Model output discussion - 7th January onwards

[kold weather]

On a positive note. Best run of the morning IMO is the control run of the GFS, outstanding.

Nick S, I agree, I noted the ECM is quite close yo going totally wrong. The GFS ensembles also only just make it.. 

[Sky Full]

Looking beyond the imminent arrival of cold conditions next week, the following week could be even colder!   Just look at the way the models are predicting the conditions to evolve by the end of the month:

ECM      

GFS       

GEM.  .  

The ECM is showing exceptional cold for the 28th January.   If these conditions verify then next week is just the precursor to an even colder spell at the end of the month when disruptive snow might be expected almost anywhere in the UK...

 

 

[nick sussex]

1 minute ago, kold weather said:

On a positive note. Best run of the morning IMO is the control run of the GFS, outstanding.

Nick S, I agree, I noted the ECM is quite close yo going totally wrong. The GFS ensembles also only just make it.. 

The ECM admittedly has a little less margin of error than last night although much better than the UKMO.

However if offered I would have happily taken this mornings outputs simply because we see more broader agreement developing . The way I look at it the envelope has narrowed so worst case is better than last night the good solutions are still very good.

Hopefully we can get solid agreement on the key timeframe tonight.

[bluearmy]

In a personal note, my disappointment at this stage is with Tuesday - for quite a while it was signposted on the ext ens and it had the potential up until yesterday to deliver a widespread snow event across the country 

looks like we have to look beyond this now although there is still time for it to correct 

[Frosty.]

The 00z model runs are cold heaven with plenty of snow potential and longevity, the Gfs operational and mean are cold / very cold throughout..lots to smile about.....Boom

[Catacol]

53 minutes ago, MattStoke said:

 

It is also completely pointless looking at precipitation and depth of cold at that range. It’s the bitter picture that matters.

Very true. Bigger picture is excellent. Being a little bit picky this morning we could do with Tuesday’s trough just adjusting back a bit further west. The modelling of 850s may now be getting a handle on the depth of cold within the trough and the lack of ocean moderation due to the speed and angle of the evolution, but there is a marginality for much of the country that would be removed if the high to the west would surge ever so slightly more to the NW allowing the trough further west. 50miles would make a massive difference.

In this regard ECM gets thumbs up for the longer term but a slight frown at 96hours. Hoping to see that slight change in the next run as the evolution coming won’t be easy for models to get accurate in microscale modelling until 24/48 so there is definitely time for adjustments. 

But this is me being a little bit picky. Overall the bigger picture remains just what snow hunters would want, and later in the week and beyond expect surprises as precipitation appears out of nowhere once deeper cold begins to feed in. With such a solid trough in position the overall pattern doesn’t look likely to stay dry - though local variation on a day by day basis is an obvious reality. It isn’t going to snow everywhere all of the time!

[kold weather]

1 minute ago, bluearmy said:

In a personal note, my disappointment at this stage is with Tuesday - for quite a while it was signposted on the ext ens and it had the potential up until yesterday to deliver a widespread snow event across the country 

looks like we have to look beyond this now although there is still time for it to correct 

The models always seem to overdo NW airflows for some reason, it's why I always add 1-2c to what the GFS shows at 850hpa, especially close to the backend of the front.

[Man With Beard]

5 minutes ago, bluearmy said:

In a personal note, my disappointment at this stage is with Tuesday - for quite a while it was signposted on the ext ens and it had the potential up until yesterday to deliver a widespread snow event across the country 

looks like we have to look beyond this now although there is still time for it to correct 

Yes it does seem to be slipping away though not unsalvagable just yet. 

What would be really good is getting the cold in first before an Atlantic attack... ECM D11? 

[Djdazzle]

10 minutes ago, bluearmy said:

In a personal note, my disappointment at this stage is with Tuesday - for quite a while it was signposted on the ext ens and it had the potential up until yesterday to deliver a widespread snow event across the country 

looks like we have to look beyond this now although there is still time for it to correct 

Always a long shot though because the angle, depth and track of the LP have to be just right. So little margin for error.

[kold weather]

8 minutes ago, Catacol said:

Very true. Bigger picture is excellent. Being a little bit picky this morning we could do with Tuesday’s trough just adjusting back a bit further west. The modelling of 850s may now be getting a handle on the depth of cold within the trough and the lack of ocean moderation due to the speed and angle of the evolution, but there is a marginality for much of the country that would be removed if the high to the west would surge ever so slightly more to the NW allowing the trough further west. 50miles would make a massive difference

In this regard ECM gets thumbs up for the longer term but a slight frown at 96hours. Hoping to see that slight change in the next run as the evolution coming won’t be easy for models to get accurate in microscale modelling until 24/48 so there is definitely time for adjustments.

Yeah good long term pattern but my alarm bells ring at 96-120hrs and the way the low comes so far east across the Atlantic. Many a good cold spell has come undone due to there being too much energy which prevent s any blocking from taking hold. Legitimate risk still.

Good news is the difference starts as soon as 72hrs so we should have a definite answer today or tomorrow, and signs are most models gave gone the right way this morning.

[northwestsnow]

GFS still bringing quite a widespread snow event tues..

But i feel altitude will be key(no idea how much), uppers always  moderated by the Atlantic which is precisely why i ALWAYS favor an east wind to a NW wind..

on a brighter note latest BEEB forecast mentioning sleet and snow next week then an easterly..

Edited January 18, 2019 by northwestsnow

[Yarmy]

56 minutes ago, kold weather said:

Solid mean at 144hrs.

This was a little "WTF?" moment for me until I realised that the thumbnail/preview image was cached.

A bit off-topic, but here's a tip to avoid this. You can obviously just download it then upload it to Netweather (and that's the best way because it ensures the image you want is always shown), but there's another way if you can't be bothered with the faff. When you copy the image URL, append a token like '?v=yarmy1.0' or whatever to the end, so that the URL becomes unique. E.g.

 

NB. It's usually not required for Meteociel charts as all the URLs have timestamps. Note also that although the thumbnail/preview image will always show correctly when appending a unique token to the URL, the original image behind it will vary. Wetterzentrale replaces the images on the model runs each day, for example.

Edited January 18, 2019 by Yarmy

[East_England_Stormchaser91]

1 minute ago, kold weather said:

Yeah good long term pattern but my alarm bells ring at 96-120hrs and the way the low comes so far east across the Atlantic. Many a good cold spell has come undone due to there being too much energy which prevent s any blocking from taking hold. Legitimate risk still.

Good news is the difference starts as soon as 72hrs so we should have a definite answer today or tomorrow, and signs are most models gave gone the right way this morning.

You don’t necessarily need strong heights to the North/ Northeast to achieve a significant snow event, as long as the heights are there. January 2013 was an example, and funnily enough January 1987. That actually happened during a +NAO. 

I cannot see any sign of zonality being modelled whatsoever. Even this winter, I would not classify as a true zonal one. More on the neutral side of things. 

If you want to see what true zonality is, then I recommend looking at the archives for years like 1988/89, 1998, 2007 and 2013/14. Thankfully the word “Bartlett” has not cropped up once this winter yet! 

[karlos1983]

PPN charts in this setup are useless!!! Easterlies almost always get modelled as dry easterlies but seldom end up that way. There will no doubt be troughs popping up in the flow, if we get to the easterly, 48 hours is all you need, sometimes less, to pick up sudden kinks in the isobars etc. 

When you have cold uppers you can’t rule anything out! Many warnings of snow in winters past have been issued 12/24 hours out.

lets get the pattern locked in first

[frosty ground]

21 minutes ago, bluearmy said:

In a personal note, my disappointment at this stage is with Tuesday - for quite a while it was signposted on the ext ens and it had the potential up until yesterday to deliver a widespread snow event across the country 

looks like we have to look beyond this now although there is still time for it to correct 

Which proves without doubt looking for snow beyond 48 hours is pointless and only leads to disappointment  

[bluearmy]

Perhaps I didn’t explain myself well - up until yesterday there was a good chance that the upper trough would drop down the west side of the uk - now it seems to be heavily favoured to be the east side

Broadly speaking

west side = country stays generally in continental air = low dp’s = snow

east side = country comes into Atlantic air = higher dp’s = rain 

wasnt looking at detail, simply percentage chances 

[Catacol]

Hotel on phone...so no charts. A last word about Tuesdays trough and marginality. ECM shows -4 850s across much of the country with a filament of -8 following in behind at 120. However these are temperature bands. The -4 could very easily be -6 plus or minus...and this - in very very broad terms without considering DPs and other factors, makes the Tuesday forecast a nightmare for the pros....and a nightmare up until the very last minute. The further west that trough tracks the greater the chance of snow. But even on a track further east there is a snow to rain back to snow potential almost anywhere. 

72 hours also reveals just how complex a picture the models have to resolve for Tuesday. The system jamming into the mid Atlantic block is very deep - big clash of 2 distinct pressure differences and so margin for error increases. Data on the low is likely to change - data on deep lows usually does. 

So genuinely Tuesday into Wednesday is likely to be a now cast situation and the models will be struggling. I usually like to nail my colours to the mast a bit, and risk getting things wrong in the process! - but right now I’m holding fire on saying anything more than has been said all along. Tuesday is the first chance of a major snow event in this forthcoming spell but it’s a chance and not a certainty.

[jethro]

49 minutes ago, snowking said:

Not to suggest that this would be what actually happens in reality, especially given those uppers over the North Sea, but you would imagine with higher pressure over our shores that cloud development would be somewhat limited in terms of height - and we see thus manifested in just some light streamers in the usual spots exposed to a NEly flow:

This is, of course, all theoretical for now, and there are some other snow events across the NW as fronts attempt to encroach

For a brief moment there I got all excited....shouldn't have clicked on the image to enlarge it. Coming after someone had posted a NW radar pic, my early morning eyes saw pink over Somerset, instant 'woohoo'. More coffee needed....

I've been around here for a while now, avidly following the winter charts and I can't remember a time other than 2010 when there's been such a strong consensus that it's going to turn wintry. There'll be daily wobbles but until the likes of GP, Catacol, Chino etc say 'it isn't going to happen' I have complete faith that winter is coming  

Looking at the pretty, blobby model pics this morning, even my totally ignorant brain can see cold, cold and more cold incoming.

[Captain Shortwave]

     

General thought for week 2, possibly that the high to our north east will decline as the next low from the north west probably drops south east on a similar course to the ones coming through over the next couple of days. So an east/north east flow for a couple of days which could bring snow showers into eastern areas before a more general band of precipitation moves south east through the country into possibly very cold air. The pattern looks primed to remain cold or very cold throughout with low heights in the Mediterranean being the constant feature.

Worth noting that the solutions keeping some weak high to our north east is perfectly feasible which would adjust any Atlantic lows westwards.

[kold weather]

ECM control run pushing a breakthrough of the Atlantic by 192hrs, looks about 48hra faster than the operational. Should be interesting to see how it handles where the LP goes on the control run and whether we end up getting a mid Atlantic ridge come through afterwards.

Block holding through 216hrs, strong low to west but the jet still splitting just far enough west. Not all ensembles are as good though.

Edited January 18, 2019 by kold weather

[edinburgh_1992]

Why is everyone so upset? Briefly scrolling through the last messages and I thought all models has flattened the evolution like GFS P had been predicting

But GFS and ECMWF are still great. Still some eastern winds showing and plenty of potential

[ICE COLD]

2 hours ago, January Snowstorm said:

And at 240hrs the ecm has lost all heights to our North. Bitterly cold over England though with ice day likely. Scope for upgrades later.....We need them

Why would we need upgrades on the ECM JS ? Looks stonking to me on the op . Very cold and possibly snowy . 

[Lloyds32]

Hm. I think today's ECM run isn't as good as yesterdays. Today's looks like the ridge is having more influence on the UK, where it has moved (sunk?) more over the UK stopping the strongest flow from the east. Which in turn pushes the low pressure further south into Europe. I'm looking for a stronger ridge and up further to the NE. I have feeling the ridge is going to sink more on the next ECM run keeping the easterly flow more towards northern France. Therefore the deep cold being pushed further south into Europe. That's just my take on the way I think it will pan out. Europe into the freezer with snow, with the UK missing out with the ridge sinking over us. I think the operational run was cold outliner.

 

 

[kold weather]

ICON 06z has moved back towards it's 18z setup with the low not separating as well come 120hrs. 00z was a good step forward but 06z definite step back again with the heights remaining more stubborn over Iceland.

[sebastiaan1973]

17 minutes ago, kold weather said:

ECM control run pushing a breakthrough of the Atlantic by 192hrs, looks about 48hra faster than the operational. Should be interesting to see how it handles where the LP goes on the control run and whether we end up getting a mid Atlantic ridge come through afterwards.

Block holding through 216hrs, strong low to west but the jet still splitting just far enough west. Not all ensembles are as good though.

I was surprised to see your comment  Because the control is quite cold 11-15 days ahead.