Model Output Discussion - Colder spell ending, what's to follow?

[Eagle Eye]

52 minutes ago, Kentish Snowman said:

I am not convinced Xander quite has the hang of this thread yet?!

Posts a random chart is asked what it relates to and then shrugs his shoulders! 

And Steve Murr leaving the group chat works every time without fail like clock work.

Steve declares winter is over leaves the chat.  Wintry nirvana immediately appears in the output!

Joking aside we are in a better place than we were this time yesterday in terms of a cold Christmas.

Definitely more amplification appearing at the right time frame that is for sure.

Fingers crossed for a continuation of the good news on that front when the 12z runs start rolling

I was joking, if you want me to analyse the chart I can. 

[Skullzrulerz]

21 minutes ago, Jeremy Shockey said:

MJO heading towards phase 6 perhaps ?

What does Phase 6 mean?

[matty40s]

4 minutes ago, XanderP007 said:

I was joking, if you want me to analyse the chart I can. 

Yes please.

[Eagle Eye]

On 10/12/2020 at 20:22, XanderP007 said:

https://images.meteociel.fr/im/3240/anim_wyt4.gif

 

On 10/12/2020 at 20:25, matty40s said:

So what does that show us Xander

That shows us that we could have a windy low across northern UK and a deep but less windy low across the rest of the uk could ve the sign of snow with a cold enough day. 

[Jeremy Shockey]

17 minutes ago, Skullzrulerz said:

What does Phase 6 mean?

Hi Sk , a greater probability of N Atlantic amplification , regards JS

[Radiating Dendrite]

12 minutes ago, XanderP007 said:

 

That shows us that we could have a windy low across northern UK and a deep but less windy low across the rest of the uk could ve the sign of snow with a cold enough day. 

Windy everywhere on that chart, especially North West. Wind from the west, too mild for snow but likely wet with bands of rain / showers. 

[Radiating Dendrite]

1 minute ago, Jeremy Shockey said:

Hi Sk , a greater probability of N Atlantic amplification , regards JS

looks pretty amplified as well. 

[Eagle Eye]

1 minute ago, Radiating Dendrite said:

Windy everywhere on that chart, especially North West. Wind from the west, too mild for snow but likely wet with bands of rain / showers. 

Less windy down south though.

[Allseasons-Si]

The ext EPS shows that Atlantic ridge post Xmas.

[alexisj9]

2 hours ago, alexisj9 said:

I actually like that one, depending on what it does next obviously, if it keeps moving east with those cold uppers it'll be game on. Just a bit late for Christmas obviously. As it's only one pert, probably not a strong signal for this though.

Obviously I meant keeps moving the cold uppers to our east coast and over. Should have put west. Don't want them to move east from Asia lol.

[Kentspur]

The CFS must have seen my post a little while ago as it couldn't be any different post Xmas now- With longfetch SWlies and +8c upper air temps instead of a Beast, maybe it will flip back to a Beast on its next run, I always look at each run and  then for the same period see which runs have forecast more colder vs milder runs, the same with the monthly CFS anomaly forecasts

[Catacol]

5 hours ago, bluearmy said:

wouldn’t surprise me to see a mild Xmas ....the pattern is mobile at our latitude - I’m surprised that so many amplified NH gefs members are showing each run ....if that ship had truly sailed then I wouldn’t expect to see so many each suite - that tells me the trop and lower strat remain prone to blocking with a persistent neg AO.  The NAO also negative though a lack of continental cold means this is of no use to us re possible snowfall .....

anyway, I see enough in this mornings output to retain my interest post Xmas - we realise that a lack of upstream amplification has meant we didn’t take advantage of what looked to be decent set up ...... now it seems that we could get that amplification later week 2 .....

will it be too late ??  

will that amplification have disappeared by tomorrow ! 

The amplification will come - momentum cycle dictates it. But just how amplified it will be is the question and just how weakened might the vortex be after wave impacts begin to fade in a week’s time. For now the vortex is under attack, and we can watch and wait and cross fingers that it gets a decent battering.

This is attack no 1. Attack no 2 will come around New Year. And then the lag impacts of that attack might possibly set us up for an interesting end of January. Having said that in a Twitter poll Amy Butler has plumped for a SSW before the first third of January is out - and she is well worth listening to. That would throw the cat amongst the pigeons and chances for earlier cold.

Lots of negativity yesterday and disappointment as amplification from the +EAMT didn’t prove enough. But it’s still early...

[That ECM]

T144 Ukmo. Met still extremely low confidence. Much interest as we move forward. Going to be fascinating to watch.

[Skullzrulerz]

57 minutes ago, Jeremy Shockey said:

Hi Sk , a greater probability of N Atlantic amplification , regards JS

Thank you

[That ECM]

More heights NE USA. We’ve seen models flip for bad numerous times however there have been rare occasions where they flip for good. Artic high drifting our way?

Edited December 12, 2020 by That ECM

[Catacol]

Quick flick through the Berlin strat charts and impacts on the vortex have increased on the most recent run. Wave 1 forcing is up a bit even at short range, and the split in the vortex goes as high as 30hpa. All good signs that this first attack is doing some damage. 

[Ali1977]

This could be good for Xmas eve, that would be good timing!! As long as the low around Newfoundland doesn’t knock the WAA attempt out the water that is!! 

Edited December 12, 2020 by Ali1977

[TSNWK]

Still looking ok for a chilly and blustery as we edge through the week up to Christmas.. upstream looks a little amplified

Nope Ali you were right that little low flattens it around 258 and we lose a Christmas chill on this run.. short waves".......

Edited December 12, 2020 by TSNWK

[Mike Poole]

If the MJO induced amplification is going to happen it should start to appear in the model output.  GEM 12z has that amplification at T240, and looks promising going forward, but anything cold in the 0-10 day range looks very unlikely to be honest:

[Tim Bland]

12z not as good as the 06z for amplification in the Atlantic unfortunately (see below for comparison) Hopefully Xander will do an analysis of all 30 ensembles later ...

[IDO]

Better amplification in the Pacific on this run thanks to troughing over the W Pacific:

On this run we get one of those spoiler lows on the jet that kills the nascent Atlantic ridge:

This will no doubt change many times before T0? It is the trend that is important at this range, get the Pacific Ridge into the game and there will be a good chance of cold downstream from the resulting wave.

[Ventnor Viking]

So close again....Not enough amplification this run, that combined with a strong jet keeps things moving rather than forming. 

We aren't a million miles from something decent. The jet needs to weaken and shift south then that will allow for the amplification to take place. I cant see this happening before christmas. It will more than likely happen new years time, if at all. Looking at the longer range models, its looking like a milder end to the winter so something needs to happen sooner rather than later. 

[Vikos]

6 minutes ago, Tim Bland said:

12z not as good as the 06z for amplification in the Atlantic unfortunately (see below for comparison) Hopefully Xander will do an analysis of all 30 ensembles later ...

If you would compare to yesterdays 12z that would be way better for analysis, due the fact that 06z and 18z differ in (less) data input as as I know.

[Mucka]

An observation.

Aside from the run to run variation of GFS operational FI the trend is toward a more amplified Atlantic sector but something that has started to appear in the output is for the Scandi ridge/ Eastern block to fight back in the 7 day+ range and not be so easily swept away as we have been seeing.

Perhaps that signal will disappear again but let's see if ECM goes the same way in 7/10 day range.

If that does develop then it is important we get the undercut so that the trough still pushes through which will raise heights to our N and W, ideal for a link up with any Atlantic amplification thereafter.

We could see some flipflopping between horror charts of wet mild and windy and wintry Nirvana over the holiday period if this is the case depending on whether the trough stalls and fills over the UK or undercuts any reinvigorated ridge.

If the trough pushes through as previously modelled then we will just be looking for the Atlantic ridge to bring real cold and/or any polar maritime flow to be more N than W in the run up to Xmas.

TWT.

Edited December 12, 2020 by Mucka

[Methuselah]

Oh dear, I guess my teddies will be having a picnic!