Model Output Discussion - 5th December - 11th December

[weathe20]

Quite a lot on here it would seem.

And yes ECM has always been the form horse when it comes to picking up on trends. I just wish it would pick up on Ian Browns hairdryer Christmas soon so it can be nice and warm like it was in April.

Can anyone explain the evolution of the ECM. If this storm breaks downs what happens then? Thanks.

[Optimus Prime]

The gfs does indeed tend to overblow these things.

A half way house is the likely winner tonight.

Pity these computer models are so unreliable

yeah when it was showing 925MB the other day I knew something Fishy had crept into that models computer.

[Weather-history]

The low tracks through pretty fast on ECM from 96hrs to 120hrs.

It looks too quick, its to west of longitude 10W and 24hrs later it off the west coast of Denmark. Does that sound plausible?

[DAVID SNOW]

Quite a lot on here it would seem.

And yes ECM has always been the form horse when it comes to picking up on trends. I just wish it would pick up on Ian Browns hairdryer Christmas soon so it can be nice and warm like it was in April.

Maybe Melony just wants a hairdryer for Christmas.

[kold weather]

And yes ECM has always been the form horse when it comes to picking up on trends. I just wish it would pick up on Ian Browns hairdryer Christmas soon so it can be nice and warm like it was in April.

Yes but there is a big difference between a 'form horse' and an outlier...which the ECM is. I'm waiting to see what the ensembles does with this system before making any conclusions based on ONE operational run...

Given the choice though between the 00z ECM, the 00/006/12Z GFs + ensembles, majority of the 00z ECM ensembles, the UKMO, JMA, Nogaps, GME, GEM... and the 12z ECM operational and 00z control run...I know for now what I'd believe at just 96hrs out

If things change then I'll be the first to shift with it. Being in the SE I'd be surprised if I got anything too severe even if the GFS did come off...maybe 60mph.

Mr.data, its fast but I suppose that is what could happen in such a fast upper flow.

[Summer Sun]

Currently ECM is only model to downgrade the storm for Friday, hopefully others will follow it can't see ECM backtracking now.

ENS has lifted to centre pressure to 965mb

http://www.wetterzentrale.de/pics/Rz500m5.gif

[DaBrigg]

yeah when it was showing 925MB the other day I knew something Fishy had crept into that models computer.

That was one ensemble member.

[Summer Sun]

The 12z ensembles for London

Durham

Aberdeen

After this storm passes there seems to be good agreement for a rise in pressure

Edited December 11, 2011 by Gavin D

[Welsh_Weather]

Remember the 'blizzard' that was forecast for southern Britain early last December. It was the ECM that started backing away from that first and that was about 120 hours out. GFS was first to pick up on it and the last to ditch it at about 72 hours out. I'm not saying the ECM is right on this occassion but it does have form on these 'big winter storms'.

Edited December 11, 2011 by Welsh_Weather

[kold weather]

Remember the 'blizzard' that was forecast for southern Britain early last December. It was the ECM that started backing away from that first and that was about 120 hours out. GFS was first to pick up on it and the last to ditch it at about 72 hours out. I'm not saying the ECM is right on this occassion but it does have form on these 'big winter storms'.

Yes I remember that now.

The big difference for me with this whole set-up is that we already have a precedent set, and that was the low we had last Thursday/Friday. That low has given me far greater confidence in a strong low that nearly all the models are still showing. It is quite possible the GFS is overdoing things, its also possible the ECM is right...

But to have 100% confidence in one run of one model that on its previous run showed a 944mbs low...is the height of insanity!

[clark3r]

ECM has another deep low winding up at 240!

[phil nw.]

With disagreements in the modelling of the Friday storm it does throw doubt on the what the later frames show covering the weekend onwards.

There is some uncertainty where and how the jet is modelled later this week.Does the energy split,does more go north or south-will the pattern flatten out as the ECM shows later?

http://www.wetterzentrale.de/pics/Recm1921.gif

or is some idea of heights trying to link to our NE really that far off evolving?--GFS

http://www.wetterzentrale.de/pics/Rtavn1921.png

but then the energy is too much further North and we topple into mid-latitude blocking.

The outsider at the moment is Pressure rising towards Scandi and cutting off the troughing into Europe.This could happen if we have a break in the jet flow to our North and allow ridging to fill the gap.

http://176.31.229.228/modeles/gfs/run/gfsnh-0-192.png?12

T192 on GFS shows the vortex a lot weaker around Svalbard but as soon as GFS enters the low resolution the pattern reverts to type.

Just some thoughts as what could happen post T120 -144 after that deep low passes.

[Richie V]

ECMWF is tredding dangerous ground tonight, If It's wrong It's a pretty epic fcuk up. If It's right and the other models, ENS and all follow then Kudos to the ECM.

I will point out though, If ECM is right in dismissing this storm and the other players rapidly follow then this tells me that ALL models use the same raw data and theres no overall REAL difference between GFS NOGAPS ECM BOM ect ect at all.

I'm very open to correction if you think i'm talking out of my backside here

[Welsh_Weather]

Yes I remember that now.

The big difference for me with this whole set-up is that we already have a precedent set, and that was the low we had last Thursday/Friday. That low has given me far greater confidence in a strong low that nearly all the models are still showing. It is quite possible the GFS is overdoing things, its also possible the ECM is right...

But to have 100% confidence in one run of one model that on its previous run showed a 944mbs low...is the height of insanity!

I agree probabaly not even 50% confidence in this run yet but it can't be disregarded. Maybe its more hope that we don't get a storm of this magnitutde. Will be interesting to see the ensembles later to see if this is backed up. I also agree that 1 storm does lead to another but also at 120 hours out tuesdays storm was looking like a beast and that is getting downgraded slightly every run.

[johnholmes]

People use the models to plan ahead, you don't sound as though you have the responsibility of ensuring the safety of others but a number of people can't just hope for the best. The attitude of believing the option of least worst outcome for anything is what puts people in dangerous positions.

Not just this post but others this evening.

Its Sunday, that is 4 more days before we can be pretty certain of its track and intensity. To keep arguing about one run to another over 5 days out is daft. To suggest that folk cannot cancel 24 hours out IF the threat is by then from UK Met assessed, as they did with the last one, serious enough to give it a red alert, seems to me not to be an accurate relection of what folk can and will do.

Just like the last one it will be no more than 24 hours out before its track is known to within 50 miles north or south and its pressure to within 5-6mb.

Fact what Iv'e just said-interesting to read so many folks views but a touch of reality about how much models can predict such a system more than 5 days away please.

end of another jh chunter so feel free to delete admin/mods but this thread is at times more like a kiddies playground.

I'll keep out of it for a few days.

Edited December 11, 2011 by johnholmes

[JP1972]

With disagreements in the modelling of the Friday storm it does throw doubt on the what the later frames show covering the weekend onwards.

There is some uncertainty where and how the jet is modelled later this week.Does the energy split,does more go north or south-will the pattern flatten out as the ECM shows later?

http://www.wetterzen...cs/Recm1921.gif

or is some idea of heights trying to link to our NE really that far off evolving?--GFS

http://www.wetterzen...s/Rtavn1921.png

but then the energy is too much further North and we topple into mid-latitude blocking.

The outsider at the moment is Pressure rising towards Scandi and cutting off the troughing into Europe.This could happen if we have a break in the jet flow to our North and allow ridging to fill the gap.

http://176.31.229.22...nh-0-192.png?12

T192 on GFS shows the vortex a lot weaker around Svalbard but as soon as GFS enters the low resolution the pattern reverts to type.

Just some thoughts as what could happen post T120 -144 after that deep low passes.

So are we waiting for this low to pass to kind of get a picture of what will happen from next weekend and beyond?

If so can you explain to a newbie like me why please?

Thank you.

[Mark Neal.]

I've just had a thought, if the ECM was to stay with its downgrade, which i can't see that happening to be honest. Would we have a better chance of snow, like the northerly forecasted for this weekend coming up? Or would we see a rise in pressure and more settled weather coming up?

Regards,Mark.

[Chris K]

I may be getting completely the wrong end of the stick here. But to me the storms has been downgraded but certainly not disappeared. The 12z run on netweather shows where it'll be placed at Thurs 1200 hrs and then Fri 1200hrs. The previous run shows it at Thurs 0000hrs and Fri 0000hrs. I thought it was predicted to me the most instense (although will chop and change as we get nearer) during Thurs night/early Friday morning so it doesnt show this on the 12z run?

Is there a link showing what ECM predicts in between these times? Sorry if this is something blindingly obvious but i generally only use this website for looking at ECM runs.

Edited December 11, 2011 by Bugganuts

[bluearmy]

Its only one op run. As Darren points out on TWO, the depression fails to engage with the jet in the same way as previous op runs and most other model output. We may be talking a difference of only 100 miles on the depression track early on. Hardly a huge cock up. Failing to engage the jet early on has massive consequences for it's development.

[Geordiesnow]

I don't think the ECM will be right in terms of splitting the low into too shortwaves which one deepens a bit due to the strength of the jet but it would not surprise me if the GFS is having the low that bit too deep. I never seen this mornings UKMO run but the two UKMO 12Z run has the low around 960MB which is more likely to be about right.

Of course with Southerly lows alot of factors go into these and they are harder to predict - I remember during winter time last year or the year before, a deep low was predicted by all the models to develop in the Azores and for it to head into France/Northern part of Spain but as we got nearer to the reliable timeframe it just fizzled out into something much weaker. The same could happen again?

Regarding the future outlook, all the models are still agreeing on a fairly chilly period, certainly no sign of any mild SW'lies that IB has been predicting for a while now.

[I remember Atlantic 252]

I don't think the ECM will be right in terms of splitting the low into too shortwaves which one deepens a bit due to the strength of the jet but it would not surprise me if the GFS is having the low that bit too deep. I never seen this mornings UKMO run but the two UKMO 12Z run has the low around 960MB which is more likely to be about right.

Of course with Southerly lows alot of factors go into these and they are harder to predict - I remember during winter time last year or the year before, a deep low was predicted by all the models to develop in the Azores and for it to head into France/Northern part of Spain but as we got nearer to the reliable timeframe it just fizzled out into something much weaker. The same could happen again?

Regarding the future outlook, all the models are still agreeing on a fairly chilly period, certainly no sign of any mild SW'lies that IB has been predicting for a while now.

middle paragraph, think you mean Xynthia (sundays low) 28 Feb 2010? yeah was good it missed us

[Osbourne One-Nil]

The 12z ensembles for London

After this storm passes there seems to be good agreement for a rise in pressure

At the risk of posting something to do with the weather, isn't that a bit like saying when the rain stops, it looks like it might turn drier?

[phil nw.]

So are we waiting for this low to pass to kind of get a picture of what will happen from next weekend and beyond?

If so can you explain to a newbie like me why please?

Thank you.

Yes ,my view is that we could have a different pattern after the big low has gone through.

If you see here GFS168

http://www.wetterzentrale.de/pics/Rtavn1681.png

and compare ECM at T168

http://www.wetterzentrale.de/pics/Recm1681.gif

The jet flattens the pattern upstream on the ECM and goes straight into a milder westerly flow

If you follow the later frames we can see GFS tries to ridge NE -unsuccesfully this time,

There are a number of possible evolutions depending on the modelling of the jet flow.

1.Continuing current cooler flow with the Azores High kept well south.

2.Ridging over the UK is quickly flattened as per ECM and we go milder zonal,the Azores High builds closer to the South.

3.We retain the Heights over the UK and we stay rather cold under an inversion.

4.Heights ridge towards Scandi over a cutoff Euro trough and we get an Easterly--this is the outsider at the moment.

Just a few things to look out for in future modelling.

[casparjack]

The 12z ensembles for London

Durham

Aberdeen

After this storm passes there seems to be good agreement for a rise in pressure

It would be unlikely to fall afterwards!!

[iceaxe]

well the storms gone from the best model bet the other are with it by tomorrow,all those posters with there brash statements like yorkshire gone .please try and be more realistic with your comments.as regards to fi i think a lot depends on where you live all mountain areas of the uk will have a fi of 24 hours or less fact i live in the mountains and rarkely is the forecast right.let alone any model predictions