Model output discussion - Closing in on Christmas

[Scott Ingham]

22 minutes ago, stewfox said:

What Artic are you referring to ? Looks pretty standard to me at present cf 1958-2020 average. Cant see the 'much warmer'

Doesnr that show the arctic above average and has stayed above for some time now?

[Lukesluckybunch]

The way I see things over the next couple of weeks is,of course turning colder possibly much colder,looking at the charts I would say there is 60/70% chance of that happening! Currently honestly I don't see anything too wintry for a few reasons,but of course all that could change very quickly.I really hope that it does as the potential is quite big right now,have others mentioned a few adjustments could make big differences!

[weirpig]

1 minute ago, Scott Ingham said:

We dont want it perfect now as well end up too far east come T-0 where we are now with the evolution is perfect as we factor in historical shifts east nearer to time in thid set up 

Agreed  I would rather the evolution require tweeks   now  then perfect     my main point was  regardless of how beautiful the ecm looks   the reality  is that its a  rather disappointing outlook ( based on that run)   however it looks like the heights towards Greenland are locked in   many days left to see any upgrades   and I do expect  there to be   fingers crossed 

[Scott Ingham]

10 minutes ago, Lukesluckybunch said:

I would kind of agree with you there scott,that's a possibly past day 10.but it's very difficult to tell anything could happen,though what doesn't look likely currently is a return to westerlies and Atlantic weather,but if we continue having to chase day 10 charts it can become very frustrating

Weve got encouraging charts at T-144 currently. Well see what happens. The greenie high has come about in the week i expected it to well see for the next stage 

[North East Blizzard]

33 minutes ago, That ECM said:

Indeed, a lot imby posts. I live in arguably one of the worst places for a northerly but  nhp is quality. Here we are last in line for some fun but we are very patient and what follows could be fun. some places will see snow from this I’m sure and I look forward to seeing some myself but I enjoy going in the regionals and see adults excited as child posting pics of snow. Could move of course but I love the south coast too much

Yeah sorry, it was a little imby

In all seriousness though, we've been in far worse situations than this and with a little patience i think anywhere could get lucky. The 850's don't make as much of a difference in a set up like this, will be colder on the ground than some think. 

[KTtom]

With all due respect to this concept that we need to be XXX miles west at + 168 hours because it will 'always' shift east when we head towards T-0, bearing in mind these 'super' computers must cost more than ill ever earn to make and run, dont you think the software experts would factor this in it it were true? ..Just a thought..?

[Matt H]

ECM 12z ensemble mean has the low further east at t168 compared to the op and there’s a more direct northerly flow at t192!

[Lukesluckybunch]

1 minute ago, Scott Ingham said:

Weve got encouraging charts at T-144 currently. Well see what happens. The greenie high has come about in the week i expected it to well see for the next stage 

Agreed we do get the amplification,it's just crucial as to where that trough from the northwest tracks

[Weathizard]

Nice ECM mean, improvement on the 0z

[Chesil View]

I know its not the met office forecast thread but what I am going to say is MODEL related because the met office extended outlooks have changed due to what the various  MODELS  changing and presumably what their own MODELS are suggesting.

So a week and half ago it was likely turning milder  in the first week of january,  earlier this week that then became likely to turn milder mid January now it remaining generally  cold with possible  ( not definite) short lived milder incursions.  

 

 

L

[Griff]

2 minutes ago, Scott Ingham said:

We dont want it perfect now as well end up too far east come T-0 where we are now with the evolution is perfect as we factor in historical shifts east nearer to time in thid set up 

9 days ago towels were being thrown in and pram toys ejected. A week ago the charts were ridiculed as pure fantasy. 

Ever since almost all of us have been sensible enough to say it's speculative at best, yet here we are. 

Netweather panto season in full swing, oh no it isn't - oh yes it is. 

This year's production is Goldielocks... It's too warm, no it's too cold... Etc etc. 

Some excellent comments, some reverse psychology evident too. 

Relax with a Grolsch... You can't rush these things

 

 

[Scott Ingham]

9 minutes ago, damianslaw said:

Just based on current outputs and this is by no means a forecast, thicknesses are conducive for low level snow, and the slacker airstream will probably help as well. As I said dewpoints are the crucial factor and we can't say for any certain what these would be until the very very very near timescale.

Nice to see someone else thinking the same. I agree. Get dew points on the right side of marginal and anything minus 4 and below uppers and well see snow lying at low levels

[Mike Poole]

Mean at T240 wasn’t quite what I expected:

The trough looks better placed from UK through Southern Europe.  

Just add in the spread, still doesn’t know quite what to do southern tip of Greenland:

Edited December 20, 2020 by Mike Poole

[Geordiesnow]

Just now, Ultima Thule said:

That graph is awful if you like cold.  Almost never below average, and it's only the ice melt in the summer that is helping suppress positive anomalies at that time.  

Wake up!

Well yeah the Arctic is warmer than average especially in autumn as the sea releases heat back into the atmosphere but the cold upper air temperatures are there. I think the problem with this set up is not down to the lack of cold air in the Arctic, its more down to the origin of the trigger low as another poster pointed out earlier in the day. 

The low is very large also, would of been better if it was more smaller and the other problem any ridge is at the wrong angle hence not getting the full northerly flow but that said, details will change for better or worse but as per the start of the month, it would be a wasted opportunity if the low just ends up over us and more modest uppers as a result. 

[weirpig]

3 minutes ago, Weathizard said:

Nice ECM mean, improvement on the 0z

Mean  is great   looks like many are bringing the low further east   with lowering uppers as a result  

 

[Catacol]

Loving this now. ECM at 240 won’t end up being exactly like this, but the core ingredients desired throughout the winter are still there

Note again the rise of pressure of ScEuro zone and a profile in the North Pacific that encourages low pressure fizzing across to the Rockies and helping promote a ridge higher up into the arctic.

I think this spells curtains for the vortex. I wouldn’t want to put a strict timeline on it, but first half rather than second half January now looks a decent bet.

For us? Let’s put together a best case scenario forecast:

1. Cold air arrives at Xmas. Favoured spots bag some sleet and snow as temps fall.

2. Greenland ridge gets enough traction to the north to embed, and given falling vortex wind speeds, a GLAAM profile that is relatively neutral and an MJO still in favourable phases it sticks around. Late December the trough over the U.K. therefore embeds also, colder air drawn SW from Scandy. Wintry mix.

3. Wave 2 forcing on the vortex around New Year adds increased strat stress. Frictional torque will begin to rise again during the first week of January. The trop pattern may relax a bit, but as frictionals promote increased mountain torque we will see amplification rise again. This amplification may be the knock out blow and an SSW. Week 2 of January.

4. For the U.K., given lengthening seasonal wavelengths this would see the block ridging east to Scandinavia

5.  The vortex splits and drops daughter vortices either side of our block, and a 2018 repeat occurs with trop impacts within 2 weeks. Vortex shard drops into Eastern Europe, reversal of the pattern pulls bitter air under the Scandy block as we hit the last 10 days of January.

This process would guarantee a cold January and in particular a very cold end to the month. No significant Atlantic influence at any stage. This represents my best case scenario mapped out in November but about 2 weeks ahead of time. The vortex has been hit harder in December than I expected back then.

Lots that can go wrong with this very cold-centred forecast but broadly speaking it stands a chance of sorts. This kind of severe potential event is what I’m on the winter forums for - and to see if we can spot things ahead of time and get one over on gloomyglosea...!

Edited December 20, 2020 by Catacol

[Met4Cast]

15 minutes ago, Scott Ingham said:

Its mot just one ecm run though is it? Its the past 9 gfs runs and the fact gfs knows how to model this pattern. Those who have seen it all time and again were waiting for the ecm to junp on board like it did 2018 and 2010 and -5uppers with l9w heights a slack flow and sub minus dew points will produce snow somewhere. We just dont know where yet but it will not be all rain. Its frustrating saying the same thing over and over hahaha its like people psychologically are trying to find the first negative so they dont build hopes up! Hahaha! 

Where is the background forcing for sustained blocking? Where is the EPS support? It's going to turn chilly, yes. But those expecting a huge Greenland block are going to be rather disappointed. 

[Scott Ingham]

11 minutes ago, sheikhy said:

Absolutely spot on mate!!!

Yes mate! Too much pesimism on here. Well see i guess!

[Lukesluckybunch]

1 minute ago, Mike Poole said:

Mean at T240 wasn’t quite what I expected:

The trough looks better placed from UK through Southern Europe.  

Not such a bad mean there mike,but the lack of cold to mix in with is concerning in my opinion.did you think this is a good mean then?

[sheikhy]

1 minute ago, Mike Poole said:

Mean at T240 wasn’t quite what I expected:

The trough looks better placed from UK through Southern Europe.  

Serious upgrade on that!!that middle ground solution gona look really juicy in the morning!!!cant wait!!

[Vikos]

For me, EC 12z is an outlier

[sheikhy]

1 minute ago, Scott Ingham said:

Yes mate! Too much pesimism on here. Well see i guess!

Check the mean out

[Kasim Awan]

The sounding profile, i.e. freezing level, warm layers, are crucial. And hi res output which nowadays models evaporative cooling well.. HIRLAM for example was very good with the 4th Dec event.

I have personally made an initial assessment on Xmas eve snow line, risk etc.

In terms of todays output, yes it's good but not incredible. Trough precip would potentially be somewhat marginal in places, even with the lower heights. However, there is time for the output to change it's upstream handling and therefore cool down the uppers. I think uppers usually decrease within 100h due to higher resolution. I would also like to see a weaker low as this would allow better meeting of the air masses, i.e. the cold air into the precip zone helping to produce snow... The air mass meeting discussed in smaller lows also helps trough formation. I fear on the ecm the low is too large for this to be particularly effective...

So. The broad scale evolution is full of potential. That potential will be better realised under a few tweaks. Further east for reasons already discussed and as above. All I want for Christmas is a weaker low on a more easterly trajectory! 

[Lukesluckybunch]

2 minutes ago, Scott Ingham said:

Yes mate! Too much pesimism on here. Well see i guess!

Well it's not pesimism people are just being realistic

[Scott Ingham]

9 minutes ago, weirpig said:

Agreed  I would rather the evolution require tweeks   now  then perfect     my main point was  regardless of how beautiful the ecm looks   the reality  is that its a  rather disappointing outlook ( based on that run)   however it looks like the heights towards Greenland are locked in   many days left to see any upgrades   and I do expect  there to be   fingers crossed 

Yeah I get you mate. My point was its an excellent run when you factor in eastward shifts nearer to time