Model Output Discussion - Into the new year

[Zak M]

The 12z GFS has a low to the SW of Britain and shows a dumping of snow across southern areas.

I'm sure loads of people will be happy if this comes off!

Edited December 28, 2020 by Zak M

[Tim Bland]

Nationwide snow event at day 10 and easterly coming...

[tight isobar]

1 minute ago, nick sussex said:

Quite remarkable pattern showing up at T228hrs .

You can follow the isobars from Russia to Newfoundland , talk about reverse zonality !

 

Is the dripping being factored in already???@ssw.. surely not.. but?!?!?!?

[winterof79]

Here's a daft thing

GFS 144Z

UKMO 144Z That's an easier route to Greenland than GFS

Edited December 28, 2020 by winterof79

[Mucka]

The main difference between UKMO and GFS starts at 96h with the Atlantic low, GFS is a little slower and has it disrupt SE whereas UKMO has most of the energy pushing NE flattening the ridge more.

I think GFS has probably over egged the pudding but UKMO under-egged it and blend is probably best bet.

 

GFS progression 96/120

UKMO progression 96/120

 

That would mean we would have a good shot of the high retrogressing enough NW to allow a trough to drop S on its Eastern flank with to open the flood gates but it would just be a little delayed as compared to GFS Op and the pattern a touch further E.

Not overly happy with the UKMO though it is not a bad chart by any means. 

ECM will likely be better than UKMO and maybe the boom run of the night. We will see.

[MATTWOLVES 3]

I'm not sure the GFS as gone crazy...its becoming anxious at its favourite Atlantic kind of weather not being anywhere to be seen..keep in mind this model is well known for going zonal at some point in its run....where are you Atlantic...Good lord we have potential snow makers cropping up all over the place..This could be epic,if these trends continue..and trust me the signs are good,when Mr GFS as know interest in zonal at all. God im excited  

[Kasim Awan]

GEM looks reasonably tilted with the retrogression.

[Met4Cast]

The GFS is surely showing a QTR to any potential SSW? Almost instantaneous, in fact. This is what a complete zonal and Atlantic shutdown looks like. Easterlies stretching from Russia to Canada!!!

[Harsh Climate]

Am I right in thinking that the met office 'no indications of exceptionally cold conditions occurring anywhere' in their long range forecast will be dropped tomorrow? 

From looking at the latest output we are on the cusp of something very big!

[Cuban Zebra]

OMG!! I’m watching the rest of this run from behind the sofa!! Look at the depth of cold that looks to be incoming.

Also, the distinct lack of cold over the other side of the other side of the Atlantic is as equally impressive!

[Weather-history]

13 minutes ago, Sweatyman said:

Can you explain why Bonkers WH ? Cheers!

Viewing it through wetterzentrale but you just get use to see purples and deep blues at the 500hpa levels on charts, even the classic winters have them 

But with that GFS run, its hard to grasp

 

[sheikhy]

4 minutes ago, Mucka said:

The main difference between UKMO and GFS starts at 96h with the Atlantic low, GFS is a little slower and has it disrupt SE whereas UKMO has most of the energy pushing NE flattening the ridge more.

I think GFS has probably over egged the pudding but UKMO under-egged it and blend is probably best bet.

 

GFS progression 96/120

UKMO progression 96/120

 

That would mean we would have a good shot of the high retrogressing enough NW to allow a trough to drop S on its Eastern flank with to open the flood gates but it would just be a little delayed as compared to GFS Op and the pattern a touch further E.

Not overly happy with the UKMO though it is not a bad chart by any means. 

ECM will likely be better than UKMO and maybe the boom run of the night. We will see.

When looking the ukmo 120 hour chart you wouldnt expect the 144 hour to look the way it did!!i expected more of a ridge going further north and east towards scandi and a stronger easterly flow further north across the uk!!

[Man With Beard]

Latest ARPEGE is pretty generous with snowfall across the UK by this Friday (worth adding this is falling snow, not laying snow)

Edited December 28, 2020 by Man With Beard

[winterof79]

The gift that wont stop giving.....we need BIG shovel now ma .... make sure our Tom gets to school tho

 

[Tim Bland]

GEM takes the middles ground between GFS and ECM Weds eve with 10cm in the south..dare is say south of the M4

[Weathizard]

The 12z between day 6 and 10 just doesn’t look right to me, it’s way too quick at first and then spends days moving that low south, another option on the table though... and it still leads to cold. 

[Matt H]

Insane synoptics on the GFS(p) 12z as well. Very grateful for these model runs at the moment, it could be years before we see anything like this again.

[nick sussex]

Ideally you want any shortwave tracking more se from the north especially if it becomes deeper .

The GFS although quite outlandish and interesting from a purely NH view is in danger of being too clever for its own good .

The problem with its more sw track is that could phase with shortwave energy in the mid Atlantic and deepen . You don’t mind phasing with shortwave energy to the east .

As much as the GFS is nice to look at it could turn into one of those Christmas  chocolates , looks great from the outside but has one of those horrible yuk liqueur fillings ! 

So thanks but no thanks . This might seem strange to be moaning about it but always best to be on the look out for what can go wrong rather than right ! Built in margin for error is what I’d like to see . The GFS could easily go wrong so I’d hope for a more favourable shortwave track in future runs.

Edited December 28, 2020 by nick sussex

[Daniel*]

God this is wacky.

[DanDorsetUK]

4 minutes ago, Met4Cast said:

The GFS is surely showing a QTR to any potential SSW? Almost instantaneous, in fact. This is what a complete zonal and Atlantic shutdown looks like. Easterlies stretching from Russia to Canada!!!

Certainly looks that way, been waiting to see the signs of this. It will be a fast response.

[Kasim Awan]

Just now, Frosty Winter said:

Insane synoptics on the GFS(p) 12z as well. Very grateful for these model runs at the moment, it could be years before we see anything like this again.

Weather works in cycles etc. So don't be surprised if we see a cluster of more blocked winters.

[snowking]

There shouldn’t just be alarm bells ringing from this most recent GFS run, there should be great bit gongs, some sort of alarming strobe lighting, and just in case that’s not enough, someone should be available in a town-cryer/Brian Blessed type role (we might have to take it in shifts) to shout that we should not take anything past day 5 right now with anything other than passing curiosity.

When we have a model run sending a low pressure system the “wrong” way, the dynamics are going to be incredibly difficult for a model to forecast with any sort of accuracy.

Fascinating watching. I still suspect the retrogression is too fast here but we shall see

[winterof79]

If this run sits within the ensembles regarding precip/ evolution  etc were in the doo doo.

[Weathizard]

Improved mean at day 7

 

Edited December 28, 2020 by Weathizard

[Beanz]

3 minutes ago, Tim Bland said:

GEM takes the middles ground between GFS and ECM Weds eve with 10cm in the south..dare is say south of the M4

I think if I were to put a probability on this, it might actually be creeping above 10% now...  

Accumulation does look impressive though.