Stratosphere and Polar Vortex Watch 2020

[Catacol]

A parting shot to see out 2021. Big hit. 

The vortex will be in a very poor state after this. Can we get a final blast of wave 2 energy to smash it....? Week 1 of January is going to be a big week - will dictate the path for the bulk of winter.

[Methuselah]

8 minutes ago, Catacol said:

A parting shot to see out 2021. Big hit. 

The vortex will be in a very poor state after this. Can we get a final blast of wave 2 energy to smash it....? Week 1 of January is going to be a big week - will dictate the path for the bulk of winter.

You may want to hold back on that, for a wee while, Cat?

[SteveB]

41 minutes ago, General Cluster said:

You may want to hold back on that, for a wee while, Cat?

Why?

[Methuselah]

1 minute ago, SteveB said:

Why?

Look at the year, Steve...? And also, remember that I am ever so slightly peesed!

[Mike Poole]

JMA is still gunning for the strat in the same way that the GFS // is, T192:

Love to know what the UKMO models make of it, the JMA is based on the UKMO model as I understand it.  But a split along those lines looks very promising for the UK in terms of cold.  

[SteveB]

6 minutes ago, General Cluster said:

Look at the year, Steve...? And also, remember that I am ever so slightly peesed!

I see, well spotted 

[SqueakheartLW]

It would seem GFS is backing away from the idea of another warming around the 10th or 11th of January now as the number of options featuring this has dropped throughout the day

It was 28 of 32 in the 00z

By the 12z it has dropped to 20 of 32 and at least half of these 20 options only featured minor or very minor warmings of peak temperatures of -30 at best

However there were a few good ones in there and these are below. They start with the warmest warming and get progressively less warm as we go along

GFS 12z Member 1

This second warming is comparable in terms of peak temperature to the first one with a peak of around -4C. Only this time it is attacking a weaker vortex than the current state of the vortex. This should result in either an even weaker displaced vortex or a split

GFS 12z Member 5

A less warm warming but also an even weaker vortex for it to attack and this is already stretched out somewhat with two colder cores. No doubt this warming will fully split this vortex

GFS 12z Member 14

Similar to the above but a slightly in better shape vortex against a less warm warming. This may weaken the vortex further and could result in a split but no guarantees of that

GFS 12z Member 14

A modest warming event here and with the vortex almost in two pieces already then this should be the final blow that sees the vortex split

GFS 12z Member 17

Even though the Siberian warming is quite modest this one has a little backup from a smaller warming on the European side. These two should be able to act together to fully split the vortex

GFS 12z Member 24

My final one to show. This time the stronger warming is an Atlantic based warming with some backup from the Siberian side and also the vortex is in an even more vulnerable state. A split must be certain with this one

After looking at the GFS runs since 20/12/2020 these are the percentage chances of each stratospheric outcome excluding any unknown outcomes that were present at the time and this is based on what was showing at the date listed

Type                    20/12    21/12    22/12    23/12    24/12    25/12    26/12    27/12

Av Date               05/01    06/01    07/01    08/01    09/01    10/01    11/01    12/01

Displacement    36.21    45.95     28.21    51.25     61.63    60.67     75.79    63.54
Split                     41.38    39.19     55.13    40.00     26.74    30.33     16.84    30.21
None                   22.41    14.86     16.66    8.75       11.63    9.00        7.37      6.25

It would seem GFS is most keep on a displacement of the vortex overall in recent runs but was going more for a split a few days ago. The latest data shows that the split options are making a bit of a comeback but will this continue?

[Windysun1]

2 hours ago, SqueakheartLW said:

It would seem GFS is backing away from the idea of another warming around the 10th or 11th of January now as the number of options featuring this has dropped throughout the day

It was 28 of 32 in the 00z

By the 12z it has dropped to 20 of 32 and at least half of these 20 options only featured minor or very minor warmings of peak temperatures of -30 at best

However there were a few good ones in there and these are below. They start with the warmest warming and get progressively less warm as we go along

GFS 12z Member 1

This second warming is comparable in terms of peak temperature to the first one with a peak of around -4C. Only this time it is attacking a weaker vortex than the current state of the vortex. This should result in either an even weaker displaced vortex or a split

GFS 12z Member 5

A less warm warming but also an even weaker vortex for it to attack and this is already stretched out somewhat with two colder cores. No doubt this warming will fully split this vortex

GFS 12z Member 14

Similar to the above but a slightly in better shape vortex against a less warm warming. This may weaken the vortex further and could result in a split but no guarantees of that

GFS 12z Member 14

A modest warming event here and with the vortex almost in two pieces already then this should be the final blow that sees the vortex split

GFS 12z Member 17

Even though the Siberian warming is quite modest this one has a little backup from a smaller warming on the European side. These two should be able to act together to fully split the vortex

GFS 12z Member 24

My final one to show. This time the stronger warming is an Atlantic based warming with some backup from the Siberian side and also the vortex is in an even more vulnerable state. A split must be certain with this one

After looking at the GFS runs since 20/12/2020 these are the percentage chances of each stratospheric outcome excluding any unknown outcomes that were present at the time and this is based on what was showing at the date listed

Type                    20/12    21/12    22/12    23/12    24/12    25/12    26/12    27/12

Av Date               05/01    06/01    07/01    08/01    09/01    10/01    11/01    12/01

Displacement    36.21    45.95     28.21    51.25     61.63    60.67     75.79    63.54
Split                     41.38    39.19     55.13    40.00     26.74    30.33     16.84    30.21
None                   22.41    14.86     16.66    8.75       11.63    9.00        7.37      6.25

It would seem GFS is most keep on a displacement of the vortex overall in recent runs but was going more for a split a few days ago. The latest data shows that the split options are making a bit of a comeback but will this continue?

Dumb ass question i suppose but if the PV splits and part of it ends up over europe and Uk, how long will it stay in that region or is there historical data to show this?

[snowking]

A timely thread - although given we still look like displacing and then splitting, our impending SSW may prove an outlier for this research if it is defined as a k=1 event.

[bluearmy]

it looks to me that the trend is for any split to drop quite quickly and for the Asian side to becomes the centre with a trough extension around the building n american high into the Newfoundland area 

so to all intents and purposes a displacement ssw with high over n America and trough over the Asian side of the NH

the temp stand off between gfs and the rest is now below day 5!!!! at 10hpa that’s pretty ridiculous 

[SqueakheartLW]

My daily round up of Stratospheric Developments

GFS

It would seem the GFS is still somewhat undecided on what the eventual outcome of this warming is. We still have non events where the vortex appears to end up still intact or slightly weaker. Then there's a big group of displacement options and also an increasing group now showing an eventual split vortex too.

Non Event

00z GFS Member 2                                00z GFS Member 3

Displacement

00z GFS Operational                             00z GFS Member 4                                 00z GFS Member 8

00z GFS Member 9                                 00z GFS Member 10                              00z GFS Member 11

00z GFS Member 12                              00z GFS Member 13                               00z GFS Member 15

00z GFS Member 16                              00z GFS Member 17                              00z GFS Member 18

00z GFS Member 24                               00z GFS Member 28                              00z GFS Member 29

00z GFS Member 30

Split

00z GFS Control                                      00z GFS Member 1                                00z GFS Member 5

00z GFS Member 6                                00z GFS Member 7                                 00z GFS Member 14

00z GFS Member 19                              00z GFS Member 20                              00z GFS Member 21

00z GFS Member 22                              00z GFS Member 23                              00z GFS Member 25

00z GFS Member 26                              00z GFS Member 27

A number of these are still showing the other warming that the GFS has been showing, particularly on the displacement set but it would seem that GFS is starting to see a vortex split as a more likely outcome but not as soon as other models have been showing it

JMA

Today's JMA has the vortex pulling apart by 156 hours away

GEM

The GEM has the vortex pulling apart by 180 hours away, a bit longer than with the JMA

ECM

The latest ECM 10hpa chart for day 10 looks like this

This still looks like ECM is going for a split of the vortex

The latest daily data showing zonal winds at different levels is below

It would seem the bottom up attack on the vortex is back on again based on the latest ECM predictions. The top down reversal has unfortunately not made it down to 20hpa like I thought it might based on yesterday's figures. It would seem the QBO could be playing a part here in what is happening

20hpa and above have the EQBO and this region is expected to quickly go into a reversal once the warming has taken place.

Also 80hpa and below have in general average easterlies too and this could explain the drop in zonal winds at 100hpa and 150hpa.

However the regions between these two areas, 30hpa, 50hpa and 70hpa have the WQBO dominating and it is these layers that are maintaining the highest zonal wind speeds at day 10 relative to the starting point

A snapshot from Earth Nullschool

Here is a nice 10hpa temperature snapshot from Earth Nullschool this morning

Within that orange area the warming is starting to show itself. Here we go then. Time so see how warm it actually ends up getting at 10hpa and what effect it is going to have on the vortex in the next few days

 

 

Edited December 28, 2020 by SqueakheartLW

[Bullseye]

 

Posted this over on model tweets thread but may be relevant here too.

Surely a good sign if SSW favours Europe whether this be split or displacement.

Edited December 28, 2020 by Bullseye

[SqueakheartLW]

It appears the GFS 06z is playing with the idea of that new warming event again after saying just earlier on today after the 00z that they appear to be dropping the idea

I have ordered these from least warm warming to the warmest

-36

GFS 06z Member 24

Although this is the least warm of the warmings at just -36 at the warmest this one is still strong enough to split the vortex as the -36 Siberian warming has backup from another -36 warming above the E Atlantic

-32

GFS 06z Member 12

Similar to the above scenario really but just a little warmer at -32 and like with the above this -32 Siberian warming has backup from another warming above Europe

-28

GFS 06z Member 7                                 GFS 06z Member 2

Two -28 warmings here under different scenarios. Member 7 has a weaker vortex and the area of -28 warming is also smaller but like with the previous 2 scenarios this one has backup from above Europe again. Member 2 is a displaced and stronger vortex but this one is up against a more widespread Siberian warming which with the reduced size vortex could lead to a split later on

-24

Quite a few -24 warmings came up in the ensembles so I have decided to split them up based on the general shape of the vortex or how many regions of warming are showing too

-24 double warmings with split vortex

GFS 06z Member 10                                GFS 06z Member 13

Both of these options have either a split vortex already or near to it and these modest warmings pushing in from both the Siberian side and the Atlantic/European side should make sure of a split vortex

-24 warming with split vortex

GFS 06z Member 6                                 GFS 06z Member 16                             GFS 06z Member 26

These three options have only one area of warming compared with the previous group but like that group already feature a vortex that is either already split or is threatening to do so. These warming should act to fully split the vortex

-24 smaller warming with displaced vortex

GFS 06z Member 18                               GFS 06z Member 23

These -24 warmings are moderate in size and with a relatively good shape vortex could pose a problem if the end outcome was to be a split vortex. More likely to displace the vortex more and weaken it a bit too

-24 widespread warming with split vortex

GFS 06z Member 29

This widespread -24 warming should be the destruction of the vortex. It is already in a bad shape and with such scale of warming and a +384 hours chart this warming could be even bigger than what is showing here. Could mean even worse news for the vortex than a full on split. It might not even exist after this warming

-20

A number of -20 warmings also came up and these are split up into two broad categories

-20 warmings with split vortex

GFS 06z Member 20                               GFS 06z Member 27

With already split vortexes here on both options then these warmings should just help to keep the vortex split up and will very likely weaken the split areas further

-20 warmings with displaced vortex

GFS 06z Member 9                                 GFS 06z Member 8                               GFS 06z Member 22

These modest warmings are all coming up against a displaced vortex in reasonable shape. Will they be enough to split the vortex. Member 9 warming probably won't but member 8 and 22 may just have a chance to split the vortex

-16

As with -20 warming we have a few for -16 too and these are in two broad categories again

-16 warmings with split vortex

GFS 06z Member 15                               GFS 06z Member 30

A decent warming event from Siberia in both cases and with the vortex in quite bad shape in both cases then a full split and weakening is odds on here

-16 warmings with displaced vortex

GFS 06z Member 21                               GFS 06z Member 3                               GFS 06z Member 28

Two of these options have smaller -16 warmings showing. At best they will very likely weaken the displaced vortex further but a split is highly unlikely. GFS 06z Member 3 on the other hand is a much more widespread warming and so this displaced vortex is going to be put under a lot of strain and will very likely split

-12

GFS 06z Member 4                                 GFS 06z Member 14                              GFS 06z Control

Two of these -12 warmings are up against a displaced vortex. The control run is probably the least likely option to come to a split with it been a smaller warming against the strongest vortex. GFS 06z Member 4 is a bit more 50/50 with a vortex and warming about the same size as each other. GFS 06z Member 14 looks like a vortex destroyed as it is already split and that large warming above the UK looks like it is spelling doom for what is left of the vortex

-8

GFS 06z Member 17                               GFS 06z Member 19                              GFS 06z Member 1

Three somewhat different scenarios here for the -8 warmings. GFS 06z Member 19 looks like it could play either way. The vortex is somewhat split already and with the positioning of the warming it could go one of two ways. Either the warming rides around the piece of vortex above Europe and splits them further apart or it pushes the two pieces of vortex back together again allowing it to reform again. GFS 06z Member 1 is a more certain bet to help keep the vortex split as the warming is further round the piece of vortex and they are also further apart. GFS 06z Member 17 is a larger area of warming coming up against a displaced vortex. This should end in a split and with the position of the vortex the pieces should end up in favourable locations to get cold into the UK

-4

GFS 06z Member 5

Now onto the top two options in terms of peak warming temperature. In 2nd position we have GFS 06z Member 5 with a peak warming of -4C, similar to the predicted warming in the next few days. The damage to the vortex by the first warming can already be seen here as it is already split in two and this new warming is likely to spell further doom for the vortex. It looks like it is going to ride over the top and push the pieces of the vortex further apart and with it been quite a major warming it could leave very little of the vortex behind.

+4

GFS 06z Member 25

Finally in top spot we have GFS 06z Member 25. The first warming just displaced the vortex into a bad area for getting cold into the UK and without the warming that would likely be winter over for the UK. However we have a strong second warming coming to the rescue of winter in the UK here with a peak +4C temperature. With a weakened vortex already from warming number 1 then this even stronger one should see the vortex get smashed. A split should be certain here and maybe even total destruction of the vortex is possible

Summary

A nice 30 of 32 GFS 06z runs showing warmings of varying degrees. After the reduction in options showing this it appears at least with the 06z that the new warming is back on again

[sebastiaan1973]

According to this study the role of North Atlantic-European weather regimes in the surface of SSW events the current EC0h output is excellent for downwelling. We see a European blocking at the charts at 144h and 240h. The seems to be important for downwelling. Hopefully we don't get a Greenland blocking at the onset of the SSW, because there won't be any significant impact on the troposhere.

[lorenzo]

So much to look at just now courtesy of that record breaking W1 monstering the vortex - looking forward to the 2020/21 seasonal loop of the entire process as I think it will show just how disruptive the North Atlantic Wave Breaking and Blocking is in terms of being that 'one catalyst;' that wreaks havoc on the vortex. A couple of the retro charts today.. remember when we had this view and little else

Berlin view at 475K and the vortex getting mashed over to our side, again this was before we got superb resolution.

50hPa is my pick of the animations today as it's just so chaotic, the energy in the W1 driving from the Pacific side, the daughter vortice / filament dropping through Asia and of course the split structure.

Then in our locale the action in the Atlantic and the reinforcing of the breaks feeding the blocking regimes.

Tremendous viewing !

[sebastiaan1973]

Tracking the stratosphere‐to‐surface impact of Sudden Stratospheric Warmings

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Abstract

Sudden stratospheric warming (SSW) events are extreme atmospheric regimes which can have a signature in surface weather up to 40 days after event onset in the stratosphere. SSWs can be classified as either vortex splitting or vortex displacement events, with the nature and timing of the surface impact potentially being different between the two. In this study, using ERA40/Interim reanalysis data, we develop a simple empirical downward tracking algorithm which for the first time allows us to estimate the time of surface impact for individual SSW events. We show that the surface impact following splitting events is, on average, about one week earlier than following displacement events, albeit with considerable variability. By compositing tropospheric responses around the identified date of surface impact, rather than around the central stratospheric onset date as common in previous studies, we can better constrain the surface signal of SSWs. We find that while the difference in North Atlantic Oscillation (NAO) anomalies between split and displacement vortices is small, surface temperature anomalies over northwest Europe and northern Eurasia are significantly colder for splitting events, particularly over the UK just prior to the surface impact date. Displacement events on average are wetter over Northwest Europe around the time of surface impact, consistent with the jet stream being displaced further south in response to split events. Our downtracking algorithm can be used with any reanalyses and gridded model data, and therefore will be a valuable tool for use with the latest climate models.

[Griff]

Latest ecm...   Vs previous 

 

[JeffC]

10 hours ago, SqueakheartLW said:

My daily round up of Stratospheric Developments

GFS

It would seem the GFS is still somewhat undecided on what the eventual outcome of this warming is. We still have non events where the vortex appears to end up still intact or slightly weaker. Then there's a big group of displacement options and also an increasing group now showing an eventual split vortex too.

Non Event

00z GFS Member 2                                00z GFS Member 3

Displacement

00z GFS Operational                             00z GFS Member 4                                 00z GFS Member 8

00z GFS Member 9                                 00z GFS Member 10                              00z GFS Member 11

00z GFS Member 12                              00z GFS Member 13                               00z GFS Member 15

00z GFS Member 16                              00z GFS Member 17                              00z GFS Member 18

00z GFS Member 24                               00z GFS Member 28                              00z GFS Member 29

00z GFS Member 30

Split

00z GFS Control                                      00z GFS Member 1                                00z GFS Member 5

00z GFS Member 6                                00z GFS Member 7                                 00z GFS Member 14

00z GFS Member 19                              00z GFS Member 20                              00z GFS Member 21

00z GFS Member 22                              00z GFS Member 23                              00z GFS Member 25

00z GFS Member 26                              00z GFS Member 27

A number of these are still showing the other warming that the GFS has been showing, particularly on the displacement set but it would seem that GFS is starting to see a vortex split as a more likely outcome but not as soon as other models have been showing it

JMA

Today's JMA has the vortex pulling apart by 156 hours away

GEM

The GEM has the vortex pulling apart by 180 hours away, a bit longer than with the JMA

ECM

The latest ECM 10hpa chart for day 10 looks like this

This still looks like ECM is going for a split of the vortex

The latest daily data showing zonal winds at different levels is below

It would seem the bottom up attack on the vortex is back on again based on the latest ECM predictions. The top down reversal has unfortunately not made it down to 20hpa like I thought it might based on yesterday's figures. It would seem the QBO could be playing a part here in what is happening

20hpa and above have the EQBO and this region is expected to quickly go into a reversal once the warming has taken place.

Also 80hpa and below have in general average easterlies too and this could explain the drop in zonal winds at 100hpa and 150hpa.

However the regions between these two areas, 30hpa, 50hpa and 70hpa have the WQBO dominating and it is these layers that are maintaining the highest zonal wind speeds at day 10 relative to the starting point

A snapshot from Earth Nullschool

Here is a nice 10hpa temperature snapshot from Earth Nullschool this morning

Within that orange area the warming is starting to show itself. Here we go then. Time so see how warm it actually ends up getting at 10hpa and what effect it is going to have on the vortex in the next few days

 

 

Just had a look at that earlier and its even clearer now, whether this IS a precursor to EAMT event I'm not clever enough to deduce. It will, however be interesting to watch events unfold, I find the Earth Nullschool site gives a fascinating pictorial depiction of what's happening!

[ALL ABOARD]

 

Anyone for some E Asia Mtn Torque!

Reports of the world record being beaten... 

 

[SqueakheartLW]

My daily stratospheric update

GFS 00z

Like always I shall begin with my GFS selection again. This time all 32 runs are showing the new warming after the current one to varying degrees and outcomes. I have them below in order from least warm warming through to the warmest of the warmings.

-32

GFS 00z Member 6

-28

GFS 00z Member 2                                GFS 00z Member 10

-24

GFS 00z Member 19                               GFS 00z Member 29

-20

GFS 00z Member 3                                GFS 00z Member 7                                 GFS 00z Member 8

GFS 00z Member 15                              GFS 00z Member 21                               GFS 00z Member 24

-16

GFS 00z Member 4                                 GFS 00z Member 5                                GFS 00z Member 11

GFS 00z Member 12                              GFS 00z Member 17                              GFS 00z Member 18

GFS 00z Member 25                              GFS 00z Member 28

-12

GFS 00z Member 9                                 GFS 00z Member 13                              GFS 00z Member 14

GFS 00z Member 20                              GFS 00z Member 23                               GFS 00z Member 30

-8

GFS 00z Operational                              GFS 00z Member 27

-4

GFS 00z Control                                      GFS 00z Member 16                               GFS 00z Member 22

GFS 00z Member 26

+4

GFS 00z Member 1

Summary

Quite a few of the GFS members are now going for a significant second warming event that peaks warmer than -20 and some are now comparable to the current event with peak figures between -4 and +4

GFS Parallel 06z                                    GFS Parallel 00z

The latest GFS Parallel has the vortex split in half by +150 hours. As this is still updating then the second image is the 00z and even the parallel has hints of this second warming event taking place too.

So far ...

GFS Displacement from first warming but second warming becoming more likely and at least half of these result in a split.

GFS Parallel Split from first warming but vortex reforms in a weakened state. Another warming showing on the parallel too.

JMA

JMA has the vortex split by +156 hours

So far ...

GFS Displacement from first warming but second warming becoming more likely and at least half of these result in a split.

GFS Parallel Split from first warming but vortex reforms in a weakened state. Another warming showing on the parallel too.

JMA Split from first warming but vortex does reform in a weakened state

GEM

GEM appears to have backed off the idea of a vortex split but it too is now hinting at a second warming event by +240 hours

So far ...

GFS Displacement from first warming but second warming becoming more likely and at least half of these result in a split.

GFS Parallel Split from first warming but vortex reforms in a weakened state. Another warming showing on the parallel too.

JMA Split from first warming but vortex does reform in a weakened state

GEM Displacement from first warming but second warming hints appearing in long range of the model now

ECM

Here is the latest 10hpa chart from ECM at day 10

It would appear even ECM is now backing out of the idea of a vortex split from this first warming but it does still get us into a reversal

Here is the daily zonal wind speed data from ECM for today

ECM still keeps the reversal very much on track even if it appears to be backing off the idea of a split vortex

Final General Summary

GFS Displacement from first warming but second warming becoming more likely and at least half of these result in a split.

GFS Parallel Split from first warming but vortex reforms in a weakened state. Another warming showing on the parallel too.

JMA Split from first warming but vortex does reform in a weakened state

GEM Displacement from first warming but second warming hints appearing in long range of the model now

ECM Displacement from first warming. No sign of the second warming showing up at 10hpa in ECM

Earth Nullschool

Finally some images showing the current warming as well as the predictions from Earth Nullschool for the next 4 days

Current Situation

10hpa Temperatures                             10hpa Winds

The warming is now more clearly visible above Europe and Siberia compared with yesterday but at this stage it has had little if any impact on the polar vortex

10hpa Temperatures +1 Day               10hpa Winds + 1 Day

Earth Nullschool's +1 day ahead prediction shows the warming intensifying further above Siberia and it has pushed closer to the north pole itself. The vortex is starting to change shape slightly in response to this warming

10hpa Temperatures +2 Days             10hpa Winds + 2 Days

By 2 days from now the warming is pushing further into the pole and this is stretching out the colder region. The polar vortex is also beginning to get stretched out too by this warming event

10hpa Temperatures +3 Days             10hpa Winds + 3 Days

At 3 days ahead the warming is reducing but the higher temperatures are now pushing right up to the north pole itself. The vortex is also under strain here as it has stretched out even further still

10hpa Temperatures +4 Days             10hpa Winds + 4 Days

By day 4 the warming has pushed right over the north pole and the colder region is stretched out quite some way now. The polar vortex itself looks to be splitting into two different pieces by this stage. It would seem Earth Nullschool is currently seeing a vortex split happening.

[Duane S.]

Wave 2 not quite strong enough at the crucial time to split the vortex this time around?

It appears to back off at the critical juncture.

Subject to change still of course.

[SqueakheartLW]

Here are the latest GFS runs and all 32 warmings. The least warm warmings are now peaking at -24 so in general an upgrade to what the 00z was showing at least. I have ordered them from least warm to warmest like before

-24

GFS 06z Operational                              GFS 06z Control                                     GFS 06z Member 17

GFS 06z Member 26

-20

GFS 06z Member 23                               GFS 06z Member 27                              GFS 06z Member 30

-16

GFS 06z Member 1                                GFS 06z Member 4                                 GFS 06z Member 16

GFS 06z Member 18                              GFS 06z Member 20                              GFS 06z Member 25

GFS 06z Member 28

-12

GFS 06z Member 3                                 GFS 06z Member 8                               GFS 06z Member 9

GFS 06z Member 22                              GFS 06z Member 29

-8

GFS 06z Member 2                                GFS 06z Member 5                                GFS 06z Member 6

GFS 06z Member 11                               GFS 06z Member 12                              GFS 06z Member 13

GFS 06z Member 15                              GFS 06z Member 24

-4

GFS 06z Member 10                              GFS 06z Member 19                              GFS 06z Member 21

+0

GFS 06z Member 7                                 GFS 06z Member 14

Below I have the summary of how many of both the 00z and 06z fell into each peak warming category as well as the average peak

                    00z GFS          06z GFS          CHANGE

-32                    1                      0                     -1

-28                    2                      0                     -2

-24                    2                      4                     +2

-20                    6                      3                     -3

-16                    8                      7                     -1

-12                    6                      5                     -1

-8                      2                      8                     +6

-4                      4                      3                     -1

+0                     0                      2                     +2

+4                     1                      0                     -1

AV PEAK     -15.13              -12.63

With the average peak getting a little warmer it is clear that the 06z GFS is overall an upgrade on the prospect of a second warming compared with the 00z GFS

[sebastiaan1973]

On 28/12/2020 at 14:51, sebastiaan1973 said:

According to this study the role of North Atlantic-European weather regimes in the surface of SSW events the current EC0h output is excellent for downwelling. We see a European blocking at the charts at 144h and 240h. The seems to be important for downwelling. Hopefully we don't get a Greenland blocking at the onset of the SSW, because there won't be any significant impact on the troposhere.

Today Domeisen said the same thing as stated above. Important development.

Edited December 29, 2020 by sebastiaan1973

[winterof79]

 

 

He goes on to add

 

 

GEFS & CFSv2 have 64 vertical levels, while ECMWF's ensemble has 91 and more of those are in the stratosphere (38 above 100 hPa vs. 24 in CFS). So, I anticipate ECMWF is on the right lines, as models with greater vertical resolution perform better (https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JD030920…) [2/2]

[sebastiaan1973]

Domela Domeisen co-author doesn't agree with her