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SUDDEN STRATOSPHERIC WARMING (Watch 2012-2013)
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There you go!! Who's talking utter nonsense now BeasterlyThat warming is fizzling out at the moment (at the 10hPa level at least) with the forecast showing the strat cooling down again.
What do you mean by displacing the vortex across the Atlantic? At lower tropospheric level there's a strong signal for the PV to stay in-situ over Canada right out to 384h. My limited knowledge of SSW's is that they can weaken or even disintegrate the PV but there's no clear signs of anything like that happening. I'm not trying to argue your point, just a bit confused by it all with nothing really happening with the vortex other than that Arctic High and the painfully slow flow pattern of late
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Blizzard 2010 wrote: »this warming event has being going on for over two and a half weeks now (6th of January) The present cold snap has nothing to do with a SSW event. If it did we would the have the full effect of it
Well, the first cold weather you had, around the 14th, was SSW connected. That was the result of the SSW polar vortex disruption, and the wave 2 vortex split. The wave 2 was coming strong from the Atlantic, so when the split occurred, it was more or less instantaneous throughout the troposphere and stratosphere. Basically geopotential height rises near and over the pole.
A few graphics.
And just prior to the cold/cool shot (I am not sure for the islands, but here in central EU it was a cold shot, not a cool shot
)
As for this second cold shot, it was amongst all, also an SSW response. I say amongst all, because the troposphere has its own dynamics and forcings besides the stratosphere, so SSW is not the main factor, but it plays an important role. In blue, I marked the height rises connected with the first split. And in green, we actually have the real SSW effect infiltrating into the troposphere, with respect to the SSW response time-lag climatology.
This SSW had a decent downwelling.
And on this graph, we can see a bit more obviously, how the SSW induced effect downwelled.
And a few graphics:
So, @Blizzard 2010, don't get me wrong, I respect your opinion. I just haven't seen any graphics in your posts, that would back you up.
I write on many different forums (some of you also know me as Recretos on Netweather), and on most of them if not all, people were seeing this SSW as a 100% guarantee for a severe winter or cold period. But that is not how stuff works. At least on NW forum, me and some others were trying to point out the fact that even tho an SSW statistically increases chances for EU cold shots, it cannot 100% guarantee its occurrence and especially not its longevity, because of the constant tropospheric dynamics and forcings constantly mixing in this year, especially the MJO.
So the bottom line is, both cold shots had a "connection" with the stratosphere and the SSW, especially the last one.
Best regards.0 -
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That warming is fizzling out at the moment (at the 10hPa level at least) with the forecast showing the strat cooling down again.
What do you mean by displacing the vortex across the Atlantic? At lower tropospheric level there's a strong signal for the PV to stay in-situ over Canada right out to 384h. My limited knowledge of SSW's is that they can weaken or even disintegrate the PV but there's no clear signs of anything like that happening. I'm not trying to argue your point, just a bit confused by it all with nothing really happening with the vortex other than that Arctic High and the painfully slow flow pattern of late
I'm going to go ahead and repost this from chionamiac over on Netweather, pistolpetes already posted it but it illustrates what I'm trying to say better than I ever could.Stratospherically we are still seeing a NH pattern dominated by the recent SSW. Contrary to some opinions, this has downwelled from the mid stratosphere and affected the troposphere. It is always hit and miss how and where the SSW can have knock on effects in the troposphere and it appears that we have been lucky to see the split vortex favourably positioned to prevent the jet stream powering through during the two week mid January period.
However, that is about to change as further warming of the stratospheric Canadian vortex which allows it's tropospheric counterpart to break free. West to east momentum initially is set to carry this across the Atlantic to its Siberian counterpart as can be seen in this 30 hPa chart.
As this occurs there will be a corresponding increase in Atlantic mobility allowing the westerlies to reach the UK rather than be held at bay. The stratospheric vortex even though weak will be positioned on the Atlantic sector meaning a far less meridional jet stream whereas the Pacific sector will have a far more disturbed flow due to the upper ridge holding strong. This pattern will be as of a direct consequence to recent stratospheric events - but the wheel of fortune will be dropping off the meridional cold flow elsewhere in the NH.
So the main question that everyone is asking is will we likely to see a pattern re- emerge that can bring back the cold and blocking to our shores. And the answer is not immediately but definitely not no!
With the weakened vortex conditions likely to persist for a period of time then it is only a matter of time before realignment occurs in line with the MJO and GWO.
The stratospheric forecasts during the next 10 days right up to 10 hPa are showing and will show signs of increased fluctuations in the exact position of the vortex.
There are signs of another split occurring around day 10 and this will need to be watched carefully.
If this does occur then we could quite easily see the door to returning cold opened back up again. I think we will need to keep an eye on the strat forecasts very closely in this period.0 -
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Thanks for cleaning up the thread pete, not sure what was wrong with my post though
To ask again..
Capillatus, a quick question if you have the time (or to anyone else who can answer..), what exactly are those cross section graphs showing? For the GPH one for example, it it a section through the north pole or the mean heights value for the whole 65-90 degree area?Dead_Rabbits wrote: »@ Pistolpete11
Do you think the SSW can or will have an effect on the last few weeks of winter, I am beginning to lose faith that the winter will have much more to give?
By now there should down welling into the troposphere and would you feel we have been just unfortunate the way the PV has been or can it smash up the PV in the coming 2 weeks.
Throw us a rope!
Capillatus post above explains that the Arctic High that's been up there for the past 10 days or so was related to the SSW. For effects on us, it didn't cause anything too interesting but I've read that it aided in slowing the wave pattern over the Atlantic so we ended up with the pretty stagnant cool spell while the rest of Europe had a good cold snap.
For February, there's no obvious signs on the basic charts on meteociel of any major effect on the vortex but forces may be at work higher up that I'm unaware of so don't pay too much attention to that!0 -
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Well, you could plot a specific region, but you would have to plot it yourself. You would have to download the datasets and "manually" plot it. But the problem would be with the dataset. Because the datasets are only focused on specific levels, like 10mb, 20mb, 50mb,... and not for the entire stratosphere like you see on those graphs. But you can plot time series for a certain level.
If the "downwelling" reaches down to Greenland at 200mb, the chances are good that it will couple with the mid troposphere somewhere around that region. But we are not talking about super domination over the hemispheric pattern. There is just this general "rule of thumb", that with the pole and Greenland under highs or blockings, there is stronger CAA (cold air advection) into the lower latitudes, but it gets a bit more complicated with time, because of the constant tropospheric forcings. That is why it is kinda hard to find two exactly the same post-SSW effects. If you make reanalysis plots for a few SSW downwellers, the pattern may look similar at first, but you quickly get some differences with time. So basically it could be a hit or miss, or something in between.
I made some plots for you. The time-series for geopotential height anomaly, over Greenland.
10mb
50mb
150mb
500mb
Basically, when going down from the stratosphere, with time, the main +ve anomaly propagates slightly southward. When reaching the troposphere, it all depends on the tropospheric dynamics at that point.
And come cross-sections for Greenland.
Here on the mean zonal wind, I marked the general circulation, as you can interpret.
And the corresponding pattern.
Best regards.0 -
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If I am reading what you are saying correctly, there still appears to be a lot of uncertainty, is that correct?Capillatus wrote: »Well, you could plot a specific region, but you would have to plot it yourself. You would have to download the datasets and "manually" plot it. But the problem would be with the dataset. Because the datasets are only focused on specific levels, like 10mb, 20mb, 50mb,... and not for the entire stratosphere like you see on those graphs. But you can plot time series for a certain level.
If the "downwelling" reaches down to Greenland at 200mb, the chances are good that it will couple with the mid troposphere somewhere around that region. But we are not talking about super domination over the hemispheric pattern. There is just this general "rule of thumb", that with the pole and Greenland under highs or blockings, there is stronger CAA (cold air advection) into the lower latitudes, but it gets a bit more complicated with time, because of the constant tropospheric forcings. That is why it is kinda hard to find two exactly the same post-SSW effects. If you make reanalysis plots for a few SSW downwellers, the pattern may look similar at first, but you quickly get some differences with time. So basically it could be a hit or miss, or something in between.
I made some plots for you. The time-series for geopotential height anomaly, over Greenland.
10mb
50mb
150mb
500mb
Basically, when going down from the stratosphere, with time, the main +ve anomaly propagates slightly southward. When reaching the troposphere, it all depends on the tropospheric dynamics at that point.
And come cross-sections for Greenland.
Here on the mean zonal wind, I marked the general circulation, as you can interpret.
And the corresponding pattern.
Best regards.0 -
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Been some unfavourable conditions throughout the troposphere lately and that looks like coming to an end soon. More of easterly influence will finally be able to get down.
There has been a sustained warming at 30mb and now is starting to cool from top down.
That is good because it helps flush the easterly anomaly down through the atmosphere.
ECM showing the Siberian high connection and Gfs similar but further south.
Lower Strat forecast showing the ridging in the Atlantic and Siberian high too. All very promising.
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This discussion has been closed.
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