Model Output Discussion 17th Dec.2013-12z onwards.

[Duane S.]

Unless I've been living under a rock I don't think anyone has actually called for a cold spell in the first half of Jan the most we hope for is a pattern change which COULD lead to something more wintry later down the line.

 

People need to stop jumping to conclusions on here or trying to slit someone's throat just because the want mild or cold weather.

 

Its actually becoming a burden to be on here sometimes with every other post contradicting the other with constant snipping at each other trying to gain the upper hand.

 

Please, if you're going to post about what happens a month can you please provide some evidence and back up your claim, there is another thread where you can discuss gut instinct but this is the model thread.

 

I thought it was just me. You would think listening to some (who only seem to raise their heads above the paraphets when the model suite shows mild and/or zonal), that they are trying to redress some sort of balance being created by others at the other end of the spectrum. I have seen plenty of posts, including mine, postulating on cold(er) potential going forward but very little, if any, calling for a definate pattern change to cold. The irony is, the only ones who are going out to deep deep FI (and even beyond) are those calling for zonal throughout the whole of January. That seems to sit fine with them though...

 

The NH profile is very different to how it was back at the start of December. The vortex is still strong and dominating but that high pressure over the pole area will shake things up to the extent it won't have it all its own way and should help squeeze the jet down south. From that comes potential. I still think the charts are under-doing the effects of this, I think we will see some very interesting charts in the next few days.

 

Also, just because the GEFS Ens aren't showing deep cold / copious HLB solutions either, means very little. I've found often when the op picks up on a new signal the GEFS members go lock stock with it. Which of course sort of negates their purpose but hey. But then the EC32 is hardly a bastion of consistency either. I'm not knocking either, more the utter fuitility of attempting to go out more than 2 weeks max.

Edited December 27, 2013 by Paul
Removed personal comment

[mcweather]

 

Indeed but it is also worth pointing out a reply to a question he was asked on the same 'tweet' about what he meant by cold:

 

Ian Fergussonâ€@fergieweather

@wingers_world colder phases BUT the Atlantic domination continues apace for the reliable forseeable. So, "unsettled with colder periods".

 

Not exactly bad though some places could possibly see snow if this was to verify? Especially further North and higher ground.

 

PS - do we have a "Twitter output discussion" thread?   

 

 

 and the reliable foreseeable according to the met office is about seven to ten days max, which takes all the way to oh yes the 5th of January leaving 26 days of January  for something different.

Edited December 27, 2013 by mcweather

[lassie23]

Thanks for the sound advice timmytour. I never knew that artic ice had risen by 60%. You could be onto something with your theory.

[martinj2]

 

In the middle of a run of mild winters we had this

Snowfalls are now just a thing of the past

Then...as a number of cold winters kicked in we had...

Expect more extreme winters thanks to global warming, say scientists

People sometimes like to shoehorn their facts in to fit their theories, rather than maybe let the facts help develop and refine theories.

On here it's often the same as folks will see patterns in the models that will fit in with the way they want the weather to go.  And good luck to them i say. It's a forum where many different views should be welcomed.  But the longer you are on here the more you'll discover who the more rational and expert folks on here are.  And there are lots of them.

As an aside....I do believe the Gulf Stream was supposed to stall as a result of arctic ice melting into the Atlantic, but this year the ice cover has risen by 60%...so who knows, this may have reactivated the Gulf Stream which in turn may have effected the strength and position of the jet stream 

 

Interesting...on the snow and ice in NH forum someone pointed out a correlation between ice cover and cold winters.

The correlation being, the greater the ice cover the less chance of a snowy, cold UK winter. I know that sounds counter intuitive to us non experts, but it does mean slightly warmer northern oceans surely?

 

 

[nick sussex]

I can understand why theres still to a degree a sense of disappointment  for some people because when push comes to shove its the weather outside your doorstep that will tell you whether there has been a pattern change.

 

So of course unless some more positive NH factors lead to snow and cold then you could say what was the point! There are no guarantees even with the high pressure to the ne that this will eventually lead to some sledge excitement, however one should view it perhaps as how many stops on the bus before you get to a destination.

 

During much of December the bus hadn't even left the station!

 

The models at the moment are in agreement for at least the first stop, this is high pressure to the ne, we then want to see this translated into the jet axis more nw/se and low heights being pushed further south and into central Europe, once that happens you stop the Azores high from pushing east into that region.

 

The upstream pattern in the USA even with the PV edging further s/se is expected to be a positive PNA so at least some amplification over there, historically speaking a positive PNA, high pressure to the ne is a colder pattern for western Europe as low pressure can't move ne towards Svalbard and this tends to track further south and se.

 

IMO the uncertainty isn't with the nw/se jet alignment, unless the high vanishes or moves away from the ne its simply the logical step in terms of where the model outputs will go.

 

The uncertainty behind the pattern is how far sw the high comes and how much trough disruption there will be near the UK. This then translates into some different weather on the ground depending on those factors, you can end up with low pressure tracking se further west snow on the eastern flank, or a PM airflow so more marginal,at the moment you'd probably go for the latter being the most likely given that the PV is expected to drop s/se into wards the ne USA, for the colder option you don't really need to look that far in terms of the outputs, the building blocks for that will either show up at around 120hrs with a stronger surge of positive heights nw into eastern Greenland and a little more amplification upstream.

 

The key throughout going forward even if you miss the colder option window is that the energy goes into Europe, you then wait for the next chance, the Azores high often seen as the scurge of cold lovers can play a role if it becomes more amplified as a response to more of that in the eastern USA.

 

Eventually if the high holds to the ne and the PV weakens then you'll more than likely end up in a colder pattern because its really only the PV which is scuppering this at the moment, the pattern to the ne is good.

[martinj2]

Interesting...on the snow and ice in NH forum someone pointed out a correlation between ice cover and cold winters.

The correlation being, the greater the ice cover the less chance of a snowy, cold UK winter. I know that sounds counter intuitive to us non experts, but it does mean slightly warmer northern oceans surely?

[Chris K]

 and the reliable foreseeable according to the met office is about seven to ten days max, which takes all the way to oh yes the 5th of January leaving 26 days of January  for something different.

 

Exactly - so anyone calling for particular pattern setting up after this is fruitless (apart from the eye candy (or burning)) in my opinion. People have already stated the operational outputs, particularly the further out you go (obviously), will vary quite drastically over the next few days alone.

Edited December 27, 2013 by Chris K

[Biggin]

Unless I've been living under a rock I don't think anyone has actually called for a cold spell in the first half of Jan the most we hope for is a pattern change which COULD lead to something more wintry later down the line.

 

People need to stop jumping to conclusions on here or trying to slit someone's throat just because the want mild or cold weather.

 

Its actually becoming a burden to be on here sometimes with every other post contradicting the other with constant snipping at each other trying to gain the upper hand.

 

Please, if you're going to post about what happens a month can you please provide some evidence and back up your claim, there is another thread where you can discuss gut instinct but this is the model thread.

Someone will drag up the EC32 and use that as evidence which is fine as long as you only use it to day 10. as days10-32  say from today, will be totally different from it current suggestion.Same people who rely on EC32 also seem to poo poo FI all the time too. . Reference the high pressure forecast bout a month ago by EC32 which didnt hang around for half as long as it was originally predicted too,

[bluearmy]

Fyi - sylvain has fixed the NH gem ens charts.

[R.P. McMurphy]

Looks like anyone wishing for cold is going to have to wait a little longer... The signs from a couple of days back looked pretty decent, but i fear some members are not taking into account how strong and dominant this W or W/SW flow has been pretty much from the start of winter.

 

4th / 5th -

 

 

The next potential for anything remotely colder comes around the 8th January...

 

 

Although, running the frame 24 hours it gets replaced by this:

 

 

The next potential for anything comes from this chart:

 

 

Cold fans might like the look of this, but in my opinion, they way the Atlantic has been, I can only see that being replaced by uppers of +5 again !

 

A bleak outlook for anything seriously cold & snowy with the odd frost here and there, and potential for Wintry in the usual suspect places.

 

I feel anyone searching for that first proper Winter Cold Spell is going to have to wait until at least the second half of January, or are we staring down the Barrel of a Mild dominated Winter  ?? Who knows, but only time will tell !

 

 

Glenn.

[syed2878]

@lassie23. Wellcome, i c u mensiond is an ssw about to take place and would it change things, i beleave it would if a ssw takes place. However it doesn't always mean cold for the u.k. Take alook at the stratosphere thread. As for the models at the moment it doesn't look inspiring for cold. Yet models and their ends showing signs of change also the mets hinting at a change, lets waight and c how the drama unfolds over the next week or 2.

[Tamara]

I just wrote a huge detailed post which took me about an hour to construct and then just as I was ready to post I went to switch between tabs and accidentally closed the netweather one. I may actually never recover. It was more stressful than watching an England batting collapse.

 

The jist of it though was that we are already seeing a pattern change, not looking for one in 10 days time.

We now have Arctic high coming into play and a Scandinavian ridge, both distinctly lacking in Decembers output, though you may not have noticed if pattern change is only defined by conditions outside your window.

That is not being pedantic because these changes could make a difference to the weather we get as we progress through January.

 

There has been a lot of blather about what defines cold in England but I think all most people are interested in regarding cold is whether it is cold enough to snow.

Personally I have never said we would get the sort of pattern that can deliver deep cold in the first half of Jan, just that there would be better conditions around late Dec/early Jan for some blocking to develop but that blocking would likely be transient ridges and/or weak blocking to the North. Those were my thoughts 10 days ago and they are my thoughts now. I said there will be increased prospects of snow falling to low levels, particularly Northern England but that the weather will remain unsettled with any snowfall likely to be transient.

 

So what of the output, what should we be looking at and is January really a write off for deep cold?

 

Firstly the Arctic high, where is it heading and will it have any influence on the pattern?

 

Secondly the Scandinavian ridge, how strong will it be and can it stall the Atlantic onslaught?

 

How much trough disruption can we get and how amplified will the pattern be behind? Can we get an Atlantic ridge for example?

 

There are a lot of complex interactions quite early in the output which means divergence is increased and foreshortened in the output which is just another way of saying there is plenty to play for.

No deep cold likely in the first half of Jan but some decent prospects for some wintriness at times to low levels. At the same time we will either be seeing the Atlantic taking back over or blocking getting a foothold keeping the pattern more amplified as we head toward mid month with the prospect of the sort of deep cold some are only interested in, still a possibility in the second half of January.

 

Keep an eye on the short, mid term as even transient blocking can have consequences later and take all output in FI with a pinch of salt, cold or mild, until we have a better handle on how much the strong zonal flow will be disrupted through early January.

Thank you to Ian for his updates and nice to hear there is at least a weak signal that some blocking might establish itself later in January.

As for the EC32, I still say we can not expect them to show cold without a very strong signal for blocking taking hold and we don't have that. What we do have is a complex situation where opposing forces will do battle as height rises to the East and weak HLB attempt to squeeze and hold back the Atlantic onslaught. Longer range output will make assumptions that the longwave pattern isn't overly disturbed by weak and transient ridges but those assumptions may still turn out to be wrong.

Well you recovered very well from that glitch and this is a very good post- I think many will appreciate how annoying it can be when effort and thought like that can be lost through buttery fingers!

 

We are now seeing some of the two pronged wave activity programmed that we need to see in the stratospheric arena to try and de-stabilise the solid lump of concrete that the polar vortex has been resembling up to this time. The changes in jet profile detailed so well in the highlighted post, can be seen clearly enough in much of the modelling at present. Enough to suggest a tendency, with time, for more disruption to low pressure cannonballing out from Canada and Greenland and across the atlantic.

 

We need to be careful how we interpret the forecasts of how the vortex behaves from a stratospheric prediction stand-point however, in the same way as we should be cautious of tropospheric model interpretations. These can flatter to deceive - at least in definitively westerly zonal winters like this one, most especially the first half of them

 

The upshot of this,as far as can be gleaned at present, is that the New Year holds the prospect of a colder form of zonal conditions gradually becoming established - but then something of a crossroads to follow. Much will depend on the continued attacks on the vortex from the wave activity and much will also therefore depend on how the models interpret these. In the unlikely event of any full blown SSW (Sudden Stratospheric Warming)  until maybe later in the winter (which is as anticipated anyway for some time in the other thread)  and with the current entrenched and very hostile polar profile, I do think that any changes are going to be slow, most especially further south and that true blocking (at least in the sense that it clearly influences our weather from a

deeply cold viewpoint) remains a thing of further continued patience.

 

At this standpoint though,the rolling programme of daily output will I am sure keep many alerted to the first sights of the jet stream splitting and some of these MOGREPS lows heading to the south west of the UK. It is important to keep stressing though, that this deeply cyclonic pattern will not break down easily and very soon.

 

Some of Carinthians ski resorts in Austria will be welcoming the troughing digging a little deeper in Europe - this has been a very accurate prediction from that point of view

Edited December 27, 2013 by Tamara תָּמָר

[fergieweather]

Latest MR assessment from Ops Centre notes strong signal from MOGREPS, DECIDER and EC EPS (plus EC32) for the cyclonic westerly theme to dominate into 10-15d trend period. They note a minority of members offer either high pressure, very deep lows or an easterly but, quote, "these are all discounted." As previously mentioned, EC32 retains a strong cyclonic westerly regime, albeit with nuance variations, effectively right through towards end of Jan. Thus on all available evidence, current UKMO summary to at least mid-Jan is for unsettled westerly; colder showery phases and transient ridging.

[Cecil Hogmanay Melchett]

Latest MR assessment from Ops Centre notes strong signal from MOGREPS, DECIDER and EC EPS (plus EC32) for the cyclonic westerly theme to dominate into 10-15d trend period. They note a minority of members offer either high pressure, very deep lows or an easterly but, quote, "these are all discounted." As previously mentioned, EC32 retains a strong cyclonic westerly regime, albeit with nuance variations, effectively right through towards end of Jan. Thus on all available evidence, current UKMO summary to at least mid-Jan is for unsettled westerly; colder showery phases and transient ridging.

OUCH!!

Thanks Ian for the heads up,i think....

[That ECM]

Latest MR assessment from Ops Centre notes strong signal from MOGREPS, DECIDER and EC EPS (plus EC32) for the cyclonic westerly theme to dominate into 10-15d trend period. They note a minority of members offer either high pressure, very deep lows or an easterly but, quote, "these are all discounted." As previously mentioned, EC32 retains a strong cyclonic westerly regime, albeit with nuance variations, effectively right through towards end of Jan. Thus on all available evidence, current UKMO summary to at least mid-Jan is for unsettled westerly; colder showery phases and transient ridging.

The other thing I learnt from this post was, my ipad bounces!!To be fair it's what most would see at this time from the output.

[TSNWK]

Latest MR assessment from Ops Centre notes strong signal from MOGREPS, DECIDER and EC EPS (plus EC32) for the cyclonic westerly theme to dominate into 10-15d trend period. They note a minority of members offer either high pressure, very deep lows or an easterly but, quote, "these are all discounted." As previously mentioned, EC32 retains a strong cyclonic westerly regime, albeit with nuance variations, effectively right through towards end of Jan. Thus on all available evidence, current UKMO summary to at least mid-Jan is for unsettled westerly; colder showery phases and transient ridging.

Many thanks. I guess the above would also support the fantastic posts from Nick S, Mucka and Lady T as well, in that we are not going to get a full blown cold spell in the foreseeable future, however coldies might get lucky in the north with some transient wintry weather. One thing I can say for certain though is that it will not stop that hunt for the Greenland high and Italian low - roll on the 12zsCheers Edited December 27, 2013 by TSNWK

[cooling climate]

Well eyes down for another intensely exciting afternoon and early evening

model watching.

Lets hope we are able to say that at some stage during this

winter when a beastely is knocking on the door at t120 and

its just a case of how cold will it get and how much snow we

will see.

Will the GFS move towards the the Euro's sending heights into

Scandi or will the reverse happen with the Euro's backtracking

towards GFS or of course another stalemate.

I would not be at all surprised to see an easterly pop up tonight

in one of the runs.

[nick sussex]

Latest NAM and GME do show a bit more amplification upstream at T84 and T72hrs respectively, the GFS at T72hrs is also a touch more amplified, a chance we might get a bit more curve back in the jet towards Greenland later on.

[karyo]

Thanks Ian, although the thought of potentially another month of more of the same feels like been served the same bland meal every day!

Karyo

[recklessabandon]

Some parts of the Scottish Highlands could have massed some terrific snow depths by the end of January if the pattern is set to continue. Ensembles in Highland typically varying between T850 of 0C and -5C should generally keep the freezing level around Munro point (although given some of the very low pressure centres freezing levels may drop further) and the ensembles show high precipitation concentrations and spikes throughout the first half of January. 

 

Slightly OT but it seems that often one of the ironies of 'deep cold' in the UK is that snow depths in the ski areas can often be a lot less that under a cool zonal regime. 

[Summer Sun]

Latest update for the NAO shows its staying around natural as we leave December and move into January

 

 

The latest AO update shows it going negative

 

[bluearmy]

Looking at all of todays model outputs I think we're looking at the most likely scenario of low pressure running through the UK into Europe on a more nw/se jet axis shown in map 1 below:

 

nat1.jpg

 

nat2.jpg

 

 

 

its worth requoting this post from nick earlier as this is where the extended ens modelling has been headed for some time. whilst i appreciate that exeter, are, for the time being, largely discounting these scenarios, i am not. dropping troughs have occurred several times already this december and will again this weekend though with a less favourable w-e jet on all occasions. once we have lower heights settled in europe, the dropping trough could deliver more seasonal weather to the uk. the recent operational of ecm in the latter timescale have shown the azores ridge to be far more progressive. whilst not taking fi ops at face value, this is symptomatic of a trend and i believe it will force the trough to more likely drop to our east (at least initially). at the moment, any retrogression of the azores ridge is a bit too far away (around day 10) to allow a measured opinion of whether this troughing will also pull westwards across the uk. in january, surface cold quickly establishes on the continent and and flow ahead of systems from a direction east of south will probably bring a good chance of snowfall.  at the very least, we are looking at a colder zonality than we currently have with systems likely to be heading across the uk rather than swinging sw/ne. that much seems to be accepted by the metoffice, judging by their updates.  not too long to see what the 12z's bring us. remember that the arctic is one of the worst modelled areas on the hemisphere. 

[TSNWK]

12z looks better to me around 144 150 with the Azores high further south west allowing troughing to drop down further over us..

12z Gfs Days 5,6,7 are all a step in the right direction in my view because that pesky Azores high is further south west

Edited December 27, 2013 by TSNWK

[nick sussex]

The GFS not upto much after a better start upstream, quite different though with the 06hrs run over the ne USA and further upstream with the next low moving east, I suspect we'll see a model divergence this evening.

[Captain Shortwave]

GFS not terrible, but not great either. Will probably show a northerly blast with a very deep trough moving through the UK in low resolution.

Note the low moving towards the Bay of Biscay

Edited December 27, 2013 by Captain shortwave