Model Output Discussion - Staying cold into the new year

[bluearmy]

The extended eps and gefs are showing a relaxation of the wintry conditions as we approach mid month. 
but lots of clusters equals lots of uncertainty......

[BLAST FROM THE PAST]

Look where all the incredible cold has gone...seeped away from North America to Siberia and Greenland

 

haven’t seen that...what would that mean and lead to?

 

BFTP

[bobbydog]

1 minute ago, BLAST FROM THE PAST said:

Look where all the incredible cold has gone...seeped away from North America to Siberia and Greenland

 

haven’t seen that...what would that mean and lead to?

 

BFTP

An incredibly cold Siberia and Greenland?....

[Froze were the Days]

24 minutes ago, General Cluster said:

But whatever the SSW does, or doesn't do, Chio, I think we're in a pretty darn good, and well-primed, position right now... Best I've seen since 2013!

Other than on February 25th 2018...oh! for more of those days! cool and crisp then cold and bone dry, then flurries of convective snow, then heavier stuff leaving a deep blanket, then a breeze picking up causing some drifting and then then...ahhhhhhh!!!!!  a snowgasm which doesn't occur enough nowdays.

Edited December 29, 2020 by Froze were the Days

[feb1991blizzard]

29 minutes ago, chionomaniac said:

The issue is here that the SSW may or may not propagate and if it does will it produce the goods because undoubtedly without a major split it will affect the Pacific pattern. You may end up wishing that a SSW never occurred in a month or so if the Pacific amplification occurs as a result of post SSW Tropical feedback. I don’t know how long the lower Atlantic trop disruption will continue for, but I have never been more wary of an SSW not being long term beneficial than this one.

Agree without the split it will probably knacker us, but we cannot wish the SSW is not going to happen right now because it pretty much nailed on will, so we desperately need a split, also though if we had massively strong zonal westerlies up above all the way through winter, would this trop pattern have been allowed to persist, you have to think that in such a scenario, the trop would have responded at some point with a +NAO.

[BLAST FROM THE PAST]

2 minutes ago, bobbydog said:

An incredibly cold Siberia and Greenland?....

Errr  .  Synoptically? Jetstream?

BFTP

Edited December 29, 2020 by BLAST FROM THE PAST

[Met4Cast]

In unrelated news.. why is the forum taking like 10 seconds to refresh and load pages? It's been like it for weeks now. I know it's nothing to do with my internet connection or laptop, it's the same on every device I use, wifi or cellular. 

[Griff]

16 minutes ago, Ali1977 said:

Day 10 EC ENS Mean is v nice, still looks like a prolonged cold/v cold spell beyond day 10 looking at this.

We would have gave money to see these charts a few weeks back, don’t look for them ending just yet. Enjoy the frost , snow, sleet , dew point saga, altitude  saga, inland/coastal saga, streamer saga, and all the other sagas that come with snow hunting in the U.K.!! 
We are just starting a few weeks or more cold spell - they don’t come around that often

Exactly this - didn't the Christmas day doom and gloom turn out to be a bit premature!

I think we've been spoilt by such a rapid evolution and I think the bigger picture emerging today is a bit slower and steadier.

I understand the frustration of cold or lack of to the East, also possible disappointment of charts showing snaw this week that have slowly receded for many of us.  Just a flake would be nice... but plenty of time yet!

I'm always happy for a balanced unbiased view - show me the charts good and bad!

Edited December 29, 2020 by Griff

[sheikhy]

Dont know if anyone else has noticed but just taken a look at ecm and ukmo and the differences start very early on!!ukmo links the atlantic ridge and the russian heights slightly better between greenland and norway where as ecm does not and has got shortwaves coming in the way between the areas mentioned above!!!all this at only 72 and 96 hours!!!does ecm have a better handle of this?

[steveinsussex]

Just now, Met4Cast said:

In unrelated news.. why is the forum taking like 10 seconds to refresh and load pages? It's been like it for weeks now. I know it's nothing to do with my internet connection or laptop, it's the same on every device I use, wifi or cellular. 

Not here, its fine

[Methuselah]

5 minutes ago, BLAST FROM THE PAST said:

Look where all the incredible cold has gone...seeped away from North America to Siberia and Greenland

 

haven’t seen that...what would that mean and lead to?

 

BFTP

It's coming, Fred... But, as a caveat, I also said that in 2019! Have I jinxed it?

[Downburst]

3 minutes ago, BLAST FROM THE PAST said:

Look where all the incredible cold has gone...seeped away from North America to Siberia and Greenland

 

haven’t seen that...what would that mean and lead to?

 

BFTP

Continental weather on the continents, switching. We are maritime, so I am not surprised it’s not over here. But perhaps a SSW if it happens may make more effect in this locale with the lower colder air over there, epic easterly perhaps?. An aside, To, too or two, never take someone too seriously, to do so twice would be two times too many, to coin a phrase.

[Paul]

2 minutes ago, Met4Cast said:

In unrelated news.. why is the forum taking like 10 seconds to refresh and load pages? It's been like it for weeks now. I know it's nothing to do with my internet connection or laptop, it's the same on every device I use, wifi or cellular. 

Not really model discussion, so please post in the support area if you're having issues.

But fwiw, this thread is a bit long right now so is a bit slow but only 2-3 secs load time. The rest of the forum is faster. So if you're having problems it should be something in your account or will be device / connection related. Perhaps clear your browser cookies and cache and also clear your notifications in your account.

But anyway, please don't continue this in here, and if anyone else has a related query, please use the help forum.

[Man With Beard]

23 minutes ago, iowpompeylee said:

Could it still skim the far reaches of the south coast? 

Will be marginal if it does, don't wake up early for it!

[Griff]

FYI apparently SSW has started...

 

[Feb2009London]

Subtle shift north on the 15z ICON vs 12z. Still all to play for near the south coast I think, but snow remains unlikely north of W/E Sussex.

[chionomaniac]

40 minutes ago, General Cluster said:

But whatever the SSW does, or doesn't do, Chio, I think we're in a pretty darn good, and well-primed, position right now... Best I've seen since 2013!

Yep. That’s my point, Pete.

[stodge]

Evening all

A chill day here in lowland East London - just 3c and slate coloured skies all day. That's what can happen with a slack N or NE'ly flow - plaudits to those who saw some snow, even temporarily.

The models last evening promised 7-10 days of cold and then a potential "battleground" with LP moving up from the south and of course lurking behind every FI evolution is the threat of the dreaded west-based negative NAO. Let's see what tonight has to offer.

12Z GEM: - T+120 takes us to Sunday which will be January 3rd. It remains cold over the British Isles with a light nE'ly flow. A ridge of HP extending out of Scandinavia to the south of Iceland holds an Atlantic trough back while LP to the south-west of the Azores seems to be going nowhere. To be honest, this doesn't feel as positive as the last few evenings - there are clear signs of more activity around NE Canada but let's see. For now, -4 to -8 uppers cover the British Isles. By T+180 not much has changed. HP dominates to the west and north-west with LP to the south centred over Morocco and the Russian HP appearing far to the east. The Atlantic has quietened. The air mass over the British Isles remains cold. Moving on and as the HP retrogresses slightly, the LP over Iberia deepens and moves NE into central and eastern Europe.  By T+240, the HP is to the south-west of iceland and signs of a new LP forming off the east Greenland coast but for the British Isles the air flow remains between north and east. The swing to a more N'ly orientation keeps the air mass cold or very cold.

12Z GFS OP - a strong opening for fans of cold from GEM. On then to the GFS OP and at T+120 no great surprises. The HP seems better defined on GFS and perhaps a notch further north - I also like to see the weak heights over Scandinavia. 850s of -4 to -8 over the British Isles at this time. On to T+180 and again it's not too far removed from GEM with a slack ENE'ly flow over the British Isles and the HP ridging SE from Greenland. The airmass over the British Isles remains cold. From there, the Greenland HP continues to control the weather with its ridge SE to the west of the British Isles keeping the jet well to the south and leaving LP to affect the Azores but there's a hint of phasing with the trough over north-west Europe and a new LP has moved NE across Europe to be over the Baltic leaving the British Isles in a slack NNE'ly flow. Needless to say, the 850s suggest a continuation of cold or very cold surface conditions. Further into FI and a lobe of HP detaches from Greenland and slips SE just to the west of Ireland which would produce a more settled outlook for southern and western areas with a NW'ly flow by T+312 and a hint of a new trough forming over Iceland. Perhaps a notch less cold but you'd think there could be some sharp frosts.  For those wanting milder conditions, far FI offers plenty of hope - the HP slips down into Europe and opens the door for milder air and an Atlantic flow to return by T+384. It looks a bit west-based negative NAO to my eyes.

12Z GFS Parallel - let's see if it follows the OP or goes its own way.  by T+120 the HP is perhaps a little closer than on other models and signs of more Atlantic activity especially off Canada and close to Greenland. by T+180 the anticyclone dominates the north of the British Isles ridging into Scandinavia and across to the south of Iceland while a deepening LP over Portugal strengthen the E'ly flow in the far south.  The uppers are generally -8 at this time so still cold across the British Isles. The LP over Portugal tries to come north, then north-west but is beaten back by the block and by T+240 there is an elongated trough from northern France to the Azores while to the north a ridge of HP extends from the southern tip of Greenland to northern Scotland. Between these, an E'ly flow continues. Any milder incursion is very brief and by T+240 uppers are again at -4 to -8 across the British Isles. Hints again of a new LP over Iceland. Further into FI, the evolution starts to get complex and a bit messy. The HP ridges south, splits the trough and leads to the formation of a new HP cell. One LP dives SE into the North Sea but another shortwave phases with the Atlantic trough. Despite all that, the airmass over the British Isles remains cold with the LP dragging down another push of very cold air.  From there to T+384, it's a pretty rapid reversion to a more typical Atlantic-based pattern 

12Z ECM - T+120 brings the Atlantic HP close to north-west Britain ensuring settled conditions while the south and east remain under the influence of the continental trough. -4 to -8 uppers at this time keeping it cold. Moving on, the HP extends back west in a classic retrogression pattern as new LP develops to the north of Iceland and the jet is held far to the south. It gets less cold in northern areas while the south remains cold. by T+240, one LP is over northern Scandinavia while another is over southern France and a slack but potent N'ly is spreading across the British Isles with HP remaining to the west and north-west. Progressively colder air is spreading south with -8 uppers coming into Scotland and some even colder air behind that. 

Looking elsewhere, 12Z Control has plenty of snow opportunities and ends with a battleground between air masses which, to be fair, the milder flow seems to be winning. Onto the 10 HPA charts and the 12Z OP ends with a split and diminished PV - the current warming does most of the damage and a smaller warming finishes off the PV in the second week of January.  12Z Control produces another very strong warming at the end of FI but the PV is still just about intact. 12Z Parallel initiates the split at T+108 and the PV looks broken and beaten throughout the rest of the run. We're used to a huge vortex with core temperatures of -88 - this season mid-January has a vortex with a core temperature of -64 which tells you all you need to know.

Conclusion: - GFS toys with ending the cold spell in mid month, whether that's a signal (MJO?) or a reset to "normal" conditions in the absence of a signal remains to be seen. Within the immediate it's cold and as far out as T+240 it also remains cold. ECM toys with another round of retrogression to bring a new cold blast from the north and in the context of a split vortex, that would release some serious cold. GEM keeps the focus more to the north-east. The 10 HPA charts continue to show the PV weak and disorganised, if not completely split. 

[bobbydog]

15 minutes ago, BLAST FROM THE PAST said:

Errr  .  Synoptically? Jetstream?

BFTP

Honestly? Not sure Fred but I'd like to see the next chart after 240, 

Would that low sink enough to allow the heights over Russia to link up with Greenland? Maybe?.. I do hope so....

[Allseasons-Si]

The anomalies are still looking good chaps...

EPS day ten

cpc 6-10/8-14 days

NAO/AO

a look at the quantiles shows that we are in a neg phase NAO(left) and blocking phase(top)

Forecast trajectories from day 0 to day 8 in the NAO-BLO space. In the latest forecast the analysis for the previous 8 days is represented by a grey line. In the previous forecasts the available analysis is represented by a black line. The ensemble mean trajectories are in red. Title shows initial date and time of ENS forecast; coloured markers show the ENS members at 24-hour intervals (see legend). EOF1: positive (right) and negative (left) phase of NAO; EOF2: blocking (top), 'anti-blocking' (bottom) For more details, see the document below;

Documentation:-

Documentation - Forecast User - ECMWF Confluence Wiki

CONFLUENCE.ECMWF.INT

 

[chionomaniac]

34 minutes ago, snow mad said:

Didn’t someone in the early days of the strat thread do something on weather before and after a SSW. And worked out that there was almost as much chance of having cold weather in the lead up to the SSW as there is after? Or did I dream that? 

It really depends on the trop and strat conditions and dynamics leading up to the SSW.  The more that I have learnt since the first strat thread is that there are many determining features between trop and strat. There are a few occasions in history where the pre SSW trop pattern was better than the post for us in the UK. And that shouldn’t be ignored.  If I was in the east USA I would be hoping that the SSW shakes the trop pattern up somewhat. I’m not. I want reinforcing of it. Risky at this point

[Mike Poole]

Just a couple of points on where I think we are vis-a-vis the upcoming SSW.  Things are looking very promising at the moment for cold without it, ECM mean T240 (without my scribbling this time!):

The technical SSW will happen on 5/1/21:

And will be a split most likely.  

But all of this northern blocking weak vortex is due to the same things that will cause the SSW, the SSW narrative is affecting our weather now, before it has actually happened.  I have a worry, shared here before, that the shuffling of the pack of cards caused by the SSW might derail an otherwise cold pattern - and it still might.  The charts I’ve viewed seem similar to SSW’s that have gone in our favour previously, but this year is quite different to anything I’ve watched on the models since joining netweather.  So we will just have to see.  

Finally, ECM strat winds reversed at T192, 5/1/21:

Whether for good or bad, it is happening....

[BLAST FROM THE PAST]

15 minutes ago, bobbydog said:

Honestly? Not sure Fred but I'd like to see the next chart after 240, 

Would that low sink enough to allow the heights over Russia to link up with Greenland? Maybe?.. I do hope so....

Sorry I Couldn’t put a laughy smiley in my initial response as not available.
 

I agree would love to see t264 etc.

 
I hope so too and wonder if the jet off US / North America would become almost non existent or shunted so far south...The East backs west?

 

BFTP

[Froze were the Days]

55 minutes ago, Met4Cast said:

I really can't understand the negativity. Ian Brown would be saying "wtf" at the current outputs.

Well you're right there! but also at the 850 uppers...but the times are changing. If I don't get any lying snow in the next few weeks I'm going to saw my leg off.

By the way latest CFS not a million miles away from ECM near day 10...perhaps lacking the Arctic blast and associated LP

 

Edited December 29, 2020 by Froze were the Days

[Penrith Snow]

32 minutes ago, Allseasons-si said:

The anomalies are still looking good chaps...

EPS day ten

cpc 6-10/8-14 days

NAO/AO

a look at the quantiles shows that we are in a neg phase NAO(left) and blocking phase(top)

Forecast trajectories from day 0 to day 8 in the NAO-BLO space. In the latest forecast the analysis for the previous 8 days is represented by a grey line. In the previous forecasts the available analysis is represented by a black line. The ensemble mean trajectories are in red. Title shows initial date and time of ENS forecast; coloured markers show the ENS members at 24-hour intervals (see legend). EOF1: positive (right) and negative (left) phase of NAO; EOF2: blocking (top), 'anti-blocking' (bottom) For more details, see the document below;

Documentation:-

Documentation - Forecast User - ECMWF Confluence Wiki

CONFLUENCE.ECMWF.INT

 

Those pressure anomaly charts seem to indicate the Russian block transferring north which will cut off the supply of warm uppers into Eastern Europe?