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Stratosphere and Polar Vortex Watch


Paul

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Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast
15 hours ago, Interitus said:

Except last year when the vortex was average until SSW at start of New Year. And 2015 when the vortex was strong throughout Autumn and early winter. But, yeah.

You're right, that was 2017, in 2018 it was just the tail end of the gfs forecast which kept forecasting a record weak vortex but every day had to readjust to make the vortex stronger. 

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent

Concerning to see forecasts now beginning to show a coupling between the strat/trop, would have been nice to see the disconnect continue through the whole of November 

Coupling.thumb.png.25ccfb9f3672e84e712902421fc4890d.png

Though it is the GFS so could change on the next run given the timeframes we're dealing with here.

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Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
2 hours ago, Met4Cast said:

Concerning to see forecasts now beginning to show a coupling between the strat/trop, would have been nice to see the disconnect continue through the whole of November 

Coupling.thumb.png.25ccfb9f3672e84e712902421fc4890d.png

Though it is the GFS so could change on the next run given the timeframes we're dealing with here.

Would be inline with the long range models, sadly.

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Posted
  • Location: Wath upon Dearne, Rotherham
  • Weather Preferences: Snow, severe frost, freezing fog and summer sunshine
  • Location: Wath upon Dearne, Rotherham
3 hours ago, Met4Cast said:

Concerning to see forecasts now beginning to show a coupling between the strat/trop, would have been nice to see the disconnect continue through the whole of November 

Coupling.thumb.png.25ccfb9f3672e84e712902421fc4890d.png

Though it is the GFS so could change on the next run given the timeframes we're dealing with here.

Let's hope the CFS is correct with its strat warming forecast!

Edited by Premier Neige
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Posted
  • Location: Kirkcaldy, Fife, Scotland 20m ASL
  • Weather Preferences: Snow,Thunderstorms mix both for heaven THUNDERSNOW 😜😀🤤🥰
  • Location: Kirkcaldy, Fife, Scotland 20m ASL

 

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
9 hours ago, Met4Cast said:

Concerning to see forecasts now beginning to show a coupling between the strat/trop, would have been nice to see the disconnect continue through the whole of November 

Coupling.thumb.png.25ccfb9f3672e84e712902421fc4890d.png

Though it is the GFS so could change on the next run given the timeframes we're dealing with here.

And indeed it did, today's 0z shows no such signs of a coupling, and the strat imprinting on the trop.

image.thumb.jpg.2242ca16cdb8f7083cc2ff039308d52d.jpg

Quite the opposite in fact.

Edited by Mike Poole
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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
3 minutes ago, Mike Poole said:

And indeed it did, today's 0z shows no such signs of a coupling, and the strat imprinting on the trop.

image.thumb.jpg.2242ca16cdb8f7083cc2ff039308d52d.jpg

Quite the opposite in fact.

Yes - big difference - don't fully understand those charts but i know blue in the bottom half is good news, that must be what Steve is talking about.

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Posted
  • Location: Scouthead Oldham 295mASL
  • Location: Scouthead Oldham 295mASL

I wonder if things are potentially getting interesting up above...

I anticipate an increase in the number of posts in the coming days......

I would be happy with even a minor warming in Nov as that gives us a ticket for the December lottery..

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

Thanks Steve - yes, anything even remotely close to 0 m/s would be great while there is already a disconnect, different once you get a coupling, then you really are more reliant on a strong SSW, particularly if you get to Jan and you have a strong zonal imprint all the way down.

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent
1 hour ago, feb1991blizzard said:

Thanks Steve - yes, anything even remotely close to 0 m/s would be great while there is already a disconnect, different once you get a coupling, then you really are more reliant on a strong SSW, particularly if you get to Jan and you have a strong zonal imprint all the way down.

Interestingly, research suggests that NW Europe sees colder conditions from the trop patterns that lead to an SSW than they do after an SSW. I can't recall the year but I think the UK was under a cold spell and an SSW actually knocked us out of it. 

Though generally an SSW is something we want to see causing a split, displacements are less favourable for us it would seem. 

Edited by Met4Cast
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Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
2 minutes ago, Met4Cast said:

I can't recall the year but I think the UK was under a cold spell and an SSW actually knocked us out of it

February 2009?

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
Just now, Met4Cast said:

Interestingly, research suggests that NW Europe sees colder conditions from the trop patterns that lead to an SSW than they do after an SSW. I can't recall the year but I think the UK was under a cold spell and an SSW actually knocked us out of it. 

Though generally an SSW is something we want to see causing a split, displacements are less favourable for us it would seem. 

Think it might be 1987 but i am not knowledgeable enough to say that it definitely did knock us out of the cold pattern in Jan, you may be right as it seems the best cold spells around the time of an SSW do seem to occur very quickly after the SSW, Feb 1991, Feb 2009, Jan 2013, however that could be as a result of a quick trop response following SSW's.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
Just now, Don said:

February 2009?

I would suggest that the SSW caused it to be honest, zonal going nowhere Jan with a strong PV, then suddenly an SSW then about 8 days after the official SSW, a beast ensues.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

Remember most of those SSW's were top down events, plus Feb / March 18, yes i know the initial wave one was followed by wave 2 from the trop, but would that have occured without the initial downwelling, one for chiono to answer perhaps.

Edited by feb1991blizzard
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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent
5 minutes ago, feb1991blizzard said:

Think it might be 1987 but i am not knowledgeable enough to say that it definitely did knock us out of the cold pattern in Jan, you may be right as it seems the best cold spells around the time of an SSW do seem to occur very quickly after the SSW, Feb 1991, Feb 2009, Jan 2013, however that could be as a result of a quick trop response following SSW's.

Then there are examples where SSW's have prolonged the cold, 62/63 for example. A January SSW in 63 prolonged the already established blocking pattern, it's a lottery and a bit of luck really. 

Last years SSW was a big one but the lack of downwelling meant it didn't really do much for us. QTR definitely seems to give the bigger impacts, not sure if there's any way to actually predict whether an SSW with have a QTR or not yet though, still an area where a lot of research is needed

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Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
4 minutes ago, feb1991blizzard said:

I would suggest that the SSW caused it to be honest, zonal going nowhere Jan with a strong PV, then suddenly an SSW then about 8 days after the official SSW, a beast ensues.

Albeit rather short lived, although the first half of the month was on the cold side before turning exceptionally mild during the second half.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
Just now, Met4Cast said:

Then there are examples where SSW's have prolonged the cold, 62/63 for example. A January SSW in 63 prolonged the already established blocking pattern, it's a lottery and a bit of luck really. 

Last years SSW was a big one but the lack of downwelling meant it didn't really do much for us. QTR definitely seems to give the bigger impacts, not sure if there's any way to actually predict whether an SSW with have a QTR or not yet though, still an area where a lot of research is needed

Yes, one thing for sure though, certainly in the post 2010 era, i would certainly rather have an SSW and take my chance than worry about it knocking us out of a pattern, last year, once the split was modelled, taking the 10mb charts at face value, i didn't think it was a wide enough split (perhaps 2018 was too wide a split and caused the spell to be short lived), but i just sort of wen't along with it last year as far more learned people than me thought it gave us a good chance of cold, always think when you get an SSW and you are just getting a drip fed SSW, you are asking for trouble, unlike before when its before xmas and you get a strat-trop-strat-trop type scenario, as its different then, you are trying to prevent a downwelling of upper Westerlies and you are far more likely to be successful.

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent
Just now, feb1991blizzard said:

Yes, one thing for sure though, certainly in the post 2010 era, i would certainly rather have an SSW and take my chance than worry about it knocking us out of a pattern, last year, once the split was modelled, taking the 10mb charts at face value, i didn't think it was a wide enough split (perhaps 2018 was too wide a split and caused the spell to be short lived), but i just sort of wen't along with it last year as far more learned people than me thought it gave us a good chance of cold, always think when you get an SSW and you are just getting a drip fed SSW, you are asking for trouble, unlike before when its before xmas and you get a strat-trop-strat-trop type scenario, as its different then, you are trying to prevent a downwelling of upper Westerlies and you are far more likely to be successful.

I completely agree - Even the Met Office were being bold out cold weather coming in their mid-extended forecasts and even talking about it on their 10 day trend videos, I don't think anybody, not even the experts expected the downwelling to stall quite the way it did. 

I'd take an SSW over no SSW any day, particularly if we've got a rampant vortex coupled with the trop, it doesn't guarantee cold but it certainly gives us a higher chance. 

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
7 minutes ago, frederiksen90 said:

Recent studies have shown that more than half of SSWs occur when MJO enters phases 6-7. Interesting if the trends of a weakened PV towards the end coincide with the evolution of MJO in phases 6 and 7?

 

https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/foregfs.shtml

Just wondering, do most SSW's occur when the MJO has gone through phase 4 at high Amplitude close to the event? I say that because would that be conducive to an East Asian mountain torque event?

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Posted
  • Location: Kirkcaldy, Fife, Scotland 20m ASL
  • Weather Preferences: Snow,Thunderstorms mix both for heaven THUNDERSNOW 😜😀🤤🥰
  • Location: Kirkcaldy, Fife, Scotland 20m ASL
6 minutes ago, feb1991blizzard said:

Just wondering, do most SSW's occur when the MJO has gone through phase 4 at high Amplitude close to the event? I say that because would that be conducive to an East Asian mountain torque event?

"We are also concerned here with three specific questions regarding the MJO–SSW teleconnection. The first is the time scale of the teleconnection. Garfinkel et al. (2012a) showed a warming of the polar vortex 10 days after MJO phase 7 and another one about a month after MJO phases 2 and 3, leaving the teleconnection time somewhat uncertain. Because the MJO is quasi periodic, an observed connection seen after a given MJO phase may be either a slow response to earlier phases or a faster response to later phases. To reduce the ambiguity in the teleconnection time scale, it is useful to understand the physical processes involved. We analyze the teleconnection time scale for this path, starting with a horizontal propagation from the tropics and followed by additional time for vertical propagation within the Arctic stratosphere, although we also note some caveats that may affect the specific time scales deduced. The second issue of interest here is the teleconnection path. Garfinkel et al. (2014) showed evidence that, through constructive interference with climatological stationary waves, the perturbation associated with MJO phase 7 (3) leads to an in-phase strengthening (out-of-phase weakening) of the eddy meridional heat flux, but they did not discuss the path of propagation. We show that there is an MJO-forced wave train propagating poleward and upward through the upper troposphere and lower stratosphere to the Arctic stratosphere, which is consistent with the abovementioned teleconnection time. The third specific issue examined here involves the way the MJO waves affect SSW events. We demonstrate two different mechanisms in which the MJO-forced transient waves affect SSW events, both distinct from the constructive interference discussed by Garfinkel et al. (2014): via a direct propagation of these transient waves and a corresponding EP flux into the polar cap and, distinctly, via a nonlinear interaction with the climatology that changes the stationary wave forcing.The teleconnection time scale is another factor considered here. Garfinkel et al. (2012a, 2014) find that MJO phase 7 occurs 1–12 days before SSW events, and MJO phase 4 occurs 13–24 days before SSW events. While this seems to suggest a 3-week teleconnection time scale, they also find correlation between the MJO and the polar cap at lags exceeding 40 days. Our idealized model, with its perfectly periodic prescribed MJO forcing, allows us to identify the propagating signal in a Hovmöller plot of pseudomomentum flux with some confidence. While this analysis cannot determine the teleconnection time scale with certainty, it suggests a horizontal propagation time scale between 10 and 20 days, and we point out uncertainties in this estimate. This horizontal propagation is followed by additional time for vertical propagation within the stratosphere." 

JOURNALS.AMETSOC.ORG

"KT17 showed that Rossby wave trains excited by MJO phases 3–5 propagate northward, then upward, to the Arctic stratosphere within one month, and as a result, that stronger MJO forcing can nearly double the SSW frequency. They noticed a northward wave train departing from the tropics in MJO phases 3–5, which corresponds to enhanced convection near Indonesia. In observations, Garfinkel et al. (2014) found that the MJO effect on the average polar cap temperature also occurs preferentially after MJO phases 3 and 7; and Schwartz and Garfinkel (2017) noted that more than half of SSWs occur after MJO phase 6/7 (other studies have found that MJO-related convection in other phases can also impact the extratropics; Goss and Feldstein 2017). These results imply that the MJO-forced waves may propagate only at certain longitudes, which can either be a result of the different forcing structure associated with different MJO phases, or because of the interaction with the background zonal asymmetry. In this work, we demonstrate the second effect by forcing a model with an idealized wavenumber-1 MJO-like forcing." 

JOURNALS.AMETSOC.ORG

"It is clear that phases 7 and 8 are preferred during the 12 days preceding SSWs (Figure 1c). During days 13 to 24 before SSWs, MJO phases 4, 6, and 7 are preferred, while during days 25 to 36 before SSWs, MJO phases 2 and 3 are preferred (Figures 1a and 1b). The lag between MJO phases 3 and 7 is consistent with the 30–60 day periodicity of the MJO. This effect is statistically significant for many phases. The results are not sensitive, in a qualitative sense, to discriminating between displacement or split SSWs (described in Charlton and Polvani [2007]), or to distinguishing between El Niño or La Niña SSW. The key point is that the potential for predictability extends back as far as one month: if a MJO phase 2 or phase 3 is occurring, the probability that a SSW will occur in one month is apparently increased. A strong connection has been shown to exist between the Madden‐Julian Oscillation (MJO) and the Northern Hemisphere wintertime stratospheric polar vortex. SSWs in the reanalysis record tend to follow certain MJO phases, likely because the MJO influences the region in the North Pacific most strongly associated with tropospheric planetary wave driving. Similarly, the strength of the polar vortex is significantly modulated by particular MJO phases at specified lags, and the magnitude of the influence of the MJO on the polar vortex (∼4 K) is comparable to that associated with the Quasi‐Biennial Oscillation and El Niño."  

AGUPUBS.ONLINELIBRARY.WILEY.COM

 

https://www.seas.harvard.edu/climate/eli/reprints/Kang-Tziperman-2018b.pdf

pmc-logo-share.png
WWW.NCBI.NLM.NIH.GOV

The effect of the Madden‐Julian Oscillation (MJO) on the Northern Hemisphere wintertime stratospheric polar vortex in the period preceding stratospheric sudden warmings is evaluated in operational...

if some of those didn't link correctly just type "sudden stratospheric warming mjo" in google and go through the articles and you will find the bits I have quoted 

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
1 hour ago, Met4Cast said:

Then there are examples where SSW's have prolonged the cold, 62/63 for example. A January SSW in 63 prolonged the already established blocking pattern, it's a lottery and a bit of luck really. 

Last years SSW was a big one but the lack of downwelling meant it didn't really do much for us. QTR definitely seems to give the bigger impacts, not sure if there's any way to actually predict whether an SSW with have a QTR or not yet though, still an area where a lot of research is needed

Interesting discussion, I think there is some truth in the spin stronger fall faster argument, I've seen many knowledgeable people suggest when the strat vortex is brought down when it is spinning way above average, the effect is more dramatic - last years wasn't a particularly fast spinning at the time IIRC hence (possibly!) the ultimate damp squib.  

The way it's going, an SSW this year could be fun!

Edited by Mike Poole
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Posted
  • Location: Netherlands close to the coast
  • Location: Netherlands close to the coast
9 hours ago, Met4Cast said:

I completely agree - Even the Met Office were being bold out cold weather coming in their mid-extended forecasts and even talking about it on their 10 day trend videos, I don't think anybody, not even the experts expected the downwelling to stall quite the way it did. 

I'd take an SSW over no SSW any day, particularly if we've got a rampant vortex coupled with the trop, it doesn't guarantee cold but it certainly gives us a higher chance. 

Somewhere buried deeply within this thread are the NH temperature anomalies the weeks after a major midwinter SSW and in around 2/3 events we get warmer than average temperatures after the event whereas the events themselves where often preceded by remarkable cold periods but there are indeed a few noticeable exceptions like 2012/13.

 

We need the vortex to set up shop in Eastern Siberia but if somehow a major vortex fragment ends up over Greenland (which often happens) we can end up worse of than before 

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Posted
  • Location: Gillingham, Kent
  • Weather Preferences: Snow, Thunderstorms,
  • Location: Gillingham, Kent

Wave 2 is still being forecast by GFS data which is nice to see, I suspect this is the reason for the forecast reduce in zonal winds

169853722_Wave2.thumb.png.1b78090741018079a2388654d24c4e9a.png

I believe this is based on GFS operational data however so I wouldn't take it as gospel, good to have CFS supporting though, even if it does tend to take things a little too far 

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