Model output discussion - Closing in on Christmas

[Daniel*]

Looking at EPS in its entirety certainly seems Atlantic ridging is a longstanding feature!! Also Euro low anomaly which is good. High confidence most of Europe is going to see some wintry weather. We’re more likely to be nearer to ridge so less obviously wintry - let’s hope it’s as far NW as possible then sky’s the limit! 

Edited December 18, 2020 by Daniel*

[alexisj9]

2 hours ago, nick sussex said:

Quite remarkable to see the drama the models are making over that low to the sw .

 

I saw that coming, may still be fi at 48 z lol. Although I'd like to hope it's finally sorted over night, then I'll start concentrating on the under cutting lows, to the west, or hopefully they will be anyway

[Man With Beard]

39 minutes ago, Mike Poole said:

ECM clusters T192-T240, there are 6 of them!

But I’d take all but the last, least probable one!

Yes, the vast majority are ridge west / trough east, in various forms. Given the large size of the mean Atlantic ridge, I feel more confident that something between a NWly and a NEly will actually verify in some form, much more confident than I ever was about the Christmas Day northerly which looked ripe for toppling from the start. The NWly being far more likely than the NEly, but a N/N/Ely could follow after if the trough is aggressive in its progress towards Europe. Likely corrections will perhaps 7 out of 10 times rule out a trough ending up west. So, I think there's a fairly good chance northern areas will see snow after Christmas. Southerners really need the pattern to fall right, but no reason why it couldn't lead to snow here too if the trough ends up east or south of the UK (which seems as good an option as any right now). Lots of continuing interest for sure, though lots of potential frustration too!

Haven't totally given up on a few snow flurries on Christmas Eve/Day but it will need something a bit unusual to happen now.

[Catacol]

Great model watching at the moment. Momentum products are generally neutral - but the key here is that the GWO hasn’t descended (yet) into a Niña style orbit, meaning the kind of forcing that would help produce a flat pattern isn’t in process. Instead the GWO is holding in a high enough orbit to suggest amplification will continue.

Meanwhile we have rising mountain torque once again, predicted on the back of frictional torque that started to rise a week ago.

Resultant pacific jet energy is very evident at the moment, not just for today but for the next 10 days or more if gfs is to be believed.

In addition wave 1 energy has surpassed forecasts of a week ago, now running significantly above the levels predicted then. 

As a result we have split vortices remaining split in the lower strat, preventing downwards reinforcement of westerlies.

And wave 2 forcing is returning - at low levels admittedly for now.

And finally we have a good bit of convective activity around the maritimes suggesting the MJO is entering a condition more conducive to supporting ridging

Sum total? We have an unhappy vortex, I’d suggest the origins of which can be traced right back to the semi permanent ScEuro High that was being cursed in November. It’s unhappiness is being sustained by strong forcing from the pacific side, and it could become extremely unhappy when forcing kicks in from Scandy again. What will cause this? We have another +EAMT helping sustain wave breaking momentum, and a GWO profile and MJO context that at the very least are not in opposition and at best are providing support for ongoing amplification. And the timing is good. Trop led amplification is going to work to hit the vortex just when the vortex is ripe for being hit. 
 

There is nothing bad here, and no driver I can see that portends the return of a flatter pattern this side of New Year. By the time we get there the vortex could be in shreds. My pre season guess at an SSW on 23rd January looks conservative now. Amy Butler, boss of Strat knowledge, might be spot on with the 9th. We need the Ural High to remain in play so that we get a split SSW....and then the rest of winter is wide open for fun. Glosea can go swivel........

Edited December 18, 2020 by Catacol

[tinybill]

all i say if this comes  off  this place  will go down in to melt  down!!!

[Uncertainty]

16 minutes ago, Catacol said:

Great model watching at the moment. Momentum products are generally neutral - but the key here is that the GWO hasn’t descended (yet) into a Niña style orbit, meaning the kind of forcing that would help produce a flat pattern isn’t in process. Instead the GWO is holding in a high enough orbit to suggest amplification will continue.

Meanwhile we have rising mountain torque once again, predicted on the back of frictional torque that started to rise a week ago.

Resultant pacific jet energy is very evident at the moment, not just for today but for the next 10 days or more if gfs is to be believed.

In addition wave 1 energy has surpassed forecasts of a week ago, now running significantly above the levels predicted then. 

As a result we have split vortices remaining split in the lower strat, preventing downwards reinforcement of westerlies. And wave 2 forcing is returning - at low levels admittedly for now.

And finally we have a good bit of convective activity around the maritimes suggesting the MJO is entering a condition more conducive to supporting ridging

Sum total? We have an unhappy vortex, I’d suggest the origins of which can be traced right back to the semi permanent ScEuro High that was being cursed in November. It’s unhappiness is being sustained by strong forcing from the pacific side, and it could become extremely unhappy when forcing kicks in from Scandy again. What will cause this? We have another +EAMT helping sustain wave breaking momentum, and a GWO profile and MJO context that at the very least are not in opposition and at best are providing support for ongoing amplification. And the timing is good. Trop led amplification is going to work to hit the vortex just when the vortex is ripe for being hit. 
 

There is nothing bad here, and no driver I can see that portends the return of a flatter pattern this side of New Year. By the time we get there the vortex could be in shreds. My pre season guess at an SSW on 23rd January looks conservative now. Amy Butler, boss of Strat knowledge, might be spot on with the 9th. We need the Ural High to remain in play so that we get a split SSW....and then the rest of winter is wide open for fun. Glosea can go swivel........

 

 

Great stuff pal. I remember in November you were praising the Urals blocking for its future gifts, not for the monotony it provided at the time.

Our last few Novembers were cold and  where did that get us?

I think November is the key month for Eurasian snow cover advance. This year October was unremarkable but it really kicked off in November in tandem with the quasi stationary block. Siberia finally cooled off the back of record warmth of this year and this very much didn’t happen last year. This in turn has provided a key part of the feedback mechanism to induce the big heat flux into the strat which we are now seeing.

The question is, *if* this does happen, why didn’t the December seasonals see it? They must have had the Russian high in their starting data yet they’re only slightly better than last year’s garbage. Or did they see a weak displacement / reflection event combined with a strong Nina which flattens everything off?

Those seasonals are the only nagging voice in my head now. I’d love for them to be proved wrong. Not only would it be a victory for human forecasting ingenuity but it would free up the future to intrigue, wonder and debate. Knowing the future for certain would completely spoil our fun! 

 

 

Edited December 18, 2020 by Uncertainy

[Daniel*]

I don’t think we need a Scandi ridge the GFS 12z was crippling and splitting vortex without it. North Atlantic, wave 2 action? 

 

very similar to early January 2013 SSW and split 8 years later Hmm could we see a similar pathway...

Edited December 18, 2020 by Daniel*

[mulzy]

1 minute ago, snowbob said:

Can’t be that good

steve hasn’t popped in ( yet )

No surprise there.  We are still a *long* way from a wintry cold spell being nailed on.  Signals are promising but a lot of water is yet to flow under the bridge.

[alexisj9]

2 hours ago, ITSY said:

Wow, only missed the 67 messages. 

Meanwhile ECM looks good to me at 192. Not sure what more we could want at that range tbh! 

 

Edit: could possibly do with the PV dropping more SEward rather than Sward in order to bring in colder uppers but, heyho, variation on a theme. That's all that matters for now!

Less of a southwesterly in the SE perhaps?

 

[Mike Poole]

On to the 18s then, ICON at T120, compared with 12z at T126:

Not bothered about the first ridge, we know that topples, increased amplification (circled) for the second ridge, suggests this model is smelling the coffee and joining the others.

[ANYWEATHER]

Evening Folks. A snapshot of January 25th 1963  a mid Atlantic Ridge. ....just like what is showing up now. Mum said it was soo cold under clear skies. Just look happened to Greenland that year!

[Mr Frost]

Evening all!

Hope you are all well!

Exciting times for a cold/snow lover! 

Lots of chat about late December/early January and rightly so! However - wee bit of naughty cold sneaking into the semi reliable timeframe of 120 hours/day five.

UKMO 120: 13:00

 

UKV snapshots for 120: 15:00

Precipitation type & sea level pressure:

 

850HPA:

 

Wet bulb freezing height (m)

Dewpoint temperature (C)

 

Thickness (dam)

 

23/12 to 25/12 at least has chilly days, risk of snowfall/wintry showers for some and frosts for many on current output - lovely seasonal/festive weather! Not to be sniffed at. 

Merry Christmas and a Happy New Year to you all when it arrives! I shall see you all again in January when the BFTE arrives! 

Cheers! 

[damianslaw]

Taken a week out of posting in here, and pleased I did, but have been viewing the charts with interest. 

There has been a lot of twoing and froing in recent days about likely developments as head into christmas period. This period is now coming into the reliable, but not quite there yet, by end of weekend will have a much better idea how things may pan out.

Alas, based on current output if it verifies as shown, then a very different christmas period to many we have experienced really.

In the short term, we have mid atlantic ridge development killing off the atlantic to a degree with more of a flow from between west and north, so turning colder, with return of frost and possibly some wintry showers through early part of upcoming week. All eyes then on developments over the Eastern USA seaboard, signs of a much more amplified and deeper trough which would have a domino effect, allowing for a more buckled jet and the mid atlantic ridge building north eventually, this is being shown on the models through next weekend, but beyond the reliable.

I do take note when we see such sudden amplification, signs something is stirring.. and especially when all models are all in sync, but only much more so when such developments are shown in the 120-144 hr timeframe.

A possible very interesting end to 2020, packs of potential for something substantively wintry. Might have to exchange a rather average christmas day for a much colder wintry New Year. we shall see.

[bluearmy]

Icon 18z is still isolated by not having a positive tilt to the flow around greeny day 5

[Mike Poole]

24 minutes ago, Daniel* said:

I don’t think we need a Scandi ridge the GFS 12z was crippling and splitting vortex without it. North Atlantic, wave 2 action? 

 

very similar to early January 2013 SSW and split 8 years later Hmm could we see a similar pathway...

Good spot, Daniel, it won’t be quite the same this year, 2013 came on the back of mild (and the scars from that Dec 2012 failed easterly), but this year the trop pattern is so much primed for UK cold before it happens, so the SSW, when it happens (and it is certain in my view that it will) and the dice are thrown in the air, to land who knows where, will now likely be double or nothing.  Where’s your money?  I genuinely have no idea, but it will be fun finding out.

[Matt H]

GFS 18z: steady as she goes at t6.

Edited December 18, 2020 by Frosty Winter

[MATTWOLVES 3]

Wow,have I missed something Firstly those 12z ens are pretty encouraging moving forward, and I'm aware the ECM earlier was a peach.

I'm gonna bring you some positive news from Jon Hammonds updated blog this week..

Brief cold snap Xmas! Weather systems perhaps being blocked by colder air to the East..the jet carrying these systems having a tendancy to split rather than dive across us. There is a very real chance colder air lurking to the East will re assert itself,and this looks increasingly likely as we enter 2021.. Its been pointed out that many Long range  Models were writing off Winter before it began earlier on, now most of the long rangers are indicating the atmosphere will continue to be blocked.And most definitely signs the Vortex will significantly weaken in the coming weeks.

Its been a long time since I witnessed snow and I tell you what if and when it comes I will be running naked through it..

[Scott Ingham]

57 minutes ago, Catacol said:

Great model watching at the moment. Momentum products are generally neutral - but the key here is that the GWO hasn’t descended (yet) into a Niña style orbit, meaning the kind of forcing that would help produce a flat pattern isn’t in process. Instead the GWO is holding in a high enough orbit to suggest amplification will continue.

Meanwhile we have rising mountain torque once again, predicted on the back of frictional torque that started to rise a week ago.

Resultant pacific jet energy is very evident at the moment, not just for today but for the next 10 days or more if gfs is to be believed.

In addition wave 1 energy has surpassed forecasts of a week ago, now running significantly above the levels predicted then. 

As a result we have split vortices remaining split in the lower strat, preventing downwards reinforcement of westerlies.

And wave 2 forcing is returning - at low levels admittedly for now.

And finally we have a good bit of convective activity around the maritimes suggesting the MJO is entering a condition more conducive to supporting ridging

Sum total? We have an unhappy vortex, I’d suggest the origins of which can be traced right back to the semi permanent ScEuro High that was being cursed in November. It’s unhappiness is being sustained by strong forcing from the pacific side, and it could become extremely unhappy when forcing kicks in from Scandy again. What will cause this? We have another +EAMT helping sustain wave breaking momentum, and a GWO profile and MJO context that at the very least are not in opposition and at best are providing support for ongoing amplification. And the timing is good. Trop led amplification is going to work to hit the vortex just when the vortex is ripe for being hit. 
 

There is nothing bad here, and no driver I can see that portends the return of a flatter pattern this side of New Year. By the time we get there the vortex could be in shreds. My pre season guess at an SSW on 23rd January looks conservative now. Amy Butler, boss of Strat knowledge, might be spot on with the 9th. We need the Ural High to remain in play so that we get a split SSW....and then the rest of winter is wide open for fun. Glosea can go swivel........

Amy is looking spot on as she usually is mate. My christmas week ssw and your end of January prediction will probably meet in the middle! Haha! Great post summing up direction of possible travel as usual!

[tight isobar]

Just showed this to my good friend and newsagent mr singh.. he has-now withdrawn all the adult magazines that I used ta buy from he’s shelves!!

Edited December 18, 2020 by tight isobar

[Matt H]

3 minutes ago, tight isobar said:

Just showed this to my good friend and newsagent mr singh.. he has-now withdrawn all the adult magazines that I used ta buy from he’s shelves!!

 

[tight isobar]

Anyway.. the rind veculations.. and momentum .. building with vigor... we ARE onto something here .. for sure

[pinball wizard]

4 minutes ago, tight isobar said:

Just showed this to my good friend and newsagent mr singh.. he has-now withdrawn all the adult magazines that I used ta buy from he’s shelves!!

And no doubt he's replaced them with that niche title Reader's Wedges....

[Allseasons-Si]

@Mr Frost

Brrrrh!!!,you just sent a shiver down my spine lol

yes if we can't have snow then i am looking foreword to a crispy/chilly/sunny and frosty Christmas morning,...bring it on,that seems like a decent starter before the main course...hopefully,there has been some consistency showing in the models since last night for more of an amplified ridge in the Atlantic but we need to see this get to closer timeframes 

The 12z ICON at 120 has some snow from the midlands north as the low pulls away but the 18z is further SW so still some uncertainty of the track of this feature.

 

Have a great Christmas and happy new year

 

 

 

 

 

 

[tight isobar]

Just now, pinball wizard said:

And no doubt he's replaced them with that niche title Reader's Wedges....

Always one ... ain’t there

[SnowSalah]

Had a few drinks and I must say, loving the charts at the minute, long may they continue (without any wobbles)