Model output discussion - another cold spell on the horizon?

[That ECM]

6 minutes ago, Zak M said:

ECM op was an outlier at day 9 and 10...don't panic!

Didn’t pick up the GH

[Kasim Awan]

3 minutes ago, Frostbite1980 said:

Is that 3 outliers on the trot?

I'd say even in the case @stevemurr discusses as being favoured (i.e. no cut off Greenland high), there is still a signal for renewed bouts of amplification, reflected in the fact the temperatures shown on the ECM12Z are well away from the mean. This suggests a relatively strong signal for renewed amplification. 

Edited January 10, 2021 by Kasim Awan

[Man With Beard]

I'll post images of some of the ecm ensembles later to show if there are any true Greenland Highs (haven't looked yet for 12z)

Correct me if I'm wrong but the definition of a high is when an area of pressure is higher than the pressure that surrounds it - is everyone working off the same definition? (For Greenland it is important that this is taken at 500mb)

Edited January 10, 2021 by Man Without Beard

[Djdazzle]

When divergence starts at T96, I don’t understand all of the fretting.

There isn’t, and never has been, anything concrete regarding a cold spell.

As has been the case, there remains potential! Regardless of the signals, we will always require luck to deliver something special.

Edited January 10, 2021 by Djdazzle

[Uncle_Barty]

3 minutes ago, chris55 said:

What if 17 went for a solid Greenland high, 17 went for an Atlantic ridge, and 17 went for an Azores/Euro ridge. How would that show in the mean?

 

Exactly.

It's why I don't take too much notice of the mean (other than for a quick comparison with the op), but wait for the clusters.

[bluearmy]

10 minutes ago, Steve Murr said:

Just looked at the 12z EPS.

Chances of a GH. 0% with 99% confidence.

552 Contour at 12z 216 EPS -

168 Jet to much positive tilt. GH will come from a northward vertical ridge not a ridge out of Canada.

A proper Greenland high

A lot of confusing wording on here being posted that should be made clearer for some of the newbies....

The *Best* case scenario is as @Kasim Awanmentioned a block in the atlantic that holds in situ long enough to deflect the atlantic track further south whilst the trough to the forces cold air south..

I won’t disagree with you based on the momentum but 99% confidence is too much with this spread around greeny at day 10. Clusters say it’s 33% 

 

[SLEETY]

the MET update  was going with the gfs and other cold models,with below average temps with snow chances etc,just need all this wintry nirvana to make it down to the reliable timeframe.

Edited January 10, 2021 by SLEETY

[Scott Ingham]

6 minutes ago, Frostbite1980 said:

Is that 3 outliers on the trot?

I thought as much!

[Frosty.]

I find the GEFS 12z mean / average quite encouraging from a wintry perspective, should be some snow from that!

️  

Edited January 10, 2021 by Jon Snow

[Griff]

Probably already said but the gem has the right idea. 

I've spent the day taking care of a very sick cat, and to some that might not mean very much, but my point is it's only the weather. There's a lot more important stuff going on. More important than poorly cats even. Let's not feel the need to be right, or argue. Take it all with good grace, without needing to be the top dog. After all we won't have to wait that long to find out. But if you suspect others aren't listening or seeing your point of view, chances are they won't anyway no matter how hard you attempt to convince them. Live and let live, and give the mods a break too. 

I think the expression goes "more runs needed"? 

Onwards to the pub (run). 

 

[Kasim Awan]

4 minutes ago, Man Without Beard said:

I'll post images of some of the ecm ensembles later to show if there are any true Greenland Highs (haven't looked yet for 12z)

Correct me if I'm wrong but the definition of a high is when an area of pressure is higher than the pressure that surrounds it - is everyone working off the same definition? (For Greenland it is important that this is taken at 500mb)

Correct but here the importance is in whether the high is strong enough to prevent failed amplification & collapsing of the pattern. 

[Scott Ingham]

2 minutes ago, bluearmy said:

I won’t disagree with you based on the momentum but 99% confidence is too much with this spread around greeny at day 10. Clusters say it’s 33% 

 

A fair assesment would be to say there is slightly more support for a Greenland high at day 10 but momentum has gone the wrong way on the 12z.

But didnt expext anything else with so much going off in the strat

[Gowon]

9 minutes ago, NeilN said:

Well, it seems the handsome Chris Fawkes has said it will possibly turn colder from Thursday onwards on the Countryfile Forecast!

There is hope, and a mild spell isn't the end of the world. 

He's not wrong - all the models show the cold from Thursday until Sunday; it's what happens after that is what's being debated.

[Frostbite1980]

3 minutes ago, Kasim Awan said:

Correct but here the importance is in whether the high is strong enough to prevent failed amplification & collapsing of the pattern. 

Which when fronts crossing the country as early as Wednesday next week are being pushed back makes it very difficult to work out what will happen after....as always more runs needed 

[Allseasons-Si]

6 minutes ago, Man Without Beard said:

I'll post images of some of the ecm ensembles later to show if there are any true Greenland Highs (haven't looked yet for 12z)

Correct me if I'm wrong but the definition of a high is when an area of pressure is higher than the pressure that surrounds it - is everyone working off the same definition? (For Greenland it is important that this is taken at 500mb)

Yep,...EPS at day ten still looking good to me MWB

[feb1991blizzard]

1 minute ago, Scott Ingham said:

I thought as much!

We still have a sniff of a chance here, that chance being that sometimes a rogue op (which i expect it to be) can tend to drive the eps TOWARDS a solution, so if the op is even a tad more moderately blocked on the next run at the end, there is a good chance the eps mean will revert back to the 0z with the ridge longer lasting and further North.

[snow mad]

15 minutes ago, Steve Murr said:

Just looked at the 12z EPS.

Chances of a GH. 0% with 99% confidence.

552 Contour at 12z 216 EPS -

168 Jet to much positive tilt. GH will come from a northward vertical ridge not a ridge out of Canada.

A proper Greenland high

A lot of confusing wording on here being posted that should be made clearer for some of the newbies....

The *Best* case scenario is as @Kasim Awanmentioned a block in the atlantic that holds in situ long enough to deflect the atlantic track further south whilst the trough to the forces cold air south..

Do we need any upstream amplification? If the chunk of pv pushes its way into Europe. When the pv slides back into its normal winter home when a high pressure is in Greenland the pv has no trouble dislodging it. What with the jet not being as strong this year surely that’s a possibility.

[SMU]

6 minutes ago, bluearmy said:

I won’t disagree with you based on the momentum but 99% confidence is too much with this spread around greeny at day 10. Clusters say it’s 33% 

 

I will give you 15% > that includes some goodwill

[Hotspur62]

Fascinating model watching although getting a bit confused with things atm.Just trying to look no further than 120 hrs atm and this front coming in from the west is an interesting feature.Normally they push through west to east quite readily but I don’t see that happening this time as this is not a normal pattern,something Chris Faulks just alluded to.The pressure to the North and east looks stronger this time and I feel that this could become a player later in the week.I would post the latest fax UKMO chart to try and show this but alas my techno skills won’t go that far sorry .

As Always time will tell and I am trying to analyse this from a neutral unbiased POV.

[Djdazzle]

Almost don’t want to see the GFS 18z because it sets you up for disappointment on the 0z!

[feb1991blizzard]

Just now, Steve Murr said:

I will give you 15% > that includes some goodwill

I still think there could be an in between solution and until the ECM i always thought this the most likely solution - 2-3 days of very cold air - toppling - yes, but would slow the Atlantic and give further chances as well afterwards.

[SMU]

4 minutes ago, snow mad said:

Do we need any upstream amplification? If the chunk of pv pushes its way into Europe. When the pv slides back into its normal winter home when a high pressure is in Greenland the pv has no trouble dislodging it. What with the jet not being as strong this year surely that’s a possibility.

Yes ...

1) High pressure enhances the advection process - Weaker high = slower / weaker CAA

2) High pressure stops / steers the movement East of the atlantic > without it cold will never last...

So the PV dropping into Scandi / Central Europe alone cannot drive the cold air west alone - it needs help..

[SMU]

2 minutes ago, feb1991blizzard said:

I still think there could be an in between solution and until the ECM i always thought this the most likely solution - 2-3 days of very cold air - toppling - yes, but would slow the Atlantic and give further chances as well afterwards.

 

A slow toppler > yes thats in the Mix....

[bluearmy]

7 minutes ago, D.V.R said:

He's not wrong - all the models show the cold from Thursday until Sunday; it's what happens after that is what's being debated.

He was speaking about the following week .... but maybe worth seeing what the 10pm news 24 says ....

[Scott Ingham]

5 minutes ago, Steve Murr said:

I will give you 15% > that includes some goodwill

Your assesment of the 12z is correct if not a slight exaggeration with some good political language thrown in but after a ssw you cant take any model or even set as gospel really after 120z and there is Steve a large amount of support at that range for a greenland high/north atlantic ridge whatever youd like to call it in a logical place after shifting of the vortex back to asia and scandi