Stratosphere and Polar Vortex Watch

[Singularity]

On 31/01/2020 at 10:27, Interitus said:

Did the MJO wave cause the UK high pressure? Easy conclusion to arrive at and it may be related but as well as a fairly short time lag, previous examples show that this was not the typical response. This graph shows three close analogues of MJO RMM1 over the 14 days to Jan 19th (x-axis day 0 - UK high pressure) -

These dates show a strengthened NAO with enhanced Azores high (your MLB?) and deepened Icelandic low, troughing to UK

One interesting feature they shared though appeared around 20 days later, with a significant negative EPO -

Composites do indeed generally reveal that the response was unusual, but it was an atypical MJO, more like a giant Kelvin Wave and very lopsided into the S. Hemisphere. This gave me cause to look elsewhere, at atmospheric momentum transports beyond the tropics.

I noticed some highly anomalous atmospheric angular momentum transport into the mid-latitudes coinciding with the event. I've observed over the years that these transports tend to displace the subtropical high northward, resulting in either mid-lat or high-lat blocking depending on how far poleward the transport travels (...and it usually falls short of high lats unless we have the MJO or a strong Kelvin wave propagating beyond the Central Pacific).

On this occasion, the momentum transport was utilized by a broad LP system developing off the Eastern Seaboard, enabling it to deepen into an exceptional system - the one that delivered parts of Newfoundland their largest storm-total snowfall on record.

Generally and much to my frustration, I've been finding the classic composites to be increasingly unreliable this past decade. There seems to be some tendency toward more extreme momentum transport events, though I need to research into it more to confirm that. Then there's the colder stratosphere complicating matters in the winter and sometimes early spring months.

[Singularity]

3 hours ago, Interitus said:

Is the stratosphere colder all over though? Not checked the data yet, but the strength of the vortex depends on the meridional temperature gradient - if it cooled more at lower latitudes for example, the tendency would be towards a weaker vortex.

I've seen the strengthening trend mentioned on Twitter by some respectable sources, but a direct look is merited...

2010s minus 1970s here, really interesting results with little change or even slight warming at some mid-latitudes, contrasting with strong cooling above most of the Arctic circle.

What about minus the 1980s instead?

Well...

An even more pronounced cooling trend over the Arctic circle, while again we see less of one in parts of the mid-latitudes (related to natural variability of wave activity, perhaps?). 

An increasing temperature gradient, strengthening the vortex.

Then when looking to the 2010s versus 1990s... the gradient trend steps up a a gear. I'm actually a little amazed at the magnitude of it.

 

[DavidS]

The 00z GFS is having a reasonable go with the secondary warming in deep FI. The vortex again being pushed around and stretched, but no split shown.

 

[knocker]

 

[oasis]

Thank you Interitus, Knocker and Singularity for taking the time to respond to me. I greatly appreciate it. I dont have the links to the data and analogs at hand/the necessary knowledge so cheers.

Looks very interesting Singularity, curious how each decade has had slightly different patterns regionally. Certainly to my untrained eye does look like in general the temperature gradient between polar and mid latitudes has become stronger in our region of the world than in North America. Hence greater mobility in the Atlantic sector.

Amy Butler's tweet offers some reassurance though.  

[summer blizzard]

Interesting to see what impact this produces.

[mushymanrob]

51 minutes ago, summer blizzard said:

Interesting to see what impact this produces.

Nothing cold i wouldnt have though, the composites suggest high pressure to our near south (phase 6), mid lat high pressure for phase 7..... or am i being too simplistic? Surely any effect on the strat would be too late to produce a cold spell?...

[Mike Poole]

1 hour ago, summer blizzard said:

Interesting to see what impact this produces.

None, because it won't happen according to ECM:

[weatherguy]

This may well get deleted, but here goes it! 

Could anyone explain, or direct me towards an explanation of, what the MJO actually is please? I know that we want to see "it" in high amplitude 6/7/8 as this aids in the development of HLB...but what do the the phase numbers mean, what is "it", and what are the mechanisms by which this promotes HLB?  Thanks in advance

[mushymanrob]

27 minutes ago, weatherguy said:

This may well get deleted, but here goes it! 

Could anyone explain, or direct me towards an explanation of, what the MJO actually is please? I know that we want to see "it" in high amplitude 6/7/8 as this aids in the development of HLB...but what do the the phase numbers mean, what is "it", and what are the mechanisms by which this promotes HLB?  Thanks in advance

What is the Madden-Julian Oscillation?

WWW.METOFFICE.GOV.UK

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The Madden-Julian Oscillation is characterised by an eastward spread of large regions of enhanced and suppressed tropical rainfall, mainly...

 

[weatherguy]

31 minutes ago, mushymanrob said:

What is the Madden-Julian Oscillation?

WWW.METOFFICE.GOV.UK

---

The Madden-Julian Oscillation is characterised by an eastward spread of large regions of enhanced and suppressed tropical rainfall, mainly...

 

Greatly appreciated, thanks! 

[Allseasons-Si]

Something to keep an eye on perhaps!!!

will see in the morning to see if this gains momentum,back end of Feb start of March could savoir this winter.

[fromey]

7 hours ago, Allseasons-si said:

Something to keep an eye on perhaps!!!

will see in the morning to see if this gains momentum,back end of Feb start of March could savoir this winter.

Even better today!

Edited February 5, 2020 by fromey

[Gray-Wolf]

Anything to do with this 'double PNJ'? (go to the 10hPA level)

earth :: a global map of wind, weather, and ocean conditions

EARTH.NULLSCHOOL.NET

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See current wind, weather, ocean, and pollution conditions, as forecast by supercomputers, on an interactive animated map. Updated every three hours.

 

Edited February 5, 2020 by Gray-Wolf

[JeffC]

earth :: a global map of wind, weather, and ocean conditions

EARTH.NULLSCHOOL.NET

---

See current wind, weather, ocean, and pollution conditions, as forecast by supercomputers, on an interactive animated map...

Two distinct areas of warming at 10hpa

 

 

[Dennis]

10Hpa warming seen 

[mb018538]

2 hours ago, Dennis said:

10Hpa warming seen 

It's only a minor warming, and is likely to have no real or lasting effect on the PV anyway. The BFTE warming 2 years ago saw temperatures go to +12c....-30c isn't warm at all in comparison.

[knocker]

 

[ItNeverSnowsInWindsor]

9 hours ago, mb018538 said:

It's only a minor warming, and is likely to have no real or lasting effect on the PV anyway. The BFTE warming 2 years ago saw temperatures go to +12c....-30c isn't warm at all in comparison.

Has the warming stopped though ?

[Interitus]

5 hours ago, knocker said:

 

As suggested last week 

Yesterday 1mb wind < 6 ms vs 10 mb wind 24 ms - negative vertical wind shear giving reflecting surface for wave 1.

[Singularity]

So, the troposphere launched an assault on the stratospheric polar vortex, but it stood strong and now there's a record-breaking backlash to contend with.

Once, the models were showing the assault punching through and doing some serious damage. The moment they picked on on the mid-to-upper stratosphere taking on reflecting profile, however, there were drastic changes in the outlook. The upper stratosphere is always difficult to model, due mainly to the resolution issue; as one moves further from the Earth's surface, it takes more and more of a certain size of grid box to cover a region. This tends to hold back the resolution of the upper-stratosphere layer(s).

That's a particularly large reason to be cautious with stratospheric projections past 10 day's range .

Edited February 7, 2020 by Singularity

[Interitus]

3 hours ago, Singularity said:

The upper stratosphere is always difficult to model, due mainly to the resolution issue; as one moves further from the Earth's surface, it takes more and more of a certain size of grid box to cover a region. This tends to hold back the resolution of the upper-stratosphere layer(s).

That's a particularly large reason to be cautious with stratospheric projections past 10 day's range .

At the moment the 0.4 mb level ranges from 52.37 km high at the North Pole to 56.52 km at the South Pole - the effective earth polar radius increase is 0.89% (the maximum, earth oblate, tropical radius greater) equating to an effective area increase of only 1.78% compared to the surface.

Edited February 7, 2020 by Interitus

[Mike Poole]

Ouch!

Heading for pretty much strongest vortex this time of year ever, according to the GFS. 

[Don]

4 hours ago, Mike Poole said:

Ouch!

Heading for pretty much strongest vortex this time of year ever, according to the GFS. 

Lets hope it over exerts itself this year and puts itself out of action for next winter!

[Mike Poole]

1 minute ago, Don said:

Lets hope it over exerts itself this year and puts itself out of action for next winter!

Yes, quite! There's quite a few things I want put out of action next winter, starting with the +IOD, west QBO (should be guaranteed that one), and adverse SSTs in the N Atlantic - that ones the worry for me.  But we have to have better luck next year, Don, surely!