Model output discussion 25th Jan onwards

[492]

Slight retrogression of the pattern as the Arctic high slips south and replaces the declined Scandinavian high and trough to the NE digs south over NW Russia where temperatures yesterday were -44 deg C. The low to the NW of the UK looks like it is about to start edging SSE. All in line with near time model predictions.

http://meteocentre.com/analyses/map.php?lang=en&map=eur_full&area=eur&size=large

[carinthian]

Hi C

Normally I try to get a 'fix' with my week's skiing in Austria, my friends flew out yesterday.  Due to the very close call my dad had last month I've had to say no.

My concern now is that there are hints of a pressure rise down the line over Europe and a SW/NE axis developing.  Early days but a potential set up to watch.  I will just enjoy this pretty chilly week ahead for now because just after that we look like having more trouble with the rain...it just keeps coming.

 

BFTP

Sorry to hear that . I am sure there will be plenty of other opportunities to get your fix. The television even over here reports the dire flooding you have in Blighty and family in West Sussex speak of the incessant rain. Euro high is my worst fears, although in our part of the Alps we have good snow cover at elevation. Model watching is very important to our seasonal planning, although presently mild by Austrian standards we have this winter so far enough precipitation at altitude to deliver regular top up of snow.

 C

[IDO]

The 06z a variation on the same theme. Next Friday now looking like rain south of Hadrians Wall. Before that snow showers E/SE. Then a westerly flow for the weekend, so western areas getting showers, still cool. By next Wednesday full on zonal.

 

T240:  T300:  T384: 

 

So the Atlantic winning still trending next weekend, just the breakdown scenario to be pinned down. GFS consistent in FI with a reinvigorated PV.

[Newberryone]

Hi C

Normally I try to get a 'fix' with my week's skiing in Austria, my friends flew out yesterday.  Due to the very close call my dad had last month I've had to say no.

My concern now is that there are hints of a pressure rise down the line over Europe and a SW/NE axis developing.  Early days but a potential set up to watch.  I will just enjoy this pretty chilly week ahead for now because just after that we look like having more trouble with the rain...it just keeps coming.

 

BFTP

It would appear BFTP your assessment as things stand is right on track for if ever a set of charts were to bear testament to your SW/NE axis theory, these would surely qualify.."Dec Revisited" 

 

Albeit on a less turbulent scale perhaps

Edited January 27, 2014 by John Foott

[Frosty.]

then it's back to atlantic domination, probably ending up with a nw / se split with the south and east improving at times and the most unsettled weather for the north and west as we go further into February.

Indeed, I have to agree with myself here

Edited January 27, 2014 by Frosty.

[gottolovethisweather]

One thing for sure that I find quite amazing with these models this year.

All signs were pointing to a nice cold spell last week

But we all knew deep down that it was knife edge due to some fantastic posts from members on here.

I think the point I'm trying to make is the pattern seems to be the models pick up a westerly regime then run with that for some days.

Then a cold continental feed

Then run with that,then the background signals flip too.

Hope I'm not to far off the mark with that, but only last week things were looking fine for cold with background signals too.

Now everything has flipped full circle so the cold was never going to happen like that. Just like prob the models in the last 24 hours won't either.

Sorry if it's a total load of nonsense post.

Just trying to get a handle on all the model flips.

 

Best way to get to grips with the NWP output is to never trust one run over another, get to a general consensus in your head by analysing all NWP suites on a given timeframe. IMHO, the best way to do this is by watching the 12pm and midnight outputs only, try to connect the various developments on an ongoing basis, save some charts to your laptop, pc or whichever device you use. Stand back from afar and don't overanalyse things, look at things from a broader perspective. The atmosphere above our tiny island is a very fluid one and very very complex. A mere change in wind flow or increased cloud cover on any given day can alter forecasts dramatically and there on into wherever FI might be. Learn to appreciate differing climatic profiles modelled within the NWP suites. I still struggle getting to grips with all the charts, so perhaps start on those showing H500 level, the 850s, Thickness Level expectations and watch them change through a run. Above all else, look for the global picture firstly, then as the timeframe moves onto tomorrow and beyond, worry about the specifics on particular days. I especially prefer to use the GEFS or ECM ensembles spreads in order to determine trends for specific days. Take the NH view first, British Isles next, regional and then locally to determine whether it will likely be dry, rain or snow above your house. We are all still learning and so are the pros, don't let anyone tell you any different, Mother Nature and its Butterfly Effect rules.

 

To get to discussing the actual outlook courtesy of the models, here's today's starting point. I think the end to this week and into start of February is far from nailed, to be brutally honest. Alas the Atlantic will push in, but how quickly?

 

 

 

Always take time out to refer to the learning area within the main forums. This of course enables us all to learn from the longer-term NW users.

Edited January 27, 2014 by gottolovethisweather

[Robbie Garrett]

The BBC weather update is about as positive as the world's economies.  Pretty chilly this week I'd say.

 

 

 

But it does look like a return to what we've had most of this winter.

 

[Thundery wintry showers]

I think a lot of the despondency stems from having got excited over individual operational model runs that showed a potentially cold snowy outlook.  For example, the NOAA's 8-14 day outlook charts never really looked promising for a significant wintry spell, and yesterday's outlook had a 500mb trough sat just to the west of the British Isles, which implies below-average pressure there and consequently south-westerly winds over the British Isles.  Today's outlook has the trough slightly further east and more dominant, but otherwise looks much the same as yesterday's.

 

Yesterday's GFS runs had a cool polar maritime shot coming in from the west on Friday/Saturday and then fairly cold air stagnating over the British Isles, but it didn't have much support from either the UKMO or ECMWF, while the easterly for this week generally looked like having too much modification from the SE with the exception of a few earlier runs from the UKMO which showed more of an east to north-easterly influence.  There will probably be some scattered wintry showers from it in eastern parts of Scotland on Wednesday and Thursday, though with lying snow confined to high ground.

 

We are still in with a shot at some frontal snowfall on Friday, especially on high ground and in Scotland and northern England.  It looks very marginal- most lowland parts will probably just have rain or sleet- but those situations sometimes spring up surprises and there is still time for the event to be toned up/down.  Here are the N-W snow risk charts' current line on it:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20140127/06/108/uksnowrisk.png

[summer blizzard]

Model consensus now appears to support a significant reduction in the length of the cold spell and location.

 

Showers are likely along eastern coasts during Thursday however the best chance of snow for the bulk of the country comes on Friday, unfortunately for the Midlands south it will quickly turn to rain with the snow threat mainly for the north of Britain.

 

[mcweather]

Certainly for the foreseable (7-10 days max) the model consensus seems to be of the Atlantic weather systems holding sway over our weather.

 

That still leaves a decent chunk of February and the first half of March to have a go at.

 

Certainly if we do get a decent cold and snowy spell in the middle or second half of February I think we should call it the Tamara Winter. In honour of she who held her nerve when all around were shredding theirs.

 

Personally having recorded a mind boggling 247mm of rain so far this month I'd be happy with cold and dry  or if we don't get a cold spell then mild and dry.

 

Think I might take a break from model watching for a week and come back and see whats on offer later next weekend.

[IDO]

I wondered who was getting all our snow:

 

 source

 

A couple, out of the 50 odd members are cold outliers in FI for London from the ECM 0z, but otherwise trending like GEFS:

 

[bluearmy]

I think a lot of the despondency stems from having got excited over individual operational model runs that showed a potentially cold snowy outlook.  For example, the NOAA's 8-14 day outlook charts never really looked promising for a significant wintry spell, and yesterday's outlook had a 500mb trough sat just to the west of the British Isles, which implies below-average pressure there and consequently south-westerly winds over the British Isles.  Today's outlook has the trough slightly further east and more dominant, but otherwise looks much the same as yesterday's.

 

Yesterday's GFS runs had a cool polar maritime shot coming in from the west on Friday/Saturday and then fairly cold air stagnating over the British Isles, but it didn't have much support from either the UKMO or ECMWF, while the easterly for this week generally looked like having too much modification from the SE with the exception of a few earlier runs from the UKMO which showed more of an east to north-easterly influence.  There will probably be some scattered wintry showers from it in eastern parts of Scotland on Wednesday and Thursday, though with lying snow confined to high ground.

 

We are still in with a shot at some frontal snowfall on Friday, especially on high ground and in Scotland and northern England.  It looks very marginal- most lowland parts will probably just have rain or sleet- but those situations sometimes spring up surprises and there is still time for the event to be toned up/down.  Here are the N-W snow risk charts' current line on it:

http://cdn.nwstatic.co.uk/gfsimages/gfs.20140127/06/108/uksnowrisk.png

 

the ens (especially the ecm) were bullish on driving the trough se into europe and had very little momentum for sending any of the jet ne ian.  on thursday evening and friday, they actually shifted the uk to the right side of the mean surface trough which was something we were thinking could be possible if the blocking was being underestimated. i assume the issue here is twofold - both the blocking to our ne being badly modelled as it sinks away se and the system that comes up from the sw and phases with the pfj creating a strong depression to our nw. of course we are seeing that happen now but with the blocking strong, the system is forced to disrupt and sink se across us.

[scottishandy]

I wondered who was getting all our snow:

 

Screenshot_27_01_2014_12_59.png  source

 

A couple, out of the 50 odd members are cold outliers in FI for London from the ECM 0z, but otherwise trending like GEFS:

 

ensemble-tt6-london.gif

And our mountains - this is the ski patrol hut at about 800m in Glencoe this morning.

 

 

 

It has been a very frustrating winter for us at around sea level, I have only seen a dusting twice this winter. This despite the models showing cold outlooks regularly. What has been interesting for me is that there often seemed to be consensus on a cold outlook at T144/168 only for it to implode after a day or so. I guess that this is just because the blocks have never been strong enough and the route to cold has always been high risk. Oh and that enthusiastic Vortex to our NW.

Interestingly though unlike a few notorious winters we had a while ago the Ski centres have done well in terms of snow cover but perhaps not so well in terms of income due to days lost to storminess. There is a serious risk that if the current modelled pattern comes off some of the lifts will be unusable due to being buried!

So if you need a snow fix come visit us up here and take a ride up Glencoe chairlift or Nevis Gondola.

 

[Ali1977]

I'm sure in the next few days the EC32 and mogreps will start to pick up in potential cold around mid feb, the warming over the stratosphere may come into effect then. It might already be coming into effect at the 15 day period but models are yet to pick up on the changes down at land level. The very end of the GFS looks to be heading down.

[nick sussex]

The UKMO further outlook in the shorter range talks about the west and south being possibly wetter at times, that would suggest that there will still be some blocking to the ne and east.

 

If you go on the ECM mean any troughing looks to be parked near or to the west of the UK, for those of you still harbouring hopes of something from the east or ne then theres one decent synoptic that still hasn't imploded and that's those lower heights shown over the northern Med.

 

Its unlikely that any blocking will get far enough west within the next ten days to develop an easterly but with low heights hanging on over southern Europe this will act as somewhat of a magnet to troughing to the west to send some energy down there, so perhaps a se flow on the eastern flank of the main trough could occur.

Edited January 27, 2014 by nick sussex

[Jason M]

Just looked through GEFS and GEM ensembles.

Some interesting possibilities around the day 10 mark on both (although more in terms of pattern than actual cold weather for us). Overall though I am surprised by how poor the output is to be honest. We are not even really seeing much in the way of cold ensembles.

However warm its been in the UK the warmth has been even more striking over Europe this winter. The chart below illustrates our problem as we are actually forecast to be under a decent easterly flow as per this ECM chart.

http://www.meteociel.fr/modeles/ecmwf.php?ech=168&mode=0&map=0&type=0&archive=0

[Dean E]

Models once again in cross agreement with a 3 or 4 days of colder weather.

 

One thing that's grabbing my attention is that, once North America have another attack of cold with help from the polar vortex. The Jet across the USA flat-lines for the first time this year and becomes a fast moving jet across the country, thus not allowing any pieces of the vortex dive south, with the vortex remaining in Canada.

 

GFS N.Hemisphere Jet H500

 

Current

 

+72hrs

 

The question I'm thinking is, would this effect things as they stand? Something the models aren't taking into consideration? 

 

SM

[nick sussex]

The ECM at T168hrs did have a little interest, hardly earth shattering but you can see those low heights over the northern Med and a ridge trying to extend back in towards the UK, something could develop from this point especially if the models have pushed the initial pattern too far east as has been the trend of recent weeks:

 

We do know that troughing will set up to to the west of the UK, as this happens you might get enough energy heading se towards the northern Med to bring back a se'rly flow into the UK:

 

 

 

[Bobby]

The various ensemble means at day 10

 

ECM ens NAEFS GEFS   GEM

 

A deep trough to our W, rising pressure over Europe and cyclonic south westerlies over the UK. Traditionally a very wet pattern which is bad news for those with flooding problems. Really bad for them and I'm tired of it now to be honest... getting cold and snow starved but it's not looking good.

This pattern could be wetter than the Dec-Jan pattern amazingly if it persists.

Don't want no Euro slug setting up shop...

Edited January 27, 2014 by Bobby

[Jason M]

On the GEM mean its worth just noting the bump of raised heights over Spain. I noticed earlier from looking through them (and also last night) that a good few ensembles really ramped up the warmth and pressure over that region. A few of the GEM ensembles are akin to a Spanish plume with very warm air indeed being pushed North towards the UK. A very long way off but I'm staring to think Feb will either bring a very cold / severe spell mid month or a very warm spell courtesy of the Ruskie high leaving us in southerly winds.

My CET guess is 6c plus for Feb with most of the warmth mid - late month, however I still think we will at least get a roll of the dice mid month. Either way I don't see Feb as being a 'normal' month weatherwise looking at where we are now. I reckon records might be broken, the difficult with the current pattern is whether its record cold or warmth (or both maybe). For the SW lets hope its cold because the alternative would be a very wet pattern indeed out west!

[WhiteFox]

This pattern could be wetter than the Dec-Jan pattern amazingly if it persists.

Don't want no Euro slug setting up shop...

 

In many ways a proper Euro (or Bartlett high) would be no bad thing for those with flooding issues. Generally, pressure is higher over Europe in these circumstances which pushes Atlantic systems further north and west making it generally drier further south and east. Some of the winters I recall with proper Bartlett highs were pretty dry down in southern England and I'm sure that would be welcome relief for many.

The problem with the current output is the presence of the deep upper-level trough to the West; this means that any blocking is further east and allows Atlantic systems to progress further east and bring wet conditions to the whole of the UK. At least with a fairly strong high centred over Switzerland/Austria the whole pattern is shifted further north and west leaving only the NW in the line of regular, albeit not flooding, rainfall. If there's no chance of cold then better a Bartlett high than the current forecasted setup IMHO!

[phil nw.]

 A reminder that please only post in here if you are discussing what is in the charts or other model output.

This thread is not for complaining about it being a poor Winter,or what's in someone's tweet or another site.

 

A number of posts have been moved for these reasons into the moans and ramps thread here

http://forum.netweather.tv/topic/78680-model-banter-moans-and-ramps-winter-201314/

 

please help the team and yourselves by posting on topic so that this thread remains useful and informative for everyone reading it.

 

Thank you everyone.

[Tamara]

Certainly for the foreseable (7-10 days max) the model consensus seems to be of the Atlantic weather systems holding sway over our weather.

 

That still leaves a decent chunk of February and the first half of March to have a go at.

 

Certainly if we do get a decent cold and snowy spell in the middle or second half of February I think we should call it the Tamara Winter. In honour of she who held her nerve when all around were shredding theirs.

 

Personally having recorded a mind boggling 247mm of rain so far this month I'd be happy with cold and dry  or if we don't get a cold spell then mild and dry.

 

Think I might take a break from model watching for a week and come back and see whats on offer later next weekend.

Hi and thanks - in truth its just the weather, which cannot be controlled, so there is no point in losing nerve in the first place really if one uses rational logic

 

This section of the winter was always going to be very hard to gauge the way ahead - the hardest part of the whole season by some way in truth.  The recent few weeks for me have been about gauging how much strength might be taken out of the Canadian vortex through a sequence and variety of wave breaking attacks on it. There was a propensity very quickly following the stormy zonal spell that straddled either side of the festive period for trough disruption to take place, which, from a synoptic point of view has set this winter aside from other typically zonal winters of this type and has led to a lot of the hopes of the last week or two as it has pitted itself against the emergence of the Russian/Scandinavian High.

 

I think that for me, while the surface conditions have been truly appalling in the UK, watching and trying to anticipate the evolution of the pattern has been fascinating and despite the frustration of any properly cold spell still eluding us, there continues (for me) to be a fascination of where this will head in the coming few weeks. I know a lot of people seem to have already made up their minds on this, but there are a few of us perhaps who continue to view things with a different perspective.

 

The trough disruption, as mentioned, which began very soon after the festive season had finished, has continued and slowly moved us towards the colder week we are seeing now - and with current wave activity still ongoing on the vortex and large question marks about the timing of a greater impact into February I would keep on cautioning about taking the erratic and unstable NWP modelling too much at face value, even though realistically I also know it will continue to happen

 

Further energy transport is indicated by the models as the vortex persists to the NW, but changes are continuing around this on the wider NH scale which are largely ignored because they are not yet making any difference to the weather in the UK. I understand the contempt growing very strongly as the last third of the winter arrives, but it is a simple fact that this winter was always going to be very end loaded if it was to take off at all. In this respect I do think that expectations should be set accordingly, and indeed should be set early on in this season. I know that along with some others, I have made many posts to this effect in recent weeks and I think that this fact rings louder now than at any time during the winter so far - through all the awful autumn like extension that this season has encompassed and is set to bring more soggy mess in the coming 5 to 10 day period after the colder and drier interlude this week

 

The hard facts are that the colder spell of this week was well advertised, and whilst it is meagre fare in terms of what it will produce and what would be hoped for instead, what we are getting this week is the precise answer to how much strength the vortex has lost since earlier in January to allow that to happen. For my own part (as well as others of course) I have tried to signpost this and plot progress as realistically as possible

 

So in very sober terms we are talking here very relatively indeed - this is the strongest and most stable polar vortex for several winters and is requiring much tougher medicine than its predecessors. In that respect it shows how expectations on net weather have been changed by a succession of, mostly, much colder winters (there was an easterly and some snow in places even in the relatively mild winter of 2011/12 during early February)

 

So where to now? I would return back to what has changed since the flat, fast and furious zonal spell in Dec/early Jan. The vortex is weaker, but still dominant over Canada of course - there have been forecasting uncertainties about the direction of travel and future strength of it - especially when pitted in terms of the ongoing and future programmed wave activity on it and model forecasts have see-sawed to make this as difficult to assess as much else. 

 

Another significant change to much of the winter to date is the modelling of the Azores High. This is consistently predicted to be weaker than what we have seen so far and also retrogressed into the atlantic. Ordinarily this would be a very good signal for the jet stream to be surpressed south, much as mentioned in the last couple of days - but we are hampered by the stubborn vorticity to the NW and also lack of a forcing signal to push upstream amplification into our atlantic sector to benefit from it. Hence in the absence of these, we see the flat atlantic pattern modelled instead in the 5 to 10 day period. Also we have a Russian High which many are wishing away in the frustration of dangling a carrot of cold air several hundered miles away, but is just waiting for a better vortex profile and something akin to an SSW. Not much to ask for eh?  

 

Putting all this into the mix makes it very hard to predict the way ahead from now on in. The safe bet, which understandably is the official line atm, is further unsettled weather courtesy of the atlantic to follow the colder conditions of this week, but it is worth bearing in mind that the pattern could tip quite quickly with some amplification and forcing on the atlantic pattern and further vortex attack to displace it further away from NE Canada which releases the jet pattern to head well south and resume latter stage trough disruption. Realistically this is not going to happen as we turn the month into at least the first days of February.

 

There is not any pattern that lasts forever, and this is true of this one too. Often persistent ruts such as this that seem never ending can end quite suddenly and abruptly when they finally do. Call it more jam tomorrow if you will, but the fact is that February, beyond the first days/week or so still holds a lot of interest for all the reasons documented in recent days and in this post. Despite the continued poor surface conditions we face, changes have/ and are occuring/ongoing in the NH pattern that cannot return the pattern back to the exact same of the first part of the winter, in terms of what is modelled.

 

The question remains how far can we move from being in this transitional holding pattern which presents us with more horrible surface conditions probably by next weekend, -  but with more than half the work done, only requires a few extra nudges to make things much more interesting. Very frustrating

 

Will we get them while time is on our side? This is not a prediction as such but a February 1991 revisited would be quite something of course, and whilst a late February 2005 f.e was lambasted for being too marginal, I would wager a few people might bite a hand off for something akin to this if nothing colder, sooner, was to occur this year.

Edited January 27, 2014 by Tamara תָּמָר

[phil nw.]

Again a really informative post Tamara and fully explains the background to this seemingly never ending Atlantic pattern.

As you say this Winter was always going to be one where a number of us thought that any cold would come late if at all.

We usually see the vortex becoming weaker late in the season as the gradual return of the sun further north starts to modify the cold of it's core. This year though we had one of the coldest vortex's for many years with temperatures of around -80C at mid-levels of the Stratosphere in mid-Winter.

This has enabled the low heights to remain stable to our north in a pretty tightly packed core until recently.

As you alluded to recent warmings from wave breaking and the gradual seasonal adjustments are now showing the vortex starting to fragment.

If we look at the latest Height anomaly forecasts at T192hrs we can see this illustrated quite well.

 

 

extensive +ve anomalies across the pole but with that frustrating block of low heights still modeled to our north west for the time being.

We can say in many years there would have been enough disruption to the pattern to give us a cold spell by now but this year so far with that stronger beast of a vortex it's been more of a battle to bring it to it's knees.

The Northern Hemsiphere profile overall is better primed now for something colder with the Russian block lurking,a near split in the vortex and the trend for trough disruption in the eastern Atlantic.

We just need a bit of luck and some further warming out of that stubborn lobe of pv around Canada-it could make all the difference to February's outlook.

Edited January 27, 2014 by phil nw.

[Bobby]

In many ways a proper Euro (or Bartlett high) would be no bad thing for those with flooding issues. Generally, pressure is higher over Europe in these circumstances which pushes Atlantic systems further north and west making it generally drier further south and east. Some of the winters I recall with proper Bartlett highs were pretty dry down in southern England and I'm sure that would be welcome relief for many.

The problem with the current output is the presence of the deep upper-level trough to the West; this means that any blocking is further east and allows Atlantic systems to progress further east and bring wet conditions to the whole of the UK. At least with a fairly strong high centred over Switzerland/Austria the whole pattern is shifted further north and west leaving only the NW in the line of regular, albeit not flooding, rainfall. If there's no chance of cold then better a Bartlett high than the current forecasted setup IMHO!

 

Yes the Bartlett although the nightmare of cold hunters would dry things out at least. A Bartlett, proper Euro high or even a Scandi high could strongly influence us perhaps if it wasn't for the Canadian cyclone cannon to our NW. The Azores high which has been a pest is now predicted to weaken allowing the jetstream further south, but with pressure predicted to rise over Europe we're left between a rock and a hard place, a wet one. (as shown in those means)