Model output discussion - January cold spell ending, what next?

[Froze were the Days]

21 minutes ago, Tim Bland said:

ECM is a snowless run but look over the pond...80cm... wouldn’t take much to shift it our way

Are you kidding?...general rule of thumb when the continent goes cold it takes a lot to get it this way, but yes sods law  if we go by that chart.

[Man With Beard]

Becoming a scratched record this, 18th Jan, Atlantic High goes up. Will it count down like clockwork as the "classics" do?

[bluearmy]

5 minutes ago, mulzy said:

Yes, I guess the scatter is quite large but more likely an outlier but an interesting evolution.

For anyone that’s bothered the control brings a BFTE with -15c uppers ..... de bilt will look a tad fresh later .....

[Matt H]

ECM 12z mean at day 10 definitely looks cold.

[That ECM]

2 minutes ago, bluearmy said:

For anyone that’s bothered the control brings a BFTE with -15c uppers ..... de bilt will look a tad fresh later .....

Any support for it? 

[Kentish Snowman in Yorks]

52 minutes ago, General Cluster said:

I do hope that @Steve Murr's somewhat less than positive post, above, doesn't lead to a mass consumption of Kool-Aid... I mean, come on -- one post by one person -- and the whole of NW is on Suicide Watch!

I always see 'negative posts by big Steve as a positive as they are often followed by Stella model output!

With that in mind eyes down for a pub run special! 

[feb1991blizzard]

1 minute ago, bluearmy said:

For anyone that’s bothered the control brings a BFTE with -15c uppers ..... de bilt will look a tad fresh later .....

It also means there will definitely be a -10c line added on the ECM 2m temperature London graph and might even be a -15c line added when the 12z comes out later!!!.

[bluearmy]

2 minutes ago, That ECM said:

Any support for it? 

I think about 16% on the clusters pre day 10 - nothing post day 10 on the clusters 

[Battleground Snow]

4 minutes ago, Man Without Beard said:

Becoming a scratched record this, 18th Jan, Atlantic High goes up. Will it count down like clockwork as the "classics" do?

The para has counted this down from about 300 to what is now 192-216... Admittedly it has dropped the signal on the odd run.

@Griff

[Mike Poole]

Couldn’t resist scribbling on the ECM mean T240 chart, yes it is a mean, but you can get an idea of why there is excitement in terms of a cold spell of weather:

Circled red is the arctic high that has resulted from the SSW.  The black arrow indicates further WAA into Greenland, the yellow arrows track the deep cold around the arctic high and, if all goes to plan, the upcoming Greenland high to the shores of the UK.  The individual op runs obscure this pattern which is how I think it will evolve.  

Edited January 9, 2021 by Mike Poole

[Tim Bland]

3 minutes ago, Battleground Snow said:

The para has counted this down from about 300 to what is now 192-216... Admittedly it has dropped the signal on the odd run.

@Griff

12z Para has 24hrs of proper cold (allowing for snow) in the south

[bluearmy]

1 hour ago, Steve Murr said:

A pretty poor day model watching.

UKMO has trended flatter, ECM also poor all the way out past 192.

We are pinning hopes on outputs past 200 again which is always dicey at best.

Shame really just as the deep cold was getting going like the good old days...

Seems odd to be looking at means and anoms at day 10 and thinking they will verify with the post  ssw fall but the spread isn’t high on the low heights and the clusters seem to all be on the same page 

the spread on uppers shows those low temps headed west from Russia into e Europe ..... 

[northwestsnow]

Just now, bluearmy said:

I think about 16% on the clusters pre day 10 - nothing post day 10 on the clusters 

Well, some kind of Atlantic block and a dropping trough through Scandy look a good shout.  

Can we get the latitude on any block to drag the really cold uppers towards us?

 

[Battleground Snow]

2 minutes ago, Tim Bland said:

12z Para has 24hrs of proper cold (allowing for snow) in the south

Yes on its current run, but if you look back at its last 10 -12 runs you will see a lot of Greenland blocking and cold uppers in general over or near the UK.

Edited January 9, 2021 by Battleground Snow

[stodge]

Evening all

Before I do my nightly bletherings, thanks to all who provide similar or slightly different. We all have our different perspectives and it's good to see the debate on here.  Most bring evidence-based argument to this forum and long may it continue.

Last night's output did nothing to dispel my confusion of recent days - the considerable divergences in synoptic evolutions across and within the models at unusually short ranges suggest a plethora of signals (or perhaps no strong signal). The significant trend towards a milder evolution have been displaced by synoptically more interesting charts. In essence, it's the perennial battle between competing air masses and as is all too often the case the battleground is the atmosphere over the British Isles. Mild or cold, rain or snow, step up and placez votre bets as I'm sure they don't say at Monte Carlo.

12Z GEM: the most bullish initially for a milder solution, GEM backtracked quite a bit last evening toward a (briefly) colder spell before the re-assertion of mild at T+240. T+120 tonight take sus to Thursday and we can see the battleground scenario evidenced. HP to the south and heights building into Scandinavia bringing a frigid air flow out of Russia while the Atlantic trough extends to the north and west of the British Isles and between these systems a W'ly flow covers the British Isles. Despite that, the briefly positive uppers have been chased away by cooler air (zero to -4) returning from the north west and I also note the sharp gradient in the uppers over Central Europe. From there, well, nothing much happens. The Atlantic LP disrupts to the west as heights try to build through the British Isles but a small LP make sit through before filling up to the south-east. By T+180, the flow is slack from a mainly W'ly point. Frigid air is over central Europe by this time but for the British Isles it's mildest to the west and coldest to the east with a broad spread of zero to -4 850s.  A cut-off trough remains in the Atlantic and this moves SE across the British Isles by T+240 and with heights building to Iceland a NNE'ly flow is established over the British isles with uppers generally below -4 and if you like that sort of fans, there's a nice area of -24 850s over north-west Russia and east Finland.

12Z GFS OP - GEM offers an oscillating background with little or no push from the Atlantic side. The American models were perhaps the most synoptically interesting yesterday - in FI it was real battleground stuff. Tonight, well, let's see. By T+120, notable differences with respect to GEM. The Scandinavian heights are better defined and the small area of HP has phased with the ridge from Iberia to put the whole of the British Isles (except the Hebrides) in a slack flow. There are milder incursions and by T+120 the 850s are zero to -4 with some very cold air over Germany. From there, it's broadly an anticyclonic tale with heights over or to close to the British Isles but by T+180 there's a slack trough to the north and a shallow feature over Europe but for most of the British Isles it remains calm with uppers broadly negative but varying from zero to -8 with coldest uppers to the north and east in a slack flow. From there, it gets "more interesting". Atlantic heights build north to Greenland and the Scandinavian trough drops over or to the east of the British isles drawing in a potent N'ly by T+240. It's much colder with -8 850s widely and -12 850s approaching from the Faeroes.

12Z Parallel - so that's 2-0 for the cold evolutions out to T+240. Parallel is always one of the more intriguing model sets. The T+120 perhaps closer to GEM than the OP with heights to the south, the north and north east and the Atlantic LP to the south of Iceland pushing in a flow of WSW'ly winds which have brought positive uppers to western regions and it's generally milder across the British Isles.  From there, it's a very different evolution as an Atlantic LP deepens and moves NE to the west of the British Isles. New heights extend it from Iberia to Greenland while a weak HP persists over Scandinavia. It remains mild over the British Isles at this time. From there, the LP spins round and eventually eases towards the British Isles. Strong heights over Greenland look to be sending the jet south but the trough has expanded from the original cut-off LP to form an elongated trough across the Atlantic and into Europe. Secondary LP are forming in the flow to the south and a frigid airmass is coming over Scandinavia with -24 uppers. For the British Isles, it remains on the mild side - more so in the south than further north.

 

12Z ECM - I'll be honest - the parallel evolution from T+120 looks nonsensical and is symptomatic of the model output "struggling" with the data and the signals. ECM should provide some sanity though I wouldn't put my money (or yours) on it. ECM's T+120 illustrates the Battleground situation well, The British Isles is on the warm side of the struggle with an HP to the south-west and LP to the north-west. However, colder air isn't far away with heights over Scandinavia and a residual cold flow over Eastern Europe. Average temperatures over the British isles at this time. By T+192 ECM has gone on its own journey - a million miles from Parallel (see above). The Iberian HP expands into a significant anticyclone to the south west but small troughs extend south down the North Sea from the north leaving a weak N'ly flow over much of the British Isles. Colder air with -4 850s is established by T+192. From there, the HP edges a little further west but ridges north toward Iceland. Heights persist over Scandinavia and that allows a shallow LP to linger close to southern England with a draw of ENE'ly air across the British Isles. It's got colder again with -4 to -8 heights generally.

I make that 3-1 to cold by T+240 but all by very different routes so the overriding message remains the number of options on the table but none of them showing a raging Atlantic and long-fetch SW'lies from huge LP systems created by strong cyclogenesis. 

Looking further on, GFS OP and Parallel at T+312 and T+384 respectively.

Those raging Atlantic SW'lies I was mentioning a moment ago - there they are in the furthest recesses of FI on both OP and Parallel. Both bring back a strong PV in the last third of the month to Greenland and NE Canada - is this a response to the next round of wave 1 warmings?

12Z Control is cold for most of the run - it doesn't bring as much of the PV back either.

On then to the 10 HPA charts - Control keeps the PV weak and disorganised though it shows some sign of rallying at the end of FI. The OP leaves the PV shredded under a succession of warmings, Parallel maintains a more robust PV despite the warmings.

Confusion II - this time it's personal: - there seem to be more routes to cold in the medium term. It will warm up a little in the shorter term but the colder air is close by and the evolution to something more anticyclonic seems one option and with a sluggish Atlantic amplification opening the door to a push of cold from the north or east remains firmly on the table, Developments into further fI looks driven by the PV but I'm finding the GFS OP and Parallel evolutions harder to reconcile with what's happening. There will be a recovery of zonal winds from the current reversal but that's to be confirmed - the theory seems to be more wave 1 warmings from the Siberian side will send the PV back over to the Atlantic and as zonal winds pick up so will the jet as we head into the latter part of January. I'm far from convinced.

[Griff]

6 minutes ago, Battleground Snow said:

The para has counted this down from about 300 to what is now 192-216... Admittedly it has dropped the signal on the odd run.

@Griff

I'm keeping  

 

[chris55]

20 minutes ago, Mike Poole said:

ECM mean T240, yes I’ll take all you’ve got of those, please:

Looking at the NH profile Scandinavia/Europe/ U.K. is the best place to be for channeling the flow from the Arctic! Pretty flat everywhere else on the globe! North America in the game but with a much weaker ridge. 
 

Obviously at day 10 the mean is well ironed out....so this signal is very good for us I think  

 

Edited January 9, 2021 by chris55

[bluearmy]

10 minutes ago, feb1991blizzard said:

It also means there will definitely be a -10c line added on the ECM 2m temperature London graph and might even be a -15c line added when the 12z comes out later!!!.

Looks like London down to -8c min on that 12z control run ... 

[XtremeUKWeather]

1 minute ago, bluearmy said:

Looks like London down to -8c min on that 12z control run ... 

Where can we see this

[MATTWOLVES 3]

Christ on a bike, i was just having me worthers original when I nearly choked on it...I wasn't expecting that from the EC mean...what an improvement....im happy now,I hope all of you are too...now go and kick back and relax...things are moving in the right direction it seems...

[bluearmy]

3 minutes ago, XtremeUKWeather said:

Where can we see this

You can’t afaik .....behind paywall 

[Man With Beard]

Still a massive temperature spread on the ecm ensembles next Wednesday. Mean maxima for London 3C and below from D10-D15 inclusive, including ice days within the main spread

 

ECMWF 14-day ensemble weather forecast for London

WEATHER.US

---

London, England, United Kingdom - The ideal weather forecast for the next 14 days. See the results of all 50 ensemble members of the ECMWF model in direct comparison for several parameters.

 

[ICE COLD]

Wow I’ve gotta admit I was feeling a bit down on today’s output , just feels like we’re chasing shadows lol . BUT then the ECM ens and mean come out and it’s really good . Please for the love of  god give us cold snow seeking netweather nutters are winter . Some really cold ens appearing now some down to  -9 850s .

[Tim Bland]

9 minutes ago, Battleground Snow said:

Yes on its current run, but if you look back at its last 10 -12 runs you will see a lot of Greenland blocking and cold uppers in general over or near the UK.

Fair enough, I take your point.   Over the last few days there has always been some eye candy within each set of runs (06z / 12z / 18z etc) but the 12z is the fist set where the ops have failed to produce, let’s hope the 18z sets us back to at least dreaming about proper snow !

[feb1991blizzard]

4 minutes ago, bluearmy said:

You can’t afaik .....behind paywall 

It gets down to -15.3 as it happens!