Model output discussion - another cold spell on the horizon?

[Battleground Snow]

2 minutes ago, sheikhy said:

Hold on are we about to be rescued with a further wedge of heights into greenland....

I thought I was looking at different charts to others then haha. Admittedly the ridge probably isnt going to be as robust as the 12z. Maybe a tiny step to ECM?

Edited January 10, 2021 by Battleground Snow

[Mike Poole]

GFS and GFS // very different at T120:

Keep your eye on the //, something about the arctic high, heights near Greenland before the ridge and what’s coming out of USA.

[Griff]

Just now, Mike Poole said:

GFS and GFS // very different at T120:

Keep your eye on the //, something about the arctic high, heights near Greenland before the ridge and what’s coming out of USA.

And at 132

[Johnp]

I predict a stonking easterly in FI on GFS...

[sheikhy]

1 minute ago, Griff said:

And at 132

One thing is clear that scandi high is getting upgraded with each run!!

[Jason M]

Just now, Johnp said:

I predict a stonking easterly in FI on GFS...

Funnily enough I was just thinking the same thing. I prefer this run tbh. It looks less dramatic but looks can be deceiving.

[Daniel*]

We might see a good block from this still good WAA.

[nick sussex]

A lot of attention on the medium term but the shortwave tracking se needs to be watched around T96 hrs.

As that clears into France you could pick up a se easterly flow which could see some snow as that undercuts the precip .

[bluearmy]

Incidentally the para brought snow as the cold undercut the front later in the week 

[Battleground Snow]

1 minute ago, sheikhy said:

One thing is clear that scandi high is getting upgraded with each run!!

A half way house would probably still be great... Don't want any more little steps to ECM though

[Weathizard]

There’s no doubt this run is a significant step towards the ECM, would be wrong to pretend otherwise. 

(12z and 18 comparison)

[sheikhy]

Gfs p looking pretty yucky at 144 hours!!!and looks way different to the previous run again!!!!how many times!!!

[Tim Bland]

Just now, bluearmy said:

Incidentally the para brought snow as the cold undercut the front later in the week 

Yes  

[Barmada_Casten]

5 minutes ago, Nick L said:

We would much rather people use the ignore facility than negatively respond to posts they don't like, for sure. 

But I will add, we have absolutely no plans to put an age limit on this or any threads on this site. I joined this site when I was 15, posting on here helped nurture my interest in meteorology. That then lead to a degree in meteorology, and now I'm employed as a meteorologist and have been for the last 6 years. There will be numerous other young people on this forum who could potentially follow that path, and posting on here will continue to nurture that interest.

So, yes, please use the ignore facility. But we have a wealth of knowledge and posts from all ages on this forum. Anyway, let's get back to discussing model output and put this evening's drama behind us, and thank you to all who reported posts - that's the way to deal with issues.

Apologies to anyone offended by my earlier post! It was perhaps badly worded and did not mean to offend anyone!!! This forum would be nothing without everyone and as I said earlier now more than ever we need to stick together.

 

As for the upcoming cold spell..... well.....

[Singularity]

The MJO activation & propagation signal has largely disappeared from EPS today - but the model may just be having it usual issue with initiating an MJO wave from phase 3 or 4 and in any case, I'm not sure this can explain the strong pressure being applied on the attempted ridging to our north / northwest by low pressure from North America on the deterministic run and a number of ensemble runs.

The process involves a low pressure system becoming extremely vigorous in about a week's time as it crosses eastern Canada and then sort of imploding (so to speak), releasing a mass of cold air to race across the northern reaches of the North Atlantic.

That outcome is arguably as extreme as one featuring a massive blocking high cut off over Greenland... and I swear I've ECM do this before; put out 3-5 runs that perform an exceptional large-scale translation of low heights across a large distance at high speed. Anyone else recall such a thing?

Not saying we can fully discount that scenario - just that it should be considered low probability unless we see consistent support for it develop in other modelling while it stands its ground.

Case in point - the 18z GFS is closer to it than the 12z was.

Worth noting, though, that being partway toward an ECM style outcome might facilitate a Scandinavian based high of some sort. Many times this past decade, I can recall seeing what was originally predicted to be a Greenland-based high latitude block end up being Scandinavia-based. Admittedly, often with less dramatic results for the UK's weather (usually less snowy in general away from North Sea coasts, especially in the north).

[Johnp]

Just now, sheikhy said:

Gfs p looking pretty yucky at 144 hours!!!and looks way different to the previous run again!!!!how many times!!!

What's weird is I can't ever remember the GFS and the para runs ever being similar. There always seems to be a massive divergence. 

[bluearmy]

Para has a look of a run that is meandering around day 6 upstream.  Unconvincing although with a weak zonal flow it could happen - makes a verifying run unlikely ....

[Man With Beard]

GFS 12Z is a useful *ridge*

but not a patch on the 12Z at the same time for probable longevity of a Nly flow

Considering the flip-flopping, my best advice is ... wait. 

I think a 2-3 day northerly is a reasonable middle ground forecast based on charts atm. However, we're not close enough *based upon NWP* to say if it will be better than this or worse than this (from a coldies perspective). Certainly no forecast from me tonight. Especially considering D3 isn't sorted yet!

[nick sussex]

The ridge toppling into Scandi wouldn’t be a bad middle ground . So all is not lost if we see that type of halfway house .

[Captain Shortwave]

 

What an absolute mess. The older GFS op is little better in that regard. Honestly I wouldn’t be going further than the front towards the end of this coming week and the transient high to our north east. Beyond that there seems to be multiple shallow features upstream trying to interact with a more substantial trough developing towards the Eastern seaboard.

I will maintain my concerns about the ECM and its Scrooge like output where it seems to want to build westerly momentum (not just Greenland high(gate)). The end of the week does look colder again after a short period of around average temperatures (risk of snow under that front before it dies out).

[Daniel*]

Scandi high is my prediction.

[Griff]

Just now, bluearmy said:

Para has a look of a run that is meandering around day 6 upstream.  Unconvincing although with a weak zonal flow it could happen - makes a verifying run unlikely ....

Couldn't tell you what's likely it follow... 

[chionomaniac]

Looks like the Atlantic amplification is heading towards a potent NEasterly if it doesn’t collapse too quickly

[sheikhy]

Hows the snow looking on the 18z gfs for thursday friday?para had some as posted above!

[Kasim Awan]

GFS 18z looking like a slow toppler. Fairly realistic middle ground.