Model Output Discussion 19th January 2014-18z onwards.

[chionomaniac]

This supposed 'return to mild' phraseology seems to have crept-in lately to some posts (perhaps misinterpretation of the term 'zonal' regarding upper patterns, and/or people assuming the words 'zonal' and 'mild', or 'westerly' and 'mild' are somehow synonymous: they are not). The UKMO have at no time in recent 6-15d forecasts indicated 'mild' temperatures in the forseeable. Average for some, yes. But it's late January and by definition, that's NOT mild.

 

The phase through which the easterly regime of next week ultimately later gives-way to Atlantic (weak) mobility has already been flagged as open to great uncertainty (refer to my post yesterday citing the Dep. Chief on that very issue, and the high level of entropy that was exhibited in analysis yesterday re days 8-9). It could be manifested Friday; or maybe not until after next weekend. Or perhaps not at all in an immediately marked sense.

 

The midnight suites have merely compounded that difficulty and so quite understandably, Exeter are leaning away from being too prescriptive on the timing and net result of any swing back to a westerly regime. The latest comments from the Dep. Chief explains very concisely why this uncertainty is currently apparent:

 

"....(a) return to a more W’ly regime will be awkward and unreliable given many eps members show upper patterns with cut off vortices over the UK. This would steer low pressure systems S and allow for renewed cold conditions from the east at times. We are happy... (he refers to UKMO forecast assessment, as it stands today) .... with the overall unsettled signal but with lots of variation in the members, confidence in details will be extremely low."

 

With this in mind - and ahead of whatever the 12z suites offer - can we please exercise caution in misrepresenting the UKMO view re anything 'mild'. They are not saying anything of the sort. Cheers...

This is a great post because of the fact that it highlights the misconceptions that are often thrown around on here regarding the zonal regime. What is patently obvious is that the Atlantic will be a spawning ground for deep depressions and that these will move westwards towards the UK, hence the westerly regime indicated. It is because these are then stalling, slipping under the block or dissipating in the vincinity of the UK that the confusion arises. We are but at the end of the westerly line in this case, rather than along the main route that we have been all winter, and the difference between this has not been picked up by some members here - hence the confusion from some and the assumption that it will turn mild when the next westerly burst ends up and dissipates on our doorstep.

 

A very encouraging set up for those who enjoy winter proper (after we get through this weekend).

Edited January 24, 2014 by chionomaniac

[Liam J]

So far so good on the 12z, a slightly different evolution but not a bad one at all. Sliders & shades of February 1996 possible? Not much going to get past a block like that to our east!

 

 

Edited January 24, 2014 by Liam J

[cooling climate]

Apart from half a dozen posts just wizzed through 8 pages of will it snow

why are the Met not on board etc,etc.

GFS t120 and low to the south over France with a continental feed and -2c

to -3c uppers so rather cold for much of England and little in the way of

snow for low laying areas.

It will be the end of the working week or start of February as I said

yesterday before we see anything in the way of snow apart from further north.

[karlos1983]

So do we want Cold from the East or cold from a warm Atlantic.....Thunder snow machine......which appears to be sliding off SE 

 

[fergieweather]

The GFS 850hpa temps are much less pronounced on the 12z compared to the 06z which had almost the whole country under -5 by T144

 That sort of detail utterly unreliable at this range (and even more so... it's from GFS)

[nick sussex]

enlighten us?

February 1996, I still have the emotional scars from that travesty! it snowed alright but ground to a halt to the west of London! anyway its a slightly different scenario but if the block proves stronger then everything will be further west. This looks to have a bit more se movement to it and I suspect the other models won't agree on the sinking low in the earlier timeframe anyway.

[Barking_Mad]

The GFS 850hpa temps are much less pronounced on the 12z compared to the 06z which had almost the whole country under -5 by T144

 

Yes the -5 line is further west on the 12z.

[TSNWK]

What would be good to extend the cold duration would be heights moving westwards over salvbard towards Greenland something be picked up around 162 onwards..

Edited January 24, 2014 by TSNWK

[karlos1983]

UKMO is teasing us big time here, stuck on 06......

[Tamara]

The next well anticipated phase of upstream development is going to plan

 

We've seen the start of the improvement and almost getting the cold nearly to our back door, . There is enough on display already this evening alone to suggest the obvious that we are into an even further different world giving a next stage of acceleration and clear blue water from those flat zonal days..

 

Trough disruption upgrade phase 2 starting. Troughing digging further south into Europe

 

We need to approach FI synoptic output with some caution.

A previous post, progressively trimmed from its original length, for the purposes of providing edited continuation highlights, bridges a period where computer model suggestions for a return of the atlantic have been equally progressive and pruned back, and the estimated evolutions as suggested and discussed in this and previous updates are still on track

 

Rather than a fairly rapid west to east return of vortex energy transport, as some of the more progressive ensemble suites (including MOGREPS) suggested prior and up to last weekend, we have instead been seeing the trend supported and maintained from other ensemble suites at the time which have persisted the theme of insiduously increasing levels of trough disruption right into Europe from the upper troughing to the NW extending from Canada which is losing strength in situ in a painfully slowly decaying defiance

 

On the basis of current progress, albeit slow, of the current wholesale NH trend, its hard to see how any mobile westerly pattern can re-assert itself from the current logjam straddling our geographical crossroads. Where is a flat SW-NE aligned jet stream going to re-incarnate itself from with the trend fully supportive for pressure to fall further over Europe (as phase 2 of trough disruption progresses) rather than rise?... and still this process is modelled as ongoing through the coming week and beyond.

 

Whatever happens, there is surely no way back from where we have come.

 

The reality is that the cold that arrived just the other side of the North Sea several days ago, is not sent packing eastwards, it simply sits there whilst the future modelling continues the theme of accelerated trough disruption (as such previously described, detailed and suggested in that highlighted post). The Canadian vortex meanwhile continues to become a paler shadow of its former strength, even if it is still sitting there spitting at us like a very badly behaved guest who has grossly overstayed their welcome (by weeks at a time)

 

The atlantic may continue to show reluctance to amplify the Azores ridge to provide us a route 2 alternative to cold (other than the more direct and coldest route 1 straight from the east) - but it could be that route 1 comes more and more of a prospect to put back on the table as get into February. In any case the suggested trend from recent long range ECM ensembles for the Azores High to retrogress westwards is coming into some of the operational 10 day range. This further underpins the trough disruption theme towards 'Stage 3' and where the properly good things would really start to come into possible focus.

 

A good assessment has been provided by Ed in terms of the stratospheric impacts on the vortex in reducing it to the current and forecasted state, in relative terms, and as reasoned we should have reasonably cautious confidence in the tropospheric prognosis of the turn of the screw being maintained sufficiently for continuance of the trough disruption theme and slow incremental westward adjustments of the pattern, even if the surface pattern has continued up to now to frustrate with wet rather than overly white conditions.

 

A measure of the further progress made from such a dreadful background pattern up to the mid winter stage is that short to medium term wintry potential is now cropping up (as posted on here) in decent enough advance of absolute months end with the whole of February yet to come, and, relative to such a dominant strong westerly pattern, this is welcomed in such circumstances even if the potential is rather marginal for many.

 

Caution should continue to prevail in terms of further progress, as the vortex whilst under sufferance, is not yet a dead beast, and fine line margins mean a lot in this micro section of the NH as we know.

 

However, with the caution caveats and disclaimers covered, I think that increasing suspicion is also merited as to how we get might regress backwards again from the position of an extended spell of increasingly penetrative trough disruption, consolidated cold pooling to the NE which will continue to provide a deepeing well of possible treats to tap into down the line on the one hand, but will also prove a greater and greater brick wall for jet energy to try and inpact into. This process crawling ever westwards.

 

A disrupted vortex, on the basis of such westward incremental adjustments over days at a time, gives good enough credence to hopes of the Canadian vortex also backing in its weakened state that bit further westwards to eventually allow hopes of the start of a sustained upper cold march from the east with time. This, if it going to happen, will be modelled extremely erratically and poorly and best not expect professional updates to change the line of a return to westerlies until/if it becomes completely clear across the modelling and ensemble suites that the current promising sections of date that show the definitely colder trend as per de bilt and all stations east are going to be consolidated and sustained. We are not there yet.

 

Whilst a disrupted vortex is not as ideally scrap-yarded to give maximum opportunity for cold as we we would like, beggars simply can't be chosers within the context of this winter and the background patterns on offer, and whilst there is a shortening window of time for the colder trend to be arrested, it seems to me its becoming harder and harder to argue the case for the trend not to progress in an ever colder cyclonic/quasi disruptive-zonal January 1978 esqe kind of way and even lead to tentative real thoughts from the east thereafter as we get into and through February.

 

That though is for another day should the train keep coming

[Barking_Mad]

Next Friday and into next weekend is at present showing up as being quite wintery . Maybe this is what Ian was referring to

 

 

[TSNWK]

Here's a question? Around 186 we have -6 uppers over the south east of England in a westerly... That sounds unusual to me, any views?

Cheers

[shaky]

Very good gfs its snow galore with those undercutting lows and very similar to ecm!!defo improvement on yesterdays 12z with the jet going south instead of flat across the atlantic!!big changes for the better on the gfs if you ask me!!

[Liam J]

Anything like this stalling front could produce shed loads of snow over large parts of the UK, usual caveats apply at this range. Definitely a very snowy looking 12z GFS. too many people panicking over 850 temps, anything sub zero would suffice in the set up we're looking at, a very unusual one and one that hasn't been seen for quite some time! Exciting times ahead folks...

 

Edited January 24, 2014 by Liam J

[gottolovethisweather]

This is a great post because of the fact that it highlights the misconceptions that are often thrown around on here regarding the zonal regime. What is patently obvious is that the Atlantic will be a spawning ground for deep depressions and that these will move westwards towards the UK, hence the westerly regime indicated. It is because these are then stalling, slipping under the block or dissipating in the vincinity of the UK that the confusion arises.

 

A very encouraging set up for those who enjoy winter proper (after we get through this weekend).

 

This coming Tuesday being a fine example of this, according to the latest GFS with a limpet surface feature predicted to be off the far NW of Scotland by then and another system to our South trundling along the English Channel. If only the uppers could drop a wee bit more for snow, but for now that's simply nitpicking. Something is up for sure and a definite colder pattern, just whether it happens to cold enough for snow is up for debate.

Edited January 24, 2014 by gottolovethisweather

[mickpips]

 That sort of detail utterly unreliable at this range (and even more so... it's from GFS)

I'm not saying this will be the case Ian , i'm stating what its showing ... nice to see your love for the GFS though

[Liam J]

The British Isles getting bombarded with cold air east & west! Cold whichever way you look 

 

 

 

 

 

 

 

[karlos1983]

Very ermmm ......Blocky. adios Canadian Vortex

 

UKMO at +42

Edited January 24, 2014 by karlos1983

[Bobby]

GEM at +210, what an odd chart

 

 

I think a good word to sum up the output is "messy". Certainly interesting and anything could happen, looks like the weather wants to throw the kitchen sink at us with rain, gales, snow, sleet, hail, thunder, frosts. Perhaps most of the cold coming from the West? Odd indeed.

Edited January 24, 2014 by Bobby

[Blizzardof82]

Way out in la la land but the GFS ends with the vortex obliterated and lots of northern blocking

[swfc]

Pv totally dismantled in fi  All in all a good run from gfs 850s look good,precipitation a plenty so whats not to like!!!!

Edited January 24, 2014 by swfc

[winterof79]

Apologies Ian, I think I worded my initial post poorly in that I was responding to a post on the MT referring to the MO calling for 'mild' rather than saying that the MO actually had used that particular wording (I understood the actual Met Office outlook to be more 'mobile'/westerly' with temperatures near or a bit below average and I broadly agree with that as well). I also understand that the main concern at the moment is, rightly, the flooding situation and that this is likely to cause more impact, certainly in the immediate term, than any cold. I also understand the need for the Met Office to be cautious on these matters, particularly in light of the propensity of mid-market rags to sensationalise even the slightest hint of cold in the outlook, and also because, at D7 onwards, there's always likely to be considerable uncertainty. I really enjoy reading your valuable insights on the thread and again apologies for any misunderstanding caused by my post RE the Met Office outlook.

Very courageous of you that post Lomond,but that shovel your digging with will have better uses next week

http://modeles.meteociel.fr/modeles/gfs/runs/2014012412/gfs-1-174.png?12

[karlos1983]

GEM at +210, what an odd chart

 

 

I think a good word to sum up the output is "messy". Certainly interesting and anything could happen, looks like the weather wants to throw the kitchen sink at us with rain, gales, snow, sleet, hail, thunder, frosts. Perhaps most of the cold coming from the West? Odd indeed.

 

Yes very odd GEM, we appear to be spawning Low pressure after low pressure over the uk at the end of the run.

[The Post-modern Winter]

Well the GFS 12z is exactly what we don't want to see the other models trending towards later in terms of cold and snow, very different to UKMO and ECM in a bad way.

Anything like this stalling front could produce shed loads of snow over large parts of the UK, usual caveats apply at this range. Definitely a very snowy looking 12z GFS. too many people panicking over 850 temps, anything sub zero would suffice in the set up we're looking at, a very unusual one and one that hasn't been seen for quite some time! Exciting times ahead folks...

gfs-2-162.png

As is often the case Bobby's post conflicts with many of the above in a dramatic way. I'm aware I may sound like a broken record and that the models can be interpreted in a number of ways but surely as meteorology is a science the opinions should not differ to the extent of the above if a relevant level of knowledge is possessed (awful for snow/great for snow) With the subjectivity in here sometimes we may as well be discussing politics. Edited January 24, 2014 by The Post-modern Winter

[Summer Sun]

Has UKMO updated fine at Exeter Ian? looks like there is a data issue in getting the 12z to meteociel ect

Edited January 24, 2014 by Summer Sun