Stratosphere and Polar Vortex Watch 2020

[SqueakheartLW]

On 05/10/2021 at 19:53, bluearmy said:

Whilst it’s extremely unlikely to pan out quite like this, the 12z gfs op reverses down to approx 75N at the end of the run.  Displacement. Note the neg AO in the trop reflected on this zonal flow chart bottom right 

Surely not an October SSW. That would be unreal.

This zonal wind chart really does show this up too

This one is based on 60N so doesn't show up as an official reversal here but any bigger anomaly and we would be close to an official SSW in October

[Don]

3 hours ago, Ed Stone said:

I think I'll stick with the Chicken Chow Mein, BA; I can enjoy that before it disappears!

Garlic chilli chicken extra hot for me! 

[bluearmy]

Anyone with the time to spare want to have a look back through the years and see where we last had a zonal flow at the back end of October in single figures ?  And when was the last late October/early November reversal ??

 

[mountain shadow]

37 minutes ago, bluearmy said:

Anyone with the time to spare want to have a look back through the years and see where we last had a zonal flow at the back end of October in single figures ?  And when was the last late October/early November reversal ??

 

It must be a long time since the zonal flow over the Atlantic has been so weak for so long. High pressure dominant with talk of water shortages in Scotland over the Winter!!

Edited October 6, 2021 by mountain shadow

[swfc]

Morning. The current set up in the Atlantic ie blocking and lack of west to east movement isn't something I can remember heading to mid autumn. Musings over a front loaded winter however distant may not be without foundation. Wind Reversal looks to be holding and I'm sure the more knowledgeable will be going forward a great help. Interesting times already indeed

[bluearmy]

1 hour ago, mountain shadow said:

It must be a long time since the zonal flow over the Atlantic has been so weak for so long. High pressure dominant with talk of water shortages in Scotland over the Winter!!

I was referring to the 10hpa zonal flow! 
 

 

[booferking]

10 minutes ago, bluearmy said:

I was referring to the 10hpa zonal flow! 
 

 

Going to try to answer this could be wrong but 2009/2010 closest i could get not a bad winter it was to.

2009/2010 would not be far away.  https://ozonewatch.gsfc.nasa.gov/meteorology/figures/merra2/wind/u45_75n_10_2009_merra2.txt

2021/2022 https://ozonewatch.gsfc.nasa.gov/meteorology/figures/merra2/wind/u45_75n_10_2021_merra2.txt

[mountain shadow]

42 minutes ago, bluearmy said:

I was referring to the 10hpa zonal flow! 
 

 

Yes, I know. but the weak 10hpa flow is leading to a weak sea level flow over the Atlantic.

[damianslaw]

4 hours ago, mountain shadow said:

It must be a long time since the zonal flow over the Atlantic has been so weak for so long. High pressure dominant with talk of water shortages in Scotland over the Winter!!

2010 and 1995/1996 probably last occasions.. mmm all 3 years brought very cold ends to the year.

[Mike Poole]

Interesting run up to the winter season in the stratosphere as well as the troposphere, I think!

My view of how winter prospects pan out, given info up to now, is roughly the following:

The additional energy inserted into the jet stream over autumn would be insufficient to reduce the highely meridional pattern left by summer (and influenced by the previous winter SSW I expect!) to one that could influence early winter with a raging jet across the Atlantic. 

Long range models support this, and I can see an early winter with a still meridional jet, and blocks moving to their winter homes (when resident!).  

Looking upwards, the strat vortex isn’t getting off to a good start, bless its cotton socks!  

Here latest from Stratobserve (few days ago now):

Posted the GEM ensemble suite as that is where the realisations with the lowest zonal wind speeds reside.  I use this site a lot, worrying it is displaying data for 3/10 still.  

Anyway, doesn’t seem there’s going to be much influence from the strat towards the early part of winter.  I’ve never felt this good about the chances of a cold December since I’ve been posting here…I joined after 2010 .

Edited October 6, 2021 by Mike Poole

[Don]

All very interesting. 

However, one thing that is bugging me is the run up to winter 2016/17 was also interesting with many (including the Metoffice I think) expecting a front loaded cold winter.  After a coldish November 2016, the PV ramped up and winter was mild, particularly December and February.  Obviously, that's not to say by any means this year will follow suit, but I was wondering if there are any key differences between now and this point in 2016, particularly as September 2016 was also very warm?

[Mike Poole]

5 minutes ago, Don said:

All very interesting. 

However, one thing that is bugging me is the run up to winter 2016/17 was also interesting with many (including the Metoffice I think) expecting a front loaded cold winter.  After a coldish November 2016, the PV ramped up and winter was mild, particularly December and February.  Obviously, that's not to say by any means this year will follow suit, but I was wondering if there are any key differences between now and this point in 2016, particularly as September 2016 was also very warm?

Let’s look at the two right now, or in the case of this year T120 on ECM, 2016 first:

The trop PV is totally different!  Despite the high pressure over the UK in 2016 there is a lot of nasty weather coming down the track from the atlantic.  Compare this year - there is nothing, literally nothing coming at us.  

 

[Don]

3 minutes ago, Mike Poole said:

Let’s look at the two right now, or in the case of this year T120 on ECM, 2016 first:

The trop PV is totally different!  Despite the high pressure over the UK in 2016 there is a lot of nasty weather coming down the track from the atlantic.  Compare this year - there is nothing, literally nothing coming at us.  

 

Many thanks for the comparison and explanation Mike.

[damianslaw]

5 hours ago, Mike Poole said:

Let’s look at the two right now, or in the case of this year T120 on ECM, 2016 first:

The trop PV is totally different!  Despite the high pressure over the UK in 2016 there is a lot of nasty weather coming down the track from the atlantic.  Compare this year - there is nothing, literally nothing coming at us.  

 

Atlantic looks weak on 2016 chart.

Other years for comparison shoul include 1996 and 2010. Also 2001 which brought quite alot of cold weather before New Year and then a sudden change after first few days of 2002.

[Griff]

Far too soon to be interesting...

[Mike Poole]

9 minutes ago, Griff said:

Far too soon to be interesting...

On the contrary, if that did happen (a SSW in October as shown by 3 ENS members) it would be very very interesting!  I think a Canadian warming is possible this year (early SSW), displacement of vortex early season away from Canada.  Haven’t had one for ages, I believe it increases chance of UK cold, but as the last one was before my time, someone else could perhaps comment, please?

Edited October 7, 2021 by Mike Poole

[weirpig]

9 minutes ago, Mike Poole said:

On the contrary, if that did happen (a SSW in October as shown by 3 ENS members) it would be very very interesting!  I think a Canadian warming is possible this year (early SSW), displacement of vortex early season away from Canada.  Haven’t had one for ages, I believe it increases chance of UK cold, but as the last one was before my time, someone else could perhaps comment, please?

Indeed all academic but if it were to happen as depicted the flood gates could open end of Nov beginning of Dec  as you say very interesting

[Griff]

35 minutes ago, Mike Poole said:

On the contrary, if that did happen (a SSW in October as shown by 3 ENS members) it would be very very interesting!  I think a Canadian warming is possible this year (early SSW), displacement of vortex early season away from Canada.  Haven’t had one for ages, I believe it increases chance of UK cold, but as the last one was before my time, someone else could perhaps comment, please?

I'm going with a PhD in reverse psychology this year  

[bluearmy]

1 hour ago, Griff said:

Far too soon to be interesting...

The strat recovery looks quite assured …….let’s hope for some early winter fun courtesy of the trop then ! 

[bluearmy]

Signs on the noaa output that the upcoming displacement will not be as strong as looked likely a few days ago.  We will see a drop in strat zonal flow towards single figures but we may not actually dip that far. In context, we have a weak spv but I don’t think it’s anything that’s going to influence events lower down and the trop patterns will dictate early winter. (As is usual). at the moment, the spv seems likely to return to average in November. Whether it becomes stronger and then couples effectively with the tpv is then the question. I guess what I’m saying is it’s still too early to make predictions based on events high up.  Had we seen a v strong  warming and almost reversal in late October, we might take a different view. 

[booferking]

1 hour ago, bluearmy said:

Signs on the noaa output that the upcoming displacement will not be as strong as looked likely a few days ago.  We will see a drop in strat zonal flow towards single figures but we may not actually dip that far. In context, we have a weak spv but I don’t think it’s anything that’s going to influence events lower down and the trop patterns will dictate early winter. (As is usual). at the moment, the spv seems likely to return to average in November. Whether it becomes stronger and then couples effectively with the tpv is then the question. I guess what I’m saying is it’s still too early to make predictions based on events high up.  Had we seen a v strong  warming and almost reversal in late October, we might take a different view. 

Return to average but early sign that it might tank again end of November early December interesting watch at the minute. 

[Don]

3 hours ago, bluearmy said:

Signs on the noaa output that the upcoming displacement will not be as strong as looked likely a few days ago.  We will see a drop in strat zonal flow towards single figures but we may not actually dip that far. In context, we have a weak spv but I don’t think it’s anything that’s going to influence events lower down and the trop patterns will dictate early winter. (As is usual). at the moment, the spv seems likely to return to average in November. Whether it becomes stronger and then couples effectively with the tpv is then the question. I guess what I’m saying is it’s still too early to make predictions based on events high up.  Had we seen a v strong  warming and almost reversal in late October, we might take a different view. 

Lots to keep us on our toes currently, as expected this early!  However, at least there is possibly more interest at this time than normal.

[virtualsphere]

16 hours ago, Mike Poole said:

On the contrary, if that did happen (a SSW in October as shown by 3 ENS members) it would be very very interesting!  I think a Canadian warming is possible this year (early SSW), displacement of vortex early season away from Canada.  Haven’t had one for ages, I believe it increases chance of UK cold, but as the last one was before my time, someone else could perhaps comment, please?

I believe there was an early Canadian warming in 1962/63 but there are doubtless other examples with a less extreme outcome for the UK...

[Don]

37 minutes ago, virtualsphere said:

I believe there was an early Canadian warming in 1962/63 but there are doubtless other examples with a less extreme outcome for the UK...

I think there may have been one in late 1984 or early 1985 which was a cold winter, but I could be wrong?

[BruenSryan]

Canadian Warmings have occurred in Nov 1951, Nov 1952, Dec 1954, Nov 1958 (also a major SSW), Dec 1958, Dec 1959, Nov 1962, Dec 1965, Dec 1966, Nov 1968 (also a major SSW), Nov 1972, Nov 1974, Nov 1976, Nov 1977, Dec 1978, Nov 1979, Nov 1980, Dec 1981 (also a major SSW), Nov 1991, Dec 1993, Nov 1996 and Nov 2000. 

A major warming occurred in early January 1985. There was no observed Canadian Warming according to University of Berlin analysis.

North Pole temperatures • Atmospheric Dynamics • Department of Earth Sciences

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