Stratosphere and Polar Vortex Watch 2020

[MR EXTREMES]

i do believe this stratospheric warming will be a quick response warming, due to the continued mixing out of the deeper cold.

since start of the season there has been continued warming,

but not to sudden warming .

so far so good.

 

jma has just picked up on it today.

 

ecm and gfs have this coming warming as sudden.

i think personally this is a watch this space moment.

 

im confident this will have a very quick effect so even if we do get a west based nao it wont last long.

just my 2 pennies worth.

regards mr extremes 

[snowking]

For anyone over on Twitter Wx, worth following Allan as he seems to be providing us with a rare glimpse into the EPS's take on the current stratospheric shenanigans

This actually means the EPS are more keen on a reversal than the latest GEFS:

 

Still plenty of distance to travel on this one, and given the current tropospheric outlook we may not even need a full reversal, but fun to watch nonetheless

Edited December 22, 2020 by snowking

[bluearmy]

4 hours ago, ICE COLD said:

We should know soon if there is gonna be a technical SSW ? As in the wording should start to change at the back end of the METO 30 dayer . Chance of cold Easterly winds etc . That’s what happened on the previous 2 SSW , obviously doesn’t mean we’re hit the jackpot (2018) BFTE we could end up like last year and not get anything. But this year feels as tho something special could happen . 

for all we know, glosea might be seeing a reversal but it may be predicting a displacement or split where nw Europe becomes blocked or maybe worse!

[Met4Cast]

1 hour ago, bluearmy said:

for all we know, glosea might be seeing a reversal but it may be predicting a displacement or split where nw Europe becomes blocked or maybe worse!

Based on a run a few days ago, GLOSEA barely had an SSW signal at all, let alone a split! 

The GFS is certainly going all in, this is beautiful chart showing the SPV essentially obliterated. 

The GEFS/EPS seem to be signalling something similar, not quite as extreme as the GFS above but the signal is certainly growing!

[ALL ABOARD]

1 minute ago, Met4Cast said:

Based on a run a few days ago, GLOSEA barely had an SSW signal at all, let alone a split! 

The GFS is certainly going all in, this is beautiful chart showing the SPV essentially obliterated. 

The GEFS/EPS seem to be signalling something similar, not quite as extreme as the GFS above but the signal is certainly growing!

Marco tweeted yesterday stating it was on board 

[Met4Cast]

2 minutes ago, ALL ABOARD said:

Marco tweeted yesterday stating it was on board 

Ah perfect! So that's the big three on board then. 

[Singularity]

Uploading an image of an Excel chart does wonders for the resolution (!).

Anyway, this is what I get from a bit of further analysis on the station data that I used for the study presented here:

Sudden Stratospheric Warming: What’s the Big Deal? - Metswift

WWW.METSWIFT.COM

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Some winters, a powerful 'sudden stratospheric warming' raises severe winter weather risk across large parts of the northern hemisphere. A detailed study.

It further supports the notion that SSWs substantially increase the chance of very cold weather in the UK and the split variety gives the highest chance of all, 3 in 4.

I was actually surprised that the chance for a displacement SSW was so high; of those I can remember, all had poor outcomes here. That's only going back a dozen years or so, though! Too small a sample size.

Also worth noting how low the non-SSW chance of an above normal number very cold days is. SSWs really do contribute a lot for us.

[ALL ABOARD]

Perfect split? 

[Singularity]

Good to see the split shown more emphatically again after five more hesitant / less convincing deterministic runs. Just need GEFS to follow suit now...

[bluearmy]

1 hour ago, ALL ABOARD said:

Marco tweeted yesterday stating it was on board 

 

1 hour ago, Met4Cast said:

Ah perfect! So that's the big three on board then. 

are you sure ? he tweeted about gfs and eps but i couldn't see a ref to glosea  ????

[ALL ABOARD]

1 minute ago, bluearmy said:

 

are you sure ? he tweeted about gfs and eps but i couldn't see a ref to glosea  ????

[Catacol]

12 minutes ago, ALL ABOARD said:

Perfect split? 

Gotta be close. Support for a northern block and some potent easterly undercut if/as the flow reverses. This assumes effective frictional downwelling. 2018 was great to watch but we knew it was hitting in March. I’m smelling another swift trop response should a split like this occur, and so impacts in January - on top of a trop pattern that might already be supporting an easterly flow. I can scarcely believe what I’m seeing to be honest.....

I wonder what strat charts would have looked like back in big events of the past. It would be fascinating to know the detailed strat context back in 63 or 47.

Edited December 22, 2020 by Catacol

[snowking]

Very satisfactory ending to the 12z GFS

 

[Catacol]

1 minute ago, snowking said:

Very satisfactory ending to the 12z GFS

 

That’s an understatement. If the ridge can force those daughter vortices even wider in Jan week 2 then my head is beginning to spin at the tropospheric possibilities.......

[Scott Ingham]

5 minutes ago, Catacol said:

That’s an understatement. If the ridge can force those daughter vortices even wider in Jan week 2 then my head is beginning to spin at the tropospheric possibilities.......

Its mind blowing.

Ive never been as positive about a winter for sustained cold.

BUT its the isles so we shall see but that is a hell of a split on top of an atmosphere already primed

[lorenzo]

Glosea on-board, properly.

[ALL ABOARD]

10 minutes ago, lorenzo said:

Glosea on-board, properly.

Hi lorenzo, 

 

For the split? Or...

[Met4Cast]

GLOSEA is a go..

 

[Scott Ingham]

30 minutes ago, lorenzo said:

Glosea on-board, properly.

Best news of the day

[Bullseye]

And further to post from @lorenzo. Now this, to add this is confirmed in comments to be latest GLOSEA. 

 

 

Edited December 22, 2020 by Bullseye
Help if I added link!

[bluearmy]

Glosea, looks to be approx a fortnight reversed and then a slow recovery towards average later in feb  .........

[virtualsphere]

4 hours ago, Catacol said:

I wonder what strat charts would have looked like back in big events of the past. It would be fascinating to know the detailed strat context back in 63 or 47.

There's some 10mb charts for 1963 in this paper - although it's behind a paywall, you can currently create a free account to read a limited number of articles per month.

JSTOR: Access Check

WWW.JSTOR.ORG

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JSTOR is a digital library of academic journals, books, and primary sources.

As for 1947 I notice that this paper looking at historical SSW onset dates through reanalysis doesn't give anything for winter 1946-47 (Dec '47 is mentioned though): https://www.mdpi.com/2073-4433/10/9/519/pdf

[Scott Ingham]

3 hours ago, bluearmy said:

Glosea, looks to be approx a fortnight reversed and then a slow recovery towards average later in feb  .........

2018 was 10 days so this is excellent news for the heart beat of winter

[Mike Poole]

3 minutes ago, Scott Ingham said:

2018 was 10 days so this is excellent news for the heart beat of winter

Yes, I posted in the MOD the similarities with this one and 2018 (both forecasts):

If this happens, any major concerns i had that the SSW could scupper things are largely gone.  You can never be certain, but I’m comfortable with a pattern I have seen before, and this time it impacts the trop in the heart of winter...

[Scott Ingham]

5 minutes ago, Mike Poole said:

Yes, I posted in the MOD the similarities with this one and 2018 (both forecasts):

If this happens, any major concerns i had that the SSW could scupper things are largely gone.  You can never be certain, but I’m comfortable with a pattern I have seen before, and this time it impacts the trop in the heart of winter...

Both vortices further apart (obviosuly on current forecasts only) and our lobe this time dropping into Scandinavia and north western europe? Colder? And in the heart of Winter? I dont know i don't profess to be a strat expert but i don't know how we could be much colder than 18. That was hella cold!

Edited December 22, 2020 by Scott Ingham