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Stratosphere and Polar Vortex Watch

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36 minutes ago, Mike Poole said:

GFS 18z T384.  Oh dear!

image.thumb.jpg.6df5447347190c6daf6c80c4cb076f71.jpg

Hey ho, see some of you for the summer!!!

Is that tongue in cheek or have you gone from eternal optimist to pessimist 😂 

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7 minutes ago, blizzard81 said:

Is that tongue in cheek or have you gone from eternal optimist to pessimist 😂 

In reality I am neither, but posting on here usually requires or encourages bias of one sort or another!  But I had just posted in another thread that I reckoned that the only way out of this mess was via the stratosphere, a SSW, so to see a perfectly circular strat vortex at the outreach of the GFS pub run, well it doesn't fill me with confidence...

Edited by Mike Poole

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16 minutes ago, Mike Poole said:

In reality I am neither, but posting on here usually requires or encourages bias of one sort or another!  But I had just posted in another thread that I reckoned that the only way out of this mess was via the stratosphere, a SSW, so to see a perfectly circular strat vortex at the outreach of the GFS pub run, well it doesn't fill me with confidence...

Understood 🙂

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How is the QBO looking? are we edging close to easterly phase territory..

The PV traditionally weakens as the winter wears on, and the transitioning QBO can only help aid its weakening I would expect.

Any arctic shots this winter should have some real oomph to them thanks to the depth of cold over the Arctic this winter.

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Interesting tweet from Michael Ventrice. It's a long way off but we can but hope....

"ECMWF EPS Day 15 500mb geopotential height anomaly forecast compared to a composite of all sudden stratospheric warming events initiated over the North Atlantic. Looks like we could be in store for a North Atlantic warming event (after our Siberian event)."

574464517_ECMENST360GPHAnom13Jan.thumb.jpg.bc133223c3898bbac832dfd9f21be660.jpg  2013785410_CompositeofallSSWeventsnAtlantic.thumb.jpg.28ff56d7591e23f67c6cddfec77d1b3d.jpg

Source: Twitter @MJVentrice

 

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15 hours ago, damianslaw said:

How is the QBO looking? are we edging close to easterly phase territory..

The PV traditionally weakens as the winter wears on, and the transitioning QBO can only help aid its weakening I would expect.

Any arctic shots this winter should have some real oomph to them thanks to the depth of cold over the Arctic this winter.

Yes, by springtime we will see the effects.

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QBO has just transitioned into the easterly phase (at 30hPa). Looking back at analogue years, coupled with low solar, when that happened - 4 in total. 50% of these saw a split SSW in the March which brought resulting cold in Apr (and May), the other 50% failed to register a SSW at all. In most of the low solar years we've seen a split SSW event the QBO transitioned well before the winter i.e. at least the summer before. So by the winter we were firmly entrenched in that phase. It's looking less likely we'll get a split SSW in time to bring the sig cold this winter season (i.e. beast from the east type stuff) but perhaps for part of the spring, though of course less significance for markets, etc. Otherwise we remain at the mercy of low Arctic sea ice driven patterns, and as per most winters since 2010 outside of split SSW events. As some have alluded to on here, I think we may have a greater chance of split SSW induced cold next winter providing QBO remains E'ly. 

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8 minutes ago, Shuttler said:

QBO has just transitioned into the easterly phase (at 30hPa). Looking back at analogue years, coupled with low solar, when that happened - 4 in total. 50% of these saw a split SSW in the March which brought resulting cold in Apr (and May), the other 50% failed to register a SSW at all. In most of the low solar years we've seen a split SSW event the QBO transitioned well before the winter i.e. at least the summer before. So by the winter we were firmly entrenched in that phase. It's looking less likely we'll get a split SSW in time to bring the sig cold this winter season (i.e. beast from the east type stuff) but perhaps for part of the spring, though of course less significance for markets, etc. Otherwise we remain at the mercy of low Arctic sea ice driven patterns, and as per most winters since 2010 outside of split SSW events. As some have alluded to on here, I think we may have a greater chance of split SSW induced cold next winter providing QBO remains E'ly. 

Good Post.

The only thing I would point out is that sea ice is better than what we had in 2010,2012,2013,2015,2016,2017 and 2018 .

There are only two years in the last decade that have had better sea ice growth as of the 25th of December.

One of those is 2014 … and we all know how that winter turned out !



 

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GFS showing a gradual weakening of zonal winds at the top of the stratosfere after 10.1. The problem is its just GFS, I prefer the ECMWF model every day of the week.

umedel60.png

Edited by Redbull165

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1 hour ago, Redbull165 said:

GFS showing a gradual weakening of zonal winds at the top of the stratosfere after 10.1. The problem is its just GFS, I prefer the ECMWF model every day of the week.

umedel60.png

Obviously the ECM HRES doesn't go out to 10/1/2020 at this point so there is no way to compare. The GFS chart above has since updated and toned down that vortex disturbance, but at that range beyond the accurate deterministic limit, a SSW is likely to appear quite suddenly if one occurs (along with numerous false alarms).

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Some warming at the top of the stratosphere showing on yesterday's Berlin EC strat diagnotics, uncertainty whether it will propagate downwards, but I suppose worth keeping an eye on in the bleak January days ahead with the formidable strong sPV/tPV 

temps.thumb.gif.9b352ce810963efa1e7e9411e73f2e34.gif

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So the question then becomes when and how this intense TPV gets shifted or distorted? I suspect even an SSW won't achieve a full split now so we're looking beyond the confines of winter to March and April.

I suspect the annual battle between colder and warmer air masses will be more interesting in 2020.

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3 hours ago, Kirkcaldy Weather said:
 

 

For tropopause defined by lapse rate the 500mb level is in the stratosphere and the GFS analysis 2PVU pressure gave a dynamic tropopause pressure of about 629mb. Interestingly though the actual GFS tropopause pressure value was 490mb, not sure how that's calculated, and at these low altitudes relative humidity is much higher than typical stratospheric air which can be seen with the dew point depression above 250mb.

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1 hour ago, Interitus said:

For tropopause defined by lapse rate the 500mb level is in the stratosphere and the GFS analysis 2PVU pressure gave a dynamic tropopause pressure of about 629mb. Interestingly though the actual GFS tropopause pressure value was 490mb, not sure how that's calculated, and at these low altitudes relative humidity is much higher than typical stratospheric air which can be seen with the dew point depression above 250mb.

Nor me as it doesn't make a lot of sense. The lapse rate tropopause as reported by the station was 631mb -51.7C which obviously agrees with the sounding

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On 31/12/2019 at 12:28, Interitus said:

Obviously the ECM HRES doesn't go out to 10/1/2020 at this point so there is no way to compare. The GFS chart above has since updated and toned down that vortex disturbance, but at that range beyond the accurate deterministic limit, a SSW is likely to appear quite suddenly if one occurs (along with numerous false alarms).

To illustrate this, the 31/12 GFS 00z had a large wave break cleave a large chunk off the vortex at the 1mb level -

NH_HGT_1mb_348_19123100.thumb.gif.2d69df1814efee2ccdfa7f006d324773.gif

NH_TMP_1mb_348_19123100.thumb.gif.63af0aad53705e3e1ea3660a92ad69f4.gif

source: instantweathermaps.com

1mb 60°N mean zonal wind 15.2 ms in the above 348 hr charts falling to 7.7 ms at 377 hr.

But by the 31/12 18z run and subsequently there has been virtually no wave propagation and dartboard charts like today's 06z -

NH_HGT_1mb_384_20010206.thumb.gif.cdb7497ea356fa81d160f8e3d1b6eb19.gif

1mb zonal wind up to 82 ms, If these were to verify it would likely guarantee no SSW in January such is the timescale for one to develop.

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11 minutes ago, Glacier Point said:

The way end of week 2 EPS and GFS look, wave 2 bottom up splits could be in play.

Hi GP. I'm assuming this is possible good news from a coldies point of view.

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20 minutes ago, Broadmayne blizzard said:

Hi GP. I'm assuming this is possible good news from a coldies point of view.

I think the vortex is now at near record strength of intensity so it hard to be confident that a stratospheric shift would actually change overall pattern 

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Posted (edited)
37 minutes ago, Catacol said:

Bottom up is troposphere led, not stratosphere. Back to the dance and who leads who. GP is referring to the signal for second half of January which sees equatorial convection return to the western Pacific and the GEFS punt for a Scandy/Euro block a bit like late November combined with a strong North Pacific ridge. I don’t have access to 14 day EPS so assume his data shows a similar wave 2 pinch.

This is the best case scenario we have to hope grows wings. It has always been on the table as an option and the hope is that it could create a split flow in the Atlantic with the southerly arm helping enhance a block over Scandy with easterly flow underneath. The current spike in GLAAM provides a supportive momentum context in the medium term.

Fingers crossed. 

Thanks Catacol. I had a feeling that GP was hinting a trop led  rather than strat led with the phrase bottom up splits. Let's face it top down bottom up who cares as long as we advect some cold in from somewhere later in the month. Apart from anything else this dull mild bilge is just so boring.

Edited by Broadmayne blizzard

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