave lows... or just stops everything getting across, which would also be fine by me.

Rather predictably blows up LP to our SW

Which then has a hasty change of heart and tries to head back NW in the face of a developing Scandi ridge 

Edited November 9, 2017 by CreweCold

[Singularity]

1 minute ago, CreweCold said:

Rather predictably blows up LP to our SW

Sometimes I wonder why I dare hope for it to do something more intelligent 

In reality I'd expect to see the HLB interfering with the organisation process and causing the troughs to become very flat on the N. flank with secondary lows splitting off and heading between NE and SE depending on how close blocking and deeper cold air has made it to the east.

 

Even with the monster low, this is getting close to a cold continental feed getting in on the act. Just imagine the flatter version of the low with a secondary feature edging under the ridge to advect a bit more of the cold air across. This run has managed with it's dartboard bias to produce the least possible goods from some truly exceptional blocking patterns. Into the naughty corner with you, GFS!

[Paul_1978]

Very good run up to the end of high res. We're just seeing variations on a theme and we have a big fat Greenland High developing. Not worried about anything that happens after T+240. 

[SMU]

We keep seeing the GFS pushing the trough through however earlier in the run now we see the flow sharpening up north > south

so with that in mind I would say this for me is the most plausable outcome so thats what im forecasting.

 

http://www.meteociel.fr/modeles/gefs_cartes.php?code=13&ech=6&carte=1&mode=0

s

[snowy weather]

1 minute ago, Steve Murr said:

We keep seeing the GFS pushing the trough through however earlier in the run now we see the flow sharpening up north > south

so with that in mind I would say this for me is the most plausable outcome so thats what im forecasting.

 

http://www.meteociel.fr/modeles/gefs_cartes.php?code=13&ech=6&carte=1&mode=0

s

Just looking to learn- what would that mean for the weather?

Thanks

[booferking]

4 minutes ago, Steve Murr said:

We keep seeing the GFS pushing the trough through however earlier in the run now we see the flow sharpening up north > south

so with that in mind I would say this for me is the most plausable outcome so thats what im forecasting.

 

http://www.meteociel.fr/modeles/gefs_cartes.php?code=13&ech=6&carte=1&mode=0

s

Ens 8 also quite similar.

http://www.meteociel.fr/modeles/gefs_cartes.php?code=8&ech=6&carte=1&mode=0

Edited November 9, 2017 by booferking

[SMU]

17 minutes ago, snowy weather said:

Just looking to learn- what would that mean for the weather?

Thanks

The low pressure in the atlantic to get stalled out & a ridge develop North out if France to scandi - setting up a Scandi block which later allign with the canadian high

[Man With Beard]

5 minutes ago, Steve Murr said:

The low pressure in the atlantic to get stalled out & a ridge develop North out if France to scandi - setting up a Scandi block which later allign with the canadian high

Might be our best hope of cold. The Atlantic gets stuck to our west rather than on top of us and heights build around the top linking eventually with Greene high.

Sounds tricky but certainly possible.