Model Output Discussion 4th Dec.2013-12z onwards.

[nick sussex]

I had the towel ready to be thrown! okay now back to the previously mentioned cold salvage plan C! I think the UKMO would look very much like the ECM possibly better at 168hrs, lots of energy heading south and the top of that troughing is negatively tilted at 168hrs so some WAA into Greenland.

 

Still though some residual energy left to the north though which is troublesome, one caveat here the ECM and UKMO have tended to over amplify the upstream pattern in recent weeks at 144hrs onwards in particular, on the other side of this the last few evenings  ECM 12hrs runs have been flatter than their morning outputs.

 

At least something a bit more interesting for us to talk about but I hope I'm not onto  plan D tomorrow!

[Barry12]

Just as everyone was writing the first half of December off, out comes the ECM!!!

 

Edited December 5, 2013 by Barry95

[cold snap]

Is this a joke ,brilliant ECM at 216!!!!

Come to daddy

Screaming potential

[bluearmy]

to me, the best part of this ecm 12z run is that its the first run (GEM super runs apart) that shows a route to an undercut of the jet. (to add that the jet does not undercut on this run but it isnt too far away). most of the northern arm energy is headed nw, though there is still enough going ne over the top of the block. at least it keeps interest in the thread which was in danger of seeing a very quiet evening.

at day 10, someone 'turns off the atlantic'. hhmmmm ........................

Edited December 5, 2013 by bluearmy

[CanadaAl]

one year anniversary of "That ECM" should we be suspicious?  

[I remember Atlantic 252]

potential yeah, but uppers are shockingly mild in FI, but a damn sight better than yesterdays 12Z, hopefully clearer skies moving in from SE

[Ali1977]

Let's hope GFS follows this evening, and some ens start toying with the idea....

As soon as hopes raise, the next run they fall.

Nothing hugely positive in any run as of today though....

[bluearmy]

that ecm NH anomoly profile at day 10 is not too far away from the 00z ens mean anomaly at the same time scale.

Edited December 5, 2013 by bluearmy

[MR EXTREMES]

the only thing I noticed on the ecm was the total disappearance of the low pressure on the t216 chart then the t240 chart its vanished....

but over all the ukmo and ecm are keeping the hopes of many alive its going to do the upgrade downgrade thing I think until the vortex and residual energy is sorted.

but it keeps are hope alive.

[nick sussex]

The ECM given some of its recent evening outings is okay in terms of trend especially where it takes the PV in its later stages, however we don't see any undercut although this might still occur later.

 

In these types of evolutions theres a narrow range between good and bad and a tipping point like dominos which catapults the whole process to an eventual cold conclusion.

 

The key is between 144 and 168hrs and that IMO will be the decider going forward, tip that domino and if the trend to take the PV further to the nw is correct then I'd put good money on a cold conclusion.

 

However the ECM is currently not impressing me, regardless of its good verification it has remained King only because the main stat is upto T144hrs, it has been IMO dismal in recent weeks, with its overamplifying bias past that point, for this reason I'd advise people to not get too excited until theres cross model support and the key synoptics are shown within T120hrs.

Edited December 5, 2013 by nick sussex

[forecaster]

MUCH, MUCH better! Postive PDO earlier in the run helped get heights near the pole which is helping to split the vortex, at 216hrs we should see part of the PV over Russia move under the block with the block moving over Scandi...

Pdo, please clarify. Clearly not pacific decadal oscillation?

[pandit-scholar]

The polar vortex looks under pressure on this run of the ECM. Thus a much better run, especially with general mood on here today.

Who knows Joe Bastardi prediction of a white Christmas in the UK made on Twitter yesterday may yet come to fruition. Still would be a tall order to get white Christmas but we shall see!

Don't write of December just yet!! There's still 25 days of the month to go and the models are probably struggling with what's happening with the synoptics. So expect a lot more chopping and changing in the coming days especially in the longer term!!

Edited December 5, 2013 by pandit-scholar

[snowmadchrisuk]

P/V moving West at 500 Miles an hour on the ECM , that is the main thing I notice.....

[nick sussex]

This current model saga reminds of that series Lost! just when you think you start to know whats going on another plotline is thrown in!

 

In the last few weeks we've had the Arctic northerly spell, which turned into a snap then a blink!

 

After that trauma the models threw in a possible easterly tease which imploded.

 

Now the ECM has thrown in tonights new plotline the high extending north with the PV desperately trying to split, thankfully it hasn't shown what could have happened had there been an undercut!

 

That might be for tomorrows plot or this will implode followed by another cold plot although I think we're using them all out at the moment. The sum total of all this is we want actions, so not to be rude but put up or shut up output, either deliver a benign dry spell with some frost and sunshine, or get to the cold and stop all this faffing about!

 

We want to get to the domino tipping point and not the we'll be old and grey before we know the result Lost plot!

[Gael_Force]

Pdo, please clarify. Clearly not pacific decadal oscillation?

 

Maybe EPO? - my brain is oscillating with all these new acronyms that are being added to the discussion.

[Gibby]

Good evening everyone. Here is the report on the 12 noon outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Friday December 5th 2013.

 

All models show the severe storm to affect the North and East today abating overnight as the storm moves East over Europe. many coastal areas are at risk from flooding at the high tides overnight. Elsewhere the weather quickly calms down as a ridge of High pressure moves across from the West. By tomorrow a warm front crosses East around the Northern flank of High pressure over carrying a band of rain across Northern areas and increasing cloud for all. By the weekend all areas will be under much quieter weather with fine and cloudy weather with temperatures close to the seasonal normal, a pattern that remains in place for the early part of next week.

 

GFS then shows a sustained period of tranquil and benign conditions with light to moderate winds from between SE and SW with a NW/SE split developing later with any rainfall restricted to NW areas while the South and East look like staying largely dry throughout the run. Temperatures would be mild for most but with some colder surface air across the South at times with some areas of mist and fog possible.

 

UKMO closes it's run with High pressure away to the East and ESE with a slack South or SE flow over the UK with fine weather predominating across the UK. The mildest conditions will be in the NW whereas Southern and SE Britain may experience less mild conditions with some mist and fog at times and a touch of frost should skies clear by night.

 

GEM tonight has dropped it's wintry scenario of this morning with a movement towards the other models in maintaining largely dry and cloudy weather with the 'will it' 'won't it clear' being the determining factor on how things feel at the surface.

 

NAVGEM also shows a mild and breezy Southerly feed across the UK next week with High pressure out to the East. It will be dry and the mildest weather will be likely in the West with somewhat colder and less breezy weather possible towards the East at times.

 

ECM tonight shows High pressure to the East and SE building across the UK with quiet and benign conditions with a lot of cloud overall. However, the chance of some clearer weather at times will increase the risk of fog dramatically and some frost may also occur locally should this occur. Late in the run High pressure does migrate to Scandinavia briefly with some rather chillier conditions for a while but with the Jet flow still riding over the top it only has one place to go and that is shown in the end days of the run as it sinks South into Europe, though for the UK in this run colder air may well hold on with some frost and fog by night, especially in the East.

 

The GFS Ensembles shows the general trend of maintaining High pressure based weather across the UK for the entire run tonight. Any rain is most likely towards the NW with very little elsewhere as High pressure is biased to be positioned over Southern Britain or to the SE. The uppers are almost universally well above average across the UK through the entire run tonight once the current cold blip dissolves over the next 48hrs.

 

The Jet Stream shows a continuous train of a NE flow crossing the Atlantic and up to Iceland and northern Scandinavia keeping the UK well and truly on the warm side of the flow with next to no change shown tonight over the coming two weeks.

 

In Summary the weather looks like becoming locked in a pattern that could stick around for a couple of weeks and maybe until Christmas. The main culprit is a strong Jet flow which becomes anchored in a strong and NE moving conveyor belt across the Atlantic up to Iceland and across to Northern Scandinavia over the coming two weeks. With High pressure over Europe and maybe Southern Britain the weather is likely to become stuck in a rut with the only differences day to day being the amount of cloud cover and whether it becomes mild or not. It will not become very cold anywhere if tonight's chart verify but if skies clear and a continental drift to the wind moves across the South then widespread fog problems could arise along with a touch of frost. As a result of this a slow clearance through the day of fog would result in cold conditions in places. On the other hand if the wind shifts more to the SW which is indicated by some output mild conditions could develop with temperatures well above average at times. We'll have to see how it pans out day to day but all in all there is little excitement for weather observers to look forward to tonight.

[pandit-scholar]

This current model saga reminds of that series Lost! just when you think you start to know whats going on another plotline is thrown in! In the last few weeks we've had the Arctic northerly spell, which turned into a snap then a blink! After that trauma the models threw in a possible easterly tease which imploded. Now the ECM has thrown in tonights new plotline the high extending north with the PV desperately trying to split, thankfully it hasn't shown what could have happened had there been an undercut! That might be for tomorrows plot or this will implode followed by another cold plot although I think we're using them all out at the moment. The sum total of all this is we want actions, so not to be rude but put up or shut up output, either deliver a benign dry spell with some frost and sunshine, or get to the cold and stop all this faffing about! We want to get to the domino tipping point and not the we'll be old and grey before we know the result Lost plot!

Since October, the models so far, and this includes the ECM especially, have modelled a significant cold snap or spell at least 3 or 4 times, only to be significantly downgraded!!

[nick sussex]

This is the previously mentioned  tipping point to a cold conclusion, black arrows show where the energy from that troughing will be dispersed if you have a negative tilt to the troughing and the high a little further north:

 

 

Here the ECM still doesn't have the correctly aligned troughing, but it does show potential of course if this trend verifies!

 

For newbies  the direction of cold into the UK or away is easily seen by simply looking at the angle of the upstream trough, when you have a scenario of low high low as we have in this case.

 

Below are two images showing what I mean:

 

Negatively tilted troughing upstream:

 

 

Positively tilted troughing:

 

 

In the UK its not just about getting high pressure to the north, you have to find a way to channel the cold into the UK from the north or ne, even if for example you're dealing with the pattern a little too far east as shown by the ECM some of that cold could still work its way back into the UK if the high topples towards Scandi but essentially many potent easterlies have an injection of deep cold into them by way of a chunk of the PV dropping south to the east.

 

 

 

 

 

[cooling climate]

Could the ECM be repeating the errors that we have seen in the model lately with it over

amplifying the pattern again. It was not that many days ago when the pattern being shown

in the extended range was much more blocked with the vortex fragmented and I said then

that for this to happen then you would have to see the effects in the mid to lower strat at

least. But with no sign of strong MJO induced ridging  or mountain torques there was no  

evidence of where this warming was to come from to produce the heights shown and sure

enough the models have now flipped to show what you would expect to see from a strong

vortex centered where it is.

Therefore personally I can not see where the amplification that the ECM is showing will

come from and remain very sceptical of what the model is showing at the moment.

[winterof79]

This is the previously mentioned  tipping point to a cold conclusion, black arrows show where the energy from that troughing will be dispersed if you have a negative tilt to the troughing and the high a little further north:

 

ECH1-192.gif

 

Here the ECM still doesn't have the correctly aligned troughing, but it does show potential of course if this trend verifies!

 

For newbies  the direction of cold into the UK or away is easily seen by simply looking at the angle of the upstream trough, when you have a scenario of low high low as we have in this case.

 

Below are two images showing what I mean:

 

Negatively tilted troughing upstream:

 

nt.jpg

 

Positively tilted troughing:

 

pt.jpg

 

In the UK its not just about getting high pressure to the north, you have to find a way to channel the cold into the UK from the north or ne, even if for example you're dealing with the pattern a little too far east as shown by the ECM some of that cold could still work its way back into the UK if the high topples towards Scandi but essentially many potent easterlies have an injection of deep cold into them by way of a chunk of the PV dropping south to the east.

 

I have made a couple of posts regarding Friday the 13th and our block......could it i wonder?

http://www.meteociel.fr/modeles/ecmwf/runs/2013120512/ECH1-192.GIF?05-0

[nick sussex]

Could the ECM be repeating the errors that we have seen in the model lately with it over

amplifying the pattern again. It was not that many days ago when the pattern being shown

in the extended range was much more blocked with the vortex fragmented and I said then

that for this to happen then you would have to see the effects in the mid to lower strat at

least. But with no sign of strong MJO induced ridging  or mountain torques there was no  

evidence of where this warming was to come from to produce the heights shown and sure

enough the models have now flipped to show what you would expect to see from a strong

vortex centered where it is.

Therefore personally I can not see where the amplification that the ECM is showing will

come from and remain very sceptical of what the model is showing at the moment.

Good points CC, by far the biggest culprit in recent weeks has been the ECM and for this reason we best treat its output with a lot more caution, however the UKMO is even more amplified at T144hrs than the ECM. We'll see tomorrow morning whether its a one hit wonder.

[Ali1977]

Looking at Gavs latest xmas update the CFS is sticking to its guns with a potent eastily starting around the 18th , the CFS is of course way out in FI but maybe the GFS will start popping up a few good charts in FI and back it up...then again maybe I'll win the lotto..

[Duane S.]

An interesting 12z run from the ECM. I think the improved run comes mainly from the way it beefs up the high centered over the East Siberian Sea and ridges it poleward. Plausable moderate Wave 2 sig? Nothing spectacular but a big improvement on the dire GFS. I would like to see tomorrow's GFS 00z / 12z Ops come on board (did I really say that?) and give us a less progressive outlook.

 

Unfortunately though, for me, anything that involves bringing decent cold uppers to UK shores in the next 7 - 10 days still sits as the rank outsider to the Euro high solution but that window of opportunity is still there for sure. Id be surprised to see a sudden shift to cold but small daily 'upgrades' of sorts, maybe possible? So with straws grasped tightly in both hands, here's hoping that the ECM has kicked off the daily upgrade show.

Edited December 5, 2013 by s4lancia

[Ali1977]

Anyone able to post the ECM ens?

[Ali1977]

This looks good to me...