Model Output Discussion 17th Dec.2013-12z onwards.

[Barry12]

I Hate to say it- the GFS is being more consistent than the ECM Op at the moment- however the UKMO is equally consistent!!!  I must say the AO looks tanked at 180 on the GFS- we are just missing the atlantic heights- More updates soon - S

The GFS could be consistently wrong for all we know.

[Cheshire Freeze]

Whichever way you look at it, it looks like goodnight Vienna for the vortex come the end of the first week of Jan with a fairly notable -AO looking reasonably likely. Nuances remain to just how the UK is affected but, as I said to someone at work a few days back, I think the snow will have made an impact by 10th January.

Edited December 27, 2013 by CreweCold

[swfc]

very confusing state of affairs on the mo this evening to put it mildly!!! The nh profile is looking traumatised at best but even in fi we cant get those sreas of low pressure to zip south east and pull down some great 850s

[bluearmy]

Whichever way you look at it, it looks like goodnight Vienna for the vortex come the end of the first week of Jan with a fairly notable -AO looking reasonably likely. Nuances remain to just how the UK is affected but, as I said to someone at work a few days back, I think the snow will have made an impact by 10th January.

no wine this time Crewe!I suspect you could well be right but I'm increasingly thinking an old fashioned snow line towards the north of the UK. current punt north of Carlisle.

[BLAST FROM THE PAST]

Now we are getting there, expect more support for N and NE'ly blasts

 

BFTP

[Mucka]

no wine this time Crewe!

I suspect you could well be right but I'm increasingly thinking an old fashioned snow line towards the north of the UK. current punt north of Carlisle.

 

I'll take your Carlisle and raise you Leeds, I might even throw in a Manchester if you twitch. 

I honestly think somewhere in the North of England has a decent chance of seeing a heavy snowfall or two first half of Jan albeit transient.

[Due South]

Now we are getting there, expect more support for N and NE'ly blasts

 

BFTP

Looks Like PC has called it again BFTP.

[Captain Shortwave]

After a little bit of thinking I might have an idea of where my viewpoint might be swaying as we heading into 2014.

Couple of things to consider or at least question.

1) The GFS is on it's own about a height rise to the north east, is it calling this wrong?

2) Are the Euro models overdoing the jetstream in the day 5-8 range, the UKMO/ECM have a much more significant polar vortex segment over Canada and hence a stronger jet. Have they got this wrong and the American (GFS/GEM) version of low heights draining from the region during this timeframe correct.

The morning runs tomorrow will be significant to see how these two points are resolved.

I currently think the GFS will try to move towards a Scandi ridge scenario, whilst the euros will drop the strong jet stream coming out of Newfoundland.

Which leaves us with the model which I believe might be closet to the correct solution. Which is.....

The GEM

Could be worse 

Edited December 27, 2013 by Captain shortwave

[NorthernRab]

very confusing state of affairs on the mo this evening to put it mildly!!! The nh profile is looking traumatised at best but even in fi we cant get those sreas of low pressure to zip south east and pull down some great 850s

 

Not very confusing at all to be honest - look at the larger hemispheric picture rather than whether or not we can "tap into" pools of cold air, which will likely be in entirely different locations when the time comes. 

[Frosty.]

Just catching up, and pleased to see some of the models again hinting at a spell of cold zonality with an increasing chance of snow, frost and ice could be ours for a large part of january..and no downgrade from met office update today either, coldies might have something to smile about soon. :-)

[swfc]

Not very confusing at all to be honest - look at the larger hemispheric picture rather than whether or not we can "tap into" pools of cold air, which will likely be in entirely different locations when the time comes. 

sorry i wasnt very clear.I was remarking on the difference between gfs,ukmo ,ecm ete.the ref to the areas of low pressure was tongue in cheek ie bad luck even in fi

[SMU]

Evening -

 

Well then, another day over & TBH for out little patch on the map- nothing much has changed, & therefor nowt is any clearer- infact its been one of the most difficult periods of model watching I have ever seen, with large disparity between all the models & little continuity from run to run.

 

The ECM, normally the king of consistency has been up & down like an emotional teenager & with the exception of the UKMO the rest have been at least as bad, perhaps without the wild swings.

 

At this stage I would like to make anycall on January- Why, its unforecastable. Anyone making bold statements either for cold or mild or for any particular weather type has to be taken with a huge pinch of salt-

 

The background signal of this winter thus far has been one of overwhelming jet energy- with low heights over the pole, & lobes of the vortex swinging into SE Canada fuelling the fast paced jet across the atlantic

If you see below at the 30 day loop of height anomalies there is no polar blocking & that vortex over Canada is prevalent

 

http://www.cpc.ncep.noaa.gov/products/intraseasonal/z200anim.shtml

 

In the next 8-10 days we possible reach a juncture for winter- a crossroads if you like where specific timings of events & net results will either spin us off into a polar opposite conditions, or at the other end of the scale the prescribed blocking wont take hold & the vortex will regain its foothold & wipe out January- If that's the case its winter over for me as going through the archives if you look at the ratio of Mild decs ( + 6.5)  that then had mild Jans following then ALL of them had a mild feb as well-

So if Dec lands @ 6.5 then January is pivotal for the rest of Winter.

 

 

There are however positives, Firstly from the top down the wave activity over the stratosphere is increasing & this can only enhance the pressure on the vortex over the pole, I cant see any imminent SSW's however increases in wave 1/2 activity will support any tropospheric led developments.,

The AO- Which represents the overall state of the zonal mean over the pole, & general blocking conditions across 50-80N.- A big swing in fortunes forecast-

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

 

In 6 days the AO is set to go negative- that's the first time since September if you exclude the brief period in November-

If we look though there is 2 phases , phase 1 where we get some polar heights - which have been modelled for some time & mostly visible over the far side of the pole with this 1040 high-

http://www.meteociel.fr/ukmo/runs/2013122712/UN48-21.GIF?27-18

Phase 2 requires a further pulse of blocking ( or pulses) moving into that polar high via MLBH's - The usual pathway to enhance the arctic high is-

* Atlantic ridge

* Scandi or Siberian Ridge

* Kumchatka ridge

 

Of these above its important that they develop as eventually these will have a net effect of cold for the UK.

 

In terms of the anomalies at day 10-

ECM

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=1&type=1

Show kumchatka ridging & weak Scandi heights, but struggling with the atlantic ridge-

GFS

http://modeles.meteociel.fr/modeles/gens/run/gensnh-21-1-240.png?12

The same as above-

 

 

In summary:

The models will struggle with the massive flux that's always evident when the AO goes from a +3 signature to a -1/-2 signature in a fairly short time- that's a big pattern swing.

We will see the cold drain into the continental interiors, making cold available for the UK easier, the atlantic ridge still missing in action is the problem-  we will need at least 1 a la GEM 12z to change the pattern emphasis upstream ....

 

http://modeles.meteociel.fr/modeles/gem/runs/2013122712/gemnh-0-240.png?12

 

My assessment tonight is that in the means the big + temp anomaly around 55N will slowly moderate over the next week, however I think out to day 8 we will be stuck on the wrong side of the trough- so December is finished.

 

If the UK is going to get cold it will come post day 9- more especially day 11/12 from the NE- & that will come in the form of a system diving SE across the UK, however the driver will come from the atlantic ridge ( displaced azores high)If the azores high just sits there flat then we may well see a moderate -2/-3 AO but a neutral top slightly positive NAO - & that's no go for a cold uk....

 

earmark the 6th-8th of Jan for our chances should it arise.

 

many thanks

S

Edited December 27, 2013 by Steve Murr

[weather eater]

Interesting run from the GFS, my take is that we are now starting to see some avenues out of the current pattern, but that there is no consistency with what will replace it, I would be loathe to favour a substantial cold shot at this stage (cautious certainly) but what I would say is that once the PV shifts and becomes fragmented a process already underway then 1. All options are on the table and 2. Events are likely to move quicker than the current modelling suggests, FI potentially becomes substantially shorter, with model output solutions becoming very volatile, by that I mean that I would expect to see a number of substantially different solutions being offered every run post 144hrs, we are already starting to see this. In the shorter term breezy rather than stormy looks likely but with no let up with the rain, especially in the areas that have been badly affected. 

[Mucka]

[draztik]

Things will change, but whether that's in mid January or late March, who knows...

 

So, maybe we should be pragmatic with our approach, and look at the next 10 days or so, and let mid January take care of itself.

The ECM op doesn't indicate any significant pattern change away from zonality. Its ensemble mean is still reluctant to build heights to our NE. So, a mobile westerly flow... for the foreseeable is heavily favoured. The height anomalies, day 6-10 for the ECM are below. They tell their own story.

 

[Joe Levy]

Good clustering on the cool/cold side and the op was some way above the mean at day 10, so pretty good for cold prospects as far as things stand at the moment.

[Richie V]

I don't wish to be a killjoy but from what I'm seeing this evening, be prepared for a long ride of current pattern thru most of jan (don't ask for charts or data, I'm not allowed to post them here) after a relitive softening up of the vortex to mid next week, looks like re organising It's strength to the back end of next week somewhere between SE Greenland and south of west Icelandic waters with a strong but relitively flat azores ridging and rapidly collapsing eastward

[Purga]

No cold signal at all from the ENS 18z, even the cold Op outlier has disappeared.

 

Ah well enjoy the wind and rain.

[Duane S.]

I still think the models are on the whole underplaying the Arctic high effects. Historically a nightmare to model accurately, with a small tweak here and a small tweak there we could very easily be staring down the barrel during the second week of Jan. Not the barrel of endless zonality but that of severe cold spell. I have to say I am perhaps a little surprised that we haven't seen any proper stellar runs creep in over the past 3 days. Maybe that does indeed tell its own story but I would be surprised if we don't see the models give us some proper FI eye candy over the coming days.

 

Bottom line is, who wouldn't have taken this if offered back at the start of December... ?

 

 

 

 

 

 

[Joe Levy]

No cold signal at all from the ENS 18z, even the cold Op outlier has disappeared.

 

Ah well enjoy the wind and rain.

Yes because we trust every single ens output... Okay maybe this particular run has no cold outliers. However, that does not define the actual outcome, it merely hints at possibilities. 20 runs will not cover every possibility. Remain open minded and resist getting drawn in by any single run or even a series of runs, as changes can be rapid or they can be gradual, whether that be mild, cold, dry or wet.

Edited December 28, 2013 by Joe Levy

[draztik]

No cold signal at all from the ENS 18z, even the cold Op outlier has disappeared.

 

Ah well enjoy the wind and rain.

 

How dare you post this in here. How dare you annoy those seeking cold.... you really should know better Purga**

This is the problem with the ens... they show cold at day 10, and then a few days tick by, and the lowers start to rise nearer the time. As I've said recently, I expect into January we will see below average, but nothing too extreme. Unfortunately, that doesn't sit well with others, who seemingly want endless days of snow and ice.

 

*denotes sarcasm.

[Jason M]

Why do you think something colder looks imminent from around the 10th? I must admit that I can't find any evidence to support that at the moment. I can't speak for people's motivation but you can't argue that its a fair point.GEFS are very poor tonight. I've looked through them and they are as poor a set as I've seen for some days. I really want to be wrong but to me everything just points to more of the same. I think Crewe will achieve legendary status if his call for a severe January comes off as there is nothing whatsoever to suggest that.

Edited December 28, 2013 by Osbourne One-Nil
Quoted post has been removed.

[LomondSnowstorm]

I still think the models are on the whole underplaying the Arctic high effects. Historically a nightmare to model accurately, with a small tweak here and a small tweak there we could very easily be staring down the barrel during the second week of Jan. Not the barrel of endless zonality but that of severe cold spell. I have to say I am perhaps a little surprised that we haven't seen any proper stellar runs creep in over the past 3 days. Maybe that does indeed tell its own story but I would be surprised if we don't see the models give us some proper FI eye candy over the coming days.

 

Bottom line is, who wouldn't have taken this if offered back at the start of December... ?

Rhavn1801.gif

 

I think you're right - hemispherically, the building blocks of a decent cold spell are there, with the AO finally forecast to enter negative territory and the MJO poised to enter into the -NAO friendly phases. Will this come together to bring in a decent cold spell by mid January? Difficult to say at this stage, but given we've spent the entirety of December in a +AO phase we're undeniably in a more favourable position going into January than we have been for most of this month. Whether that actually translates to cold and snow on the ground is largely dependent on smaller scale developments closer to the time i.e. disrupting troughs, increased amplification of the Azores ridge etc. and I'm not all that concerned about the lack of goodies in FI at this stage because we're all (with perhaps the exception of Crewe 'coldest winter since the Younger Dryas' Cold ) aware that this is likely to be a slow burner, if it is indeed a burner at all.

[nodrog]

Maybe we should split this topic for cold lovers and zonal spotters. It's becoming like a discussion of politics.

I seek zonal, like gales not do much rain and do naturally look for this.

The theme for what I see is unsettled for second week of January - longer than I thought. It seems the models want to play a colder card in FI expecting it to move closer but the Atlantic is a big signal other things are afoot. I'm sure it will go cooler in this period but interrupted easily and poss not able to take a hold.

For cold lovers I have sympathy but it's been a good example of why we love the weather. Think my post may last due to the time it is.

[Joe Levy]

In a word - correct. What we want or hanker for is never likely to be the end results on the ground, more so considering the current set up!Probably one of the most sensible posts i've read - granted some are very technically minded and know their stuff - and for those who continue to straw clutch for the sake of it - yes, I'm a coldie, it is allegedly Winter and likewise in Summer I enjoy heat...time for more to realise. Emotionally attaching yourself to the weather will not make it happen, whatever you may or may not want?Facts are usually written in black and white - whilst models can throw up all the possibilities, direct human input will always be subject to change or worst case mistakes. Fact.

Thank you, I do try to be reasonable in my posts! I enjoy the weather full stop so model watching for me is fun whatever it shows, even if it is continuous. Also, one half of my degree is anthropology, so if I am not analysing the models, I am assessing the personalities that fluctuate and interact on this forum! Fascinating stuff, you will all become part of my dissertation next year I am sure