Model output discussion - The run up to Christmas

[That ECM]

3 minutes ago, Steve Murr said:

Pretty ropey ECM tonight apart from the marginal snow event @168 its very tame.

Lets hope its for the scrapper.

Would you be kind enough to put some meat on the bone? We are all learning. Is this in terms of 850’s, longevity, or something different? TIA

[TSNWK]

I was hoping for something for little more at 240.. but after a moment reflection I thought if that chart had been issued last winter or the one before we would been flipping somersaults..I guess to me that says we are not in a bad place general if that 240 in isolation disappoints me a tad.

 

 

[Kasim Awan]

1 minute ago, NewEra21 said:

Yeah hopefully the GFS is correct and we see the other models showing a smaller low in the days to come.

A smaller and more stretched out low would give us a chance to draw some more cold air in from the north. With these ball shaped lows we have nothing to draw on and they just mix the cold out.

Smaller lows: less distance between cold air to North & moisture to South, promoting convergence & better shortwave development as a result.

Nontheless, a dartboard low as per ecm still has noteworthy snow event potential.

[heath]

Just noticed the deep cold pool on ECM over western Kazakhstan. Where might that go? If anywhere. Any thoughts from those more expert than me? Not on GFS. 

[Mark wheeler]

2 hours ago, WxHerts said:

Anyone know when GEM got its warm 850hpa temp bias fixed?

Well I did notice navgem’s  may have broadly come in to line during the last hot spell of this year in September I believe I made a comment on it in here at the time .

[Cold Winter]

1 minute ago, Daniel* said:

Not sharing enthusiasm at all about ECM 12z more wet than white day 6-7 determines how much cold air we can get the low is like a bowling ball on this run and gets stuck over us. Let’s hope it’s an outlier.

Agree. The charts look nice after what we’ve been used to for years but for actually delivering to the majority then they aren’t brilliant. As others have said, a smaller low positioned further east would be ideal rather than this canon ball that goes down the eastern half of the country. 
 

Prior to all that however, some lucky eastern areas could get a few snow flurries Christmas Eve and overnight into Christmas Day!

[MATTWOLVES 3]

9 minutes ago, Kasim Awan said:

216 BOOM.

Trust me kasim as the king of the Boom gifs thats a rather average ECM run, but I'm hopeful it will be an outlier come the mean..

[Mr snowman 2018]

GFS operational ensemble is the mildest of the lot !

[Snowman.]

You would hope that at D10 the trough clears sufficiently SE allowing heights to link over the top. Icelantic-Scandi high? Few GEFS members seem to think so... first week of Jan defo without interest.

[Kasim Awan]

Just now, MATTWOLVES said:

Trust me kasim as the king of the Boom gifs thats a rather average ECM run, but I'm hopeful it will be an outlier come the mean..

ECM signal for polar maritime energy + GFS signal for amplification = very cold moist feed / snow. A halfway house solution.

[Matt H]

Just now, Mr snowman 2018 said:

GFS operational ensemble is the mildest of the lot !

Only in the extended range though, it’s fairly in line with most of the other ensemble members out to day 10.

[Kasim Awan]

1 minute ago, Mr snowman 2018 said:

GFS operational ensemble is the mildest of the lot !

Only right at the end. It's very well supported otherwise.

[Mr snowman 2018]

Just now, Kasim Awan said:

Only right at the end. It's very well supported otherwise.

Yes that’s what I’m saying it’s in good agreement 

[Scott Ingham]

10 minutes ago, Allseasons-si said:

ECM At 240...

if it doesn't snow from now into Jan,..then i will join @Scott Ingham

Full Monty -

Our name? EAMT

Eesily Arrested Man Tramps

[sheikhy]

Right so thats a very good ecm!!!BUT my one concern is that greenland high in the last 24 hours!!!more energy seems to be going over the top on both gfs and ecm !!ukmo is the outlier with the slightly more amplified pattern!!as long as the eastward progression of lows over the top of greenland stop here im happy but if they carry on then we know how badly things can go wrong!!on the 18z i am looking for that ridge to get slightly higher around 120 to 144 hours!!apart from that the runs look pretty good!!

[Howie]

Is it me or is the Russian high starting to re-orientate like it's about to retrogress at the end of the ECM run?

[SMU]

7 minutes ago, That ECM said:

Would you be kind enough to put some meat on the bone? We are all learning. Is this in terms of 850’s, longevity, or something different? TIA

To get some cold longevity out of an atlantic high we need a cut off wedge over Iceland to keep the atlantic alligned on a very sharp NW > SE Axis, when you weaken the wedge the jet axis softens up to a more positive angle ( more towards west to East ) 

The ECM is the worst of the bunch however overall its modelling has been pretty poor.

Compare the ECM 216 1st the GEM 216 you see the key difference which leads to a milder ECM. 

Thats why even post 168 you never see anu proper cold air over the UK

[booferking]

17 minutes ago, That ECM said:

Would you be kind enough to put some meat on the bone? We are all learning. Is this in terms of 850’s, longevity, or something different? TIA

Short term start of cold spell the below.

Several things Amplification torwards Greenland the 850s colder and that low needs to move to just off the east coast and be more elongated preferably.

Edited December 21, 2020 by booferking

[Allseasons-Si]

14 minutes ago, heath said:

Just noticed the deep cold pool on ECM over western Kazakhstan. Where might that go? If anywhere. Any thoughts from those more expert than me? Not on GFS. 

Hi Heath i will try and explain...

1,we need the trough to be cut off and to drop a lot further S/SE as much as possible

2,this will then open up the heights over the  top

3,once 1 and 2 do that then the advection would take place from east to west

of course this is just based on that chart and it is day ten,the modelling will come up with different types of scenarios up until then.

Edited December 21, 2020 by Allseasons-si

[kold weather]

Yeah the 12z ECM is fairly meh compared to the clear potenial seen on other runs.

Still does deliver a marginal snow event (and height would make a difference) but the rest of the run definately is a little underwhelming from there. It'd probably go on to give one of those limp wristed low pressure driven easterlies that probably is the wrong side of marginal for most to benefit from and the upper low probably sits close to the UK stopping anything too cold from arriving.

Thankfully the other models hold much more interest down the line and the ensembles from the GFS are decent.

Edited December 21, 2020 by kold weather

[Vikos]

Party is over before music even started...

That's my feeling, once again I got screwed by the models proclaming some real wintery days...

Notice to my self: don't get hyped, don't listen to +144h charts in winter, as blue as their might be..

At least, some real cold air could make the move to ME by southside sliding of that mighty russian HIGH

 

But even "stable" (and my preferd) model EC is swining and dancing.

Time will tell...

 

Edited December 21, 2020 by Vikos

[That ECM]

5 minutes ago, Steve Murr said:

To get some cold longevity out of an atlantic high we need a cut off wedge over Iceland to keep the atlantic alligned on a very sharp NW > SE Axis, when you weaken the wedge the jet axis softens up to a more positive angle ( more towards west to East ) 

The ECM is the worst of the bunch however overall its modelling has been pretty poor.

Compare the ECM 216 1st the GEM 216 you see the key difference which leads to a milder ECM. 

Thats why even post 168 you never see anu proper cold air over the UK

Thanks for taking the time to reply and add to my learning. That’s why I enjoy this site. Was a time I didn’t know what I was looking at all but through learning areas and from others you learn more and more. 
 

Thank booferking also.

[Anthony Burden]

All about 144 hrs and track of Arctic low from the north of us how will it track.over us,to our

west,or east.Still undecided ecm has changed their opinion a few times tonight more to the west, 

tomorrow who knows.I feel when we get at 96hrs a positive position will have been established.

Still cold regardless but how cold being the key for wide spread snow.

[PolarWarsaw]

There has been a lull of posts in here today because for all money we look to be heading into another situation as we did early month - close but no cigar. Yes, there is certainly more back bone to the cold this time and yes, over the years there has been numerous little events unfold that have delivered surprise snowfalls (and are likely to again) - I couldn't even begin to count the times that haven't? So I find that a bit of a flimsy argument. The reality for the most of us, is that after weeks of waiting and being patient we are not even remotely staring down the barrel of a cold and snowy spell. 

Lots of cold rain, sleet and some isolated snow looks likely. 

If I lived in Scotland, Northern England or somewhere like Oldham for example then I'd be quietly content that I will see some potentially accumulating snowfall in the next 10 days or so. Given the vast majority of posters live at 100m's< in this country and the wider population of this forum will be posting from inner city locations or more specifically south of the M4, this is not a pattern that should be rejoiced in for current prospects at the surface - for the immediate term that is. 

Again this evening, we are seeing 'amazing' looking synoptical charts that for whatever are NOT fulfilling the same potential for the weather at the surface. I refer back to early month for a rinse and repeat, albeit with more potential to deliver this time. 

If there was signs of a Bartlett or an aggressive Atlantic spell in the models for the 1st week of January...the model output thread would be a very different place tonight. It's a dangerous thing to spend 6-8 weeks of winter pinning hopes on an SSW. They aren't a new form of meteorology, it's just we are starting to learn more about them as they become more prominently discussed as a tool to use, we have had them for decades and our winters haven't changed for the better on the whole. (Rather the opposite)

This winter has been devoid of the Atlantic as we know it for the almost 4-6 weeks now. It's time to start seeing the Day 10 charts that have been stuck at Day 10 for 6 weeks now actually deliver.

Let's hope the ECM comes back towards the GFS. 

Edited December 21, 2020 by PolarWarsaw

[Daniel*]

I was actually expecting to see worse. There’s an inevitability higher ground of north will do well.