The hunt for cold - Model discussion (late November)

[Methuselah]

Come on peeps, lighten up...it'll be cold for at least the next four days (and maybe longer); many of us will even see some snow, even it is only a few flakes, in most places...Given that the models are still disagreeing on what'll happen and when, we ought to just enjoy the ride...?

[Stuie]

5 minutes ago, Bristle boy said:

People keep posting about "battleground" situs towards end of week but classic ones usually involve a few days of bitter temps before Atlantic fronts encroach. Under those situs ground temps, as well as air temps, are low. 

End of this week aint classic "battleground".

I thought it was when milder air met colder air. Pretty sure if you had ground temps then it wouldn`t be a battle as the cold side would win hands down.

[phil nw.]

So the Atlantic incursion is being delayed bit by bit.It's arrival into the UK with southerly winds ahead of the warm front modeled to arrive on the 13th is this evening due on the 15th-so now a delay of 48 hrs. 

Compare any of the12z runs GFS/UKMO/ECM from 3 days(7th) ago with today's runs.

The reason seems to be as each day goes by the upstream pattern is evolving with a weaker jet heading this way with signs of splitting.Today's GFS is the first image with the run from 7th next.

so we see the eastwards push in the Atlantic slowing and the trough disruption gaining traction especially in the ECM model.

 

 Looking north we see the ridging of +ve ht anomalies westwards towards Greenland from the residue of heights over Scandinavia, another sign of the waning Greenland vortex all part of the bigger picture of a weaker Atlantic jet profile.

A look at the latest gef ht anomalies for days 5 and 10 shows this trend up quite well

 

The Atlantic may well get in if only for a short while but as each day goes by it seems to lose impetus and the vortex grows weaker.

The main interest is in the medium term and how the pattern will develop.Certainly with Strat.warmings and the forecasted decrease in zonal winds forecasted around Christmas it promises to be a fascinating period to watch how things evolve in the next 2/3 weeks. 

[Stuie]

7 minutes ago, phil nw. said:

So the Atlantic incursion is being delayed bit by bit.It's arrival into the UK with southerly winds ahead of the warm front modeled to arrive on the 13th is this evening due on the 15th-so now a delay of 48 hrs. 

Compare any of the12z runs GFS/UKMO/ECM from 3 days(7th) ago with today's runs.

The reason seems to be as each day goes by the upstream pattern is evolving with a weaker jet heading this way with signs of splitting.Today's GFS is the first image with the run from 7th next.

so we see the eastwards push in the Atlantic slowing and the trough disruption gaining traction especially in the ECM model.

 

 Looking north we see the ridging of +ve ht anomalies westwards towards Greenland from the residue of heights over Scandinavia, another sign of the waning Greenland vortex all part of the bigger picture of a weaker Atlantic jet profile.

A look at the latest gef ht anomalies for days 5 and 10 shows this trend up quite well

 

The Atlantic may well get in if only for a short while but as each day goes by it seems to lose impetus and the vortex grows weaker.

The main interest is in the medium term and how the pattern will develop.Certainly with Strat.warmings and the forecasted decrease in zonal winds forecasted around Christmas it promises to be a fascinating period to watch how things evolve in the next 2/3 weeks. 

Interesting anomaly for Saturday, Phil. The HP risidual block sits across the midlands through France. Pretty underestimated and no wonder the Atlantic is struggling.

Edit: Which is shown well from your 1st JS chart.

Edited December 10, 2018 by Stuie W

[Guest]

I do wonder how long it will be until the first "lack of data over the holiday period" post pops up... very interesting indeed to see the Atlantic being pushed back with every run, no science behind it but i really do get the feeling we could be on the cusp of a really special winter period that will be spoken about in years and decades to come.

[mulzy]

Given what we have had to endure during the first 10 days of winter, the next 5-7 days shows plenty of interest.  Yes, it's a not a nationwide snowy nirvana but at least we are in the game both short term and long term.  

Folk need to remember we live in a mild maritime climate - snow is the exception rather than the rule.  For example, where I live, the last four winters (13/14 to 17/18) have given me a grand total of 4 days with *lying* snow (that's one per winter!).

Edited December 10, 2018 by mulzy

[BLAST FROM THE PAST]

33 minutes ago, Steve Murr said:

Nice ( not concerned about IMBY as expecting a bit more continental flow ) but for December thats a big deal for the UK !

Yes it is!  And folk seem to go way too much on IMBY Tendings.....snow for England and Wales is not snow  for London Cardiff etc.  Looking good for a fair few here....nothing for me but feeling raw....I’ll have that in grand scheme

 

BFTP

[chris55]

Interpretation is key, taking the charts at face value, including the ensembles, at present seems futile, the changes in the mid term in the last 48 hours have been substantial. 

The Atlantic keeps being blocked and held at bay, initially it was Thursday when we had the fronts piling in and now it looks like the block will deflect the systems so far south it’ll stay dry for nearly all.

With the block exerting way more influence than modelled just 36 hours ago these Atlantic systems will struggle to make it past the meridian going forward. 

If the trend continues then those ‘snowfall’ charts will look vastly different come mid week.....

 

 

 

 

[northwestsnow]

Well if nothing else, EC rekindles the interest in a snowy saturday for some-

Gawd the wifes not going to be happy..(another 23.99 hours a day on here)..

[BLAST FROM THE PAST]

3 minutes ago, mulzy said:

Given what we have had to endure during the first 10 days of winter, the next 5-7 days shows plenty of interest.  Yes, it's a not a nationwide snowy nirvana but at least we are in the game both short term and long term.  

Folk need to remember we live in a mild maritime climate - snow is the exception rather than the rule.  For example, where I live, the last four winters (13/14 to 17/18) have given me a grand total of 4 days with *lying* snow (that's one per winter!).

But we had interest during Oct and Nov....first 10 days are of little concern.......indeed serious cold blocking end of Nov into Dec tends to ease and wane somewhat come New Year and then real winter subsides.

 

BFTP

[swfc]

Wow anarchy in here and it's not even a "slider" holy God!!!!anyway better ECM and heights trying to build north of the low later on.im not understanding the stress for transient snow but I applaud your commitment even tho it's not mid December yet!!!

[swfc]

3 minutes ago, northwestsnow said:

Well if nothing else, EC rekindles the interest in a snowy saturday for some-

Gawd the wifes not going to be happy..(another 23.99 hours a day on here)..

You should get a hobby NW! knitting would be handy when winter proper arrives lol

[Met4Cast]

ECM rather snowy indeed for those North of the M4.. given it's 1 run against all the others though I'm not really all that inspired, it's possible but a lower probability outcome for now.

[bobbydog]

Well... some of us might see a bit of snow before Christmas. A bonus I think, a taster of what's to come...

A consistent signal for an SSW to arrive around the big day, 

Zonal winds predicted to tank,

That's (tantalizingly) as far as that chart goes but it's a reversal from that point.

Looks like my investment in a set of snow tyres was a good one...

[phil nw.]

5 minutes ago, Stuie W said:

Interesting anomaly for Saturday, Phil. The HP risidual block sits across the midlands through France. Pretty underestimated and no wonder the Atlantic is struggling.

Edit: Which is shown well from your 1st JS chart.

Yes that's the Azores ridging at that point.

On a general note sometimes it pays to take a step back from the details in every single run.I compare the same run,in this case the12z with the one from 3 days back,we can see that trend developing.

In a situation like we have this week with each model run ebbing and flowing wrt the east-west split it's a good way of monitoring the overall trend.As long as you compare any run with it's earlier one from 24 hrs earlier.Something John H has always said and one of the tips i took on board many years ago.  

[Summer Sun]

The ECM op is on the cold side of the mean a few times this evening on the 850s firstly around Friday though the mean is distinctly cold anyway getting down to around -7.

Then 2nd is period from around Sunday and Monday with the op down to around -4 and the mean around -1

[MattStoke]

Just now, Daniel Smith said:

ECM rather snowy indeed for those North of the M4.. given it's 1 run against all the others though I'm not really all that inspired, it's possible but a lower probability outcome for now.

I’m in prime position according to the ECM but I’ll eat my hat if I see anywhere the amount of snow it has for here.

In an unrelated issue, does anyone know where I can buy a hat?

[Methuselah]

2 minutes ago, swfc said:

You should get a hobby NW! knitting would be handy when winter proper arrives lol

Willy warmers with the GFS logo?

[feb1991blizzard]

Just now, MattStoke said:

I’m in prime position according to the ECM but I’ll eat my hat if I see anywhere the amount of snow it has for here.

In an unrelated issue, does anyone know where I can buy a hat?

A hat shop.

[Met4Cast]

1 minute ago, MattStoke said:

I’m in prime position according to the ECM but I’ll eat my hat if I see anywhere the amount of snow it has for here.

 In an unrelated issue, does anyone know where I can buy a hat?

I'm sure there's a couple laying around in the NW "toys thrown out of pram" lost property box..

[Guest]

4 minutes ago, Daniel Smith said:

ECM rather snowy indeed for those North of the M4.. given it's 1 run against all the others though I'm not really all that inspired, it's possible but a lower probability outcome for now.

oh me oh my look at all that Snaw over Scotland...

[Methuselah]

1 minute ago, More Snow said:

oh me oh my look at all that Snaw over Scotland...

What good is GREEN snow?

[Guest]

1 minute ago, Ed Stone said:

What good is GREEN snow?

As long as it isnt yellow.

[snowangel32]

2 minutes ago, More Snow said:

oh me oh my look at all that Snaw over Scotland...

Yh mate early Christmas present for my Scottish relative's. Could be significant snow north of the wash i would say and about 50% chance of the midlands seeing some snow before the rain hits. But with the mods chopping and changing every 6 hours its like pin the tail on the donkey.

[swfc]

15 minutes ago, northwestsnow said:

Well if nothing else, EC rekindles the interest in a snowy saturday for some-

Gawd the wifes not going to be happy..(another 23.99 hours a day on here)..

Btw will it snow in Sheffield?I'm due out about 7pm Tia !!