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

[mcweather]

So yet again the models tease us first flashing us a Scandinavia high then whisking it away.. It seems that some kind of cold northwest or northerly outbreak is reasonably nailed on although how potent is still open to question. Beyond that as IF has pointed out is anyone's guess with low confidence in any option whilst such wild operational swings occur. More than ever a case of wait and see. Hopefully we'll be pleasantly surprised but after many years model watching I wouldn't,t count on it.

[Man With Beard]

The cold air for the end of this week still roughly where it has been for some time - about 48 hours of decent cold, snow chances best further N and W but not out of the question anywhere. 

The d10-15 picture is trying to change things a little - as that ridge pushes towards Scandi, troughing in the N Atlantic realigns itself so that a W or SWly is prevalent in the direction of the UK (at least in the north). The Joker card is the one Bluearmy suggests above - push the ridging so far into Europe that it catches up the Siberian High and an easterly gets underneath. However, normally this pattern doesn't set up far enough to the north to benefit the UK. Might be a return to a high pressure dominated scenario for us without any deep cold?

 

Edited January 7, 2017 by Man With Beard

[knocker]

4 minutes ago, bluearmy said:

the propensity to increase the amplification of the upper ridge ne (just to our west) as we entered eps high res over the past 36/48 hours is notable. Whilst it currently looks odds on to collapse across us as per the end of the current suite, there comes a point at which the ridge gains enough latitude to force the pattern to change and the Euro trough backs west underneath to support it. as per the 12z op yesterday. The spreads seem to be firmly with the strengthening Atlantic running across to our north by day 10 but the next two runs will dictate if this trend of amplification continues to gain traction far enough nw to allow an easterly. 

in general, the eps are far more anticyclonic across nw Europe than the GEFS/geps 

Yes I quite agree that this is a possibility blue but apart from that little flurry that you mentioned there appears little support for this scenario, either with the later EPS or the GEFs so at the moment I don't feel it's the percentage play. Certainly no support at 100mb

[snowbunting]

2 hours ago, Penrith Snow said:

The GFS from +200 has a January 1984 look about it with cold zonality and the -5c 850 line south of the U.K., I imagine it would be cold enough for snow showers up north on many days.

Cant be taken seriously at this range but I think the ECM easterly last night was a ghost anyway.

So many options on the table but cross model agreement that next Friday's north westerly will be quite potent, should be able to squeeze a wintry shower out of that mother.

Nothing like Greece however where my Greek friends are complaining of near record cold!

Andy

Hi Andy. In complete agreement with you on this one. This was the outbreak of cold zonality in 1984 I was rumbling on about in previous posts. I remember it really well as a child. It brought blizzards to the North of Scotland.  This pattern is remarkably similar. One thing to note the OZ run hasnt sobered up the previous runs. Thats the coldest run yet. No Nly blockings or beasts fromthe easts the cards as Tamara et al have suggested. But, that doesnt mean to say we cannot get mobile cold Nly outbreaks instead. This OZ is I think going to be definitive for January.  The patterns are not unrealistic. Unsettled. Colder than average, snow at times in the North. Slightly drier in South. Fringes around coasts even as far south as kent and SW wales will see wintry showers. When fronts collide with colder air a chance for some frontal snow for inland parts. Winter of wild cards indeed!

[snowbunting]

14 minutes ago, Summer Sun said:

 

Im I dont really understand teleconnections that well. But, that ECM GFS 18z was grasping at straws. That I could see! 

[bluearmy]

9 minutes ago, knocker said:

Yes I quite agree that this is a possibility blue but apart from that little flurry that you mentioned there appears little support for this scenario, either with the later EPS or the GEFs so at the moment I don't feel it's the percentage play. Certainly no support at 100mb

Are they GFS op or gefs knocker?  I generally find 100hpa are fairly representative of 500hpa anyway. 

I note a pretty solid strat ridge across N Europe is now consistent in the output and if you look at the eps trop and the GEFS strat, you might be thinking the vortex will be relaxing it's hold on e Canada as we head through week 2. where the lobes are left and the axis of the fella will dictate if we can build some ridging to our north but I wouldn't be surprised to see some more  amplified output again in the the extended modelling over the next few runs. 

[Nick F]

Yesterday's 12z EC chart at d10 for 150mb chart shows the ridge NE, not so evident at 100mb, certainly a connection there re: strong Canadian and Greenland trop vortex too

 

[knocker]

6 minutes ago, bluearmy said:

Are they GFS op or gefs knocker?  I generally find 100hpa are fairly representative of 500hpa anyway. 

I note a pretty solid strat ridge across N Europe is now consistent in the output and if you look at the eps trop and the GEFS strat, you might be thinking the vortex will be relaxing it's hold on e Canada as we head through week 2. where the lobes are left and the axis of the fella will dictate if we can build some ridging to our north but I wouldn't be surprised to see some more  amplified output again in the the extended modelling over the next few runs. 

I think they are GFS op but not positive. The problem here is we are getting into something I try to minimize and that's too much theorizing on not very substantial evidence. I agree there is some indication of the Canadian vortex abdicating to some extent but it's not clear, to me at any rate, what the knock effect, if any, that will have downstream. I can not see any believable evidence to support a Scandinavian ridge, rather the opposite and if the anomalies are to be believed and more an Atlantic trough.

[Timmytour]

In terms of "back-loaded" winters,do we have any experience in what models are projecting in the weeks before such winters materialise?

I suppose 1947 is the obvious example and we simply don't know when the runs of models we have at our disposal today would have got to grips with what actually happened. I do recall that models must have shown the 78/79 winter to get swept away more easily than it turned out to be eventually as I remember the forecast of snow turning to rain one evening and the glory of waking up to more snow the next morning!

I don't think I've ever known such a rollercoaster winter of modelling as we are currently experiencing. And I've seen mention plenty of times of the unusual conditions that are around. Maybe the impact of the decline of such a strong El Nino?  But I suspect the weeks ahead could deliver anything, from a Siberian freeze to a Southerly blowtorch, and the lack of algorithms within the model to address such conditions means we will end up knowing only at relatively short notice what the overriding theme of these next two months of winter will be. 

[Gael_Force]

9 minutes ago, knocker said:

I think they are GFS op but not positive. The problem here is we are getting into something I try to minimize and that's too much theorizing on not very substantial evidence. I agree there is some indication of the Canadian vortex abdicating to some extent but it's not clear, to me at any rate, what the knock effect, if any, that will have downstream. I can not see any believable evidence to support a Scandinavian ridge, rather the opposite and if the anomalies are to be believed and more an Atlantic trough.

Looks like GFS. View on instant weather maps.

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2017010700&var=HGT&lev=100mb&hour=240

 

[Iceaxecrampon]

Excellent 00z keeps up the optimism.

Strong azores high up to Tuesday.

But......not enough to stop the floodgates as early as Thursday 

Brief respite then a reload of more of the same early next week - obvious trends but  a bit  FI.

 

[Iceaxecrampon]

8 hours ago, Changing Skies said:

I think my reverse psychology worked! Fantastic GFS 18z pretty much a replica of ECM 12z. Allseasons is 100 per cent right the GFS OP on consecutive runs had that evolution which was later dropped - it seems it has resurfaced. We do know the GFS is good at picking up things! While the teleconnections are supposedly considered to have no influence on Blighty a tweet by mr fergie? It's interesting how we're sneaking increased amplification by the models, maybe the weather gods want to make up for our suffering. Hopefully the only one suffering in the future, will be that pesky squirrel, frozen stone cold! Don't call RSPCA on me.  

Would be typical of the winter for it all to crash down with 00z runs I suspect not. This Siberian high is an absolute monster EC T240 mean, surely it must be leaving a 'stamp' on the NH atmospheric circulation?

00z a peach - keep calm.

[Iceaxecrampon]

11 minutes ago, Timmytour said:

In terms of "back-loaded" winters,do we have any experience in what models are projecting in the weeks before such winters materialise?

I suppose 1947 is the obvious example and we simply don't know when the runs of models we have at our disposal today would have got to grips with what actually happened. I do recall that models must have shown the 78/79 winter to get swept away more easily than it turned out to be eventually as I remember the forecast of snow turning to rain one evening and the glory of waking up to more snow the next morning!

I don't think I've ever known such a rollercoaster winter of modelling as we are currently experiencing. And I've seen mention plenty of times of the unusual conditions that are around. Maybe the impact of the decline of such a strong El Nino?  But I suspect the weeks ahead could deliver anything, from a Siberian freeze to a Southerly blowtorch, and the lack of algorithms within the model to address such conditions means we will end up knowing only at relatively short notice what the overriding theme of these next two months of winter will be. 

Sorry to be a bit OT and covering the same boring old ground but why why why do some bother with long range forecasts..!!! - and that includes the METO.

[Duane S.]

I still can't make my mind up If (and it's still a very BIG if) we end the winter without a notable cold spell. Should we should consider ourselves incredibly unlucky with the amount of non-zonal / blocking around the NH there has been or not be overly surprised considering the strength of the W-QBO and relative lack of tropospheric forcing on hand.

 

 

[Singularity]

49 minutes ago, Summer Sun said:

 

UKME the most aggressive with P5, other models less so and wide spread before general consensus from ECMF, GEFS and JMA on eastward propagation across Pacific but with mean straddling the +1SD line and enough spread either side that extent to which MJO will support high latitude ridges is very uncertain.

No wonder the ECM and GFS 00z runs are far apart even at just 7-8 days range, and with the GFS incredibly inconsistent too.

Influence from Pacific activity could  start to manifest in our sector 8-14 days from now. So we have an amplification signal that occurs right when the longwave pattern is shifting markedly. GFS 00z has a modest response with the trough right over us, while ECM has a slightly stronger response while the trough is still in the mid-Atlantic. Both feasible outcomes within the spread of MJO guidance.

[karlos1983]

8 minutes ago, s4lancia said:

I still can't make my mind up If (and it's still a very BIG if) we end the winter without a notable cold spell. Should we should consider ourselves incredibly unlucky with the amount of non-zonal / blocking around the NH there has been or not be overly surprised considering the strength of the W-QBO and relative lack of tropospheric forcing on hand.

 

 

I think we have to consider ourselves extremely unlucky!!Greece for example could so easily of been us. 

Ill be happy with some cold N'lys/ NW'ly now, at least it will be of interest. That now looks pretty nailed on with good cross model support.

now when was the last time we were able to say that with a D6 chart.

after that is anyone's guess imo. 

Edited January 7, 2017 by karlos1983

[Ali1977]

Already at T96 the flow looks slightly better angled towards North

[SMU]

48 minutes ago, mountain shadow said:

Just to be clear , it would be more correct to refer to ECM ops runs, not the whole suite.

If some people want to take day 10 charts as gospel then thats their downfall.

The teleconnections have never supported an Easterly.

Just RE the last sentence - that is 100% incorrect.

Irrespective of what any OP shows today or yesterday the teleconnections cannot forecast or pinpoint a wedge of sub 564 heights developing over a thin strip of NW europe.

The 'reality' of this forum & the met & anyone on here using broadbrush teleconnections is as follows- theres a key fundemental flaw in the deck of cards that is teleconnection based - which also applies to the strat as well which is everything that is used to infer the future is model based & also assuming that 'persistence' is going to continue.

relating to teleconnections -

* hindcasting - When the data is in & historic ( whether thats 1 week or 1 month ) its very easy to demonstrate whats happened ( or in the UKs case - whats not happened ) - it will usualy be a combination of the strat zonal wind being to strong or not enough tropospheric waves / amplitude in our vicinity to send the cold our way- there are a number of composites & analogues relating to the teleconnections that drive these ( enso / la nina / MJO / GLAAM ) etc - so it can be very easy to use the data & analogues to present a compelling case for a hindcast - however within that comes 3 things that fail generating a forecast based on this data -

-assumption of persistence

-model data 

- impact 'weighting'

* Whilst the former of the 2 is not so apparent in the best posts on here from the people that do try to review then forecast the problem comes with EVERYONES ability to forecast 'change' & that will always be the downfall because its near impossible to forecast change without relying on point 2 -

- model data....

Whether that be more volatile data like the operational model runs or slightly less volatile areas like the strat the failings of the models will always be the failings of a forecaster who uses them as the guide -

So like today the MJO is forecast to move out of COD into a phase that matt hugo tweets the composite- if that modelling is wrong & we verify in another phase then the hindcast will show the model was wrong.

The other element/s that perhaps need to be posted to which it may be for another day is the weighting that some people are applying in terms of 1 specific teleconnection & how it impacts NW europe - but this isnt just 2D in terms of if X happens then Y changes it has to be 3D if X happens how does that feedback with A B C & D & again there in lies the problem - if we was to generate a dashboard of global drivers -

* Strat levels plus sunspot phase

* El Nino strength

* PDO phase

* SSTA's atlantic based

* SAI feedback

* MJO phase 

* overall GLAAM levels  

 

& so on it would be impossible to forecast still because noone can forecast the weighting...

so going back to the original point if a small high pressure is going to develop over scandi & whether it does or does happen it want be forecastable from teleconnections.- incidentally I believe that based on the starting point alone with no forecasting models just hard strat data etc there is a significantly higher chance of a MLB developing over scandi than there is retrograde block developing over greenland within the continued +VE AO phase.....

S

 

 

[bluearmy]

37 minutes ago, knocker said:

I think they are GFS op but not positive. The problem here is we are getting into something I try to minimize and that's too much theorizing on not very substantial evidence. I agree there is some indication of the Canadian vortex abdicating to some extent but it's not clear, to me at any rate, what the knock effect, if any, that will have downstream. I can not see any believable evidence to support a Scandinavian ridge, rather the opposite and if the anomalies are to be believed and more an Atlantic trough.

 Didn't say scandi specifically and I'm theorising late and beyond week 2 although I don't find the current extended anomolies v convincing given the difference between the eps and the GEFS/geps

 

 

 

Edited January 7, 2017 by bluearmy

[karyo]

6 minutes ago, Ali1977 said:

Already at T96 the flow looks slightly better angled towards North

Yes, the cold is coming to us faster and the Atlantic is a little more amplified. 

[Singularity]

I believe teleconnections are a means of seeing which day the dice is weighted, meaning we can get a sense of what's more likely, but not be able to rule out the less likely options until the short range.

Some years there's so much supportive forcing that factors such as the MJO are to do with how good things will get. Others, like this one, are about whether we can overcome the odds at least for a short time in the season.

[bluearmy]

The 06z slower and bit more amplifed over n America - wonder what that will do to the days 8/10 period? 

[Ice Day]

Yep, definitely an improvement so far and at 138 -6 uppers across the whole country.  Coming into the reliable now.

[Singularity]

I believe teleconnections are a means of seeing which day the dice is weighted, meaning we can get a sense of what's more likely, but not be able to rule out the less likely options until the short range.

Some years there's so much supportive forcing that factors such as the MJO are to do with how good things will get. Others, like this one, are about whether we can overcome the odds at least for a short time in the season.

[Polar Maritime]

Purely an observation for the up-coming cold spell as there will be many more macro differences over the coming days of interest... But the 6z shows a much better chance of snow further South.

Edited January 7, 2017 by Polar Maritime