Model Output Discussion 18th Nov.2013-12z onwards.

[fat chad]

Most folks who enjoy the cold are liking the charts this morning. But if you think you understand the models enough to post your thoughts, then back up your post with a chart please. I don't get much time to learn about reading the models with shifts and other commitments. I do find it very tough sometimes to judge whether someone's getting carried away or they have made their judgement from reading the charts. Happy Friday everyone !! FATCHAD .

[nick sussex]

Still no conclusion to the ongoing upstream uncertainty. Although the ECM delivers a northerly toppler with a decent depth of cold I wouldn't be overly confident in its output at that range in view of the bias it has recently shown for over amplifying the upstream pattern and overdoing ridging into Greenland.

It's a case of waiting to get agreement across the big 3.

[tight isobar]

Not a massive change through 00,z runs.only perhaps a more short lived northerly blast if anything...(rex block).then back to what were getting a custom too. However as per, still more than ample, and small changes could occur....

[Tom Montalbano]

After the overnight runs I think its safe to say that the models are starting to sing from the same hymn sheet now, the northerly forecast at the end of next week looks very much, to be a blink and miss it affair at best.

 

GFS suggest a glancing blow to the N and E of Scotland, with some wintry/snow showers about, for no more than a 24 hour period though, before high pressure builds in over the country, from the NW.

ECM, although slightly delayed, would give a similar 24 hour window, where wintry/snow showers would occur but penetration further south, along the east coast, down as far the N.Norfolk coast, obviously being 192t, too distant to be sure of that kind of detail but that would be my interpretation, at the moment. But then the pattern quickly gets shunted east, with high pressure anchored to our SW.

 

Thereafter the synoptic profile over our side of the pond is up for grabs and events further afield, as ever, being an important player as to where we go from here but I would suggest that with the PV showing signs of strengthening and with too much energy close to Greenland any high-latitude blocking looks to be off the menu, in that area, as we head further into December. Our best chance of attaining a coolish/average December CET, at the moment, looks to come via a cold inversion high, brought about by  mid-latitude blocking.

 

Tom.

Edited November 29, 2013 by Kentish CZ

[Frosty.]

I'll tell you what..some of these GEFS 00z perturbations are showing a more potent cold spell towards the end of next week with reloads further on, we are not necessarily going to have a short cold snap, it could be more substantial and be repeated through the rest of december.....and the GEFS 00z mean looks good to me.

[itsnowjoke]

Wow Frosty lots of charts to look at there thankyou.

#chartsrus.

[SMU]

Morning- safety once agsin in the ever rock solid euros-Anyway, the next 24-48 hours for 5/6 runs of the ECM will need to start seing a change over the northern states of america as its trying to develop a deep low that wants to merge back into the vortex - producing a sinuous circular polar flow again-Still thats a long way away....Back to 144/168 its all about timing, at 156 the ecm and UKMO have the phasing if the arctic energy and the small area of low phasing in a jet streak moving at an acute angle south south east across the UKThis serves to allign the flow northerly all the way to the pole-As a result widedpread -10c air and possibilities of -12/-13c into Scotland-For the start of December thats about as good depth of cold as you can hope for.Combined with the low heights and track over sea that is still quite mild - convection will be producing some deep shower clouds -There would be some good snow for the North-Anyway thats getting carried away, because we are reliant apon timing of these systems and its at 168 it will be 2 days to have over 80/90% confidence.Still a chance if the cold sliding quickly to the east as per GFS - but any sensible money will always be on the EURO blend.S

Edited November 29, 2013 by Osbourne One-Nil
No need for the constant crticism of others who have a different take on things.

[LomondSnowstorm]

What's really quite striking to me is the depth of cold both the ECM and GFS want to bring southwards. Now of course it might end up significantly watered down but even for this location a sub -10C 850hpa temperature from a northerly is impressively low and yet both 00Z ops manage it at D7. Not only that but both dig it quite a long way south, although it must be said that it is fairly brief.

The potential on this has always been greater the further north you go so with the latter parts of FI very much up for grabs still depending on how the energy separation is resolved I'm personally quite looking forward to seeing if this notable cold plunge actually verifies and if so how long the 'toppled' can last. Just under a week ago many were calling for a 'zonal reset' but I'm sure now we can all see the benefits of keeping what amplification we do have upstream in order to try and squeeze out as much cold from a hemispherically unfavourable period as we possibly can.

[shedhead]

Still no conclusion to the ongoing upstream uncertainty. Although the ECM delivers a northerly toppler with a decent depth of cold I wouldn't be overly confident in its output at that range in view of the bias it has recently shown for over amplifying the upstream pattern and overdoing ridging into Greenland.

It's a case of waiting to get agreement across the big 3.

Agreed Nick...the overall sitiation is not hugely different to what we saw a week or so ago, when the much colder ECM eventually got dragged back into line with milder GFS, but that's not to say the same will happen again this time of course...one day, just one day things might actually go the other way for us!

 

The overall concern for me remains the same though and that is the timeframe involved, I just can't get over enthused when anything from the north and/or east is progged beyond T+120hrs - been there and been burnt far to many times...

[Gibby]

Hi everyone. Here is this morning's account of the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Friday November 29th 2013.

 

All models maintain High pressure close to the West of Britain over the next three or four days. It's centre has pulled a little further West today which has allowed a colder and fresher NW flow down across the UK today behind a weak cold front, For most this will mean largely dry conditions still but brighter and cleaner air later will improve the complexion of the day. This weather type with a few showers, wintry on hills in the NW will last through until later tomorrow when the High moves back towards the UK and brings a return to cloudy skies down from the NW with benign and non-descript weather for the following few days, taking us towards the middle of next week when some change begin to take place.

 

GFS then splits High pressure East and west of the UK but with very little difference felt at the surface as winds remain very light and slack over the UK away from a stiffer westerly breeze in the far North. Then at the end of next week, probably on Friday a cold front introduces cold and clearer air down to all areas with some wintry showers over the North and East for a time before High pressure returns across the UK with sharp frosts and fog patches. The second half of the operational today sinks High pressure down to the SE but close enough by to maintain largely fine conditions. Temperatures would steadily rise through the period with some very mild weather possible across Southern Britain later if a low level inversion can be avoided.

 

UKMO today shows High pressure over the Eastern Atlantic next Thursday orientated West to East with a strong ridge across Southern Britain maintaining the theme of cloudy and largely dry weather with average temperatures for England and Wales while Scotland and Northern Ireland see a stronger Westerly wind and occasional rain later.

 

GEM this morning shows High pressure close to or over Southern Britain towards the end of next week relaxing South briefly to allow a change in weather type to dry and cold weather with clearer skies later in the run with frost and fog at night becoming much more of an issue as High pressure builds back across all areas to end the run.

 

NAVGEM shows High pressure close to the SW late next week with rather cloudy and dry conditions giving way to a spell of wet and windy weather in the North as a small Low zips East across Scotland. The South would probably see a little rain from this as it's cod front cleared SE.

 

ECM shows a ridge across Southern Britain next Thursday with winds freshening markedly from the West with rain over the North. The High is then pulled West as a strong Northerly flow pushes down through Friday to all areas with very cold conditions with snow showers giving accumulations in Northern and Eastern areas for a time. Then through next weekend the cold air relaxes as winds back NW then West bringing less cold and more cloudy air across the UK from off the Atlantic with temperatures slowly returning to average.

 

The GFS Ensembles show a rather cold set overall this morning with the operational I described above very much one of the warmest members of the pack later on. It looks like most members support a rather cold period between the 5th -11th and with some precipitation around sleet and snow is a possibility for a time, especially across the North and East while the South look likely to avoid this. As usual a wide range options are shown late in the run with the most likely scenario being a return to average early December values with rainfall amounts looking still quite suppressed through the period, especially in the South.

 

The Jet Stream this morning is programmed to maintain it's path to the North of the UK for the next 5-6 days before it turns SE or South across the UK in association with the colder phase late next week. It then returns slightly further north to a positions between Scotland and Iceland thereafter on a NE course indicating a bias towards High pressure close to SE England.

 

In Summary this morning the models are all over the place with conditions in the interesting part of the output from the middle of next week. In the shorter term the quiet and benign pattern remains with few features in the weather offering any interest with much cloud cover, light winds and temperatures close to average with little in the way of frost and fog away from tonight and possibly tomorrow night in the South. The fun and games begin later next week with some output showing a potent plunge of cold air from the North leading to some snowfall for some, more especially in the North and East. Some output make little of this pushing the thrust of this too far East while most others weaken it quite quickly as High pressure builds back in from the West with a spell of cold and clear weather with sharp frosts seeming likely before the inevitable infill of cloud returns with slowly less cold conditions and a return to what we have now possible. It remains interesting over the next few runs how this phase of potentially very cold weather is developed or dissolved to nothing more than a blip. Time alone will tell.

[Ian Brown]

We shall Steve but the UKMO at T144 would follow the GFS route onward because the shortwave would cut off the link of heights South of Greenland.

If the ECM verifies then yes some snow showers for Scotland and especially NE Scotland later at T192 but then it is all shunted East fairly quickly.

[Cecil Hogmanay Melchett]

We shall Steve but the UKMO at T144 would follow the GFS route onward because the shortwave would cut off the link of heights South of Greenland.

If the ECM verifies then yes some snow showers for Scotland and especially NE Scotland later at T192 but then it is all shunted East fairly quickly.

I think i agree.

UKMO looks a closer match to GFS than the ECM IMHO.

We hope the ECM is correct from a coldies POV as this will certainly produce snow for some,at this range its impossible to tell where but certainly the scottish contigent will benefit the most.

The outlook remains fluid,and will change no doubt over the next 48 hours when we should see a firming up on the finer details.

[joggs]

Frosty i love your optimism but your a blinking nightmare when it comes to viewing your posts on a mobile lol.Keep up the good work all,appreciate it.

[TSNWK]

Frosty i love your optimism but your a blinking nightmare when it comes to viewing your posts on a mobile lol.Keep up the good work all,appreciate it.

Funny I was thinking the same, my fingers were smokin after I had scrolled through.. But it's fun to read

[SLEETY]

Yes it shows a short cold plunge before HP moves back in, the NH profile is poor going forward though on both the ECM and GFS.

 

 

Do you really think the ecm and gfs have the Northern hemisphere correctly modeled 9-10 days away?

 

If they are both correct then I SALUTE them,as I have never seen them be correct at that time-frame ,ever!

 

The start of the cold spell isn't even certain yet,until it hits the reliable time-frame,which is usually about 4-5 days ahead,max.

 

I bet even the MET can't decide which way this is going yet.

 

They don't call FL fantasy land for nothing you know.

 

At least the ecm has been fairly consistent in it's latter output.

 

The last 3 gfs runs have been nothing but cold or mild outlers in it's latter output,so that model  is obviously clueless what the eventual outcome will .be.

 

As ever,more runs needed

Edited November 29, 2013 by SLEETY

[Frosty.]

It's the same every winter, if the models are showing mild beyond T+240 it has to be right, and if it shows cold..no chance

 

I think we have taken another step in the cold direction this am.

[Captain Shortwave]

The one thing I will say, the temperature means look a bit better today, for example the ECM ens have the -6C isotherm down to a line from norfolk up to around Merseyside

Yesterday we were only dealing with -4C  getting down to about Bristol eastwards. So we are at least moving in the right direction. For now 

Solution 2 looks the likely solution so lets see how much we can get out of this northerly toppler then.

Edited November 29, 2013 by Captain shortwave

[shedhead]

It's the same every winter, if the models are showing mild beyond T+240 it has to be right, and if it shows cold..no chance

 

I think we have taken another step in the cold direction this am.

Except in your world Frosty, where the polar opposite applies...  That said there has to be room for all views, all styles and even all hopes, as long as those views, styles and hopes are conveyed correctly.  I'm not sure the MDT would be a better place if everyone wanted exactly the same thing and expressed their hopes/desires in exactly the same way....variety after all is what keeps the whole thing so interesting. 

Edited November 29, 2013 by shedhead

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=6

 

morning  all things  look interesting  after  dec 5  at the moment  ex  the north and  the  east  of  the  u.k,

Edited November 29, 2013 by tinybill

[Summer Sun]

Once again ECM shows 2 cold days UK wide (though the north gets 3) later next next potentially very cold for some before high pressure moves in at the end shifting the coldest air away east

 

 

t168 sees the arrival of the cold air in the north

 

 

So a 3 day cold snap (2 for some) before temperatures start to relax

[MR EXTREMES]

the express should be banned from posting that crap.

 

as for the models gefs control and gfs operational both look like heights building into oslo .

[Barry12]

Its 10 days away when the cold conditions leave though, so time for plenty of changes, and some of them changes could be to extend the cold spell. If the models forecasted it the other way round; mild temperatures at days 7-9, and cold at day 10 then would anyone really take it seriously?

[Northern Sky]

Except in your world Frosty, where the polar opposite applies...  That said there has to be room for all views, all styles and even all hopes, as long as those views, styles and hopes are conveyed correctly.  I'm not sure the MDT would be a better place if everyone wanted exactly the same thing and expressed their hopes/desires in exactly the same way....variety after all is what keeps the whole thing so interesting.

Yes, from manic, slightly scary optimism to a huge wet blanket laced with schadenfreude. Netweather MOD has got the lot....

[johnholmes]

the anomaly charts, not totally consistent with one another, overall do show that the cold snap next weekend or thereabouts will be just that, a snap, not a spell. You never know it might actually give deep cold rather than the very watered down version crossing the UK today. This also had been shown as a deepish if short cold shot.

[MR EXTREMES]

well to be honest it was always going to be a cold snap still might be a European onslaught instead of uk yet.

oh well shame it was not for Christmas eve or day be nice to have a white Christmas not likely well theres always January.