Model output discussion - Into 2021

[Battleground Snow]

11 minutes ago, Mr Frost said:

Just browsed the latest UKV run and there is plenty of sleet/snow showers showing - especially Eastern parts of the UK through next week as expected,

Here is the lying snow depth chart for this run out to 06/01 15:00:

 

Look closer...one for the SE ladies and gents here...

It’s coming @Paul Sherman @Steve Murr 

For balance - arome, arpege and Harmonie snow depth charts.... Granted it's not that much still.

 

[MJB]

39 minutes ago, Anthony Burden said:

Marco Patanga on Twitter just stated major SSW to take place in next week or so prolonged 

easterly ie beast from the east on it’s way,only short temperature pick if any.

As good as that sounds , I don't think anyone can say for certain where the cold ends up - it might be over the UK but equally we could well go mild 

[Kasim Awan]

1 minute ago, MJB said:

As good as that sounds , I don't think anyone can say for certain where the cold ends up - it might be over the UK but equally we could well go mild 

Mild is one word any credible forecaster wont be using in the next couple of weeks.

[I remember Atlantic 252]

3 minutes ago, Battleground Snow said:

For balance - arome, arpege and Harmonie snow depth charts.... Granted it's not that much still.

 

Thats the snow moving NE to SW tomorrow evening, on models, not much mention of tomorrow's snow on here

[MJB]

1 minute ago, Kasim Awan said:

Mild is one word any credible forecaster wont be using in the next couple of weeks.

And again you cant say that , if the SSW impacts on the UK , we could end up on the mild side - 14 days is a lifetime in model watching world. Equally we could get even colder , let's wait and see 

[Updated_Weather]

Check this out!

[matty40s]

43 minutes ago, Tim Bland said:

It will probably end up in the Chanel again and miss all of us

Is that perturbation No.5 you are looking at?

[Griff]

1 minute ago, Updated_Weather said:

Check this out!

Yes, I just posted Judah's tweet to the tweet thread...

 

[DanDorsetUK]

Why is it people are taking these day 10 charts seriously again given Marco recent tweet? Surely there is no likelyhood of it looking this way in 10 days given there is a MAJOR SSW about to hit. To me its completely pointless looking past 5 days untill it really shows it head.?

[Radiating Dendrite]

5 minutes ago, Rapodo said:

Why is it people are taking these day 10 charts seriously again given Marco recent tweet? Surely there is no likelyhood of it looking this way in 10 days given there is a MAJOR SSW about to hit. To me its completely pointless looking past 5 days untill it really shows it head.?

Yes, we all know that but this is the model thread. If we just discussed reliable and not potential it would be dull 98% of the time!

Lighten up or call the weather police  

Edited January 1, 2021 by Radiating Dendrite

[iceman1991]

16 minutes ago, bluearmy said:

I suspect he didn’t phrase it like that .......

[Frosty_wsm]

1 hour ago, Tim Bland said:

This is final frame of ECM. It won’t show final snow depths as it’s still going at the end. Would need to see day 11 for the big numbers

Well god damn, wouldn't  that be a kick in the nuts if it actually ended up like that, that lp needs to get trending further south lol

Edited January 1, 2021 by Smartie

[Mr Frost]

All joking aside though - definitely a risk of Kent streamers (other areas also of course!) setting up...especially Tuesday/Wednesday.

Few UKV snapshots from the 15z run for 06/01 at 12:00

Precipitation type:

 

850HPA and sea level pressure: 

 

Dewpoint temperature (c)

 

500-1000hpa thickness (dam)

 

850-1000hpa thickness (m)

 

Higher ground favoured but surely a dusting for low ground can’t be ruled out at some stage through the first half of next week at least!?

All the best to you folk down there - hopefully a wee upgrade nearer the time! 

Edited January 1, 2021 by Mr Frost

[SMU]

ECM mean @96 V the operational shows that the op was nearer the top end of the table for 850s especially the further south you go-

I think 96-120 the ECM got another downward drop of 1c in it...

[Battleground Snow]

5 minutes ago, Steve Murr said:

ECM mean @96 V the operational shows that the op was nearer the top end of the table for 850s especially the further south you go-

I think 96-120 the ECM got another downward drop of 1c in it...

Yes, you can see even at that timescale there is an almost 3 degree range in the ensembles

 

[Eskimo]

As others have mentioned already. Definitely a risk of some snow across the Midlands tomorrow as a features drops south westwards. Whilst the models seem to be in some sort of agreement, these things are still tricky and it's worth radar watching tomorrow. Could be some accumulations of 1-3cm, possibly a bit more in favoured locations if it can keep itself together and doesn't fizzle out.

Arpege 

Arome 

GFS

ICON


Harmonie 

 

Edited January 1, 2021 by Eskimo

[wellington boot]

7 minutes ago, Mr Frost said:

All joking aside though - definitely a risk of Kent streamers (other areas also of course!) setting up...especially Tuesday/Wednesday.

Few snapshots for 06/01 at 12:00

Precipitation type:

 

850HPA and sea level pressure: 

 

Dewpoint temperature (c)

 

500-1000hpa thickness (dam)

 

850-1000hpa thickness (m)

 

Higher ground favoured but surely a dusting for low ground can’t be ruled out at some stage through the first half of next week at least!?

All the best to you folk down there - hopefully a wee upgrade nearer the time! 

Agree with this. Admittedly it might be partly blind optimism, but I'm expecting some snow, at least in favoured spots within the SE corner through the first half of next week.

Been through enough of these situations over the past 17 years or so to know that unexpected snow is always possible via streamers. 

Additionally topography and local conditions vary considerably across the SE and maps showing a single dew point or temperature reading across that whole corner are simply not high enough resolution to help with forecasting local detail.

Over the downs, the hills, and here in the Weald, for instance, I think we have a solid chance of some good falls next week, even if the detail is difficult to predict because the exact location of streamers is impossible to know in advance.

At my home, I would hope 150m of altitude, 30-50 miles inland (depending on orientation), and the relatively shorter sea track will be enough to modify temps and dew points down, especially at higher ppn rates. Just need to get into a shower stream!

[Paul]

Just ran a small update on the UKV snow depth charts, to show amounts of <1cm on there, which ought to then pick up temporary coverings/dustings more. It'll be live from the 21z, but before that's out, here's one from the 18z, showing the cover for overnight Saturday.

[Man With Beard]

ECM ensembles 12Z ... a teeny bit warmer than the 00Z suite, but not much. London averaging daily between 2C and 3.5C maxima up until 12th, and Manchester generally below 2C until the same date. Still very cold, still major snow risk temperatures. Slight uptick at the end.

[Eskimo]

8 minutes ago, Paul said:

Just ran a small update on the UKV snow depth charts, to show amounts of <1cm on there, which ought to then pick up temporary coverings/dustings more. It'll be live from the 21z, but before that's out, here's one from the 18z, showing the cover for overnight Saturday.

Yes, I can certainly see something there. 

 

Edited January 1, 2021 by Eskimo

[northwestsnow]

6 minutes ago, Man With Beard said:

ECM ensembles 12Z ... a teeny bit warmer than the 00Z suite, but not much. London averaging daily between 2C and 3.5C maxima up until 12th, and Manchester generally below 2C until the same date. Still very cold, still major snow risk temperatures. Slight uptick at the end.

Could you post them ?

I like the graph forms, thats really cold for Manchester  and would suggest maxes of 1 or just less locally ...brrrrrrrr...

Edited January 1, 2021 by northwestsnow

[ANYWEATHER]

Happy New Year To All .looks like we have a colder and colder outlook. Models are just firming up on an Historical Winter.! Tuesday across Southern Britain could be very snowy...and then there is Thursday....!

[Catacol]

4 minutes ago, Updated_Weather said:

Check this out!

Ah.....the gilt edged golden split scenario appears again. Kinda hoped it might happen a week earlier, and it still may not happen at all - but does it matter? Maybe not. So much that is good coming over the hill....like the Riders of Rohan charging down the mountain towards Helm’s Deep. The split would add the Ents.......

Bangers, mash, cheese and jacket potato just had with 2 of my children. Cracking. And for pudding - a dose of NWP. This one - stuff the mini blizzard that may or may not hit Wales and the Midlands - more significant the long draw easterly building in the background...easterly flow as perhaps the first sign of dispersed vortex energy appears in the trop output.

 

And before GFS loses the plot with its traditional westerly obsession we have a similarly tantalising mix of northerly plunge and easterly rampage. Again - look at those contours to the east and spot the long draw hoving into view, first flagged a day or so ago when EPS forecasts lost the positive anomaly over SE Europe.

Better yet - the parallel run. Bit more of an amplified northerly on offer with all kinds of mayhem in terms of what next.

Not to be outdone, our Canadian friends and allies come up with their own little corker - cold air pooling, spreading, drooling towards all parts of the UK.

Ok. So how realistic is all this, and should we be concerned at the GFS collapsing scenario? Well - let’s be honest. A westerly scenario over the U.K. is always an option. Can’t completely write off a short lived collapse while energy tumbles over the top....except there’s a real problem with the gfs modelling of this I think. First of all our best strat product shows that there is scarcely any westerly momentum left at any level of the strat come 9th Jan, and while it is possible to argue that westerlies are being flushed out by the descending reversal the zonal average at 70-90 is either close to 0 and south of 70 it is in reverse.

In the mid strat we have the vortex splitting and a net westerly wind speed of about 0.5 m/s. Despite my wrecked knee, courtesy of a scum sucking No 7 who took out my ACL while I barrelled through the midfield off a short pop, I reckon I could still run faster than that.

 

And in the lower/mid strat the GFS’ own appreciation of the vortex is a split, again with little momentum to add via downwelling and flushing out of residual westerlies. 

 

And in any case, even if the gfs isn’t overcooking westerly momentum at 60/65N there is yet another significant surge of pacific jet energy in the wings, ready to force up yet another burst of amplification.

 

If we get a relaxing I don’t think it will knock us out of a northerly/easterly pattern for any length of time, and personally I’m unconvinced. Let’s see what the black hole Aleutian Low travelling right now across the North Pacific does to modelling as it hits the US. For me the ECM modelling of substantive amplification at that point has a great deal more basis to it than the flatter GFS.

So...while it rained here again today much to my sadness, and I’m yet to see any lying snow or more than a few flakes in the air I remain convinced we are heading for significant and long lasting cold, with only an outside chance of a relaxing phase that would take the edge off for a day or two. Remember - the cold has only been knocking on our door for 6 days so far. I reckon we might have 31 more to come and maybe, just maybe, a good more than that.

Back to Al Murray on the TV courtesy of Amazon Prime....a perfect accompaniment to the bangers/mash with NWP and cream already served up tonight. Lovely for the New Year.

 

 

[iceman1991]

So sound like read through  the comments us southerners all will be having is rain and more rain like mid term mettoffice but anything above m4 be in luck ? 

[Scott Ingham]

57 minutes ago, Battleground Snow said:

For balance - arome, arpege and Harmonie snow depth charts.... Granted it's not that much still.

 

90% of that is from a trough tomorrow around 2pm that sinks south east.

The rest of saturday and sunday looks more like icy rain