Model Output Discussion - the cold has arrived

[Ben27]

I’d love more than anything for the GFS to be right but in a battle of GFS vs ECM/UKMO you’d have to fancy the latter two, but you never know  

[Bricriu]

I think we will get one model meeting the others halfway, which will probably mean a wet rather than White Christmas. I hope the GFS is leading the way here. I really do, but I fear sometime tomorrow it will  change for the worse. 

[Jake March-Jones]

Still don't see this cold happening for xmas

[Met4Cast]

The AAM has as expected fallen through the floor with a further strong -MT event & signs of westerly momentum returning to the mid-high lats. The UK likely to be on the boundary between cold/mild with snow possible (mostly in the N) before milder air eventually wins out.  i.e any colder periods for the remainder of this year are likely to be transient affairs but may still produce snowfall for many.

MJO prediction suggests renewed Greenland blocking end of 1st > 2nd week of Jan but my current thinking is it'll be more west based, i.e UK remains milder with probably low pressure sat over the UK rather than being forced to the south like this current cold spell.

Had the MJO cycled around into these phases during the second half of this month like early forecasts had suggested things would be very different, but the timing is off to support prolonged cold into the UK and of course is only one aspect of the global budget.

To add to the above.. the trop led running of things may be on borrowed time with signs of the stronger u-winds descending down from the stratosphere. SPV possibly setting up shop over Greenland again. Cold lovers *perhaps* living on borrowed time now.

No signs of an SSW in the forecast nor any sign of an SSW precursor pattern appearing on the outputs. Unfortunately I'm growing more & more confident that an SSW is unlikely this year, or at least in the next 3-4 weeks. 

So.. transient periods of colder weather but the trajectory does appear to be increasingly towards a milder one for the UK. Indeed, GLOSEA suggests westerly winds becoming more dominent as January progresses, fitting well with the above background signals.

[blizzard81]

7 minutes ago, northwestsnow said:

GFS 18Z = VICTORY..

Chance of it being right ?

I'd say ,hand on heart 20%..

We're all gunning for the gfs. It wouldn't be the first time it has trumped the ecm. It's rare but it has happened a few times over the years. Christmas 2005 just one example. Hope Matt Hugo is correct with regards his post earlier on this evening. 

[tight isobar]

Just now, Ali1977 said:

I imagine it’ll pull back, the op looks in the more extreme end of the ENS at 144 - especially for that snow event. 

We need to try to eliviate the spell bounding of “snow for a minute “- and just concentrate on the operational evolution/ evolutions. Otherwise the distraction can cause model miss- interpretations... we need cold 4 snow.. and it’s that we need to concentrate on- for now...

[goosey007]

Steady as she goes on gfs 18z something seriously wrong somewhere ….. ecm op massive outlier still on its op gfs op has its ensembles in tow …..what do you forecast ?

[Allseasons-Si]

I must say,...i wonder what will happen with this HP cell that has been touted at by the gfs recently,..can we get more amp out of it into Scandi?

will they become charts of wisdom,...in future

Edited December 18, 2022 by Allseasons-si
typo

[geordiekev]

17 minutes ago, Ali1977 said:

For those that don’t know, look at ECWeather about 10 mins after a T240 GFS local details on the latest run. I’ll post Alston in cumbria soon to show what this latest run was showing. All for fun at the min but I imagine we are talking 40-50 cm 

The 12z showed a fair bit for Alston - it’ll be eclipsed some what

My long lost cousin lives there. She's been snowed in since the 80s. She posted a pic of her sandwich van on Nenthead Rd, sort of reminded me of Elvis. Sorry just needed to lighten the mood but yeah anyone after a few snow days, defo get locked in at Alston

[tight isobar]

3 minutes ago, Met4Cast said:

The AAM has as expected fallen through the floor with a further strong -MT event & signs of westerly momentum returning to the mid-high lats. The UK likely to be on the boundary between cold/mild with snow possible (mostly in the N) before milder air eventually wins out.  i.e any colder periods for the remainder of this year are likely to be transient affairs but may still produce snowfall for many.

MJO prediction suggests renewed Greenland blocking end of 1st > 2nd week of Jan but my current thinking is it'll be more west based, i.e UK remains milder with probably low pressure sat over the UK rather than being forced to the south like this current cold spell.

Had the MJO cycled around into these phases during the second half of this month like early forecasts had suggested things would be very different, but the timing is off to support prolonged cold into the UK and of course is only one aspect of the global budget.

To add to the above.. the trop led running of things may be on borrowed time with signs of the stronger u-winds descending down from the stratosphere. SPV possibly setting up shop over Greenland again. Cold lovers *perhaps* living on borrowed time now.

No signs of an SSW in the forecast nor any sign of an SSW precursor pattern appearing on the outputs. Unfortunately I'm growing more & more confident that an SSW is unlikely this year, or at least in the next 3-4 weeks. 

So.. transient periods of colder weather but the trajectory does appear to be increasingly towards a milder one for the UK. Indeed, GLOSEA suggests westerly winds becoming more dominent as January progresses, fitting well with the above background signals.

A great summary- however and please take nil offence, but I remember you vividly shouting down the cold spell just leaving us.. and my questioning whether you were viewing parameters on a 10hpa level!! Initially. I’ve bounded through an array of teleconections and the spreads are vast into early January!!

[Don]

3 minutes ago, Met4Cast said:

So.. transient periods of colder weather but the trajectory does appear to be increasingly towards a milder one for the UK. Indeed, GLOSEA suggests westerly winds becoming more dominent as January progresses, fitting well with the above background signals.

A very sobering post, particularly for those of us who saw very little or no snow during the last 10 days!! 

[Paul_1978]

9 minutes ago, Met4Cast said:

The AAM has as expected fallen through the floor with a further strong -MT event & signs of westerly momentum returning to the mid-high lats. The UK likely to be on the boundary between cold/mild with snow possible (mostly in the N) before milder air eventually wins out.  i.e any colder periods for the remainder of this year are likely to be transient affairs but may still produce snowfall for many.

MJO prediction suggests renewed Greenland blocking end of 1st > 2nd week of Jan but my current thinking is it'll be more west based, i.e UK remains milder with probably low pressure sat over the UK rather than being forced to the south like this current cold spell.

Had the MJO cycled around into these phases during the second half of this month like early forecasts had suggested things would be very different, but the timing is off to support prolonged cold into the UK and of course is only one aspect of the global budget.

To add to the above.. the trop led running of things may be on borrowed time with signs of the stronger u-winds descending down from the stratosphere. SPV possibly setting up shop over Greenland again. Cold lovers *perhaps* living on borrowed time now.

No signs of an SSW in the forecast nor any sign of an SSW precursor pattern appearing on the outputs. Unfortunately I'm growing more & more confident that an SSW is unlikely this year, or at least in the next 3-4 weeks. 

So.. transient periods of colder weather but the trajectory does appear to be increasingly towards a milder one for the UK. Indeed, GLOSEA suggests westerly winds becoming more dominent as January progresses, fitting well with the above background signals.

Well that isn’t what we wanted to hear. 

Seems at odds with Matt Hugo’s thoughts earlier though unless I am misinterpreting?

 Edit: Matt’s post was focused on Christmas and New Year - you’re looking much further ahead. 

Edited December 18, 2022 by Paul_1978

[Battleground Snow]

The op was actually one of the slower members in bringing the cold south Xmas day! Good set so far

[Met4Cast]

4 minutes ago, tight isobar said:

A great summary- however and please take nil offence, but I remember you vividly shouting down the cold spell just leaving us.. and my questioning whether you were viewing parameters on a 10hpa level!! Initially. I’ve bounded through an array of teleconections and the spreads are vast into early January!!

I didn't shout it down at all? Go back through my posts. 

[phil nw.]

The latest 850hPa ens graph incl some of the ops from different models .

Just to show the wide spread from Christmas and beyond-these are for Warks.

Pick the bones out of them.This underlines that the UK is very much on the boundary of cold and mild,small developments in the track/development of the lows running across still to be pinned down.

 

[E17boy]

7 minutes ago, Met4Cast said:

The AAM has as expected fallen through the floor with a further strong -MT event & signs of westerly momentum returning to the mid-high lats. The UK likely to be on the boundary between cold/mild with snow possible (mostly in the N) before milder air eventually wins out.  i.e any colder periods for the remainder of this year are likely to be transient affairs but may still produce snowfall for many.

MJO prediction suggests renewed Greenland blocking end of 1st > 2nd week of Jan but my current thinking is it'll be more west based, i.e UK remains milder with probably low pressure sat over the UK rather than being forced to the south like this current cold spell.

Had the MJO cycled around into these phases during the second half of this month like early forecasts had suggested things would be very different, but the timing is off to support prolonged cold into the UK and of course is only one aspect of the global budget.

To add to the above.. the trop led running of things may be on borrowed time with signs of the stronger u-winds descending down from the stratosphere. SPV possibly setting up shop over Greenland again. Cold lovers *perhaps* living on borrowed time now.

No signs of an SSW in the forecast nor any sign of an SSW precursor pattern appearing on the outputs. Unfortunately I'm growing more & more confident that an SSW is unlikely this year, or at least in the next 3-4 weeks. 

So.. transient periods of colder weather but the trajectory does appear to be increasingly towards a milder one for the UK. Indeed, GLOSEA suggests westerly winds becoming more dominent as January progresses, fitting well with the above background signals.

Yes indeed a very sombering outlook if it goes to plan. This means that we are looking at least till the end of January to see if anything changes in terms of the above parremiters you have mentioned.

Then again it’s the weather and things could easily change again, but the above could be reality and as you have mentioned even a SSW being unlikely where will that leave us. I am now just trying to think of the worse case scenario.  Makes you think more and more about the long term indications from several forecasting models, with this winter being front loaded.

Anyway not to dampen the mood than what it probably already is I think the best is to just follow this ride and see what pans out.

[Met4Cast]

1 minute ago, E17boy said:

Yes indeed a very sombering outlook if it goes to plan. This means that we are looking at least till the end of January to see if anything changes in terms of the above parremiters you have mentioned.

Then again it’s the weather and things could easily change again, but the above could be reality and as you have mentioned even a SSW being unlikely where will that leave us. I am now just trying to think of the worse case scenario.  Makes you think more and more about the long term indications from several forecasting models, with this winter being front loaded.

Anyway not to dampen the mood than what it probably already is I think the best is to just follow this ride and see what pans out.

Until then, still plenty of interest in the short-medium term. The xmas-new year period for example offering the potential for further cold & wintry weather as mentioned in that post. 

EPS less certain with far more spread (though quite a few cold/extreme cold members), the GEFS seems more consistent in terms of bringing the cold in across the UK again during that period. 

[Don]

2 minutes ago, Met4Cast said:

Until then, still plenty of interest in the short-medium term. The xmas-new year period for example offering the potential for further cold & wintry weather as mentioned in that post. 

EPS less certain with far more spread (though quite a few cold/extreme cold members), the GEFS seems more consistent in terms of bringing the cold in across the UK again during that period. 

The GLOSEA you mention for a progressively more westerly January, when was that last updated, just out of interest?

Edited December 18, 2022 by Don

[Mucka]

I take all this talk of Westerlies and zonal and raise you twenty.

JFF

 

[E17boy]

1 minute ago, Met4Cast said:

Until then, still plenty of interest in the short-medium term. The xmas-new year period for example offering the potential for further cold & wintry weather as mentioned in that post. 

EPS less certain with far more spread (though quite a few cold/extreme cold members), the GEFS seems more consistent in terms of bringing the cold in across the UK again during that period. 

Yes I agree there may be periods in between where we get some snow which would be better than nothing. However I think a lot of posters like myself are probably looking for a longer sustained period of deep cold with no one missing out, yes a high expectation for our island. 
In your opinion do you think taking all the factors you mentioned in your earlier post including an unlikely SSW event we can still pull in a 2 week period of deep sustained cold or in your opinion are odds against that as well from your analysis. I know this is the weather and things can change but would there still be scope? 

[Met4Cast]

3 minutes ago, Don said:

The GLOSEA you mention for a progressively more westerly January, when was that last updated, just out of interest?

GLOSEA runs daily but it has been fairly consistent in it's outputs for January. i.e starting off with a weak westerly bias with that bias growing the further into January we go. That's not to say the model is perfect of course but does appear to fit with the broader developing background signals from where I'm sitting. 

[Derecho]

Quite a change there on the latest GFS ensembles.

[Beanz]

4 minutes ago, phil nw. said:

The latest 850hPa ens graph incl some of the ops from different models .

Just to show the wide spread from Christmas and beyond-these are for Warks.

Pick the bones out of them.This underlines that the UK is very much on the boundary of cold and mild,small developments in the track/development of the lows running across still to be pinned down.

 

There’s more spread there than a family sized tub of Flora.  All to play for, but I suspect we’re in for a mild Jan.  

[Don]

1 minute ago, Quicksilver1989 said:

Quite a change there on the latest GFS ensembles.

Not a good one either with the -5 line going from the south coast on the 12z to the Scottish borders the 18!!

[Met4Cast]

4 minutes ago, E17boy said:

Yes I agree there may be periods in between where we get some snow which would be better than nothing. However I think a lot of posters like myself are probably looking for a longer sustained period of deep cold with no one missing out, yes a high expectation for our island. 
In your opinion do you think taking all the factors you mentioned in your earlier post including an unlikely SSW event we can still pull in a 2 week period of deep sustained cold or in your opinion are odds against that as well from your analysis. I know this is the weather and things can change but would there still be scope? 

Well.. we've just had 2-3 weeks of below average temperatures without an SSW, although the difference there is the trop was leading things. The MJO event was perfectly timed and we had a very anomalously positive AAM on the back of two strong +MT events.

The trouble we have now going forward is the AAM is unlikely in my eyes to get anywhere near as positive as we saw during December and we have a strengthening SPV with increasing signs of coupling to the troposphere & moving back into the Greenland region.  La Nina is very much making a comeback in terms of atmospheric/ocean coupling which heavily sways things towards a milder mid-second half of winter.

That makes it very difficult to get any sustained cold weather/blocking without an SSW, that's not to say it can't/wont happen but it does make it difficult. But we're talking really long-term here so it's difficult to be overly specific re UK detail.