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

[ghoneym]

Gem not far away at + 144 looking very cold and that precip on the west coast moving east to hit the cold would be a pretty decent event.

[frosty ground]

1 minute ago, nick sussex said:

OMG more shortwave drama! Nooooooooooooooooo!

Just when there was hope of a less stressful route to an easterly the UKMO delivers that T144hrs output, no we're reliant on that shortwave cutting se at T168hrs.

The GFS after a more promising 06hrs run brings the PV further east on its 12hrs run with too much energy running over the top. I really hope the ECM won't go down the shortwave from hell route, we've suffered enough!

It''s all down to the Jet not Shortwaves..... 

[terrier]

So in the space of 6 hours the gfs goes from hero to zero. All looks abit meh so far. Never easy in the uk. And we always seem to pick up the shortwave dramas. But as we all know the easterlies are rare as hens teeth and have seen many fail even at t72 range. Be very surprised if ecm gives us another cracker tonight 

[Snowman.]

Just now, frosty ground said:

It''s all down to the Jet not Shortwaves..... 

No its down to the shortwave, the UKMO could get us an easterly but we're reliant on a trigger shortwave which is a thin thread to hang from over northern scotland. 

 

[That ECM]

Never trust a potential easterly until t72 and less. We are in the game but this evenings output so far is a concern for sure. 

[Ali1977]

The GFS still gives us a slack E/SE flow at day 9 with very cold nights, and the GEM looks like following suite but maybe a little better - its still very close to being good and the ECM could still be as good or better later as it was this morning.  

[nick sussex]

Just now, frosty ground said:

It''s all down to the Jet not Shortwaves.....

Obviously but its easier to just pick out the shortwave as the marker. The jets the chicken and the shortwaves the egg!

[Summer Sun]

Not bad

[frosty ground]

1 minute ago, SN0WM4N said:

No its down to the shortwave, the UKMO could get us an easterly but we're reliant on a trigger shortwave which is a thin thread to hang from over northern scotland. 

 

Not at all, the energy heading south East is like what the 06z GFS run showed earlier. 

On the GFS the Jet is positioned slightly differently and therefore surface pressure reacting accordingly. 

[tight isobar]

The signal remains positive. .for an easterly component. 

Confidence grows for an easterly flow/incursion. Its once again the formation and eventual settlement of pressure. ..

There shall be monumental differnces in synoptic s in form of 850 hpa's via eventual establishment. 

Edited January 10, 2017 by tight isobar

[frosty ground]

1 minute ago, nick sussex said:

Obviously but its easier to just pick out the shortwave as the marker. The jets the chicken and the shortwaves the egg!

Not in this case...... Assuming the Met carries on like the 06z GFS run then an easterly would arrive a few frames later.

 

[Paul_1978]

5 minutes ago, terrier said:

So in the space of 6 hours the gfs goes from hero to zero. All looks abit meh so far. Never easy in the uk. And we always seem to pick up the shortwave dramas. But as we all know the easterlies are rare as hens teeth and have seen many fail even at t72 range. Be very surprised if ecm gives us another cracker tonight 

Deary me - if you think that's a poor run after what we've endured this winter so far then you're in the wrong game. 

[Ben Sainsbury]

There must be growing confidence regarding the snow event Thursday evening over Southern England. One of the best charts we've seen in a while down here! Beginning with rain at first I must add!

Edited January 10, 2017 by Ben Sainsbury

[warrenb]

To be honest, after 240 the GFS is just a mess.

[Ali1977]

4 minutes ago, Ben Sainsbury said:

Must be further confidence regarding the snow event Thursday evening over Southern England. One of the best charts we've seen in a while down here! Beginning with rain at first I must add!

Yes that looks like a good chart, I imagine a forecasters nightmare over the next 48 hours as it is quite borderline for many places, but more towards snow than rain i'd say.  As for the GFS it's still a good run, but so different from the last by day 10, this proves it hasn't a clue on this yet as no consitancy - unlike ECM.

Edited January 10, 2017 by Ali1977

[Seasonality]

3 minutes ago, warrenb said:

To be honest, after 240 the GFS is just a mess.

Exactly. What is this?

 

Edited January 10, 2017 by Osbourne One-Nil
No - that abbreviation is not acceptable!

[nick sussex]

1 minute ago, frosty ground said:

Not in this case...... Assuming the Met carries on like the 06z GFS run then an easterly would arrive a few frames later.

 

The UKMO has what is well known in here as the trigger shortwave and yes the easterly will arrive as long as that cuts se and ejects cleanly to the se.

[frosty ground]

We generate our own cold pool on the run. 

[Zakos]

3 minutes ago, warrenb said:

To be honest, after 240 the GFS is just a mess.

I think the same,

Most peculiar chart I think Ive ever seen!

Gfs lost the plot maybe?

 

Edited January 10, 2017 by Zakos

[Luke Attwood]

2 minutes ago, warrenb said:

To be honest, after 240 the GFS is just a mess.

Yes to be honest,I think the 6z could be a very misleading run.I still feel the easterly is very much on! And the ECM later will put it in its place

[AWD]

11 minutes ago, Ben Sainsbury said:

Must be further confidence regarding the snow event Thursday evening over Southern England. One of the best charts we've seen in a while down here!

Made a post in our regional thread about this mate.  Those GFS PPN charts are too simplistic re snowfall.  A lot of high res modelling such as the 06z Arpege, WRF NMM & 12z Hirlam keeps the majority of PPN in the channel;

With condition inland (south UK) the wrong side of marginal for anything other than a wintry mess;

The GFS Op is the most optimistic 12z output I've seen so far with regards to the northern extent & even that is a rain - sleet - slush/snizzle event for a lot of low lying southern constituencies.

Hopefully further high res output will improve conditions for more away from higher ground.

Edited January 10, 2017 by AWD
Spelling

[SMU]

UKMO is fine @144 the jet is acute in its split North south so that trigger low would edge south south East over the UK with possible snow as the cold re-engages..

I think im just going to ignore the GFS from now on.... as its to volatile & bias... 

[AWD]

1 minute ago, nick sussex said:

The UKMO has what is well known in here as the trigger shortwave and yes the easterly will arrive as long as that cuts se and ejects cleanly to the se.

So it isn't all too bad then with regards to any continental flow next week?

I assume the UKMO T168 chart posted later this evening would show the intention of said shortwave?

[igloo]

12 minutes ago, ghoneym said:

Gem not far away at + 144 looking very cold and that precip on the west coast moving east to hit the cold would be a pretty decent event.

there is a problem with the GEM model the 850 uppers tend to be far to high with every run i should have been fixed a long time ago thats why most people ignore it and call it cannon fodder

[Panayiotis]

Worrying chart from the UKMO at 144hrs, its an evolution which we dont want to see! To express the concern, theres a very similar chart in the 06z GFS ensembles at 144hrs (Pert 20), which almost matches the UKMO 12z 144hrs:

Pert 20 GFS 06z 144hrs                                UKMO 12z 144hrs 

That shortwave over Northern Scotland is the devil in the charts. We want ideally the Atlantic high to stay connected to the high developing over Scandinavia without any shortwave drama in between, otherwise we get the Scandinavian high 'running away' from us along with any easterly opportunities! This is shown below at 168hrs in Pert 20:

We need the cleanest way to get from 120hrs >> 144hrs, the ECM and UKMO 00z showed this perfectly but getting cold from the E is never easy:

I would advise a lot of caution on this potential easterly, especially if the UKMO sticks to that shortwave and more so if the ECM has it later on the 12z!

 

Edited January 10, 2017 by Panayiotis