Model Output Discussion - January 11th.

[Osbourne One-Nil]

No no no, if ECM backs GFS/METO then maybe (or maybe not?) we will have to wait a week longer. That's very misleading of you, on the 11th of January, to start writing off the remainder of the month when the models can't even get the next 5 days right!

You can't disagree every time someone doesn't go with the cold theme can you?!

[swilliam]

You can't disagree every time someone doesn't go with the cold theme can you?!

You can disagree with them writing off the whole of January - the models currently only go out to the 27th (and the GFS is showing and Easterly at that point)

[Duane S.]

You can't disagree every time someone doesn't go with the cold theme can you?!

Absolutely not (my earlier post said I thought the GFS/METO 12z was more than feasible) but I will take exception to somebody writing off the rest of the month after a poor run of 12z charts (assuming the ECM will be as dodgy). Unless of course they want to highlight exactly why they think that may be the case.

[Tim Bland]

No no no, if ECM backs GFS/METO then maybe (or maybe not?) we will have to wait a week longer. That's very misleading of you, on the 11th of January, to start writing off the remainder of the month when the models can't even get the next 5 days right!

What we are going to see eventually in the models IMO will likely be similar to what happened in the run-up to November 2010, in that no matter what the changes upstream are, cold will be the eventual outcome in one form or another. A reversal of early winter if you were.

I agree, whilst it's always "Jam tommorow" whatever the synoptics they always lead to cold down the line. Don't forget even in the deep reaches of FI on the GFS don't show the start or Feb yet. GP always said either middle or end of Jan for the start of winter weather and that still holds even IF things panned out similarly to the 12z GFS. We will know soon how the GFS fits with its ensebles but I will be shocked if it isn't one of the milder options.

Edited January 11, 2012 by Tim Bland

[andy_leics22]

I think a lot of the members who have been on the site for 2 years+ know that the models never handle an Easterly evolution well. They are great when it comes to zonal Weather, they can normally forecast a flat jet and zonal Weather with decent accuracy even around 5-7 days away. If the Weather hints at going against the status quo and hints at a Greenland high or Scandi High... The models change so much at mid range.

Hopefully the newer members will start to realise that after they have experienced the ups and downs of the models during a typical Winter! Over the last 7 Winters I have seen many of these situations, we shouldn't throw in the towel when a few dodgy runs show up. I have a feeling that Scandi high will win over the Atlantic and the end result will be an Easterly in 10-14 days time. That's just my feeling though, hope it's an accurate one! :lol:

[swilliam]

It has to be said the ensembles do not look great either with most of them supporting the OP at 192 hrs.

[Andy Bown]

amazing how every 6 hours later a run can be so far apart even at t96. so obviously what u see now u will not see on the 18z run.

I could have quoted many posts to make this point ...

... Isn't it a more correct comparison of model runs to compare today's 12z with yesterday's 12z rather than with the 6z?

Today's 6z should be compared to yesterday's 6z.

I'm sure John Holmes has posted about doing so on previous occasions.

In this case, how does this run compare with the same one from 24 hours ago?

[Grimsby Snow Lover]

GEFS Ensembles are really poor.

Looks like the models have reacted to more energy being ejected from that mind numbingly resiliant PV over Greenland.

All eyes on ECM but i suspect the writing is on the wall,again.

until the next run, when chances are things will be different again. They certainly were after the 06z run from this morning.

[phil nw.]

I thought it might be an idea to post some of the output from the 12z UKMO with explanations to help the less experienced members who may be trying to fathom out what the rest of us are talking about,

So apologies in advance if this appears less than technical.

Anyway here are three of the charts from the 12z Met run.

We can see in the first chart T72hrs that the UK is under the Yellow block-High pressure,Notice that finger of blue coming south from the main vortex over Greenland to our west.That is what we call a trough(low pressure extension).

To prevent the High(yellow)near the Azores extending towards us we need that trough to maintain and extend further south or south east.

Now look at the next chart T96 hrs and already we can see the trough is split by the advancing high pressure.

Notice too the dark blues/purples to our north-thats the vortex extending across towards Scandinavia starting to flatten our own high and preventing it ridging North East.

The last frame is at T144hrs, and it`s all over for the block the Azores high ridged across towards the UK and the flow has turned to the South West-milder direction again-the cold air remains elusive stuck out east towards Russia.

I hope this helps at least one member anyway.

[andy_leics22]

GEFS Ensembles are really poor.

Looks like the models have reacted to more energy being ejected from that mind numbingly resiliant PV over Greenland.

All eyes on ECM but i suspect the writing is on the wall,again.

Don't read too much into the Ensembles, i've noticed that the Ensembles change quite a lot sometimes from run to run, the 12z Ensembles look a fair bit different to the 06z and I can bet my last pound that the 18z Ensembles will be quite a bit different to the 12z ones.

You should only really compare yesterdays 12z Ensembles to today's to get an idea of what might happen.

Edited January 11, 2012 by andy_leics22

[Nick L]

I think a lot of the members who have been on the site for 2 years+ know that the models never handle an Easterly evolution well. They are great when it comes to zonal Weather, they can normally forecast a flat jet and zonal Weather with decent accuracy even around 5-7 days away. If the Weather hints at going against the status quo and hints at a Greenland high or Scandi High... The models change so much at mid range.

Hopefully the newer members will start to realise that after they have experienced the ups and downs of the models during a typical Winter! Over the last 7 Winters I have seen many of these situations, we shouldn't throw in the towel when a few dodgy runs show up. I have a feeling that Scandi high will win over the Atlantic and the end result will be an Easterly in 10-14 days time. That's just my feeling though, hope it's an accurate one! :lol:

I disagree with this. I think it's more to do with the fact if it's zonal, we don't really care about the models and don't scrutinise every little detail because zonal is zonal! In times like this, we are more likely to notice minute changes down to nearest mm because it's showing something more interesting and IMBYism is rife.

Edited January 11, 2012 by Nick L

[Shunter]

GEFS Ensembles are really poor.

Looks like the models have reacted to more energy being ejected from that mind numbingly resiliant PV over Greenland.

All eyes on ECM but i suspect the writing is on the wall,again.

Yes and IF the 12z OP verifies we have to ask whether the stratospheric Warming is Fuelling rather than displacing/destroying the PV in this case.

[Zakos]

Don't read too much into the Ensembles, i've noticed that the Ensembles change quite a lot sometimes from run to run, the 12z Ensembles look a fair bit different to the 06z and I can bet my last pound that the 18z Ensembles will be quite a bit different to the 12z ones.

You should only really compare yesterdays 12z Ensembles to today's to get an idea of what might happen.

Yes, the ensembles have their uses, especially during times like a marginal snow event a few days away e.g if more go for snow instead of rain/sleet then snow is more likely etc...

The mean is also quite useful, as it is a good indication if goes below -5. But of course, as you say, their only useful if you compare them to 24 hours ago not the last run.

[swilliam]

I disagree with this. I think it's more to do with the fact if it's zonal, we don't really care about the models and don't scrutinise every little detail because zonal is zonal! In times like this, we are more likely to notice minute changes down to nearest mm because it's showing something more interesting and IMBYism is rife.

Yes this is true - people often say the models are more accurate when the weather is zonal but that is only because they are not scrutinised so much - I made this point a while back. A good example is when we have a big storm in a zonal setup - the strength and position of this then varies run to run and has a major impact on our weather.

Edited January 11, 2012 by swilliam

[Zakos]

I disagree with this. I think it's more to do with the fact if it's zonal, we don't really care about the models and don't scrutinise every little detail because zonal is zonal! In times like this, we are more likely to notice minute changes down to nearest mm because it's showing something more interesting and IMBYism is rife.

perhaps, but the models don't swing as much in terms of t850 values and show more consistency than during easterlies (at least in this case, and I think possibly the effect of strato warming is playing its part aswell)

[Nick L]

perhaps, but the models don't swing as much in terms of t850 values and show more consistency than during easterlies (at least in this case, and I think possibly the effect of strato warming is playing its part aswell)

True. But you have to remember that our predominant weather comes from the W/SW. It takes a lot of factors for us to get a decent cold outbreak, and a slight change in detail can throw a massive spanner into the works. It's more difficult to do the same to our default winter pattern - ie. westerly dominated.

[andy_leics22]

I disagree with this. I think it's more to do with the fact if it's zonal, we don't really care about the models and don't scrutinise every little detail because zonal is zonal! In times like this, we are more likely to notice minute changes down to nearest mm because it's showing something more interesting and IMBYism is rife.

You've got a point there sir Nick, I know when I see zonal on the models I don't look at it into detail like I do when a cold snap is showing on the models :lol:

[WINTRY WALES]

I thought it might be an idea to post some of the output from the 12z UKMO with explanations to help the less experienced members who may be trying to fathom out what the rest of us are talking about,

So apologies in advance if this appears less than technical.

Anyway here are three of the charts from the 12z Met run.

We can see in the first chart T72hrs that the UK is under the Yellow block-High pressure,Notice that finger of blue coming south from the main vortex over Greenland to our west.That is what we call a trough(low pressure extension).

To prevent the High(yellow)near the Azores extending towards us we need that trough to maintain and extend further south or south east.

Now look at the next chart T96 hrs and already we can see the trough is split by the advancing high pressure.

Notice too the dark blues/purples to our north-thats the vortex extending across towards Scandinavia starting to flatten our own high and preventing it ridging North East.

The last frame is at T144hrs, and it`s all over for the block the Azores high ridged across towards the UK and the flow has turned to the South West-milder direction again-the cold air remains elusive stuck out east towards Russia.

I hope this helps at least one member anyway.

Superb explanation here backed up with charts so us with little knowledege can begin to fathom the charts ourselves!

Thankyou for that...if only others would follow suit

[Zakos]

True. But you have to remember that our predominant weather comes from the W/SW. It takes a lot of factors for us to get a decent cold outbreak, and a slight change in detail can throw a massive spanner into the works. It's more difficult to do the same to our default winter pattern - ie. westerly dominated.

Interesting way of thinking and I agree.

[Paul]

Just to clarify for any who are unsure - if your post consists of something along the lines of:

"This run is awful, maybe the 18z will be better"

or

"This run is an upgrade, it's going to snow and be -10c here for weeks"

or

"I hate the cold weather so this run is great as it's going to be mild all the way"

Then please post it into the model mood thread - that thread is specifically for this type of post - in fact any post which is more about how you feel about the models than the actual model runs themselves:

http://forum.netweat...el-mood-thread/

Then this thread can be used for actual model discussion...

Thanks

[phil nw.]

Superb explanation here backed up with charts so us with little knowledege can begin to fathom the charts ourselves!

Thankyou for that...if only others would follow suit

Thanks WW.I am glad it`s been of use.

I just think that the more understanding folks get wrt the models the more they will enjoy this thread.

Hopefully more of you lurkers will then feel more confident about posting.

[ChartViewer]

Maybe their confident enough that the Azores High will ridge north with a stronger jet tilting NE wards to put out that forecast...Or maybe just hedging their bets until nearer the time

Anyway eyes down for a huge ECM tonight.

Edited January 11, 2012 by Paul

[igloo]

Yes its really dragging its heels, it's frustrating because without that monster PV that Arctic high would have been moving in imminently!

Even just an average PV would have been blown to bits by now, of course we had to end up with the super strength variety.

im not sure what it will take to shift that monster PV over greenland this year if anything its geting bigger not a good sign for the second half of winter let's hope this evenings ECM shunts it west its the only chance

Edited January 11, 2012 by igloo

[Zakos]

Ensembles are out http://www.wetterzentrale.de/pics/MT8_London_ens.png

Mean dips significantly below the average, change due to take place on the 19th of Jan.

Op not an outlier, but certainly at the mild end of the pack, especially towards the end.

I only post this because some said the ensembles where poor, when they're really not.

[cooling climate]

I must admit to being very surprised by the model output so far this evening as I am sure many are.

After poor model runs yesterday evening relating to cold weather for the UK all three models did a

complete turnaround this morning showing a strong likelyhood of cold weather to affect the UK in the

not to distant future. All three models output had changed showing much more resilience

from the growing high to pressure to the northeast and a weaker PV to our north allowing a better

than average chance of a big pattern change to much colder weather, with the 06z GFS run reinforcing what the 0z had shown.it was only natural then to think the models would expand on this. This is now not the case although we are yet to see what the ECM will do.

This could very well turn out to be nothing more than a wobble from the models pushing to much

energy into the jet etc and I would urge caution in dismissing any notion of a much colder set up in the 10 to 15 day range.Until we see some consistency in the models all the cards so to speak are onthe table.

Edited January 11, 2012 by cooling climate