Model Output Discussion - Into the new year

[Matt H]

6 minutes ago, Met4Cast said:

Hot off the press! The latest EC46 update has blocked the Arctic off right through until week 4. Strongest signal yet!

I can't remember ever seeing such a persistent signal.

Clear demonstration of the UK high right there (sorry couldn’t resist)!

[XtremeUKWeather]

4 minutes ago, Matty J said:

IMO the UKV has it too far south currently.
 

The 6:55pm forcast on the beeb was quite suprising really, snow plastered all over EA and the Southeast. I usually find they are the last to show what we are ramping about in here so they must have a degree of confidence  

BBC graphics on telly use ECM i think thatsw= why

 

Edited December 28, 2020 by XtremeUKWeather

[kold weather]

17 minutes ago, lorenzo said:

Oh go on then... don't think anyone here would complain...

Yeah thats abit of a stonker, the evolution is certainly on the table. The threat of a rapid switch over to a west based -ve NAO has reduced somewhat today, and even if it does happen the mid atlantic block looks to hold long enough that any LP attack from our SW starts from a decent position instead of starting way out in the mid Atlantic like some of the models were trying before.

[Griff]

No doubt this will get lost under a deluge of strat and -nao based excitement, but I can't for the life of me remember a week ahead forecast IMBY across multiple weather services with daytime temperatures of 1°c showing precipitation type as rain?!?

Presumably 2m surface temperatures, but dew points must be higher than 0. Not sure what's happening, are we under inversions?

[sheikhy]

6 minutes ago, Howie said:

It's been very consistent with this as well 

That ecm 46 has to be one of the best if not the best updates i have ever seen!!defo one for the archives!!!!!

[Snipper]

59 minutes ago, Tim Bland said:

The Met are obviously taking note of the ECM rather than UKV though if they have issued a warning right up to midlands?

Yes but the word “slight”. Is used

[Guest]

57 minutes ago, Kentspur said:

The more  Southern coastal members will no doubt prefer the Arpege outcome of course, still with a very small amount around London and the Thames region on that too

Not wrong, ECM is warm sector hell with onshore winds for the south coast and no benefit from the wrap around. It’s an absolute nil poi down here. Arpege all the way. 

 

[Beanz]

24 minutes ago, Mark wheeler said:

Can you show me where to find this please .

It’s on the fax chart that @That ECM just posted (sorry, was having my dinner!) and it’s also on their animated forecast that popped up on my Facebook feed - if you do Facebook and follow the Meto

this might work..

https://fb.watch/2F_dOp8gD9/

 

Edited December 28, 2020 by Beanz

[APerez]

Evening all, not much to add to the thoughts in here today. Given the solid agreement in the reliable timeframe, there aren't any wholesale changes compared to yesterday.

In the short-term, our attention of course turns to the snow potential. A few different perspectives on offer here with inland areas at elevation predictably looking best placed for modest amounts of accumulating snow. Far from a done deal, mind! Here's a few different takes on early tomorrow morning...

ARPEGE:   WRF-NMM:  EURO4:  HIRLAM: 

You can see the WRF and EURO4 favouring northern parts of Yorkshire with much of any accumulating snow falling over the Pennines and NY Moors, while ARPEGE and HIRLAM take a southerly track with South Yorks and the N Mids more in the firing line. In all cases the precipitation begins to fizzle and break up as it heads further south and west during the latter part of the morning.

Looking at Wednesday's potential for the south, it looks fairly likely that the famed 'M4 corridor' will be best positioned, though some question marks over rain/snow distribution as well as track will likely remain until the event itself. Given how these things usually progress, the further north you are in the precip band, the better...

ECMWF IFS HRES:   is the pick of the bunch and presumably the reason behind the BBC's bullish optimism!

Note the more southerly track of the WRF-NMM for the same timeframe...

Nail-biting stuff if you're of snow-starved persuasion further south! The latest FAX charts don't exactly calm the nerves, either! ...

t+60:  t+72:  It's gonna be a close one - fingers crossed on the ECM track  

Still, as other members have mentioned, the FAX charts will be an invaluable resource this week and beyond as they pick up small disturbances at short notice. A bit of luck and we can all see a flake or three at some point during this lengthy cold spell. I say lengthy cold spell because the extended ECM 32-dayer looks set on below average conditions for the next fortnight at least...

 

Full link here: 

ECMWF | Charts

APPS.ECMWF.INT

Enjoy your evening guys and gals

Alex

 

Edited December 28, 2020 by APerez
edited ECM HRES to include key

[Scott Ingham]

15 minutes ago, Met4Cast said:

Hot off the press! The latest EC46 update has blocked the Arctic off right through until week 4. Strongest signal yet!

I can't remember ever seeing such a persistent signal.

Thats comfortably the best ec46 of the season! 

What a january on the way!

[Anthony Burden]

8 minutes ago, Nick F said:

Plenty for cold and snow lovers to be optimistic about, and probably not prudent to look too far ahead of 5 days, but I think if I have any concerns, it could be a west-based -NAO perhaps allowing low pressure tracking under a west side of Greenland block then edging too far north over NW Europe - keeping deep cold out of reach and even allowing Tm air in across the far south.

But this is not a strong possibility at the moment and the models seem less certain run to run beyond 6 days where to build heights to our N or NW.

High Nick,

thanks for your take on the current position,can I push you to ask your opinion of the positioning 

of northern blocking in the extended 5/6day period.

[Anthony Burden]

1 minute ago, Anthony Burden said:

High Nick,

thanks for your take on the current position,can I push you to ask your opinion of the positioning 

of northern blocking in the extended 5/6day period.

 

[Mike Poole]

3 minutes ago, Snipper said:

Slightly get the feeling that if you cherry pick charts they will never come to fruition. Might as well read the Express or Mail. What was all that excitement a week ago?

Be nice to have some careful consideration of all the forecasts, models and charts in a balanced way. 

That excitement is still here, as you well know, yes, the Express have now got wind of it, but there is no obvious return to mild for at least three weeks,  conservative that, if the SSW goes with us, make it six, or nine...

And that is considering all models (that i can see anyway).

And I’m the model of balancity....

[Allseasons-Si]

Thanks for that @Met4Cast,stunning

not had the time to post again today,just been a bit busy spending time with my family

great synoptic charts again but i am sensing a retrogression of the hp cell into Greenland looking at the latest from EPS day ten,this would in turn allow for a flow from N/E as has been depicted by the op runs and means out to day ten of late

EPS and ext-EPS also signals +ve heights into Greenland but caution should be advised as there is a few boxes should a WB-NAO(GREEN) but i am not worried at this stage

 

cpc extended in the same ballpark as^

so all in all still looking good but the position of the high is crucial here in terms of getting some proper cold weather from the E/NE/N 

i was so gutted not to get any snow last night but i am grateful to others for getting it but maybe tonight i may get in on some of the action from a small feature coming in of the north sea,further afield there looks to be loads more opportunities down the line in the next 7-10 days>,so good luck everyone.

C U for the 18z

P.S,Gfs trying for a split for the second time.

Edited December 28, 2020 by Allseasons-si
typO/added info

[Harsh Climate]

Anyone doubting the convective potential of next weeks potential easterly think again, just for fun look at what ECM shows for Tuesday 5th january with just -4 / -5 uppers..

And I believe that the precipitation packing in from the North Sea would be all snow, due to the relatively short distance the air is tracking over the North Sea!

 

Edited December 28, 2020 by Harsh Climate

[MATTWOLVES 3]

Great output guys..the extended ECM mean out to day 14....is yes..you guessed it....staying cold.

And not long posted from John Hammond..its cold out there,but things could become a lot colder.. signs now of an imminent SSW..looks like all the big boys are now on board also. Great EC46 anomalies update also..Hights to the North and North West look the key developments.

[Singularity]

Just now, Harsh Climate said:

Anyone doubting the convective potential of next weeks potential easterly think again, just for fun look at what ECM shows for Tuesday with just -4 / -5 uppers..

And I believe that precipitation packing in from the North Sea would be all snow, due to the relatively short distance the air is tracking over the North Sea!

I'm afraid it isn't on this particular run - air not cold enough at the surface despite the short fetch across the North Sea.

Trouble is, that sea is currently about as warm as it gets at this time of year, though it should cool a fair bit in the coming week, while we also have a big shortfall on cold air availability to the near-east.

As the vast HLB pattern takes hold in the coming fortnight, we'll either see something colder find its way down from the north, or - perhaps more likely given the tenacity of highs to our NE lately - be waiting and watching for deep cold to make a long trek from somewhere between Siberia and East Asia.

[iceman1991]

40 minutes ago, Met4Cast said:

Hot off the press! The latest EC46 update has blocked the Arctic off right through until week 4. Strongest signal yet!

I can't remember ever seeing such a persistent signal.

Bloody hell man

[Smokeone]

3 minutes ago, Harsh Climate said:

Anyone doubting the convective potential of next weeks potential easterly think again, just for fun look at what ECM shows for Tuesday 5th january with just -4 / -5 uppers..

And I believe that the precipitation packing in from the North Sea would be all snow, due to the relatively short distance the air is tracking over the North Sea!

 

With a warmer then normal North Sea I thought it would be mostly rain on the coast and a little bit inland. Surely you would need lower uppers to be safer for snow.

[sheikhy]

2 minutes ago, Singularity said:

I'm afraid it isn't on this particular run - air not cold enough at the surface despite the short fetch across the North Sea.

Trouble is, that sea is currently about as warm as it gets at this time of year, though it should cool a fair bit in the coming week, while we also have a big shortfall on cold air availability to the near-east.

As the vast HLB pattern takes hold in the coming fortnight, we'll either see something colder find its way down from the north, or - perhaps more likely given the tenacity of highs to our NE lately - be waiting and watching for deep cold to make a long trek from somewhere between Siberia and East Asia.

Funny thing is i bet you had the 850s been a bit colder the precipitation would not be as widespread as it looks on that chart

[stodge]

Evening all

A chilly day in lowland East London rather than a real wintry one but there's an expression about getting the cold in first and then worrying about snow.

Last night's models continued the very positive outlook for fans of cold and snow in the coming 7-10 days though with some small complications in far FI as you might expect.

As we move into 2021, let's see how the year starts (meteorologically at least):

12Z GEM: T+120 takes us to January 2nd and the cold theme remains evident with the LP now in the Gulf of Genoa and heights building toward Iceland leaving a weak NE'ly flow over the British Isles. Uppers -4 to -8 by this time. The HP eases back west to the south of Iceland and re-orients rather than retrogresses and a new trough moves down into Scandinavia keeping a NNW'ly airflow over much of the British Isles but the emphasis on drier conditions especially for western areas. The briefest of milder incursions before colder air returns by T+180. I'm not quite sure what to make of the evolution beyond T+180 - the heights withdraw further west and LP starts to move down from the north within a lobe of very cold air moving through Iceland (uppers below -20). This pulls the wind direction back to a W'ly and draws in some milder air over the British Isles. Looking at the NH profile, I see a piece of the PV has detached and moved round the top of Greenland and started to come south. Is it heading our way? 

12Z GFS OP - well, an interesting offering from GEM to start the evening and perhaps an example of what synoptics could develop with a disorganised PV. Let's see what the GFS OP makes of all this. At T+120, we have the NE'ly airflow over the British isles but the eye is drawn to the disturbance to the north of Iceland and how that might develop. -4 to -8 uppers over the British Isles at this time. From here, the Atlantic HP moves in briefly before starting to retrogress toward Greenland and this allows new areas of LP to form to the north of the British Isles and move south in the N'ly airflow. The 850 profile at T+180 is informative with a burst of very cold air on the western flank of the LP (is it a Polar Low - well, not really). The LP deepens and moves south through Ireland and by T+240 is just off the tip of Cornwall. Two other observations - there's a tiny LP to the south of Greenland which doesn't seem to belong and I'm wondering if we're heading toward a west-based negative NAO if the LP over south-west Britain phases with the Atlantic LP to the west of the Azores. Meanwhile, the E'ly over the British Isles is drawing in increasingly cold air. Looking on, I was wrong to worry about the west-based NAO - instead, the Atlantic LP phases with the small LP to the south of Greenland but northern blocking has thrown a ridge south over Iceland and down to the north of the British Isles and by T+312 we remain in a chilly if not cold NE'ly airflow with the trough over central and southern Europe and heights over Scandinavia. By T+312 -8 850s are in charge. By T+384 battle is joined as the Atlantic LP tries to move in against the block of cold air. The temperature gradient just to the south-west suggests snow close at hand.

12Z GFS Parallel - another stunning run for cold and snow fans from the OP. On then to the Parallel and by T+120 the main elements are in place but perhaps the parallel is making a bit more of events in east Greenland with more defined LP development. Uppers over the British Isles -4 to -8 but I can see the rationale for the LP development with a wedge of less cold air moving up from the south interacting with the frigid air over Greenland and initiating cyclogenesis. To be fair, and slightly surprisingly, this doesn't really have any impact - heights build first to the north of the British Isles and then ease to the north-west with the HP centred to the south of Iceland leaving the jet far to the south and a slack airflow over the British Isles. While the south remains cold, some milder air is approaching the north of Scotland having moved round the top of the Atlantic HP. From here, the evolution becomes more interesting - to the south, the LP system over the Azores starts to move NE towards the British Isles but is only over northern Spain by T+240. Meanwhile, cyclogenesis has occurred to the west of Iceland and a new LP is heading south toward the British Isles which, by T+240, is effectively in a col but with the two troughs threatening to phase together over the British isles. In short, colder air is coming south as milder air is coming north. The phasing occurs and by T+312 a complex and elongated trough covers the British Isles with heights negatively aligned to both NE and SW. There's a calm airflow for most but a NW'ly for southwestern areas and a SE'ly for the far northern isles. The coldest air is mixed out by the phasing of the troughs but the uppers remain at -4. By T+384 it's just messy with heights to the north-east and a deepening LP over Biscay. Milder air is slowly encroaching by this time.

12Z ECM - so Parallel ends messy with any number of potential battleground scenarios as we move toward the middle of the month. Finally, to ECM. At T+120 no great surprises. From there, the Atlantic HP builds a ridge to Scandinavia with the remnant of the trough over Europe and a new LP to the east of the Azores. An ENE'ly flow covers southern Britain with the uppers -4 to -8. From there, the LP slows and deepens just off Portugal while the HP re-orients in situ throwing the ridge south as it partly retrogresses. The E'ly flow strengthens over southern Britain with -8 uppers in the mix as milder air inches through France.

Looking elsewhere, 12Z Control is cold until the very edge of FI when there's a big push of much milder air (including +20 uppers over North Africa). The 10 HPA charts from GFS continue to tantalise - OP splits the strat at the very end of FI (January 13th) as does Control. Parallel achieves an initial split by T+180 but the PV re-forms and just about survives FI though it is much reduced.

Conclusion: - more interest for cold fans though another night brings another theme and that's the attack from the south and/or from the north. All the models suggest an attack from the south into the cold block but this will be a real struggle if successful and obviously the opportunity for snowfall is there. GEM and GFS OP tease with a simultaneous attack from the north caused by cyclogenesis to the west of Iceland and that obviously also has interest. For now, 10 days of chilly if not cold conditions look assured - beyond that battle may be joined to the south and as we know such battles between competing airmasses are the perfect breeding ground for snow events. Someone will hopefully get lucky.

[Allseasons-Si]

44 minutes ago, Met4Cast said:

Hot off the press! The latest EC46 update has blocked the Arctic off right through until week 4. Strongest signal yet!

I can't remember ever seeing such a persistent signal.

NOW THAT'S A ""W.T.F."" MOMENT

[Badgers01]

36 minutes ago, Griff said:

No doubt this will get lost under a deluge of strat and -nao based excitement, but I can't for the life of me remember a week ahead forecast IMBY across multiple weather services with daytime temperatures of 1°c showing precipitation type as rain?!?

Presumably 2m surface temperatures, but dew points must be higher than 0. Not sure what's happening, are we under inversions?

The 850 temps are not low enough

[Harsh Climate]

13 minutes ago, Singularity said:

I'm afraid it isn't on this particular run - air not cold enough at the surface despite the short fetch across the North Sea.

Trouble is, that sea is currently about as warm as it gets at this time of year, though it should cool a fair bit in the coming week, while we also have a big shortfall on cold air availability to the near-east.

As the vast HLB pattern takes hold in the coming fortnight, we'll either see something colder find its way down from the north, or - perhaps more likely given the tenacity of highs to our NE lately - be waiting and watching for deep cold to make a long trek from somewhere between Siberia and East Asia.

You and smokeone are probably right regarding widespread snow. Maybe IMBY but with -4 uppers across a much longer draw across the North Atlantic sea we had sleet here with snowline about 750 feet yesterday. I'm sure with a shorter and dryer feed from the east the same -4 uppers would make the world of difference here atleast. But I could be wrong haha

Edited December 28, 2020 by Harsh Climate

[sheikhy]

Icon further north with the snow wednesday!!12z off the south coast now 18z is north of the m4!!