Winter Model Discussion 18Z 12/2/13 onwards.

[london-snow]

TEITS has the right of it this morning, a good GFS but the ECM fast becoming a watered down version of itself from a few days ago, as suspected, the idea of heights emerging over Greenland seems to be fast disappearing, Cold and snowy the GFS, cool/cold and dry the ECM, if the GFS has been rubbish all winter which it has then better hope it’s now going to come good.

How is the ecm becoming watered down?

It is a great run in the reliable to medium term if its cold with some connective potential in the mid range.

If your looking into fi then it is a bit of a downgrade but the point being is that it fi & the pattern itself would not need a major shift to retrograde in which i am saying that there is ample time for that to happen.

Its great if you are in the se & ea and yes i am being imby.

[chionomaniac]

I think that we need to concentrate on events upto T+144 not what happens after. Let us get the cold pool in place first before wondering about what happens after that.

So if we all imagine that the models don't go past T+144 this morning then there is a lot of promise, slightly tempered by the UKMO which would leave us cold and dry by day 6 - but still not a bad chart from that point.

UKMO day 6 has been showing a little more variety of late, but this has been the model of the winter so we should keep this in mind. The cold pool is not yet guarateed to arrive, so I am not going to spend any time looking for its demise.

[TEITS]

How is the ecm becoming watered down?

It is a great run in the reliable to medium term if its cold with some connective potential in the mid range.

If your looking into fi then it is a bit of a downgrade but the point being is that it fi & the pattern itself would not need a major shift to retrograde in which i am saying that there is ample time for that to happen.

Its great if you are in the se & ea and yes i am being imby.

If the GFS is right then the Met O/BBC forecast would be something like "snow showers becoming heavy and prolonged in E areas and spreading well inland". If the ECM is right then the forecast would be "a few wintry showers along E coastal counties".

[Guest bjaykent]

Well we we now have much closer agreement at 144 with GFS finally finding an easterly but the ECM and UKMO being somewhat more watered down versions of a couple of days ago. The worry is that ECM & UKMO continue to reduce the easterly flow and most likely GFS will follow as its 144 chart today is only really copying other models homework and is in reality probably still behind. Past 144 looks very uncertain, Heights to North in Scandi or Greenland or eroded altogether look very difficult to predict. Unfortunately ECM & UKMO don't look as rock solid as they did in the run in to the last cold spell.

[weather eater]

How is the ecm becoming watered down?

It is a great run in the reliable to medium term if its cold with some connective potential in the mid range.

If your looking into fi then it is a bit of a downgrade but the point being is that it fi & the pattern itself would not need a major shift to retrograde in which i am saying that there is ample time for that to happen.

Its great if you are in the se & ea and yes i am being imby.

Certainly room for the ECM to revert back to something more potent, just look back at the charts it was putting out two or three days ago compared to what it is putting out now.

http://www.meteociel.fr/modeles/ecmwf.php?ech=72&mode=1&map=0&archive=1

Gone are the height rises over Greenland, gone is the really cold air from the east, only in the 120-144hr range do we really get the cold uppers, even in the south you are hoping on charts at 192hrs plus to deliver something really decent. Watered down is what has happened, I guess if you live in the SE then maybe better with the possibility of snow showers in the mid range, but I don’t comment on charts from an IMBY prospective ever.

[Liam J]

Why does this constantly happen?

or is it just me!

ECM + UKMO = awesome cold synoptic = GFS rubbish

ECM + UKMO = watered down synoptic of cold = GFS awesome cold

end result: all watered down and middle ground average?

It's not just you. I think it's that old adage if something looks to good to be true it normally is, NWP models included! Long way to run with this latest saga so don't get overly disheartened or ecstatic for the moment. High hopes lead to huge falls so expect little and we may end up being surprised!

[mcweather]

Rule No 1 of chart watching in the internet age. Don't take any operational after 144 seriously no matter how good or bad it looks.

It might be a possble trend but thats about it.

Rule no 2 The 500 mb hieght anomily charts that JH bangs on about will give you a far better idea of how things might go in the longer term

than any operational output.

So no point talking about downgrades past 144 on a cold spell that hasn't even arrived yet and if you are going to comment then take a look the 500mb charts and you might be pleasantly surprised.

http://www.cpc.ncep.noaa.gov/products/predictions/814day/814day.03.gif

[Frosty.]

Cross model agreement for a cold spell to develop after the relatively mild and rather cloudy weekend, there are no real downgrades to the easterly because these are only op runs, there are plenty of colder options within the ensembles, don't treat the op as gospel because it will change as we get nearer. Get the cold air entrenched and then think about snow.

[SMU]

Broadscale synoptics still remain the same this morning, GFS on board with a stonker run, ECM medicore although still possibly very snowy -

Much up in the air this morning, the reserved approach from the met office looks like a good bet at this early stage which is fair do's

Hopefully some better orientation from the Euros 12z.

S

Edited February 15, 2013 by Steve Murr

[Glacier Point]

High water mark approach to model interpretation in evidence once again...(Steve not you !)

The ECM op evolution is very reasonable in my book, in bringing in an increased cyclonic signal towards the UK from the SW and falling pressure over Europe with height rises across the North Atlantic extending right across to Hudson Bay. Cold with a ppn signal with on ongoing risk of snowfall. UKMO evolution this morning therefore considered unlikely.

Edited February 15, 2013 by Glacier Point

[Timmytour]

Nothing too wrong with this morning's charts and good to see the GFS getting there at last......that's another step down the well-trodden path this winter.

It would be nice to see the models show us the ok stuff far out and then switch to the mindblowing stuff in the nearer timeframe though instead of the other way around :lol:

[Tim Bland]

Why does this constantly happen?

or is it just me!

ECM + UKMO = awesome cold synoptic = GFS rubbish

ECM + UKMO = watered down synoptic of cold = GFS awesome cold

end result: all watered down and middle ground average?

Was just about to post almost exactly the same. Unfortunately the GFS is running a few days behind so it will probably water it down too in the coming days. Looks like Meto were right to just go for a few wintry showers in the East. Let's just hope for a battleground snow event before it breaks down

[cobby]

I think that we need to concentrate on events upto T+144 not what happens after.

Should be a seperate thread for upto T+144 and any post for after that removed

[Chess01]

Problem is with the ecm is last few runs its shunted the vortex over to greenland and canada so the high has got to fight that and any atlantic attack

[Theresnoway]

Why does this constantly happen?

or is it just me!

ECM + UKMO = awesome cold synoptic = GFS rubbish

ECM + UKMO = watered down synoptic of cold = GFS awesome cold

end result: all watered down and middle ground average?

If you have different modles or even different ensebles showing varying solutions, then middle ground would have to be the form horse (in most circumstances). I have seen this many, many times. I guess because of peoples personel weather preference, sometimes they will choose to go with one of the solutions. But this will often lead to disapointment.

[mcweather]

High water mark approach to model interpretation in evidence once again...(Steve not you !)

The ECM op evolution is very reasonable in my book, in bringing in an increased cyclonic signal towards the UK from the SW and falling pressure over Europe with height rises across the North Atlantic extending right across to Hudson Bay. Cold with a ppn signal with on ongoing risk of snowfall. UKMO evolution this morning therefore considered unlikely.

Thanks for your post GP. Pretty much as per this height anomaly then GP

http://www.cpc.ncep....y/814day.03.gif

Edited February 15, 2013 by mcweather

[chris78]

Why does this constantly happen?

or is it just me!

ECM + UKMO = awesome cold synoptic = GFS rubbish

ECM + UKMO = watered down synoptic of cold = GFS awesome cold

end result: all watered down and middle ground average?

It happens because very very cold weather is not common in the uk..so any model showing it should be viewed with caution.....even this winter the models have hinted at a 47 or 63 spell at least twice.......only for us to end up with average cold spells......but this is to be expected...I dont understand the charts but I think I understand what the models are and are not....they offer a range of possibilities ..they are not a forecast...thats were the meto come up in...and every time the models have hinted (or more than hinted) at a severe spell this winter they have advised caution, I have seen many posts on here have given them stick for not backing the models...but every time they have been correct...(I dont see much praise).....

Yet every time people build up there hopes...ignore the words of caution here, worse still ignore the meto FORECAST......and trhen blame the models for watering down a severe cold spell that nobody actually ever forecast.....

[Severe Siberian icy blast]

This morning its nice to see the models coming together with the easterly , lets get the easterly at t72 before we look at 850's ,I know it's hard not to look because it can appear that the models water the uppers down with time . But that's why it's really not even worth getting stresses or obsessed with the upper profile at something that's 7,8 days away , because as we'v seen so far , every single run changes the upper flow slightly that has massive repercussions for us regarding weather it's a snowy easterly or a dry and dull one.

Really knowbody knows at the minute , so all we have to look at is trends , And the trend is for an easterly airflow of sorts , with a block to the north of of us which means it will be cold at the very least .

[Cecil Hogmanay Melchett]

Superb gfs0z run with a pretty prolonged cold spell on offer,ecm also looks decent,ukmo not keen at all.

its starting to look unlikely that we will see a greenland high this winter

[Stu_London]

Good to see the big three and some ensemble agreement on at least another cold snap next week.

Probably nothing exceptional - but maybe some snow opportunities for some.

[Methuselah]

It happens because very very cold weather is not common in the uk..so any model showing it should be viewed with caution.....even this winter the models have hinted at a 47 or 63 spell at least twice.......only for us to end up with average cold spells......but this is to be expected...I dont understand the charts but I think I understand what the models are and are not....they offer a range of possibilities ..they are not a forecast...thats were the meto come up in...and every time the models have hinted (or more than hinted) at a severe spell this winter they have advised caution, I have seen many posts on here have given them stick for not backing the models...but every time they have been correct...(I dont see much praise).....

Yet every time people build up there hopes...ignore the words of caution here, worse still ignore the meto FORECAST......and trhen blame the models for watering down a severe cold spell that nobody actually ever forecast.....

It's just 'one of those years', perhaps, chris? How many times have we seen the Euros' tendency to over-egg Snowmageddon being countered by the GFS's 'Easterly bias'; only for the weather to end-up with the UK under battle-ground synoptics, with neither extreme dominating?

[Gibby]

Good morning. Here is the report from the 00z output of GFS, UKMO, GEM and ECM for today Friday February 15th 2013.

All models show a fine weekend ahead as the current High pressure ridge nudges over to the East of the UK and a slack Southerly flow develops over the UK through the weekend. Mostly dry weather with variable amounts of cloud seem likely for all through the weekend with patchy frost and fog overnight with daytime temperatures well up to normal for most. Into next week and the trend is still shown by all models to develop Higher pressure to the NE over Scandinavia though the process of Easterly winds is rather slower this morning with a strong ridge from it holding the colder air to the East well in towards the middle of the week. The net result would be further days of quiet Anticyclonic weather early next week with daytime temperatures falling slowly day by day but with an increasing risk of more general frost by night along with mist and fog in continuing light ESE winds.

From midweek GFS builds High pressure to the North of the UK increasing the pressure gradient over the UK with a fresh and cold Easterly flow taking hold with snow showers reaching the East, spreading West especially over Southern and Eastern England. Little change then occurs through the weekend with further snow showers at times. Through FI the NE flow weakens as High pressure to the NW by then slips down over the UK cutting the feed of cold winds and snow showers off but bringing cold crisp days and very frosty nights. Late in FI the High slips further SE and allows a milder SW flow to develop, first in the NW and gradually extending to all areas by the end of the run though any rainfall will be held towards more Northern and NW areas.

The GFS Ensembles show a fairly strong agreement now for a colder spell next week before things warm up again towards the end of the run. The operational did become a warmer member of the pack late in the run but does have support in what is a relatively dry fortnight, especially through the first half of the output.

The Jet Stream shows the flow continuing to break up around the UK over the coming few days before realigning into two arms from 4-5 days onwards. The weaker Northern arm will show Eastward movement well up over Iceland to Northern Norway while the stronger Southern arm tracks East across the Atlantic and Southern Europe.

UKMO shows High pressure further South over Southern Scandinavia this morning with a strong ridge over the UK. A cold feed of Easterly winds will make it into the SE of Britain by Thursday. All areas will have a dry and rather cold spell but with plenty of winter sunshine and the odd wintry flurry in the SE.

GEM shows the colder synoptics this morning holding High pressure North of the UK and with the correct alignment to feed cold and windy East winds across the UK, especially in the South with the risk of sleet or snow showers much more extensive over Eastern and Southern parts with cold and frosty nights, harshest in the clearer NW. The High does begin to pull away SE at the end of the run though with a trough approaching the SW at Day 10.

ECM shows a strengthening SE flow after the middle of the week with a lot of dry weather with variable cloud and just an odd flurry of snow here and there. Late in the week and through the weekend the flow backs East and as the flow becomes more unstable the risk of wintry precipitation increases. It too shows the High to the NE releasing some grip towards the end of the run as it shifts further East to Russia but maintains a ridge West through Scandinavia and to the North of Britain holding the Jet flow well South at that stage.

In Summary today a change back to colder weather is on the way although the progression is rather slower than yesterdays runs. In fact we have a good few days of very benign and in many places decent conditions to get through with sunny spells by day with temperatures close to average but patchy frosts and fog at night. It's not until the middle of next week and more especially beyond when a more Easterly flow tightens its grip bringing cold weather with the threat of wintry showers in towards the South and East. Longer term the jury is out with various options shown but all in all a quick shift to anything mild is unlikely with the synoptic patterns on offer this morning. However, having said all that anyone expecting snowy armageddon will probably end up disappointed with what will end up a largely dry two weeks for many.

[johnholmes]

Thanks for your post GP. Pretty much as per this height anomaly then GP

http://www.cpc.ncep....y/814day.03.gif

It has always been the form horse

As to whether it will be cold enough for snow and it is too far ahead to be very sure that will happen. Detail to me is far from clear as to just where both the upper ridge and its surface pal will be and their position is crucial for how cold the air gets at heights relevant to what may fall from the sky.

[Bristawl Si]

Meto's caution yday re any v cold/snowy outbreak looks backed up by this morning's model runs (bar gfs)....at this stage.

Although GP's post earlier seems to maybe question?

[snowking]

Will post in more detail later but as per GP's post, the ECM mean heights this morning (along with GEM/GFS) set up a west based negative NAO just west of Greenland (ridging east with time) which MAY still end up very favourable for the UK...

SK