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Stratosphere and Polar Vortex Watch


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1 hour ago, Premier Neige said:

Am I right in thinking there is a correlation between the Pacific high and the very warm SST's in that region over the past few years? And given the developing La Nina, would that not cool the seas in the northern Pacific over the next few months reducing the chances of such a stubborn area of high pressure developing?

This is something Gavin Partridge has been talking about recently.  Whilst a La Nina could lead to a cooling of the northern Pacific, it may not been in time for winter, as there is currently little sign of this occurring.

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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

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3 hours ago, Don said:

This is something Gavin Partridge has been talking about recently.  Whilst a La Nina could lead to a cooling of the northern Pacific, it may not been in time for winter, as there is currently little sign of this occurring.

La Nina and the PDO/Victoria Mode are not the same thing though usually correlated. I also suspect there's too much focus on the high in the Pacific in isolation. If you look through the Jan-March composites we see that while 2011 and 2020 did see significant ridging, so did 2013 and 2018. Other than 2016 having a stonking trough there the rest of the years are actually quite mixed suggesting that we might be placing a bit too much hate on this feature in isolation.

Notably although we have seen a persistently positive Victoria Mode in 2013 onward we also saw a weak or positive PDO signature from 2014-2019 (there is a weak decadal PDO-AO correlation). That will not be the case this winter as like winter whether we have a positive victoria mode or not we will have a -PDO. 

Edited by summer blizzard
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3 minutes ago, summer blizzard said:

La Nina and the PDO/Victoria Mode are not the same thing though usually correlated. I also suspect there's too much focus on the high in the Pacific in isolation. If you look through the Jan-March composites we see that while 2011 and 2020 did see significant ridging, so did 2013 and 2018. Other than 2016 having a stonking trough there the rest of the years are actually quite mixed suggesting that we might be placing a bit too much hate on this feature in isolation. 

Yes it depends how the jet stream behaves around the N Atlantic sector...which is highly dependent upon how upstream troughing behaves stateside. It is possible to have that Pacific HP and a meridional jet stream across the NAtlantic...but it's highly dependent on other factors- I suggest we would need to see a N Atlantic tripole for a start.

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4 hours ago, Don said:

This is something Gavin Partridge has been talking about recently.  Whilst a La Nina could lead to a cooling of the northern Pacific, it may not been in time for winter, as there is currently little sign of this occurring.

Fingers (and toes) crossed then!! 🙂

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With regard to the North Pacific high, would the effects be negated somewhat by the warm SST's in the north Atlantic which I would imagine would stop the jet from blowing up as it exits the eastern seaboard? (Assuming that north Atlantic SST's remain on the warm side...).

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40 minutes ago, Premier Neige said:

With regard to the North Pacific high, would the effects be negated somewhat by the warm SST's in the north Atlantic which I would imagine would stop the jet from blowing up as it exits the eastern seaboard? (Assuming that north Atlantic SST's remain on the warm side...).

Yes whole of the atlantic is very warm at present from top to bottom, exceptionally warm around eastern seaboard, labrador strait. Important to monitor temp changes over the rest of the autumn, with an active hurricane system I can't see much change in the mid atlantic to create a tripole, instead heat will continue to be pumped into the mid atlantic I imagine.

In recent winters though we have had the cold atlantic blob to our NW, the current base state and tropical storm activity I think this year is not conducive to one reappearing in time for winter, so we look quite likely to be starting the winter on a very different atlantic profile to most recent ones..

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13 hours ago, Steve Murr said:

Its worth noting that the current 10-14 day forecast sees the vortex beginning to take a different path to last winter-

Very early days but we may as well start in the right direction !

1F5727C1-A6F7-4966-AC28-E765636EECA3.thumb.png.ce7234c5c06f06a8e631d37890dfd75d.png

QBO expected to be weak westerly DJF...

A lot of members going for weak vortex state Nov-Dec...which adds more weight towards the notion of a colder start to winter.

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23 hours ago, Steve Murr said:

Its worth noting that the current 10-14 day forecast sees the vortex beginning to take a different path to last winter-

Very early days but we may as well start in the right direction !

1F5727C1-A6F7-4966-AC28-E765636EECA3.thumb.png.ce7234c5c06f06a8e631d37890dfd75d.png

QBO expected to be weak westerly DJF...

2010 maybe 🤔 

Hopefully 😁

 

Edited by Penicuikblizzard
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Before we get excited i would remind you all that we are still probably a month early to even really note such deviation and even then for every Autumn 09 there is a Autumn 16 and 17. 

I'll get more excited if the vortex is persistently weak into November but even then i'll urge caution until the AO is actually responding and we don't get a January rebound.

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