model discussion Model output discussion - closing in on Winter

[damianslaw]

12 minutes ago, Mike Poole said:

Hey, does anyone, actually think the GFS 18z going down this route T300:

…would actually happen?

I don’t, it is probably unphysical, no way, this is totally against the background signals…well more about them to tomorrow when hopefully this abomination won’t be stage front….

 

 

GFS going off on one as per usual. Discard.

[Tamara]

On 24/11/2021 at 19:28, Met4Cast said:

I wouldn't get too bogged down with what individual deterministic runs show beyond day 5 at the moment. The GEFS mean is sharpening up in terms of another cold plunge from the north during the first few days of December.

Originally we were looking at a return to flat more zonal during this timeframe but that's been pushed back, largely I suspect thanks to the persistent phase 6 MJO signal, albeit low amp.

Going forward, models are picking out another emerging phase 6>7 signal during early December, taking lag time this leads to a potential re-amplification of the pattern by mid December. 

It's possible (and perhaps likely?) that we'll see the pattern finally flatten out 5th-13th December bringing in less cold conditions, but beyond that signals seem to look good for another round of amplification, this time hopefully into Greenland. 

Based on yesterdays attempts to provide some balanced grounding about the MJO and the wind-flow budgets on the broader scale - your analysis persists in this stand-alone magic bullet concept that MJO x+y = desired solution.  I am not a prophet, and do not profess to have the ability to second guess the diagnostic, even though its (real) purpose is invaluable and gives some very helpful insight looking ahead as to what *might* happen in terms of *ranges* of probabilistic solutions. That as opposed to fitting to one bias solution.. But I certainly do know that this persistence in trying to fit to bias is  flawed, other than the broken clock analogy where it comes right eventually and appears to vindicate the bias confirmation.

As for the time-lags and 'signals seem to look good for another round of amplification'  - . Quite apart from the extra tropical wind-flow budget not accounted for in favour of taking the MJO in isolation because it is believed to deliver an arctic flavoured  happy pill - it makes it further impossible to start to extrapolate what *might* happen in mid December.

On the other hand if the GSDM is considered in respect of total global wind-flow, and objectivity can resist trying to tie analysis down to a pre-conceived ideal - then it starts to become a worthwhile discussion and probabilistic outcomes can begin to be reasoned.

Edited November 25, 2021 by Paul
Removed the unnecessary barbs - I can understand the frustration at times with the cold chasing but we all have a responsibility to treat others in the way we'd expect to be treated on here.

[tight isobar]

On 24/11/2021 at 23:41, Tamara said:

Based on yesterdays attempts to provide some balanced grounding about the MJO and the wind-flow budgets on the broader scale - your analysis persists in this stand-alone magic bullet concept that MJO x+y = desired solution.  I am not a prophet, and do not profess to have the ability to second guess the diagnostic, even though its (real) purpose is invaluable and gives some very helpful insight looking ahead as to what *might* happen in terms of *ranges* of probabilistic solutions. That as opposed to fitting to one bias solution.. But I certainly do know that this persistence in trying to fit to bias is  flawed, other than the broken clock analogy where it comes right eventually and appears to vindicate the bias confirmation.

As for the time-lags and 'signals seem to look good for another round of amplification'  - . Quite apart from the extra tropical wind-flow budget not accounted for in favour of taking the MJO in isolation because it is believed to deliver an arctic flavoured  happy pill - it makes it further impossible to start to extrapolate what *might* happen in mid December other than admission that it is pure hope-casting.

On the other hand if the GSDM is considered in respect of total global wind-flow, and objectivity can resist trying to tie analysis down to a pre-conceived ideal - then it starts to become a worthwhile discussion and probabilistic outcomes can begin to be reasoned, The problem is that the why's and wherefore's don't interest many on this thread and such a discussion is never going to happen because any credible outcome other than wintry nirvana is not up for discussion and needs to be closed out . The 'background signals' are only ae of interest if they make it snow and so discussing  actual 'background signals' (which has become a grinding cliche anyway)  is a waste of time..

A good balancing post- however I’m sure the majority in here-as everywhere, are well and truly on the fence for the mid- December period. And as it’s obviously now a more winter based thread- persons will look for all entry’s for a colder soulution. So I found some of you’re post a little bitter in quotation!.@Bias etc. But I suppose it would be a boring place.. And indeed world if we were all one way thinkers on the same page.

[Allseasons-Si]

The latest gefs ens show an almost unanimous decision of another cold shot around the turn of the month(red circle)

that is a big upgrade from the previous runs,then after that,...well,shannon comes to town.

[TSNWK]

00z moving beyond this weekend. Has transitory colder snap middle of next week. Then it ain't looking good for anything more with high pressure core to our south west of west and plenty of purple to our north and north west for rest of run.  Next run please

[sheikhy]

Very dissapointing runs this morning!!after a bit of hope on the 12zs we have gone backward again!!make the most of the next 5 days of cold for now!!

[mountain shadow]

The return of the purple blob of doom to NE Canada has been hinted at for a while, now it looks certain. 

If it does occur then we can write off December for sure.

[Premiere Neige]

4 minutes ago, sheikhy said:

Very dissapointing runs this morning!!after a bit of hope on the 12zs we have gone backward again!!make the most of the next 5 days of cold for now!!

Or wait and see what today's 12z has to offer?

[cyclonic happiness]

It looks great for the next few days folks, we don't really need to worry about that. 

as for next month, it looks a bit more zonal, but we aren't even in winter yet and are about to get the best weather action in months.

chins up!

[mbrothers]

So we’re writing off December on the 25th November? Brave call.

[mountain shadow]

14 minutes ago, mbrothers said:

So we’re writing off December on the 25th November? Brave call.

Only if the tropospheric PV does set up shop in NE Canada, that may not prove to be the case of course.

We'll know soon enough whether the MJO phase 7 occurs and if it's at a high enough amplitude to bring positive impacts. 

[TSNWK]

On 25/11/2021 at 07:02, mountain shadow said:

The return of the purple blob of doom to NE Canada has been hinted at for a while, now it looks certain. 

If it does occur then we can write off December for sure.

Yep.  First signs yesterday morning... Seems a stronger signal this morning for the vortex to our north west.. with potential thats  December settled with exception of flirting passages of slightly less mild air as systems pass through. 

[sheikhy]

After viewing the ecm snow charts for friday night saturday im surprised it still shows a smattering of snow anywhere across england!!

[Nick F]

5 minutes ago, mountain shadow said:

Only if the tropospheric PV does set up shop in NE Canada, that may not prove to be the case of course.

We'll know soon enough whether the MJO phase 7 occurs and if it's at a high enough amplitude to bring positive impacts. 

The trop PV moving in over NE Canada is not such a bad thing if it pumps WAA across the GIN corridor and builds heights over Scandinavia. Hints of that longer term in the ensemble guidance and this may occur through 1st half of December as the MJO wave moves towards phase 7. It's when the trop PV extends over Greenland too that can be the issue with driving a +NAO pattern.

In the shorter to medium term, inevitable the cold northerly reload later next week would be downgraded, the models can often over amplify at that range, though that's not to say it may come back. If we can at least keep a NWly flow it will remain on the chilly side, and there are chances it may still veer northerly briefly to keep temperatures close to or slightly below average rather than a westerly keeping us mild. 

[blizzard81]

Its not the be all and end all nor the death of winter if that purple blob sets up to our north west. As long as we can eak out some pressure rises to our north east. History has proved that. 

Edited November 25, 2021 by blizzard81

[TSNWK]

Best I can offer this morning is ECM 240 if we can lose that low between Canada and Scotland the vortex might then be able to pump up those fledgling heights to our north east and we two into some decent cold air over scandi.

[mb018538]

12 minutes ago, TSNWK said:

Yep.  First signs yesterday morning... Seems a stronger signal this morning for the vortex to our north west.. with potential thats  December settled with exception of flirting passages of slightly less mild air as systems pass through. 

Never a great look for the UK once those purples start appearing to our NW. Thankfully the strong vortex doesn't appear to be coupling up just yet. No need to worry, just par for the course in winter....and hopefully this cycles through and doesn't set up shop.

[blizzard81]

3 minutes ago, TSNWK said:

Best I can offer this morning is ECM 240 if we can lose that low between Canada and Scotland the vortex might then be able to pump up those fledgling heights to our north east and we two into some decent cold air over scandi.

Yep, whilst at first glance that chart doesn't look great, on greater inspection it is hardly zonal. In fact its the sort of chart that could lead to something much better just a couple of days later. 

[SLEETY]

You know when things look grim again for cold when people start posting charts from 47,87 etc

December in UK is rarely a bitter month anyway,coldest weather seems to be right at the end of the winter, rarely at the beginning. 

[mb018538]

3 minutes ago, TSNWK said:

Best I can offer this morning is ECM 240 if we can lose that low between Canada and Scotland the vortex might then be able to pump up those fledgling heights to our north east and we two into some decent cold air over scandi.

The only problem we get when we start to see charts like this appearing is that very cold air start to pour off the eastern seaboard and creating a strong thermal gradient to turbo charge the Atlantic. We haven't seen this at all so far this autumn as pressure patterns have been far from the norm....but a period of more mobile weather could be on the way

[tight isobar]

On 25/11/2021 at 07:48, TSNWK said:

Best I can offer this morning is ECM 240 if we can lose that low between Canada and Scotland the vortex might then be able to pump up those fledgling heights to our north east and we two into some decent cold air over scandi.

We can as we have, see a drain of the main lobe Canadian pv.. extracting to the north eastern side!.. models are toying with both scenarios atm- with a limp it pv also at its home point!@canadian geographical.. either are as likely as the other as we stand... so need need for panic on any front atm!!- on we go..

Edited November 25, 2021 by tight isobar

[Eagle Eye]

Saturday looking more and more likely with the Icon at the moment swaying  towards a mass of snow across the south early morning, the question still remains about later Saturday and Sunday. I'm not sure as to Icon's role in overplaying or down playing the event but it seems to almost ignore any North Sea showers in the day potentially becoming snow (although brings more in at night) and focusing on the Irish Sea so still all to play for I guess.

[knocker]

The medium term anomalies are beginning to indicate what the ext means have been indicating for a while. Which is the tpv lobe returning to it's winter residence northern Canada; a westerly upper flow, perhaps nudging a tad north of west, courtesy of the Azores HP retaining some influence; and the Euro trough retreating to eastern parts. Temps around average. I mean, what's not to like!!

 

[Tim M]

9 hours ago, Kirkcaldy Weather said:

Yep I am watching extremely closely as I am in / directly next to those highest wind zones

Where do we think the worst of the winds will be. My area, north Notts, has veered from max predicted gusts of 50 to now 60plus this morning on latest GFS run. Yet MO say 45mph. Which is more reliable? 

[Dennis]

Goodmorning all  most certainly is snow to the east into saturday