Stratosphere and Polar Vortex Watch 2020

[Catacol]

Prior to any downwelling impacts we continue to see the same anomaly pattern that seems to have been in place since November for a Ural High and in general a North Pacific / Aleutian trough. 

Its not such a strong signal as earlier in December but it shows wave 2 forcing isn’t going away. With GFS picking up on the impacts of this, then maybe we can get back to the gilt-edged scenario of an initial displacement with reversal, and then wave 2 shatter effect. That ends the vortex as a westerly influencer for the season, and brings back visions of the 8 week historic cold spell. Yum...something like this perhaps by mid month. Absolute carnage.

 

Edited December 30, 2020 by Catacol

[bluearmy]

2 minutes ago, Catacol said:

Prior to any downwelling impacts we continue to see the same anomaly pattern that seems to have been in place since November for a Ural High and in general a North Pacific / Aleutian trough. 

Its not such a strong signal as earlier in December but it shows wave 2 forcing isn’t going away. With GFS picking up on the impacts of this, then maybe we can get back to the gilt-edged scenario of an initial displacement with reversal, and then wave 2 shatter effect. That ends the vortex as a westerly influencer for the season, and brings back visions of the 8 week historic cold spell. Yum...something like this perhaps by mid month. Absolute carnage.

 

Extended eps drive a sig e Alaskan ridge ......

the 12z ec op seems to be attempting to split the vortex through Asia leaving Atlantic and e Asian vortices.  The gfs op wasnt too far from heading that way. the ec zonal chart eagerly awaited to see how it plays out. 

[TSNWK]

3 minutes ago, bluearmy said:

Extended eps drive a sig e Alaskan ridge ......

the 12z ec op seems to be attempting to split the vortex through Asia leaving Atlantic and e Asian vortices.  The gfs op wasnt too far from heading that way. the ec zonal chart eagerly awaited to see how it plays out. 

Not an option UK coldies would like then blue.. ?

[Catacol]

7 minutes ago, TSNWK said:

Not an option UK coldies would like then blue.. ?

In a perfect world we’d prefer not to see a vortex shard in the Atlantic, but if it is as badly shattered and broken as some charts are suggesting then it probably isn’t an issue. But in any case if we have reverse flow in action it won’t stay in the Atlantic for long. The “bad” scenario we have seen before is a displaced vortex into the Atlantic not sufficiently weakened. When coupled all this does is whip up the westerlies. However we are not looking to be in that context this time around. 

[snowking]

I’m really liking this pretty picture:

 

Just to add even further weight to @Catacol’s post above, even if we do end up with part of the vortex in the Atlantic, is it really going to have much influence? I would think not.

Note the big void around Greenland and the North Atlantic....I wonder what could fill that gap...

[Cloud 10]

Vortex super-split on the 18z gfs.

 

Instant Weather Maps

 

[sebastiaan1973]

Displacement SSW. The vortex is placed in the Atlantic Ocean.

[Scott Ingham]

20 minutes ago, sebastiaan1973 said:

Displacement SSW. The vortex is placed in the Atlantic Ocean.

Just out of interest. What are the charts for 216 and 240 because that also looks likr the start of a split looking at it again 

Also the zonal winds are that weak for that long and the vortex that stretched even on that chart i can see it making zero difference to the tpv. The vortex is a dead duck no matter where it is

Edited December 31, 2020 by Scott Ingham

[sebastiaan1973]

15 minutes ago, Scott Ingham said:

Just out of interest. What are the charts for 216 and 240 because that also looks likr the start of a split looking at it again 

Also the zonal winds are that weak for that long and the vortex that stretched even on that chart i can see it making zero difference to the tpv. The vortex is a dead duck no matter where it is

This is based from the output of EC12h yesterday.

[Scott Ingham]

2 minutes ago, sebastiaan1973 said:

This is based from the output of EC12h yesterday.

Okay. Like i say not really my area mate i know enough to read the charts and have a spinal level of knowledge but to forecast forward from a particular chart what the trop pattern might look like its above my pay grade. My skill set is long range forecasting having a knowledge of the tropics momentum enso states and the likes. Them comments were based out of common sense due to what i could see possibly happen next whilst factoring in the current state of the tpv. Im likely to be wrong but this is a learning tool for me this year

[bluearmy]

Ec 00z day 10 at 10 and 50 hpa 
 

   
 

 Not too far from the gefs and gfs at this point ........

would be a good day to get a ventrice tweet on the eps strat charts late week 2 

however, the glosea zonal flows tweeted yesterday showed a general reversal of -20m/s which would indicate the polar high getting way over the pole ....

Edited December 31, 2020 by bluearmy

[sebastiaan1973]

Scott and Blue Army thanks for your answers

[Scott Ingham]

3 minutes ago, bluearmy said:

Ec 00z day 10 at 10 and 50 hpa 
 

   
 

 Not too far from the gefs and gfs at this point ........

would be a good day to get a ventrice tweet on the eps strat charts late week 2 

So a split was possible going forward from that chart then

[bluearmy]

6 minutes ago, Scott Ingham said:

So a split was possible going forward from that chart then

Yes it is as per today’s gfs op run later on but it could easily stay displaced with the vortex stretched around the edge of the high

[Interitus]

On 29/12/2020 at 22:35, ALL ABOARD said:

I take it this could be the first time in our recorded history that we have a major SSW with a troposphere that is as weak as it is. 

Therefore the papers the theories the wills it's or won'ts it can't be answered. 

We can summerize but the weather will make fools of us all. 

Its going to be so interesting to dissect this after the event. 

 

No, not really. There is always some tropospheric blocking in advance of an SSW, usually Atlantic side for wave 1 like this.

[SqueakheartLW]

As always my daily stratospheric update

GFS 00z

I shall begin with GFS as always and like with previous updates the first main warming results in a displaced vortex but there are still strong signs of a second warming in the middle of January which in most cases through the ensembles finally split the vortex and some almost totally destroy what is left of the vortex

Here are the biggest second warmings showing up in the 00z today

Also just for fun here are the second warmings that result in the weakest or almost destroyed vortexes

The GFS is also seeing a big shift towards a split of the vortex as we get to mid January too. The latest outcomes show this

STRATOSPHERIC WARMING OPTIONS
Type                    20/12    21/12    22/12    23/12    24/12    25/12    26/12    27/12    28/12    29/12    30/12    31/12
Displacement    21          34          22          41          53          54          72         61          42          53          32          4
Av Date               05/01    06/01    07/01    08/01    09/01    10/01    11/01    12/01    13/01    14/01    15/01    16/01
Split                     24          29          43          32          23          27          16         29          52          43          64         28
Av Date               05/01    06/01    07/01    08/01    09/01    10/01    11/01    12/01    13/01    14/01    15/01    16/01
Unknown            38         22          18          16          10          7            1            0            0             0           0            0
Av Date               05/01    06/01    07/01    08/01    09/01    10/01    11/01    12/01    13/01    14/01    15/01    16/01
None                   13          11          13          7            10           8           7            6            2             0           0            0

Note the last figures in bold are just from the 00z today so far.

GFS initially went for a split with the first warming then backed out of this but is now heavily in favour of a split with the second warming event

GEFS Legacy

Like yesterday I want to add this model in the mix again. This one is following a similar path to the GFS with a displacement from the first warming then strong signs of another warming mid January too. This one has some very big second warmings showing up and the three warmest are below

That +12 warming is one monster warming and should do a lot of damage to the vortex

GFS Parallel

GFS Parallel is still going for a split at +96 hours

However the vortex soon reforms above the Atlantic and Europe. The parallel is still showing the second warming too at +270 hours

JMA

JMA is still nailed on for a split but like with GFS Parallel reforms the vortex over Atlantic and Europe

GEM

GEM also going for the split by +90 hours and the second warming still showing up at +240 hours

ECM

ECM still deciding to continue on its new displacement path. No sign of second warming showing up yet

Here is the daily zonal wind data based on the ECM for all levels

Looks like a decent reversal taking place and at least it is getting closer to the current timeframe rather than sticking to +240 hours all the time. A recovery of the vortex is clearly visible at 1hpa but the reversal looks to be sticking around a bit longer lower down. The reversal gets down to 70hpa on this run by 240 hours which is a big step forward from yesterday

Earth Nullschool

Finally wanted to show you the current situation and what is predicted in 4 days time by Earth Nullschool

Current

The warming appears to be peaking now at +2.6C which is quite a strong warming event. It is already putting the vortex under pressure as it has started to stretch out a little bit. The core of the vortex is currently at an icy cold -80.3C

4 Days Time

In 4 days time it appears Earth Nullschool is still going for a vortex split as two distinct areas of rotation have started to appear. These two cores are roughly the same size and temperature too as the USA one is -71.6C and the European one is -71.7C. Between these are what is left of the stratospheric warming at -26.9C above Siberia and a smaller warm area above the Atlantic at -32.1C

[sebastiaan1973]

24 minutes ago, Interitus said:

No, not really. There is always some tropospheric blocking in advance of an SSW, usually Atlantic side for wave 1 like this.

He means 100 hPa.

[Interitus]

1 minute ago, sebastiaan1973 said:

He means 100 hPa.

That's in the strat.

[sebastiaan1973]

I know, but I guess that's what he meant. But he can better will reply on your comment.

Edited December 31, 2020 by sebastiaan1973

[lorenzo]

Does this chart worked up by Simon Lee help answer perhaps..

[Interitus]

1 minute ago, lorenzo said:

Does this chart worked up by Simon Lee help answer perhaps..

Nothing out of the ordinary there.

From out of the chaos comes order - 3 of the 4 closest 30-day 10mb 60°N wind analogues to 31/12/20 feature an SSW in the following 3 week period -

 

[ALL ABOARD]

3 hours ago, Interitus said:

No, not really. There is always some tropospheric blocking in advance of an SSW, usually Atlantic side for wave 1 like this.

Hi thanks for reply. 

I agree there is usually some kind of block but never as weak as it is currently. 

 

[Interitus]

1 minute ago, ALL ABOARD said:

Hi thanks for reply. 

I agree there is usually some kind of block but never as weak as it is currently. 

 

Of course green is forecast and 100 hPa is in the strat.

Here's an interesting chart a few days prior to Jan 87 SSW, posted a couple of times before -

Of note, large anticyclonic wave break north of UK. Compare with this forecast for few days time -

[chionomaniac]

I would say that the lower strat mean U wind strength is pretty unprecedented whether or not, it is not unusual to have blocking episodes prior to SSWs.

here are the 150hPa u mean winds forecast, and jan87

[sebastiaan1973]

GFS12h follow the same road: displacement followed by a split.