Jump to content

Stratosphere and Polar Vortex Watch


Recommended Posts

  • Replies 3.9k
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

Some useful tropospheric developments upcoming which are likely to have stratospheric impacts towards the end of November and more particularly into December. A strong convectively coupled tropic

so after many days the GFS & FNMOC & canadian finally now follow the Euro with 44 out 64 Members with a split at day 9- The ECM is day 8. We will call it - SSW & Split for 1st Ja

For all that watch the zonal winds. Let me urge you to look at the geopotential heights more. At least as far as weakening/strengthening trends go. Because as the polar vortex cries for help, you migh

Posted Images

On 26/10/2018 at 17:31, northwestsnow said:

Yet last Winter was a negative phase and it was a mild winter unless you count March..

There have been a fair few mild winters which have occurred during an easterly QBO, just like cold winters have occurred during westerly phases, too.

  • Like 3
Link to post
Share on other sites
5 minutes ago, Don said:

There have been a fair few mild winters which have occurred during an easterly QBO, just like cold winters have occurred during westerly phases, too.

Indeed.

I wonder what the 'odds' against a severe winter would be in a situation where all the teleconnections were favourable, and where all the building blocks were in place?

Edited by Ed Stone
  • Like 3
Link to post
Share on other sites
56 minutes ago, Ed Stone said:

Indeed.

I wonder what the 'odds' against a severe winter would be in a situation where all the teleconnections were favourable, and where all the building blocks were in place?

I would say that 2014/2015 had the best enso-qbo combination since the winter of 2009/2010. It flopped because a rampant +PDO meant we had a persistent +AO.

  • Like 4
  • Thanks 1
Link to post
Share on other sites
3 hours ago, summer blizzard said:

I would say that 2014/2015 had the best enso-qbo combination since the winter of 2009/2010. It flopped because a rampant +PDO meant we had a persistent +AO.

Isn't the PDO trending positive now?

Link to post
Share on other sites
1 hour ago, sebastiaan1973 said:

Solar acitivity was causing the positve NAO.

Although i certainly think solar activity has an impact (that winter was just after peak) i don't think it's as simple and with a weak Nino/-QBO combination i certainly don't think it outweighed it. I blame the PDO which was at record positive levels. 

  • Like 1
Link to post
Share on other sites
2 hours ago, summer blizzard said:

Although i certainly think solar activity has an impact (that winter was just after peak) i don't think it's as simple and with a weak Nino/-QBO combination i certainly don't think it outweighed it. I blame the PDO which was at record positive levels. 

Have you got any more up to date data on the PDO than this please? If it goes neutral I will have to re-build some analogues.

https://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Data/pdo.long.data

Link to post
Share on other sites
1 hour ago, feb1991blizzard said:

Have you got any more up to date data on the PDO than this please? If it goes neutral I will have to re-build some analogues.

https://www.esrl.noaa.gov/psd/gcos_wgsp/Timeseries/Data/pdo.long.data

This is a little more up to date. Looking neutral at present.

http://research.jisao.washington.edu/pdo/PDO.latest.txt

 

Edited by Catacol
  • Like 1
Link to post
Share on other sites
On 24/10/2018 at 18:47, Leo97t said:

When did the last November warming happen 

Last full SSW - at the end of November 1968!

 

33 minutes ago, knocker said:

 

Not knocking it, but looking back this season here is a typical CFS forecast (posted by SM) -

E8CFEAB1-6FDF-4EEF-8A51-A9CED3794E57.png

And here is how it panned out on today's weatheriscool plot -

968052556_u10serie18102906.thumb.png.312d1fcdbaa358d758c17873d9076616.png

Are these CFS plots ever right?

  • Like 5
Link to post
Share on other sites

Snow–atmosphere coupling in the Northern Hemisphere

Quote

Local and remote impacts of seasonal snow cover on atmospheric circulation have been explored extensively, with observational and modelling efforts focusing on how Eurasian autumn snow-cover variability potentially drives Northern Hemisphere atmospheric circulation via the generation of deep, planetary-scale atmospheric waves. Despite climate modelling advances, models remain challenged to reproduce the proposed sequence of processes by which snow cover can influence the atmosphere, calling into question the robustness of this coupling. Here, we summarize the current level of understanding of snow–atmosphere coupling, and the implications of this interaction under future climate change. Projected patterns of snow-cover variability and altered stratospheric conditions suggest a need for new model experiments to isolate the effect of projected changes in snow on the atmosphere.

https://www.nature.com/articles/s41558-018-0295-6

  • Like 1
  • Thanks 1
Link to post
Share on other sites

No surprise one of the authors was Yannick Peings, his earlier works have already shown that the data has brought into question the long term impact of the whole snow extent/advance of Cohen etc.

edit: interesting that another author is Jason Furtado who collaborated with Cohen on "The combined influences of autumnal snow and sea ice on Northern Hemisphere winters" (2016) - https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL068108

Edited by Interitus
Link to post
Share on other sites
5 hours ago, Interitus said:

Last full SSW - at the end of November 1968!

 

Not knocking it, but looking back this season here is a typical CFS forecast (posted by SM) -

E8CFEAB1-6FDF-4EEF-8A51-A9CED3794E57.png

And here is how it panned out on today's weatheriscool plot -

968052556_u10serie18102906.thumb.png.312d1fcdbaa358d758c17873d9076616.png

Are these CFS plots ever right?

We will know in 4-6 weeks

The CFS hasnt changed all season with forecasting that significant deceleration- however it was poor at identifying the fast move to the high speed phase we are currently in-

Lucky the trop > strat are disconnected !

Link to post
Share on other sites
55 minutes ago, Interitus said:

No surprise one of the authors was Yannick Peings, his earlier works have already shown that the data has brought into question the long term impact of the whole snow extent/advance of Cohen etc.

I witnessed a fairly pointed exchange on Twitter between Cohen and Jason Furtado a year or so back which suggested the latter is none too convinced by the idea now despite being a co-author on the original paper. Feels like everyone’s chasing shadows with these October patterns.

  • Like 2
Link to post
Share on other sites
3 minutes ago, Yarmy said:

I witnessed a fairly pointed exchange on Twitter between Cohen and Jason Furtado a year or so back which suggested the latter is none too convinced by the idea now despite being a co-author on the original paper. Feels like everyone’s chasing shadows with these October patterns.

They were seeing new patterns in October that preceded cold european winters and looking for cause. Ice loss, leading to open water, leading to more snow in eurasia.....all taking place round last solar minimum. We're here again, maybe another chance to sort the wheat from the chaff. 

  • Like 1
Link to post
Share on other sites

It could be that we get the early SSW while in a (more) favourable QBO state and even when the QBO strong westerly downwells, we still have a vulnerable vortex open to further attacks, it could be either a double SSW year or if we don't get an early one, we might not get one - all or nothing.

Link to post
Share on other sites
21 hours ago, Interitus said:

Are these CFS plots ever right?

Not really.

The configurations and systematics of the CFSv2 model, are not really that appropriate for stratospheric forecasting beyond the normal operational range (15-16 days).

Anything beyond that should be ensemble (breeding) only.

Edited by Recretos
Link to post
Share on other sites
1 minute ago, Recretos said:

Not really.

The configurations and systematics of the CFSv2 model, are not really that appropriate for stratospheric forecasting beyond the normal operational range (15-16 days).

Anything beyond that should be ensemble (breeding) only.

Exactly ?

Link to post
Share on other sites
Guest
This topic is now closed to further replies.
×
×
  • Create New...