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Winter Model Discussion 18Z 19/1/13 onwards.


phil nw.

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Posted
  • Location: Aldborough, North Norfolk
  • Location: Aldborough, North Norfolk

Just a word of caution to those hanging on to promise of a cold February delivered by SSW. The early part of February 2009 bought a cold snowy spell and at that time there was a similar promise that the second half of February would deliver an even colder spell. it never materialised and instead the month ended up quite springlike.

If this does breakdown friday as the models suggest, it's be disappointing but it'll be another pleasing winter overall, whatever further cold spells might come our way. But i do agree that the five day breakdown seems to be a recurring theme of late. The GFS bought it in first. Now others are following as they so often do. So perhaps instead of just the GFS being wrong, they all are now!

I'd wait for the CMA to deliver its verdict! smile.png

Couldn't agree more. Add that to the fact that the SSW takes place at the "roof of the world, and we're on part of a hemisphere, some people will win with excellent cold, others will lose, because cold air leaving the arctic has to be replaced by warmer air flowing from the warmer climes

Looking at today's models, still looks as though T96 is the start of FI and any change to milder conditions can't really be called until runs later today or even tomorrow.

In the meantime a snow event running in from France tracking up over the East of the country could make tomorrow's rush hour interesting

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Posted
  • Location: Aldborough, North Norfolk
  • Location: Aldborough, North Norfolk

Without this normal 'winter fare' cold spell (temp dropped below zero for the first time last night by the way), we would still be desperately waiting for building of Greenland heights to be seen in the models.

So far there has been no building of high pressure towards Greenland. Time is fast running out. Hopefully next winter will be forecast as mild because everytime its forecast as cold with the long range models showing it, it just dosent materialise.

Where are you Derek? as the temperature here rose above zero fro the first time in 4 days yesterday

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Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

Just for fun, Blizzards for the North..

gfs-2-150.png?6gfs-0-156.png?6gfs-5-156.png?6

The GFS really hasn't got a clue what to do with that low pressure..

Edited by Polar Maritime
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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

Agree that the atlantic is consistently overmodelled - that is an observational feature that chart watchers have identified for years, especially with GFS.

However I remain concerned this morning that the Canadian vortex half is still looking like the dominant one, and that means too much atlantic energy and the end of the pattern that has pushed the energy so far into Europe. Comments by better members than I in the recent past had suggested that the Siberian lobe would become increasingly dominant, allowing a pressure rise to the NW as the Canadian half retreated and a drop in from the NE. At the moment the models are just not picking up on this. My Strat knowledge is paper thin, but this chart from GFS does at least show a sustained attack on the Canadian lobe at 120h

gfsnh-10-120.png?6

but if anything long range modelling is suggesting the siberian lobe retreating to the east and low pressure anchoring itself over the mid atlantic. Once the current cold is gone - just as in December - it has the horrible look of cold rain.

Looking at the MJO which is in phase 7 and looks likely to stay there for the week I am not seeing a match with the composites at all. I wonder whether this winter will go down in the books as the one which showed that mean and composite methods of medium range forecasting are fallible. Unless we get a decent mid atlantic / Greenland ridge modelled soon then that MJO plot looks almost irrelevant. Mean anomaly forecasts back in December were also not representative of what actually happened.

Edited by Catacol_Highlander
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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Without this normal 'winter fare' cold spell (temp dropped below zero for the first time last night by the way), we would still be desperately waiting for building of Greenland heights to be seen in the models.

So far there has been no building of high pressure towards Greenland. Time is fast running out. Hopefully next winter will be forecast as mild because everytime its forecast as cold with the long range models showing it, it just dosent materialise.

welcome Derek but you need to put your town in otherwise your reports really do not help anyone-thanks

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

I'll wager that come the day the chart won't look like this.

http://www.meteociel...4&code=0&mode=0

The worlds biggest col?

Jason

Are you suggesting that a certain Scottish postman, who cannot be named, is getting fat!rofl.gif

​Interesting synoptics indeed!

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Couldn't have seen a more brilliant post this morning.

Its really surprising to see the models be that off at a timescale of a week. I often wonder of they feed in norms in to the background modelling. Probably one for the technical discussion, but do they use past trends to support model progress and does this induce model bias towards a long term mean when synoptics are say..a standard deviation away from what would be average at t0. We constantly see the GFS over egging lows and gradually trying to return us to mild before backtracking and I wonder if this influences models on a macroscale basis.

Incidentally, monday/tuesday looks like a forecasing nightmare

13012118_2000.gif

Sorts of a southerly flow due to the low west of ireland and a NE or so flow from the shortwave/low to the SE. Wouldnt want to be the one calling that one, especially given the marginality.

Edit: The last sentence going on the GFS of course

hi John

No, nothing other than the current data at cut off time, nothing else, no past history, no future predictions of anything, actual data only and then off the models go with their data sets.

And re the post from Cloud 10, yes not very good but as a forecaster I would have been looking at the upper air pattern each was showing rather than the pictorial representation; judging by the 500mb anomaly charts 7 days ago one can see why we have the current sort of continuing stand off between the Atlantic and the high. Actual location at the surface is wrong obviously but the low is not far out nor the suggestion that low pressure would transfer SE not NE and a block would still be there, too far north to what the actual Fax chart shows but a block.

Edited by johnholmes
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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

Agree that the atlantic is consistently overmodelled - that is an observational feature that chart watchers have identified for years, especially with GFS.

However I remain concerned this morning that the Canadian vortex half is still looking like the dominant one, and that means too much atlantic energy and the end of the pattern that has pushed the energy so far into Europe. Comments by better members than I in the recent past had suggested that the Siberian lobe would become increasingly dominant, allowing a pressure rise to the NW as the Canadian half retreated and a drop in from the NE. At the moment the models are just not picking up on this. My Strat knowledge is paper thin, but this chart from GFS does at least show a sustained attack on the Canadian lobe at 120h

Yes that has been my main concern with recent output. I also get slightly nervous when GP hasn't posted for a few days because it seems this occurs when his forecast isn't going to plan.

If we take the model output at face value then it appears towards the end of Jan we're going to see a mild spell right at the time when some suggested our coldest spell could begin from the NE. This forecast would only be correct if we viewed the models with our laptops upside down.

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Posted
  • Location: London, UK
  • Weather Preferences: MCC/MCS Thunderstorms
  • Location: London, UK

I don't see a breakdown at all, where are people getting this breakdown from?

GFS operational is a mild outlier at 00z from 22nd/23rd Jan 2013. That's 3 days away, gives me no confidence at all......

t850London.png

If the fax chart at 120hours is to be partially believed, then we are about 2 weeks away minimum from a complete change in weather type/pattern.

PPVO89.png

Edited by Robbie Garrett
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Posted
  • Location: Londonderry , Northern Ireland
  • Location: Londonderry , Northern Ireland

Looks like from Friday the cold spell will end according to CFS, it's been hinting at this for the last couple of days.

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Posted
  • Location: portsmouth uk
  • Weather Preferences: extremes
  • Location: portsmouth uk

Are you suggesting that a certain Scottish postman, who cannot be named, is getting fat!rofl.gif

​Interesting synoptics indeed!

theres one thing all the models have in common there trying to bring in milder air.

but the low heights continue on sliding se into europe which always keep the door open right now there are changes due because of the strengthening of the vortex and were it will set up shop.

i think theres been lots of input regarding the ssw this has happened and clearly has made an impact but i dont think it has been prefect in every way but the effects seem to be starting to weaken and that it is likely milder air will make slow inroads across the uk in the next 3 to 5 days.

amazing to think that the little heights to our northeast had this much effect so yes you could imagine a stong 1050mb block either ne or nw would of had i think its not been a dissapointment by far but has also been another year were we could learn a little more about ssw and models ect ect.

still plenty of winter to be had this week.

and for anything special we need to see were the vortex over the canadian side goes and how strong the reformation will be if any.

i could be wrong but i think the effects of the ssw are starting to weaken so where do we go from here.

i wonder if the pros have there idears can pop in to say were do we go from here because GP has not been about most likely enjoying the snow and chiono thoughts on future developments.

i personally cant see feb being a cold month until the battered vortex stays weakened or relocates more to a favourable area.....

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

copied from the in depth thread

I honestly cannot see that any major change in pattern prediction has occurred in the past 24 hours so I would stand by my post from yesterday, less cold and blocked yes into the end of the month, not mild. Beyond early February and again nothing looks to have altered from the data I looked at yesterday morning so a return to cold blocked is the form horse in my view.

In basics then yes some are going to lose their snow cover during the next 7 days, hillier areas from the Midlands north probably holding on to it. Frosts still likely in clearer slots beyond 7 days.

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Posted
  • Location: Irlam
  • Location: Irlam

I don't see a breakdown at all, where are people getting this breakdown from?

You only have to look at the mean pressure charts of ECM and GFS and they suggest a breakdown. The argument of that they are overplaying the Atlantic is a fair one but the problem is that the ensembles ain't budging infact they are firming up on the idea. It looks a breakdown from the continental airmass to a less cold polar maritime airmass.

It's hard not to ignore it.

Edited by Weather-history
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Posted
  • Location: South Essex
  • Location: South Essex

Big differences in the ensembles even at 78 hours. Mind you, if offered the charts GFS has shown on this run at 78 hours, of the 22 available including ensembles and control, I'd normally bank about 20 of them as a day 1 chart.

Jason

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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset

It does seem that the Greenland energy is going to be around for a while to come. It's very much been our friend recently and hopefully well into next week, spawning features that track SE keeping us very much in the cold and of course with plenty of snow opportunities for most thrown in as well. I suspect we may have to endure a mild(er) period in about a week as not as a non-favourable tilt takes place and SWerlies raise the temp away from the NE. But IMO,that would be the worst case scenario, thereafter I'd favour that only being transient before we settle down to more cold again.

Obviously GEM is pick of the bunch. Is it on to something? Has been known to be the leader in trendspotting before. Taking into account the movement of the MJO and the effects of the SSW, I am surprised not to see more HLB FI showing up in the mid / long term charts as of yet.

I have to say though, GFS has really lost the plot of late and the more and more I think about it, I reckon it just struck lucky last December. It always seems to fire up the Atlantic too much and it just so happened that on that occasion the Atlantic did pipe up and blaze through.

Going to have to mention comments about this cold spell so far. Obviously it differs from location to location so everyone will have different experiences but whilst (so far) it has not been of the proper classic variety (aka Dec 10 / Feb 91 / blah de blah de blah) it has been far from bog standard winter fare for many parts of the south. Even if the Atlantic piled in tomorrow (which it won't) it will (or ought to) go down as a very decent cold spell.

For some reason certain posters seem virtually obsessed with only looking to get the coldest possible uppers here. Great but often with V cold uppers it is a pretty dry affair. Me, i'd much rather have this cold (of the non severe type) and snowy with the inevitable marginality that comes with it (and mine will always be one of the most marginal locations!).

Worth also mentioning that we have (and still are) eeking the very best out of this, with a dominant daughter vortex sat around Greenland, things could be so much worse.

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Not the best looking FI from the Gfs 06z, rather progressive and no sign we had any strat warming at all from this chart, more a throwback to christmas and before.

post-4783-0-35635300-1358680068_thumb.pn

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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

Yes that has been my main concern with recent output. I also get slightly nervous when GP hasn't posted for a few days because it seems this occurs when his forecast isn't going to plan.

If we take the model output at face value then it appears towards the end of Jan we're going to see a mild spell right at the time when some suggested our coldest spell could begin from the NE. This forecast would only be correct if we viewed the models with our laptops upside down.

Agreed. I too sense that GP is holding off posting until pressure rises to the NW and the siberian lobe backs west... and the longer he stays quiet the more concerned I become. If December hadnt so massively under modelled the amount of energy dropping out of Canada I wouldnt be so bothered: as it is everyone I think was caught out by the amount of energy that the "flick of the tail" sent towards us back then, enough to completely destroy 2 weeks of weather (unless you l like cold rain of course)

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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

This cold spell is far from over and there's no 'guarantee' that the Atlantic will win out. Atlantic influence doesn't mean Atlantic winning out just that a change/repositioning atmospherically will occur. The 120hr Fax chart is fascinating and under clear skies and no wind we'd see some serious overnight low temps come Thurs. Will there be a less cold period? Well there has to be a change to the set up we have whether large scale or subtle sooner or later and less cold is most probable [for a short time], but the models are doing nothing to concern me re the longer term outlook. Indeed the breakdown, delayed breakdown, breakdown, delayed breakdown churning out is quite satisfying. Currently sub zero and persistent light snow here as it has been for a couple of hours.

BFTP

Edited by BLAST FROM THE PAST
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Posted
  • Location: Ware, Herts
  • Location: Ware, Herts

i personally cant see feb being a cold month until the battered vortex stays weakened or relocates more to a favourable area.....

Nobody can, especially when we still have so much chopping and changing this week ahead. The trend is for less cold conditions by the weekend but it's by no means a formality - when we've seen how a 1016mb high pressure can influence the path of low pressure systems over the past week I wouldn't bet on any of the current outcomes coming to fruition.

The FAX 84hr shows another potential snow event for the south on Wednesday.

Honestly sometimes I wonder what will make people happy in winter - by next Friday most of the country will have had cold conditions for nearly two weeks and many have had snow, some of it very deep. From an IMBY perspective it's not been the deepest snow but it has been consistently snowing, I think 5 days of the past week have had some snow and there's going to be a couple more days this week.

post-1908-0-10653600-1358680026_thumb.gi

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Posted
  • Location: Ribble Valley
  • Location: Ribble Valley

Not the best looking FI from the Gfs 06z, rather progressive and no sign we had any strat warming at all from this chart, more a throwback to christmas and before.

It could be right Frosty, remember how the PV lobe moved out of Canada in December. We could be looking at something similar happening now.
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Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

Obviously GEM is pick of the bunch. Is it on to something? Has been known to be the leader in trendspotting before. Taking into account the movement of the MJO and the effects of the SSW, I am surprised not to see more HLB FI showing up in the mid / long term charts as of yet.

Agree, agree and also surprised at lack of greenland or mid atlantic heights being modelled with current MJO phase. Maybe later today...
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Posted
  • Location: South Essex
  • Location: South Essex

In the interests of balance its worth noting that the GFS 126 chart has quite strong support from its ensemble suite for the first time.

Given how the ensembles are diverge quite a lot by 70 plus hours its strange that they largely come back to some sort of agreement. Will it be right? Who knows, but can't be ignored.

Jason

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Posted
  • Location: Afan Valley South 4 Miles Port Talbot
  • Location: Afan Valley South 4 Miles Port Talbot

I think personally it might be a good thing the adlantic has some influence towards end of the week, it will give us a clean slate to start over. Maybe the next cold spell if it comes will be more severe or maybe it wont. But it sparks healthy debate and it gives us a respite from nasty gas bills. I like things to be sesonal big differances between summer and winter its what makes the UK so great. To have some snow has been fantastic, I have also learned a massive amount from the experts as well as from the novices like me asking very sensible questions. I will always favour the fax chart as its written by experts using there brains instead of a computer churning out maths after maths, only takes one number to be slightly out and it has massive implications as an example that insane low preassure. If the latest fax chart is to be belived then it looks like things will remain cold, but over clear skies with high preassure in control with lows out to the adlantic. That means not much in the way of snow for anyone so I agree S4lancia its better to have more marginality than dry and cold.

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