Early run up to Winter 2020/2021 discussion

[damianslaw]

9 minutes ago, Mike Poole said:

I’m not concerned as yet re our chances of a disastrous winter.   It isn’t really the weather that affects us per se that is important in October or early November either.  It probably will be off the Atlantic and wet.  ECM T168 and T240:

It is where the blocking is that is more important at this stage, E Scandi and Russia good for putting pressure on the vortex early doors, if it comes good, flip to cold last week November, i reckon, not earlier.  Which is the earliest we want it anyway!

Yes some truth in this, if we see the trough come unstuck making inroads into east scandi this can be a sign pressure may be placed on the PV and in time we see the trough back away on a slider NW-SE trajectory the undercut solution, with heights to the NE. Keep an eye on developments to our east in coming weeks.

[daz_4]

GFS certainly didn't hold back with Siberian blocking this evening in FI.

Edited October 21, 2020 by daz_4

[northwestsnow]

EU weeklies will be interesting for those of us hoping to see some decent vortex disruption brought about by the  blocking to the NE .(way to the NE).

I'm non fussed about the vortex ramping up...

[I remember Atlantic 252]

2 minutes ago, northwestsnow said:

EU weeklies will be interesting for those of us hoping to see some decent vortex disruption brought about by the  blocking to the NE .(way to the NE).

I'm non fussed about the vortex ramping up...

Aye but surely that screams rain, lows stalling against the high, would rather traditional zonal, where fronts sweep through

[Catacol]

49 minutes ago, daz_4 said:

GFS certainly didn't hold back with Siberian blocking this evening in FI.

This is all going rather well. If the North Pacific can stay clear of sustained high pressure for a bit, and that sceuro high holds its ground, then watch for wave 2 activity through December. As Amy Butler has reported some of the best split vortex SSW events have happened in La Niña years. Just about getting late enough in the year to get properly interested in things. And if ECM is to be believed sceuro positive anomalies will be there for the first half of November at least....

[Cheshire Freeze]

51 minutes ago, I remember Atlantic 252 said:

Aye but surely that screams rain, lows stalling against the high, would rather traditional zonal, where fronts sweep through

Just like Nov 2009...and we all know what happened shortly after. 

[Cheshire Freeze]

53 minutes ago, Catacol said:

This is all going rather well. If the North Pacific can stay clear of sustained high pressure for a bit, and that sceuro high holds its ground, then watch for wave 2 activity through December. As Amy Butler has reported some of the best split vortex SSW events have happened in La Niña years. Just about getting late enough in the year to get properly interested in things. And if ECM is to be believed sceuro positive anomalies will be there for the first half of November at least....

Things look great from where I'm sitting. If we can get this big Russian high anomaly to manifest, we should find ourselves in a favourable feedback loop.

December has the potential to be a cracker.

[Allseasons-Si]

17 minutes ago, CreweCold said:

Just like Nov 2009...and we all know what happened shortly after. 

Yes an absolute deluge that was and i couldn't believe what happened afterwards

run this through to the latter part of Nov to see what happened,quiet a switch through the month.

 

WWW.METEOCIEL.FR

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Archives NCEP de 1851 à maintenant

Edit:the day ten EC looks poised.

Edited October 21, 2020 by Allseasons-si

[Don]

45 minutes ago, CreweCold said:

Just like Nov 2009...and we all know what happened shortly after. 

Us coldies hit the jackpot!

[damianslaw]

2 hours ago, I remember Atlantic 252 said:

Aye but surely that screams rain, lows stalling against the high, would rather traditional zonal, where fronts sweep through

We had a similar pattern I remember in Nov 2009, that time low pressure was unable to break into scandi and we ended up very mild and very wet with troughs becoming unstuck..

This time around the pattern looks like being further east, with more a colder polar maritime air feed, low pressure coming unstuck over scandi and warm air advection further east, the jet likely to be on a NW-SE trajectory.

I think the GFS might be a little early in suggesting such a set up, likely to be a temporary build of heights further south as shown by ECM but the overall pattern heading to that mentioned above.

[sebastiaan1973]

In this blog I read about the development of a mixed La Nina this winter.

http://easternmassweather.blogspot.com/2020/10/mixed-signals-regarding-enso-for-winter.html in

1970-1971

1999-2000

2007-2008

All of these years had a SSW. 

[SMU]

Just an update while its quiet & minimal happening.

The EPS 46 ( last run 19/10 ) sees plenty of excitement come November with ural blocking transferring west to Greenland-

Could unlock the cold for the UK ...

[LRD]

1 hour ago, Steve Murr said:

Just an update while its quiet & minimal happening.

The EPS 46 ( last run 19/10 ) sees plenty of excitement come November with ural blocking transferring west to Greenland-

Could unlock the cold for the UK ...

That does look promising although I'm not a fan of anomaly charts. Signs of low pressure heading towards Iberia and Southern Europe too. Something to keep an eye on to see if the trend is maintained

Edited October 22, 2020 by LRD

[Daniel*]

2 hours ago, Steve Murr said:

Just an update while its quiet & minimal happening.

The EPS 46 ( last run 19/10 ) sees plenty of excitement come November with ural blocking transferring west to Greenland-

Could unlock the cold for the UK ...

Yep it was interesting reverting back to blocked conditions we had been experiencing. Next update tomorrow 00z will love to see a continuation.

 

[bluearmy]

The new ec 46 won’t get too much airtime on here as November progresses into December ......

[blizzard81]

10 minutes ago, bluearmy said:

The new ec 46 won’t get too much airtime on here as November progresses into December ......

I'm quite cheered by that news. I've noticed how chilly and possibly quite snowy early December's fizzle out into anti-climax by mid to latter half of December's with regards to cold. Let's have the fun and games for the Xmas period for a change. 

[Paul_1978]

28 minutes ago, bluearmy said:

The new ec 46 won’t get too much airtime on here as November progresses into December ......

Why’s that then?

[jules216]

As the vortex finds its usual location between Greenland and Hudson Bay you will find  medium to long range models adjusting and suddenly realising it wont be bumped from there easily.Also the persistant Sceuro/Western Russian ridge will ensure that there is like 0% chance for a northerly flow or utopistic northeasterly in to Europe. The blue colors of below average temps in far western Europe is a cool westerly from raging +NAO. Yet La Nina November analogs had a strong mid Atlantic ridge and Sceuro trough anomaly.This will not happen in November 2020 and far more useful tool is to go with height anomalies of last 5 winters instead of the obsession of chasing the best case scenario. 

[LRD]

9 hours ago, blizzard81 said:

I'm quite cheered by that news. I've noticed how chilly and possibly quite snowy early December's fizzle out into anti-climax by mid to latter half of December's with regards to cold. Let's have the fun and games for the Xmas period for a change. 

I agree - mid-December to mid-Feb for cold please. Dec 2010 was a 1 in 100 year event (probably even worse odds than that as we're warming up) and we won't see that again.

However, I presume from bluearmy's post he's suggesting that EC46 looks particulalry bad. Moan alert but I've just got a sinking feeling about this winter again. In fact my hopes are sinking south about as fast as a promising ridge of winter high pressure around Greenland and Iceland 

[Catacol]

8 hours ago, jules216 said:

As the vortex finds its usual location between Greenland and Hudson Bay you will find  medium to long range models adjusting and suddenly realising it wont be bumped from there easily.Also the persistant Sceuro/Western Russian ridge will ensure that there is like 0% chance for a northerly flow or utopistic northeasterly in to Europe. The blue colors of below average temps in far western Europe is a cool westerly from raging +NAO. Yet La Nina November analogs had a strong mid Atlantic ridge and Sceuro trough anomaly.This will not happen in November 2020 and far more useful tool is to go with height anomalies of last 5 winters instead of the obsession of chasing the best case scenario. 

All a question of timing Jules. We want that Sceuro high to hang around - at as high a latitude as possible - to perturb the vortex and potentially setup an interesting heart of winter. At the same time we want Nina to approach a bottom of around -1.5 and no lower to promote that referenced mid atlantic ridge. At the moment both these scenarios are still in play and possible....though your doomsday scenario will always be more than just possible given the usual tendency towards atlantic dominance in all northern hemisphere winters.

However check your first temperature graph more closely. There is no way that it signals a raging vortex over Greenland. Temps are too high. That's a ridge. Here's the mean anomaly 500 chart that goes with it....

 

[booferking]

8 hours ago, jules216 said:

As the vortex finds its usual location between Greenland and Hudson Bay you will find  medium to long range models adjusting and suddenly realising it wont be bumped from there easily.Also the persistant Sceuro/Western Russian ridge will ensure that there is like 0% chance for a northerly flow or utopistic northeasterly in to Europe. The blue colors of below average temps in far western Europe is a cool westerly from raging +NAO. Yet La Nina November analogs had a strong mid Atlantic ridge and Sceuro trough anomaly.This will not happen in November 2020 and far more useful tool is to go with height anomalies of last 5 winters instead of the obsession of chasing the best case scenario. 

Full of joy i see the day again.

[sebastiaan1973]

Negative NAO options are low.

[jules216]

8 minutes ago, Catacol said:

All a question of timing Jules. We want that Sceuro high to hang around - at as high a latitude as possible - to perturb the vortex and potentially setup an interesting heart of winter. At the same time we want Nina to approach a bottom of around -1.5 and no lower to promote that referenced mid atlantic ridge. At the moment both these scenarios are still in play and possible....though your doomsday scenario will always be more than just possible given the usual tendency towards atlantic dominance in all northern hemisphere winters.

However check your first temperature graph more closely. There is no way that it signals a raging vortex over Greenland. Temps are too high. That's a ridge. Here's the mean anomaly 500 chart that goes with it....

 

The missing part for me is that where are those trigger low heights-low pressure areas that can pull the cool surface temperatures? One thing is the temporary above average heights in NAO corridor for a week or so, but what about the trigger low that can put us to more below average anomalies? If we get a combination of temporal -NAO but with a sort of Sceuro or western Russian ridge never far away, where will we be pulling the below average temperatures from? I am increasingly concerned we will be enduring a blend of 2007/08 winter and default last 5 years anomalies. When was the last time a proper Sceuro trough established in the month of Nov til January? Every blend of past week/moderate or strong La Ninas had a strong signature of Sceuro trough in November, what I see on the ensemble modeling is the opposite backed up by meteogram from near my city that goes all they way to the end of November and mean never drops below 0C at 850hPa. To me this is a proof that past analogs no longer apply anymore and better to go with recent climo, not to be disapointed again. 

[summer blizzard]

The ridge is the result of GLAAM close to neutral and the MJO. Unless it has freaky persistence I would imagine that it relents to a more normal Nina background pattern as we head into the second half of November.

[jules216]

16 minutes ago, summer blizzard said:

The ridge is the result of GLAAM close to neutral and the MJO. Unless it has freaky persistence I would imagine that it relents to a more normal Nina background pattern as we head into the second half of November.

And this is where I find the whole GSDM debate misleading. You are talking about GLAAM going neutral that promotes ridging. But if you look at composite of -AAM for months of NDJ that is actually showing anomalies we'd like to see.