Model output discussion - Winter has arrived

[I remember Atlantic 252]

4 minutes ago, Mike Poole said:

ECM T144, and GFS for comparison:

For sure, but the bacon has yet to be brought home, i might remind you!!  

ECM T144, and GFS for comparison:

It seems to me that with the vortex over t’other side, we are at the mercy of shortwaves and wedges all over the place.  Should throw up some surprises I would guess.  

 

heard on here, wedges bring sledges! but suppose damn things have to be in right place

[BlackburnChris]

3 minutes ago, Scott Ingham said:

I posted it 3 or 4 days ago but my forecast was surprise snowfall first 2 weeks of December a UK hight back end of December. A zonal period first half of January while zonal winds get flushed down from Strato warming back end of a December and the coldest period of winter Late January and all of February

La Nina normally means the Coldest period for the UK is normally early winter ... Doesn't always go to plan though so good luck with your prediction . 

[Skullzrulerz]

1 hour ago, dragan said:

indeed, and this is by far the most likely outcome unfortunately. Would be a nice to have a change but i’m not positive 

Exactly 

I would love to see a change but at the moment I don't think it's going to happen 

It's not cold enough

[Mucka]

http://www.meteociel.co.uk/modeles/ecmwf/runs/2020120212/ECH1-216.GIF?02-0

 

Some potential for frontal snow if that verified I would have thought

Edited December 2, 2020 by Mucka

[Matt H]

I’m hopeful for a bit of wet snow in Cambridge on Friday but I’m not expecting much. Looking longer-term, the EC 12z still holds interest out to day 10 but I’m hoping we start to see some proper blocking appearing more regularly soon. Would be great if the Greenland high on the morning GFS runs made another appearance soon.

[Mike Poole]

I think tonight’s ECM shows the importance of the Southern Europe trough:

At T192 it looks like a low pressure destined under normal circumstances for the UK, but even this big feature slides T216, and then goes under the relatively modest high over Scandi (not the big Russian one), T240:

Edited December 2, 2020 by Mike Poole

[DEYS(Kent)]

Wow, lots of people are setting themselves up for disappointment. Elevation will be key. Anyone else will have transient, wet stuff in amongst the rain. 

[Mapantz]

The latest UKV keeps the bulk of PPN in the channel, in to the North sea. The best risk of anything wintry is parts of Kent, and then in to East Anglia. Even then, it's only a rain/snow mix - nothing anywhere near 9" of snow!

The UKV  has been consistent though..

Edited December 2, 2020 by Mapantz

[Trom]

2 hours ago, Mike Poole said:

It is a new development from HIRLAM apparently, this explains:

http://en.wikipedia.org//static/favicon/wikipedia.ico HIRLAM - Wikipedia

EN.WIKIPEDIA.ORG

 

I'm pretty sure it's been around for a while (at least last year)

[TSNWK]

1 minute ago, DEYS(Kent) said:

Wow, lots of people are setting themselves up for disappointment. Elevation will be key. Anyone else will have transient, wet stuff in amongst the rain. 

Disappointment is logging onto this thread once a day seeing a handful of posts in 24 hours in the middle of January with no change in sight for the next couple of weeks as the purple monster to the top left just keeps on giving... we really are in good place, vortex for some reason not setting up, cold side of jet and we are having a giggle at some outlandish snow prediction charts in 48 hours....

most know the rules of  this place and the charts give no quarter, we roll with the punches and enjoy the good times.. and frankly speaking at a broad level we are about to the best mid winter set up for 10 years... the beast of 18 not withstanding I felt always loss a little gloss with being so late...

[stodge]

Evening all

Is this the start of the countdown to a winter wonderland this weekend? I suspect not - I'm not expecting any snow in lowland east London - just a good soaking of cold rain. Some may get a little sleet and snow and kudos to you if you are in such a fortunate group but a widespread national snow event - nope.

Anyway, the models churn on as they always do and after some interesting evolutions last evening let's see where this evening's offerings take us:

12Z GEM - by the end of the weekend (T+96) the LP still sits over us with weak heights to the NW and NE. By T+150, the enxt Atlantic feature has swung SE through Ireland and the south west of England and is sitting over western France but it's a complex trough with a residual centre over northern Scotland so the unsettled and cold theme remains very much in evidence. Clear signs of positive alignment further west but there's still a weak ridge coming north from the Azores HP. The trough quickly splits as pressure rises from the SW and there's a return of an Atlantic-sourced flow as a new deep Atlantic LP develops but is that a renewed negative alignment in the face of the block to the east at T+210. To a point, yes but the trough fills in situ over or just to the west of the British Isles by T+240 and the block looks to be extending into Scandinavia at the same time.

12Z GFS OP - it's been the model keenest to bring back the Atlantic and with GEM having more of an Atlantic influence tonight, I suspect that's where the American model is heading. At T+96, perhaps further south than the GEM and a more defined ridging to the north but that's nit-picking. The next Atlantic feature duly heads SE but by T+174 we have a complex but shallow trough from central Europe through southern Britain to the mid-Atlantic with a new vigorous LP coming off the Eastern Seaboard. However, that soon fills and just joins the weak trough - heights over Greenland don't look strong but it's a weak or non-existent PV so the block can force the Atlantic systems south and there's a broad but shallow LP covering much of northern Europe by T+240.  However, the next LP changes everything - it pulls down a lobe of very cold air into the Atlantic which drops the trough south and encourages a new LP to form around the Azores. The response is to push the HP east into Europe and draw up a mild SW'ly over the British Isles. There's also signs of vortex energy moving back towards Canada and there's little warming on the 10 HPA so some ominous signs for cold fans.

12Z ECM - so we're 2-1 down with 20 minutes to paly, can we force an equaliser? Possibly the cleanest drop of the trough through the British Isles by T+96 and the most defined height rises to the north so an encouraging start.  That comes to little as the second Atlantic also swings SE and fills into Europe but the Atlantic looks in a mean period by T+192 albeit with quite a defined ridge of the Eurasian HP into Scandinavia. That's significant as we see by T+240 which is as good a chart as many cold fan would want to see from this evolution. The HP is moving into Scandinavia and the block is forcing the LP to disrupt SE once again. As we've seen, the 850s don't float everyone's boat but the block is looking promising.

Moving beyond the models I've already mentioned, 12Z GFS Control ends with a real stand-off between an active Atlantic and HP over both Scandinavia and Greenland. It doesn't work well for the British Isles in terms of cold . 

Conclusion - a step back for cold fans this evening. While it may be the next 7-10 days will be cold and unsettled and possibly just on the wrong side for snow, the hope that might draw some colder air over us looks misplaced this evening. The block to the east looks resilient however and it remains to be seen if it can force the bulk of the energy SE into Europe which will always give us a chance to import some frigid air. It all looks very knife-edge to this observer and the medium to longer term trends suggest a return of the Atlantic as PV energy seeps back over to Canada and re-invigorates the jet. 

 

Edited December 2, 2020 by stodge

[Mike Poole]

7 minutes ago, Trom said:

I'm pretty sure it's been around for a while (at least last year)

Sure, quite probably, but like the HIRLAM it replaced, I only use these models when a weather event is imminent and i want a good high res handle on precipitation, can’t remember having to go look for that for months!!  Any way from what I’ve just read about HARMONIE, it should be a really decent short term high res model that handles convection well (regardless if it snows in Oxfordshire on Friday!).  

[northwestsnow]

After viewing ECM 12z I predict the word 'slider ' may well have prominence over the coming days ...

[stewfox]

14 minutes ago, DEYS(Kent) said:

Wow, lots of people are setting themselves up for disappointment. Elevation will be key. Anyone else will have transient, wet stuff in amongst the rain. 

GFS is suggesting height will make a difference so getting ready with some practice runs.

[Skullzrulerz]

16 minutes ago, DEYS(Kent) said:

Wow, lots of people are setting themselves up for disappointment. Elevation will be key. Anyone else will have transient, wet stuff in amongst the rain. 

Not sure if you seen the ECM snow charts I think it's inaccurate 

It's own a league on its own in regards to its snowfall and thinks that wet rain is snow

Anything to keep people's hopes up though!

[Tim Bland]

4 minutes ago, northwestsnow said:

After viewing ECM 12z I predict the word 'slider ' may well have prominence over the coming days ...

Yep, plenty to keep us entertained, Friday, then Monday..then we look forward the sliders
 

re Monday (below) the uppers started off wrong side of marginal, now they are just about low enough to raise an eyebrow of interest...reminds me of how Friday was being viewed 4 days ago...

Edited December 2, 2020 by Tim Bland

[sheikhy]

23 minutes ago, Mapantz said:

The latest UKV keeps the bulk of PPN in the channel, in to the North sea. The best risk of anything wintry is parts of Kent, and then in to East Anglia. Even then, it's only a rain/snow mix - nothing anywhere near 9" of snow!

The UKV  has been consistent though..

Any images mate?

[Mike Poole]

8 minutes ago, northwestsnow said:

After viewing ECM 12z I predict the word 'slider ' may well have prominence over the coming days ...

I think it will NWS, and partly because of the cold on offer, or lack of it, such sliding systems may require less cold uppers than other snow scenarios, the one on Friday may or may not illustrate this, but we’ve been here before in early December, think it was 10/12/17 (I only just qualified, the M4 shield in force that day for sure).

Edited December 2, 2020 by Mike Poole

[I remember Atlantic 252]

1 minute ago, Mike Poole said:

I think it will NWS, and partly because of the cold on offer, or lack of it, such sliding systems may require less cold uppers than other snow scenarios, the one on Friday may or may not illustrate this, but we’ve been here before in early December, think it was 10/12/17 (I only just qualified, the M4 shield in force that day for sure).

that's my facebook profile pic! the snow from it anyway,

[TSNWK]

36 minutes ago, Mucka said:

http://www.meteociel.co.uk/modeles/ecmwf/runs/2020120212/ECH1-216.GIF?02-0

 

Some potential for frontal snow if that verified I would have thought

Mucka! Back for another season then? Still on the night shifts ? Part of winter routine over the years  was my morning model briefing from you as the kettled boiled.. hope you’re keeping well

Edited December 2, 2020 by TSNWK

[mountain shadow]

16 minutes ago, northwestsnow said:

After viewing ECM 12z I predict the word 'slider ' may well have prominence over the coming days ...

Unfortunately, the sliders are sliding into less than impressive uppers so the wintry stuff confined to higher hills maybe?

Granted the flow may be continental so we may get lucky.

Edited December 2, 2020 by mountain shadow

[Sky Full]

1 hour ago, Weather vane said:

Really appreciate that. Thanks.

Hi WV - sorry I only just saw your post but I see SussexSnow has replied anyway.  I find I have to click on the finished GIF in Meteociel and save it to photos so the file can be uploaded to NW but there may be easier ways to do it...

[Midlands Ice Age]

9 minutes ago, Mike Poole said:

I think it will NWS, and partly because of the cold on offer, or lack of it, such sliding systems may require less cold uppers than other snow scenarios, the one on Friday may or may not illustrate this, but we’ve been here before in early December, think it was 10/12/17 (I only just qualified, the M4 shield in force that day for sure).

Yep-      Thats the one. Just look at my avatar it produced 25cms in here in 12 hours.

I got up at 03:00 to watch the whole event.

It also was North, South, up and down rain or snow for the last 3 days.

It ended up as a lamp post job......    (wonderful)  and ended up as all snow in Bham, and this extended to many central areas as the snow spreadout. 

MIA

[northwestsnow]

6 minutes ago, mountain shadow said:

Unfortunately, the sliders are sliding into less than impressive uppers so the wintry stuff confined to higher hills maybe?

Granted the flow may be continental so we may get lucky.

Not sure mate.

Dews critical, always low when the westerly feed is interrupted so 850s not as important ...

Still to far away to know for sure but I would imagine it might get interesting...

[Frosty.]

The longer term GEFS 12z mean excites me..it really excites me!!..in the meantime, good luck to every snow starved coldie on netweather during the days and nights ahead!..lamp posts at the ready!!!