Model Output Discussion - 14th - 20th November

[No Balls Like Snow Balls]

Seems to me that the (mean of the) ECM ensembles show the blocking more to the East/South-East rather than the North-East, so not so good for a "cold" evolution. The ECM operational could be an outlier...

Today's 7-10 day 500mb height anomoly shows ECM with heights further North than the GFS anomoly, the GFS anomoly would probably stand side by side with the majority of the ECM ensembles then. But it does seem to suggest the ECM anomoly stands by it's op run. Whats going to happen is still as clear as mud IMO.

[nick sussex]

Not a great deal of support for the ECM this morning with the GFS much flatter with the jet near the UK and only until the far reaches of FI does anything remotely interesting appear which has little chance of verifying.

The ECM is of course the one you'd want to verify if you want some colder conditions, its ensembles though don't lend much support to its operational run, although the control run does follow the operational which is a small positive.

The reason for the ECM's better synoptics is it takes the jet further ne and ejects some energy into Iberia which pushes lower heights into southern Europe supporting the high.

You have to have this energy into Iberia otherwise the high will likely be pushed much further south. It's very hard to have too much faith in the ECM as it's been throwing out more teases within the 240hrs than the GFS, talk about attention seeking!!!

The UKMO has the troughing further east and south at 144hrs than the ECM and looks more like the GFS, you really need to see the troughing as far west and north as possible if you're looking for the ECM to verify.

Let's see what the GFS 06hrs run does.

[cheshire snow]

If i remeber correctly was it the ECM that correctly called last years cold spell from well out in FI,it took the GFS days to come on board with

the ECM,i just wonder if the ECM is onto something?

C.S

[peterf]

what time does the ECM update?

[wolvesfan]

what time does the ECM update?

Around 6-7pm this evening. Edited November 14, 2011 by wolvesfan

[peterf]

cheers.

[Gray-Wolf]

I have to wonder whether the models now do accommodate the Arctic Amplification type 'cold plunges' that we may be now seeing occur in early winter? this would increase the likelihood of such 'north /south' exchanges from mid -Nov until late Dec (when things settle back down into the 'normal (?)' winter patterns) across the N.Hemisphere. These would,understandably, be hard to 'forecast' without an understanding of that process being included within the forecast model?( and for that to be the case it would only reinforce that such a novel forcing was 'accepted as real' by the bodies running those forecast models?)

Put simply ,if an Arctic High pressure system was to annually appear due of the anomalous temps over certain Arctic sea areas then ,as with 'monsoons' that annual 'switch' ,in atmospheric pressures in that area, would naturally impact the synoptics developing 'normally' in the lower latitudes.

I posted over late summer that any repeat ( which many folk seem to be 'expecting') of the Late Nov to Late Dec direct Arctic Displacements ( and subsequent W.A.A. up into the high Arctic) would settle the notion that low ice levels over summer ( and the delayed re-freeze whilst heat is shed by the Ocean) is indeed producing a 'Faux High' above such 'hot spots' (forcing Arctic cold pools south) and dictating early winter synoptics across the N.Hemisphere.

At present the Arctic Ocean areas most impacted seem to lead to that displacement of 'Arctic cold' finding it's way here ( and sadly increasing transport of older ice out of the Arctic Basin ,via the Trans polar Drift and the Fram straight, as it travels here).

With such 'warm' synoptics dominating early /mid Autumn the return to an 'Arctic Amplification' type displacement will be even more apparent to seasoned model watchers.

I will now be watching the 06Z model runs with interest !(until we return to the mild in Early Jan).

[wolvesfan]

Morning all,

GFS 6z,continuing to stall the atlantic unlike last nights runs,low pressure shunted round the top and high pressure staying close to our east and building from the south giving it support.looking likely the switch to a more zonal type flow now being delayed yet again.i for one am starting to wonder when we're going to see some sort of pattern change?be interesting to see UKmet extended update later.

[kold weather]

Well the GFS is pretty dominated one way or the other by SW airflows, pattern is a pretty horrible one overall. The ECM is quite alot better but my guess is its on the cold side of its ensemble members and abit too keen on the strength ofr the upper high to our east.

[clark3r]

least models are starting to hint of colder weather in FI :-)

[shedhead]

I have to wonder whether the models now do accommodate the Arctic Amplification type 'cold plunges' that we may be now seeing occur in early winter? this would increase the likelihood of such 'north /south' exchanges from mid -Nov until late Dec (when things settle back down into the 'normal (?)' winter patterns) across the N.Hemisphere. These would,understandably, be hard to 'forecast' without an understanding of that process being included within the forecast model?( and for that to be the case it would only reinforce that such a novel forcing was 'accepted as real' by the bodies running those forecast models?)

Put simply ,if an Arctic High pressure system was to annually appear due of the anomalous temps over certain Arctic sea areas then ,as with 'monsoons' that annual 'switch' ,in atmospheric pressures in that area, would naturally impact the synoptics developing 'normally' in the lower latitudes.

I posted over late summer that any repeat ( which many folk seem to be 'expecting') of the Late Nov to Late Dec direct Arctic Displacements ( and subsequent W.A.A. up into the high Arctic) would settle the notion that low ice levels over summer ( and the delayed re-freeze whilst heat is shed by the Ocean) is indeed producing a 'Faux High' above such 'hot spots' (forcing Arctic cold pools south) and dictating early winter synoptics across the N.Hemisphere.

At present the Arctic Ocean areas most impacted seem to lead to that displacement of 'Arctic cold' finding it's way here ( and sadly increasing transport of older ice out of the Arctic Basin ,via the Trans polar Drift and the Fram straight, as it travels here).

With such 'warm' synoptics dominating early /mid Autumn the return to an 'Arctic Amplification' type displacement will be even more apparent to seasoned model watchers.

I will now be watching the 06Z model runs with interest !(until we return to the mild in Early Jan).

I've read you post 3 times now and still can't get my head around what you are trying to say....

[wolvesfan]

I've read you post 3 times now and still can't get my head around what you are trying to say....

i think he's expecting it to turn cooler shortly?.

[Thundery wintry showers]

The Atlantic return keeps getting delayed- on the latest GFS it sits out at T+168, just as it did yesterday. GFS cloud cover estimates suggest that today will be another cloudy day for most of the country but that brighter weather will spread from the south-east on Tuesday and Wednesday, with temperatures falling close to the seasonal average. On Thursday and Friday a weakening rain belt is set to push slowly and erratically eastwards, but most eastern areas will probably stay dry. Meanwhile, the UKMO and ECMWF keep the Atlantic held off by the continental high pressure right to the end of the respective runs.

The ECMWF 00Z operational is certainly interesting for cold/snow lovers, with the high orientating favourably to direct a pool of cold continental air across from the east (not as cold as on the 20th-22nd November 1993, but probably cold enough to support some wintry showers especially on high ground). However, a quick survey of the ECMWF ensemble mean suggests that it's an outlier, with the ensembles going for an anticyclonic south-westerly type.

[nick sussex]

Looking at the GFS ensembles so far for the 06hrs run they all bar one keep that troughing to the west of the UK, so chances of any PM incursions are very low.

I know alot of people are bored of the Euro high but as I mentioned last night given the NH pattern thats the only plausible way at the moment to get any colder conditions into the UK.

You don't want a halfway house here as that ends up with a sw flow for most of the UK. Much depends on the jet to the west of the UK if that can track ne further west and you get some energy splitting into Iberia then you could get the high in a decent position to advect some colder surface air into the UK.

Edited November 14, 2011 by nick sussex

[rich1]

I've read you post 3 times now and still can't get my head around what you are trying to say....

His view is that summer ice melt has an influence over winter weather patterns in the north atlantic and promotes winter blocking in that area

its one method how those who strongly advocate AGW reconcile themselves/explain the recent tendency for colder winters than normal in this part of the world [a change in tack from the trend which was the creation of a pseudo med climate in the UK/'even larger teapot' guff]

it is an interesting theory. May be something in it, who knows

dont expect a lot from the 6z eithe rin the short term or in FI, but be interested to see if some patterns seen earlier reemerge in this or later runs. Euro High being stubborn here though

Edited November 14, 2011 by rich1

[shedhead]

His view is that summer ice melt has an influence over winter weather patterns in the north atlantic and promotes winter blocking in that area

its one method how those who strongly advocate AGW reconcile themselves/explain the recent tendency for colder winters than normal in this part of the world [a change in tack from the trend which was the creation of a pseudo med climate in the UK/'even larger teapot' guff]

it is an interesting theory. May be something in it, who knows

dont expect a lot from the 6z eithe rin the short term or in FI, but be interested to see if some patterns seen earlier reemerge in this or later runs. Euro High being stubborn here though

Cheers for the explanation rich1.

[tollgateiow]

Interesting UKMO 6-15 day update. Perhaps the ECM model is on to something!

[nick sussex]

Looks like the UKMO are favouring troughing to the west with the Euro high extending some colder surface air into the se in their 6-10 day further outlook.

Although they seem a little unsure which given todays output is understandable. I'd say it could go either way as its too early to say how far north the ridge could extend.

Generally theres only so long that any ridge can hold against the jet running across to the north, the pressure eventually sinks the ridge unless you get some upstream amplification and some energy heading se into southern Europe.

I think we'll have to wait and see what the models do in terms of agreeing how far east the first Atlantic attack gets, this in a sense acts as a starting point in terms of where the high will be at that time.

The troughing to the west is likely to spawn shortwaves running east then ne, if you want a chance of something colder and drier then the further west and north this is the better chance the high will be able to influence events.

I know mention of yet more Euro high influence will be driving some people into utter boredom but its really a case of this or milder and wetter conditions, theres little chance that low pressure will be able to track far enough east and se to deliver any PM air for the timebeing.

[Tim Bland]

Interesting UKMO 6-15 day update. Perhaps the ECM model is on to something!

Not that exciting realy, unless you live on the top of the pennines! Meto aren't as fickle as us lot though, if the ECM continues with it's theme then expect daily upgrades to the chances of snow.

[No Balls Like Snow Balls]

Not that exciting realy, unless you live on the top of the pennines! Meto aren't as fickle as us lot though, if the ECM continues with it's theme then expect daily upgrades to the chances of snow.

I think exciting in the fact that it covers both bases, i.e. the ECM or GFS scenario, so exciting in terms of it's not been decided yet whether we get a roaring atlantic or cold from the euro high.

[snowfall09]

How much notice did the GFS give us last year before the cold spell that started in November??

because if im right there was quite a bit of a turn around regarding the outputs last year

Edited November 14, 2011 by snowfall09

[bluearmy]

just to put an issue to bed - by this time last year, the models were counting down to the onset of the 'freeze' like clockwork. the amazing thing was that there were very few hiccups in the fi output. in fact the modelling was often more 'armageddon like' than actually transpired the naefs picked up the greenland block at T384 and never wavered. all very different to now. i'm afraid that some of you need to find another straw !!!

[nick sussex]

How much notice did the GFS give us last year before the cold spell started in November??

because if im right there was quite a bit of a turn around regarding the outputs last year

Last year there was a very strong signal to develop high pressure near Greenland, the NAEFS was rock solid on this and the teleconnections did signal that, however there is little sign of any decent pressure rises over Greenland especially with the stratosphere cooling.

To make the best out of what is a poor NH pattern for cold then its the Euro high for the timebeing, if that gets far enough north and orientates favourably cutting off any southerly flow then that could deliver some colder temps more especially for se areas.

I know people might be hoping for the jet to barrel right through bringing low pressure much further east but this will likely lead to the worst of stalemates, wet and mild as the curve of the jet means sw'erlies.

The ridging to the east and south is unlikely to go far, because of this IMO its better that it at least gets far enough north to bring some quieter drier and colder conditions, it maybe boring but at least it might feel a bit more like winter.

[rich1]

just to put an issue to bed - by this time last year, the models were counting down to the onset of the 'freeze' like clockwork. the amazing thing was that there were very few hiccups in the fi output. in fact the modelling was often more 'armageddon like' than actually transpired the naefs picked up the greenland block at T384 and never wavered. all very different to now. i'm afraid that some of you need to find another straw !!!

Last year that did appear to be the case, the year before though was rather different from what i can remember, stuck in a very disturbed mild mobile set up then. Is why i wouldnt have been against that reappearing for a bit to see if we could get another abrupt change [like the late GFS 00z]. At the moment its leaning a bit away from that so maybe we might have to look for something to happen with this European block in a few weeks. May be some cooler surface stuff to begin with. For now though, expect nothing this november is my call

[snowfall09]

Last year there was a very strong signal to develop high pressure near Greenland, the NAEFS was rock solid on this and the teleconnections did signal that, however there is little sign of any decent pressure rises over Greenland especially with the stratosphere cooling.

To make the best out of what is a poor NH pattern for cold then its the Euro high for the timebeing, if that gets far enough north and orientates favourably cutting off any southerly flow then that could deliver some colder temps more especially for se areas.

I know people might be hoping for the jet to barrel right through bringing low pressure much further east but this will likely lead to the worst of stalemates, wet and mild as the curve of the jet means sw'erlies.

The ridging to the east and south is unlikely to go far, because of this IMO its better that it at least gets far enough north to bring some quieter drier and colder conditions, it maybe boring but at least it might feel a bit more like winter.

Thank you for your reply