Model Output Discussion 4th Dec.2013-12z onwards.

[Jason T]

WOW Just pulled this from Twitter. Superb image Of the stratospheric Vortex, Slightly off topic sorry mods.

 

http://earth.nullschool.net/#current/wind/isobaric/10hPa/orthographic=-10.29,61.29,432

[nick sussex]

OK some crumbs of comfort.

 

Here are the ENS for Rome showing the mean SLP edging down in time.

 

 

Same for Vienna.

 

 

Ditto Warsaw

 

 

 

Back to Vienna - being right in the centre of the continent (more or less) & the 850 hPa's show a more unsettled picture developing

 

 

So if the trend is correct and bear in mind that quite a few ENS members do not support it, then there could be some hope of at least the first steps towards getting a somewhat colder pattern.

Very tentative I must stress!

Yes that's really the key going forward, in this type of set up there won't be any changes until pressure falls in central Europe, that will suggest that the limpet high is being pulled further west.

[mulzy]

The extended ECM ens do push the trough into Europe, though on a nw/se axis. We are on the ' mean' colder side which will translate to some milder incursions and colder ones, though on the whole, probably the lower side of average. That will allow for some possible snowfall on the north side of features running w-e. the higher anomolys over s Europe and the eastern med, with the latter looking more convincing. cool to cold zonality the buzz phrase, once the trough has pushed in. If we can get under the trough, it is a good time of year with min solar input. Nothing tedious - now where's that three month Bartlett?

 

In my experience, the models have a tendency of placing the PFJ on too much of a southerly trajectory in the extended range.  I think the Met Office 15-30 forecast suggesting "colder nights in the south and east with a risk of frost and fog in places" suggest that that significant troughing over Europe is unlikely.  I sincerely hope that the extended ECM ens are right but I can't see the current pattern changing anytime soon.

[Iceaxecrampon]

It's the overall pattern I like most, there is good potential for cold incursions during the next few weeks which is a far cry from how desperately poor the models looked around a week ago with a seemingly all conquering euro high snuffing winter out for the next 4 weeks, things are on the up I think.

 

 

Yes agreed - glad to be shut of this murk -  just got to lose that Southern Sierra - Mistrel (or whatever!!!) wind  aspect  - Jet looks to be sinking so cant be a bad thing.

 

Ian

[gottolovethisweather]

In order to show both sides of the current outlook (near-term) I will post some UK 850s and SLP charts below, courtesy of the wonderful NW extra. In fluid situations such as we are in currently, although not everyone's idea of fun, there can often be some transient snowfall events which seemingly turn up "out of the blue". Yes, the GFS 6z on the face of it was a milder run than those recently shown by the GFS and other outputs and I personally prefer to view the mix of afternoon suites and then make a judgement call on the developments from there on in. As an example, I firmly believe the latter part of next week's runs will be much more revealing for colder prospects given the start signals and its quite probable a switch over in the Jet position may occur around Boxing Day to something at least more wintry. This last comment is based on a hunch more than anything but all it will take is one of Nick's undercutting Shortwaves to dive South and voila.

 

So firstly at t+84 hours it's suggestive of being way more mild than usual for most up to then, bar most of Tuesday.

 

 

 

12 hours later, at only t+96, some might get lucky IF there is precipitation around, think back-edge snowfall or heavy wintry showers mostly streamer type.

 

 

6 hours thereafter, still under -6c uppers from the Midlands Northwards so plenty of potential again by Thursday midday.

 

 

Then as far as I am prepared to go with posting up NW extra charts as freebies, here's Friday midnight, i.e. t+114 hours.

 

 

So yes even some hope there, late Wednesday evening ( the day of a very intense depression) and right through to Friday (another windstorm event) morning is a definite watch period for notably active weather and some potential for brief wintriness. As ever, the further North and West you are and with added elevation you are more likely to strike lucky with snowfall potential. I have deliberately focussed on the nearer-term once again and I must state that after Friday 20th December the outlook is much of a muchness but for me, that matters not given the timeframe.

Edited December 15, 2013 by gottolovethisweather

[shedhead]

Lol, I'm nicking that one for the next time I play Scrabble.

Looking at the models and I don't see the same despondency as most others here, we have a jet which is looking likely to dive further and further South with time once any fronts push well into Europe. From there we could start too see tentative signs of height rises to our NW towards the months end, yes it's a glass half full viewpoint of the models but least we forget some were talking about a long fetch from the SW only a week ago and look how that prediction went.

Got to say as a cold weather lover SI I just don't get comments like this, indeed it's difficult to imagine a more dire set up for protracted cold than the current one. Yes the models appear to want to shunt the Jet ever further south, but even by Xmas Eve it's still firmly sat on it's big fat buttocks right over the Alps, with only tentative signs that it might consider moving on towards New Year. OK the odd 12-36hr shot of Pm air might make if feel it bit more seasonal at times, but at least as far as ambient air temps are concerned it will be on the mild side generally, especially across the southern half of the UK.

 

Frosty said in an earlier post that it will feel more like Winter and it's hard to argue with that, but only because Winter in the UK is essentially wet and windy....unfortunately Winter from a wintry perspective still looks a very long way away and as such the current despondancy over this remains fully justified imho.. 

 

Edited December 15, 2013 by shedhead

[nick sussex]

In my experience, the models have a tendency of placing the PFJ on too much of a southerly trajectory in the extended range.  I think the Met Office 15-30 forecast suggesting "colder nights in the south and east with a risk of frost and fog in places" suggest that that significant troughing over Europe is unlikely.  I sincerely hope that the extended ECM ens are right but I can't see the current pattern changing anytime soon.

That's a good point re the PFJ at outer timeframes, that bias is certainly very evident with the GFS, it does also depends on the set up, I've often found that with a strong PV to the north it will show low pressure coming south over the UK, this often leads to suggestions in here of some colder conditions but the models at that range don't factor in shortwave activity near Iceland which will often cut the cold flow off. I use a simple rule for these set ups which with experience I think works,a uniform PV blob to the north which covers the entirety of Greenland  is a no go for cold regardless of what the outputs show it doing in outer timeframes, unless you see a trigger to sink the PV or disrupt it like for example some polar height rises then if the models show the PV blob to the north and try and bring in cold it simply won't happen.

 

There are many biases associated with NWP, blocking and undercutting is another situation that is prone to error, I know  I keep harking back to the ECM T240hrs of last night putting aside whether it would verify the outcome of the sinking trough there is plausible synoptically because of the lifting out of those low heights in the north half of Greenland and that pressure rise near the pole.

[Downpour]

You need to get a job with the Tories they could do with someone like you Frosty to spin mediocre/bad news into something more positive! Do you have an aversion to uttering the word mild? The much vaunted cold zonal is a rarity in the truest sense, you certainly need some forcing on the pattern to head south and unless theres a pressure rise to the ne/n then its not going to happen.

 

I admire your optimism Frosty but I do think you've gone into spin overdrive here, the jet axis nw/se isn't even showing up in any more reliable timeframe, a couple of GFS lower resolutions at T360 are really not worth taking seriously.

 

The ECM which is fast becoming a major irritation for me throws out a more positive solution at T240hrs which never sees the light of day, overall its not the worst zonal set up I've seen as in at least there might be the odd cold blip and a little snow in the north but my sledge rating is flatlining at 1/10 and that's being charitable.

 

The jet doesn't just say hey lets head south it needs a trigger and that needs to come with a relaxation of those low heights to the north , something like last nights ECM T240hrs would be a start, show me that at T144hrs and I might be a bit more optimistic. We'll see over the coming days if theres any real progress to a southwards jet adjustment.

 

Keep up the good work though Frosty, if the power of positive thought could change this pattern you would have succeeded already!

 

PS I hope people don't think I'm being a miserable sod here, I'd love to see a change in this pattern but we're a long way from what many coldies would like to see especially for the Xmas period.[/quote

"You need to get a job with the Tories..." LOL. Indeed Nick!

As much as I am a Frosty fan, putting a positive spin on the dretch that yet models are currently churning out is spin worthy of George Osborne and his mates, that's for sure.

We are now staring down the barrel of a wet and windy Christmas which means kids cooped up and climbing the walls for days on end.

The one caveat is the old adage that intense low pressure systems have the potential to trigger major changes by essentially shaking up the weather. Let's see where we are by the weekend - needless to say though my holiday plans of banging around Epping Forest on the mountain bike and having bracing winter walks to wear our my four year old have been dealt a blow by the models.

Come back Uncle Barty, all is forgiven. There is a mince pie and a glass of good Madeira waiting for you.

[legritter]

WOW Just pulled this from Twitter. Superb image Of the stratospheric Vortex, Slightly off topic sorry mods.

 

http://earth.nullschool.net/#current/wind/isobaric/10hPa/orthographic=-10.29,61.29,432

That is one hell of an image ,thats what makes meteorology so fascinating ,Models still looking very interesting ,and one or two tweeks here and there and it could be game on for some ,tonights runs eagerly await ,cheers 

[gottolovethisweather]

WOW Just pulled this from Twitter. Superb image Of the stratospheric Vortex, Slightly off topic sorry mods.

 

http://earth.nullschool.net/#current/wind/isobaric/10hPa/orthographic=-10.29,61.29,432

 

Impressive and you can move to any part of the globe too and zoom in and out if folk didn't realise this.

[weatherguy]

Here's that low I mentioned the other day moving NE over the UK again, quite good consistency from the GFS on showing this feature now:

 

This time the orientation and track is slightly different (worse), bringing in more mild air and reducing the snow threat, though even here there is some shown for the UK:

 

 

Again, something to keep an eye on - The consistency is there for some sort of system to cross the UK around christmas time, what will change is the exact track and orientation as to whether it brings us any snowy joy

 

Of course, the low could vanish entirely as it's so far out, but it's the only crumb of comfort I can offer right now for those looking for snow! 

Edited December 15, 2013 by weatherguy

[stewfox]

Impressive and you can move to any part of the globe too and zoom in and out if folk didn't realise this.

 

Says I need """This site requires IE9 or newer""

 

Is that Internet Explorer ??

[Summer Sun]

Says I need """This site requires IE9 or newer""

 

Is that Internet Explorer ??

 

Works fine here with Firefox

 

Yes IE9 is Internet Explorer

Edited December 15, 2013 by Summer Sun

[UV-RAY]

Got to say as a cold weather lover SI I just don't get comments like this, indeed it's difficult to imagine a more dire set up for protracted cold than the current one. Yes the models appear to want to shunt the Jet ever further south, but even by Xmas Eve it's still firmly sat on it's big fat buttocks right over the Alps, with only tentative signs that it might consider moving on towards New Year. OK the odd 12-36hr shot of Pm air might make if feel it bit more seasonal at times, but at least as far as ambient air temps are concerned it will be on the mild side generally, especially across the southern half of the UK.

Frosty said in an earlier post that it will feel more like Winter and it's hard to argue with that, but only because Winter in the UK is essentially wet and windy....unfortunately Winter from a wintry perspective still looks a very long way away and as such the current despondancy over this remains fully justified imho..

Well maybe you need to read my post again Shed because I did say towards the latter end of the month. IMO there isn't a single chart that is showing a mild spell of weather, more a case of alternating mild and cold with cold becoming more dominant in the latter stages. It's far far removed from December 2011, then there was no positives to take forward whatsoever. The outlook is unsettled, windy ( stormy at times ) and average with the emphasis on the jet diving South around Xmas time. Of course those in the south of the country will just see copious amounts of rain, but there is more to the UK than here you know. Edited December 15, 2013 by Sceptical Inquirer

[Tim Bland]

If you want a white Christmas best head to Egypt. They have seen their first snow for over 100 years! Unless we get some heights to out north then transient sleet on high ground is the best we will see. Hoping FI continues to show the stretching of the PV and makes more of that higher pressure over the pole. All eyes on the GFS in an hour

[legritter]

Well certainly at this moment looking at all available data the coming week looks very Disturbed apart from this Tuesday ,with areas of very hvy rain and bouts of severe gales .Late wed into thursday being a more potent windy spell ,and IF the modelled low were to take a track further south it could be storm force winds across many areas .There are signs of eventually low pressure tracking further south pulling in colder air with an increasing risk of wintryness turning up .But i feel beyond sunday the 22nd of December there remains much uncertainty at this range .Yes as some have posted and of course with data to back it up it looks like the Jet will start to shift south with time so we could see some better synoptics with a better chance for us coldies appear .looking around the northern Hemisphere today there is plenty of newsworthy weather going on so that for me is a Big Straw to clutch and with just a bit of luck the  Dice could fall in our favour ,of course if your fix is wild zonal you should be currently over the moon .Lets hope tonights runs and current run by GFS brings a bit more lowering of pressure over southern and eastern Europe; but at the end of week two of winter still plenty of weeks left for some Goodies .

[shedhead]

Well maybe you need to read my post again Shed because I did say towards the latter end of the month. IMO there isn't a single chart that is showing a mild spell of weather, more a case of alternating mild and cold with cold becoming more dominant in the latter stages. It's far far removed from December 2011, then there was no positives to take forward whatsoever. The outlook is unsettled, windy ( stormy at times ) and average with the emphasis on the jet diving South around Xmas time. Of course those in the south of the country will just see copious amounts of rain, but there is more to the UK than here you know.

Yes SI, fair point re months end, however I must also ask you to read my post correctly, as I simply stated 'but at least as far as ambient air temps are concerned it will be on the mild side generally,'  Moreover your contention that 'more a case of alternating mild and cold with cold becoming more dominant in the latter stages' is rather misleading imo. There is not one day on any model that could be considered 'cold', in fact even the coldest days shown are average to rather cold at best. Finally when looking at the daily mean temps, that lack of any real overnight low mimima is likely to result in values of 2-4c above the mid Dec average, which equates pretty much to this... 'but at least as far as ambient air temps are concerned it will be on the mild side generally,' 

[UV-RAY]

Yes SI, fair point re months end, however I must also ask you to read my post correctly, as I simply stated 'but at least as far as ambient air temps are concerned it will be on the mild side generally,'  Moreover your contention that 'more a case of alternating mild and cold with cold becoming more dominant in the latter stages' is rather misleading imo. There is not one day on any model that could be considered 'cold', in fact even the coldest days shown are average to rather cold at best. Finally when looking at the daily mean temps, that lack of any real overnight low mimima is likely to result in values of 2-4c above the mid Dec average, which equates pretty much to this... 'but at least as far as ambient air temps are concerned it will be on the mild side generally,' 

I was referring to the latter stages again, but the overall picture is neither mild nor cold Shed, hence my average comment as we will see daily temps fluctuate from  slightly above average to slightly below more so for those North of the Midlands and then as the jet sinks Southwards, below average temps would effect more southern areas with time. 

Edited December 15, 2013 by Sceptical Inquirer

[gottolovethisweather]

A similar signal to the GFS 6z being picked up by the GFS 12z with the Wednesday/Thursday surface feature, just no certainty over the exact depth and track. Again, a good chance of some wintriness following it up as per my post from earlier. The UKMO chief forecaster having a similar view of things, note the 2nd paragraph.

 

A rapidly deepening area of low pressure will pass close to the NW of Scotland during Thursday morning. Although there is some uncertainty about the depth and exact track of this low, the high gusts, in combination with heavy rain, and some coastal flooding seems likely to bring disruption to travel.

 

In the wake of the main storm, (beyond the period of this warning), a regime of wintry showers will bring an increased risk of hill snowfall and icy roads.

 

Given the potential for a significant winter storm the public should continue to monitor the Met Office website for updates to this warning.

 

If this proves anything, it's that we shouldn't be looking too far ahead when the jet is ragingly rampant. Yes, no prolonged deep cold but still plenty of mixing of airmass types on offer.

Edited December 15, 2013 by gottolovethisweather

[Mr Frost]

I was referring to the latter stages again, but the overall picture is neither mild nor cold Shed, hence my average comment as we will see daily temps fluctuate from  slightly above average to slightly below more so for those North of the Midlands and then as the jet sinks Southwards, below average temps would effect more southern areas with time.

Yes, would agree with that SI.

Not relevant to this thread but the Metoffice sum it up.

UK Outlook for Friday 20 Dec 2013 to Sunday 29 Dec 2013:

It is likely to remain generally unsettled, often windy and rather mild at first across much of the UK, with showers or longer spells of rain and a continuing risk of severe gales, mainly affecting parts of the north and west. There will also be some colder, clearer and showery spells interspersed, with showers likely to turn wintry over higher ground in the north and also some overnight frosts during clearer periods. Through the following week, conditions look set to remain unsettled, with further spells of wet and windy weather expected and some heavy rain at times. The north and west are most likely to see the wettest and windiest weather. It should still be mild, however there will be colder and showery interludes, and these are more likely later.

UK Outlook for Monday 30 Dec 2013 to Monday 13 Jan 2014:

Conditions look likely to remain rather unsettled, especially towards the north and northwest of the UK, with the best of any drier and brighter conditions towards the south and southeast. There is also the chance of some colder and showery spells in the north and west at times. Otherwise, temperatures probably staying around normal across the United Kingdom generally, although there could be some colder nights in the south and east with a risk of frost and fog in places.

Issued at: 1600 on Sun 15 Dec 2013

[shedhead]

I was referring to the latter stages again, but the overall picture is neither mild nor cold Shed, hence my average comment as we will see daily temps fluctuate from  slightly above average to slightly below more so for those North of the Midlands and then as the jet sinks Southwards, below average temps would effect more southern areas with time.

Yes, would agree with that SI.

Not relevant to this thread but the Metoffice sum it up.

UK Outlook for Friday 20 Dec 2013 to Sunday 29 Dec 2013:

It is likely to remain generally unsettled, often windy and rather mild at first across much of the UK, with showers or longer spells of rain and a continuing risk of severe gales, mainly affecting parts of the north and west. There will also be some colder, clearer and showery spells interspersed, with showers likely to turn wintry over higher ground in the north and also some overnight frosts during clearer periods. Through the following week, conditions look set to remain unsettled, with further spells of wet and windy weather expected and some heavy rain at times. The north and west are most likely to see the wettest and windiest weather. It should still be mild, however there will be colder and showery interludes, and these are more likely later.

UK Outlook for Monday 30 Dec 2013 to Monday 13 Jan 2014:

Conditions look likely to remain rather unsettled, especially towards the north and northwest of the UK, with the best of any drier and brighter conditions towards the south and southeast. There is also the chance of some colder and showery spells in the north and west at times. Otherwise, temperatures probably staying around normal across the United Kingdom generally, although there could be some colder nights in the south and east with a risk of frost and fog in places.

Issued at: 1600 on Sun 15 Dec 2013

Well the MO forecast posted by Mr Frost is far more indicative of my post SI.  This goes out to the 30th, which is very much the latter end of the period model wise and they sum the temps us thus.... It should still be mild.

 

Yes they go onto mention colder, showery interludes, especially later, but again that just emphasises the points I was making. 

 

Unfortunately I just can't see how you or anyone else can look at the current outputs and make an equal case for cold or mild, not even longer term IF the latest GFS is correct, but perhaps I'm missing something.

 

Edited December 15, 2013 by shedhead

[Mucka]

Turkey on the patio?

 

[draztik]

Turkey on the patio?

 

 

 

So much for the unsettled Christmas

I suspect this run will be binned. Just a hunch.

Edited December 15, 2013 by draztik

[nick sussex]

A poor start to the evening from a cold perspective with a hideous rounded PV developing in the GFS higher resolution output.  Flat upstream and with no positive heights developing near the pole or help from the Pacific side this is pretty hideous stuff!

 

The jet axis has no chance of becoming more favourable with this type of set up.

[UV-RAY]

Well the MO forecast posted by Mr Frost is far more indicative of my post SI.  This goes out to the 30th, which is very much the latter end of the period model wise and they sum the temps us thus.... It should still be mild.

 

Yes they go onto mention colder, showery interludes, especially later, but again that just emphasises the points I was making. 

 

Unfortunately I just can't see how you or anyone else can look at the current outputs and make an equal case for cold or mild, not even longer term IF the latest GFS is correct, but perhaps I'm missing something.

 

Again I'm saying the overall picture is not one of mild or cold and with time the jet does look like dropping further and further south. Of course this all FI and by next week the trend could be something completely different, good or bad.