Model output discussion - Post SSW - Will it turn cold?

[chionomaniac]

2 hours ago, chionomaniac said:

I'm ready for it! 

 

 

Anyone want any salt? It's going cheap.....

 

In all seriousness even though the ECM doesn't show the nirvana type synoptics, it still shows an awesome block with exceptional cold never far away. A variation on a theme I reckon, and whilst that block hold firms we have no worries concerning the output!

Come on, if this is the worst chart that we are worrying about then we need to get another hobby - it's still fantastic - we would kill for this most times. So look at the bigger picture.

 

[johnholmes]

1 hour ago, Youcan'tbecirrus said:

You are not a voice to be ignored John, how do you see this all panning out and when would you expect the "heat up" to occur ? 

Hard to tell, we are too far out yet. It may not happen, but watch for any isobars over the UK having their origin over the Med. Lots to look forward to for coldies from later this week and perhaps by next weekend the air having deep enough cold combined with N Sea temperatures to set of snow showers. How far they get inland will depend on the wind strength.

It sure is an interesting spell of weather coming up. Hats off to those who have believed in this since first talking about the SSW.

[The Eagle]

I think overall we are still on for an exceptionally cold hit.

 

I think there is more uncertainty creeping in though which is inevitable, let's be honest. Actually seeing quite a split now in evolution to 96 hrs. Hopefully one way or another we'll have more agreement on the 72 - 96hr forecast by tomorrow which will help clarify things for us later on. 

[chris55]

GEFS highlight the facts clearly.

Just look at the spread from 23rd!!

I know they can be easy to ignore but they are an important tool in deciphering the probability of the operational run, 

tight clustering = high confidence in outcome

large spread = low confidence in outcome

 

in laymans terms, until we see solid clustering on that cold pool smashing into the UK then nothing is guaranteed, and frankly ensemble data is the true forecast tool, taking operational runs in isolation can lead to a skewed view of probabilities and ultimately a misrepresented view of model performance.

That being said obviously we are still in with a massive chance of proper cold just that the spread on the ensembles highlight the other routes we could end up with.

[Banbury]

My word we have one model on one run that doesn’t give us blizzards on day 8 and 9 and the world crashes in. 

I think we’ve been fortunate to have most of the models agreeing at 96 and some at 120 

[pureasthedriven]

3 minutes ago, chris55 said:

GEFS highlight the facts clearly.

Just look at the spread from 23rd!!

I know they can be easy to ignore but they are an important tool in deciphering the probability of the operational run, 

tight clustering = high confidence in outcome

large spread = low confidence in outcome

 

in laymans terms, until we see solid clustering on that cold pool smashing into the UK then nothing is guaranteed, and frankly ensemble data is the true forecast tool, taking operational runs in isolation can lead to a skewed view of probabilities and ultimately a misrepresented view of model performance.

That being said obviously we are still in with a massive chance of proper cold just that the spread on the ensembles highlight the other routes we could end up with.

All absolutely correct although that dispersed spread is heavily weighted towards variations on cold. 

[Stuie]

5 minutes ago, chris55 said:

GEFS highlight the facts clearly.

Just look at the spread from 23rd!!

I know they can be easy to ignore but they are an important tool in deciphering the probability of the operational run, 

tight clustering = high confidence in outcome

large spread = low confidence in outcome

 

in laymans terms, until we see solid clustering on that cold pool smashing into the UK then nothing is guaranteed, and frankly ensemble data is the true forecast tool, taking operational runs in isolation can lead to a skewed view of probabilities and ultimately a misrepresented view of model performance.

That being said obviously we are still in with a massive chance of proper cold just that the spread on the ensembles highlight the other routes we could end up with.

Not being picky, Chris, I would say the 24th (every day matters!) As massive scatters go, that is a scatter in the coldies favour for sure.

[The Eagle]

5 minutes ago, Banbury said:

My word we have one model on one run that doesn’t give us blizzards on day 8 and 9 and the world crashes in. 

I think we’ve been fortunate to have most of the models agreeing at 96 and some at 120 

The models don't agree at 96 hrs.

ECM

GFS

 

That difference in the trajectory of those height rises (more north north-east on ECM) and that extra bit of energy over the top may look benign enough there - it's actually very significant with real changes at 120 + on the back of it. GFS/NAVGEM/ARPEGE/GEM/JMA - these are very similar and give us the best outcome. The others are not so great.

Plenty of time - it's going to change, hopefully it goes the way of the consortium listed. At least we'll see convergence over the next couple of runs.

Edited February 18, 2018 by The Eagle

[pureasthedriven]

5 minutes ago, Spah1 said:

 

Indeed. Though plenty of ‘cold’ options amongst those ensembles would be cold enough. As long as it’s cold enough for some snow and ‘proper’ winter weather for a bit, I can live without the severe. 

[WalsallWeather123]

ECM mean pretty decent. Most of country draped in -8 uppers

[Lukesluckybunch100]

Well the ECM mean is fantastic so I wouldn't worry too much about the op.

[carinthian]

Not sure what models the BBC World service use for their weather for the week a head. Yes cold established in most of Europe by mid week quite widely but from what I made of the graphics still had much of the British Isles in mild air mass for mid week and talk of gradually getting colder in SE by Thursday with a max of 9/c, hardly edge of the seat forecast. May be still some doubt of the extent of the cold advection west not yet shown in some of the main models. Just an observation of what I just watched. 

C

 

 

 

 

[Summer Sun]

ECM ens keeps the easterly

[Stuie]

2 minutes ago, carinthian said:

Not sure what models the BBC World service use for their weather for the week a head. Yes cold established in most of Europe by mid week quite widely but from what I made of the graphics still had much of the British Isles in mild air mass for mid week and talk of gradually getting colder in SE by Thursday with a max of 9/c, hardly edge of the seat forecast. May be still some doubt of the extent of the cold advection west not yet shown in some of the main models. Just an observation of what I just watched. 

C

 

 

 

 

Before this speak of BBC etc gets deleted, it`s a true report C.

ECM Friday.

[The Eagle]

It does look like the ECM op run is on the milder side of it's ensemble suite for most.

[Iceberg]

Ec ops clearly outside the ens window re pressure centring over us. Very little support for t216+ Synoptics 

[NorthYorksWeather]

The EC Op does appear to be out of kilter with the rest of its suite when looking at Pressure and Z500 ensembles.

[January Snowstorm]

ECM clearly an outlier which is great.

Roll on 18z gfs now

[Ali1977]

1 minute ago, vizzy2004 said:

The EC Op does appear to be out of kilter with the rest of its suite when looking at Pressure and Z500 ensembles.

This will keep this place smiling - good news 

[Mike Poole]

Very happy with the ECM ensemble mean

But we've seen two op runs that highlight the risks that we face, the GFS 0z taking the High too far north, and the ECM 12z leaving the block too close to the UK so the cold air goes south.   And, of course, all the other runs that say Game on!

Should we be worried?  Not today, let's see what tomorrow's runs bring.

Edited February 18, 2018 by Mike Poole

[The Eagle]

3 minutes ago, Iceberg said:

Ec ops clearly outside the ens window re pressure centring over us. Very little support for t216+ Synoptics 

Distorting the mean a bit as well. Quite positive.

[pureasthedriven]

7 minutes ago, Stuie W said:

Before this speak of BBC etc gets deleted, it`s a true report C.

ECM Friday.

Gradual leak of cold air. By stealth. 

[karlos1983]

And the mean has something to say about the coldest air heading to Spain 

[Catacol]

13 minutes ago, Lukesluckybunch100 said:

Well the ECM mean is fantastic so I wouldn't worry too much about the op.

It is a definite shift to the south.

But only one run. With luck a bit further north tomorrow...

[The Eagle]

5 minutes ago, Banbury said:

Two models lol 

I think most give us a Similar picture at 96 

Don't think so.

GEM

GFS

ICON

UKMO

 

Crucial time period for the evolution here. The differences are fairly significant.

Edited February 18, 2018 by The Eagle