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chionomaniac

Stratosphere Temperature Watch

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Yes, yes, yes! This is what we've been waiting for: http://strat-www.met.fu-berlin.de/cgi-bin/...mps&alert=1

The beginning of a significant warming event! Coupled with a major drop in zonal wind anomalies: http://strat-www.met.fu-berlin.de/cgi-bin/...xes&alert=1

If this happens, the second half of February and March look promising!

Karyo

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Yes, yes, yes! This is what we've been waiting for: http://strat-www.met.fu-berlin.de/cgi-bin/...mps&alert=1

The beginning of a significant warming event! Coupled with a major drop in zonal wind anomalies: http://strat-www.met.fu-berlin.de/cgi-bin/...xes&alert=1

If this happens, the second half of February and March look promising!

Karyo

Easy tiger easy! I have been waiting since starting this thread to track through a warming event. All I will say is that it is too early to get too excited regarding a MWW/SSW. This predicted warming is at the 10hPa level and we will have to track it to see what happens from here - it may just come to nothing!

Look forward to full update this evening.

c

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yes caution indeed, we have the cooling effect to work through before we even think about a possible warming; its unlikely that (any warming) will impact before early to mid February in my view.

That is NOT to say we cannot have cold before then.

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yes caution indeed, we have the cooling effect to work through before we even think about a possible warming; its unlikely that (any warming) will impact before early to mid February in my view.

That is NOT to say we cannot have cold before then.

Absolutely, i am not expecting any positive effects before mid February at the earliest as my post states. My optimism is also based on the drop of zonal winds which should encourage a significant stratospheric warming. The next few days should hopefully show this.

Until then, some cold zonality or northwesterly episodes will be our best chance for cold and snow.

Karyo

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Guest North Sea Snow Convection
Absolutely, i am not expecting any positive effects before mid February at the earliest as my post states. My optimism is also based on the drop of zonal winds which should encourage a significant stratospheric warming. The next few days should hopefully show this.

Until then, some cold zonality or northwesterly episodes will be our best chance for cold and snow.

Karyo

We have to see where this leads over the next day or so, but there is no doubt that is a most encouraging thing we could see at this time in January. We should bear in mind that under a +QBO we are unlikely to see an MMW as such, but any recovery of temps (especially if in surfeit of the average) is the best we could wish for.

I have touted that the strength of the west QBO was having its final hurrah in Dec and would wager that it is tumbling from its peak now into the Spring. Coupled with the decelleration in upper zonal winds then this should be good medicine for the polar vortex. Improving prospects for late Jan and Feb for sure.

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We have to see where this leads over the next day or so, but there is no doubt that is a most encouraging thing we could see at this time in January. We should bear in mind that under a +QBO we are unlikely to see an MMW as such, but any recovery of temps (especially if in surfeit of the average) is the best we could wish for.

I have touted that the strength of the west QBO was having its final hurrah in Dec and would wager that it is tumbling from its peak now into the Spring. Coupled with the decelleration in upper zonal winds then this should be good medicine for the polar vortex. Improving prospects for late Jan and Feb for sure.

Morning Tamara,

Having looked at all the SSWs that have occurred in the last 30 years or so, many have still occurred in a westerly QBO.

Whereas I realise thats its unlikely I guess it can't be ruled out.

http://www.geo.fu-berlin.de/en/met/ag/stra...pole/index.html

A few days ago I thought the polar vortex was setting itself up for a vortex split but the forecasts have veered away from that now. It is probably too strong for that to accur anyway.

c

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Guest North Sea Snow Convection
Morning Tamara,

Having looked at all the SSWs that have occurred in the last 30 years or so, many have still occurred in a westerly QBO.

Whereas I realise thats its unlikely I guess it can't be ruled out.

http://www.geo.fu-berlin.de/en/met/ag/stra...pole/index.html

A few days ago I thought the polar vortex was setting itself up for a vortex split but the forecasts have veered away from that now. It is probably too strong for that to accur anyway.

c

Hi -in a fast decaying west QBO it is possible to have an SSW yes - but I am basing the current developments on a bit of a hunch that a relaxation of the west QBO must be occuring to allow both the upper zonal winds to drop and for the warming wave to come through. With time, if the west QBO decayed fast enough then an initial warming could lead onto a more significant one down the line.

But for the here and now, I agree it is best to see how ECM programmes this change and watch how the forecast settles with this warming programmed this morning. The positive mountain torque over Asia is defintely a factor in this, and combined with an equally negative mountain torque over N America, it may well be manufacturing a good result for us in terms of creating a cold pattern and favourable placement of the jet stream, +PNA etc. Even without a vortex split, in the short term, the most important thing is the placement of the PV- and as GP indicated, this is towards Scandinavia. So whilst it has some strength - we are not necessarily suffering the consequences of that through a mild flat zonal pattern. The other aspect of course is that the stronger nina signal is being squashed, which would threaten that warmer pattern occuring - and would feed the PV.

So we are increasingly looking at a colder zonal pattern till the vortex weakens. The current stratospheric develoments are going to be a great help in this regard for the seond half of winter. So who knows! Not a bad scenario when related to the warmer surface signals that have been trying to get through. We seem to have some cold teleconnectors on our side for a change this winter perhaps? :lol:

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Hi -in a fast decaying west QBO it is possible to have an SSW yes - but I am basing the current developments on a bit of a hunch that a relaxation of the west QBO must be occuring to allow both the upper zonal winds to drop and for the warming wave to come through. With time, if the west QBO decayed fast enough then an initial warming could lead onto a more significant one down the line.

But for the here and now, I agree it is best to see how ECM programmes this change and watch how the forecast settles with this warming programmed this morning. The positive mountain torque over Asia is defintely a factor in this, and combined with an equally negative mountain torque over N America, it may well be manufacturing a good result for us in terms of creating a cold pattern and favourable placement of the jet stream, +PNA etc. Even without a vortex split, in the short term, the most important thing is the placement of the PV- and as GP indicated, this is towards Scandinavia. So whilst it has some strength - we are not necessarily suffering the consequences of that through a mild flat zonal pattern. The other aspect of course is that the stronger nina signal is being squashed, which would threaten that warmer pattern occuring - and would feed the PV.

So we are increasingly looking at a colder zonal pattern till the vortex weakens. The current stratospheric develoments are going to be a great help in this regard for the seond half of winter. So who knows! Not a bad scenario when related to the warmer surface signals that have been trying to get through. We seem to have some cold teleconnectors on our side for a change this winter perhaps? :)

Great post. Certainly agree that the way things look a far better outlook for the second half of winter, far better than the outlook at the start. With the recent stratospheric cooling, the PV heading towards Scandinavia is certainly a surprise bonus (if it happens) and really the best Jan option we can hope for! I think that the unprecedented size of the mountain torque events must have a bearing on us, hopefully positive both in the short and longer term.

c

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Here are the NCEP forecast temps at the 10hPa level.

Today:

post-4523-1231765835.gif

T+192:

post-4523-1231765897.gif

Almost there

T+240

post-4523-1231765947.gif

Interesting!

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Here are the NCEP forecast temps at the 10hPa level.

Today:

post-4523-1231765835.gif

T+192:

post-4523-1231765897.gif

Almost there

T+240

post-4523-1231765947.gif

Interesting!

Good grief, that's severe warming of the stratos :lol:

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Guest North Sea Snow Convection
Great post. Certainly agree that the way things look a far better outlook for the second half of winter, far better than the outlook at the start. With the recent stratospheric cooling, the PV heading towards Scandinavia is certainly a surprise bonus (if it happens) and really the best Jan option we can hope for! I think that the unprecedented size of the mountain torque events must have a bearing on us, hopefully positive both in the short and longer term.

c

Nice GFS plots! :lol:

Interesting that Jim H feels there is more warming to come. And that it is only the current strength of the PV that is (currently) preventing a full blown warming.

Intriguing times ahead methinks!

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GFS runs have recently shown large a Siberian high develop, and well into FI an Arctic High.

Does GFS take into account stratos warming? If not, certainly interesting parallel forecasts.

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nope no input other than the actual data on each run, NOAA are quite emphatic about this, no AO/NAO QBO, Stratosphere etc.

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Quick report

Just a word of caution regarding the latest forecast. The temp at 10hPa level is still forecast to rocket, but soon we would like the 30hPa level to show a similar pattern.

post-4523-1231840949_thumb.png

The zonal winds look forecast to reverse almost at the upper end of the stratosphere (1hPa), but we need to see a reversal at the 10hPa level for this to be classified as a SSW.

post-4523-1231841091_thumb.png

What we need to see on the following chart for this is for the wind reversal line (0) to cross over the 10hPA /60N intersection heading towards the pole.

post-4523-1231841227_thumb.png

The zonal winds here are still around 30m/s at T+192.

c

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Guest North Sea Snow Convection
Quick report

Just a word of caution regarding the latest forecast. The temp at 10hPa level is still forecast to rocket, but soon we would like the 30hPa level to show a similar pattern.

post-4523-1231840949_thumb.png

The zonal winds look forecast to reverse almost at the upper end of the stratosphere (1hPa), but we need to see a reversal at the 10hPa level for this to be classified as a SSW.

post-4523-1231841091_thumb.png

What we need to see on the following chart for this is for the wind reversal line (0) to cross over the 10hPA /60N intersection heading towards the pole.

post-4523-1231841227_thumb.png

The zonal winds here are still around 30m/s at T+192.

c

I think that an SSW is becoming an increasing possibility now. If the upper zonal winds at the top do switch in polarity, then the whole engine of the stratosphere that goes on to drive the vortex collapses it top downwards. It must propagate surely?

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I think that an SSW is becoming an increasing possibility now. If the upper zonal winds at the top do switch in polarity, then the whole engine of the stratosphere that goes on to drive the vortex collapses it top downwards. It must propagate surely?

One would think so. The evolution so far is very similar to a vortex split MMW in Jan 1971. Just a few more days and we should find out.

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One would think so. The evolution so far is very similar to a vortex split MMW in Jan 1971. Just a few more days and we should find out.

I'm impressed how you find these comparisons like a rabbit out of a hat! You are quite a research bunny! :D

Might be worth looking at Jan/Feb 71 archives to see what happened. I know that there was a major mild spell around this time in the jan, following the easterly and white xmas into New Year 70/71

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I'm impressed how you find these comparisons like a rabbit out of a hat! You are quite a research bunny! :D

Might be worth looking at Jan/Feb 71 archives to see what happened. I know that there was a major mild spell around this time in the jan, following the easterly and white xmas into New Year 70/71

I have done so - not too great: CET in the 4's both Jan and Feb, qbo was neg though so differences elsewhere to consider.

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I have done so - not too great: CET in the 4's both Jan and Feb, qbo was neg though so differences elsewhere to consider.

Yep - as we well know, and oft say, there are many factors at play of which the stratosphere is one component part. Albeit a major one.

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I have done so - not too great: CET in the 4's both Jan and Feb, qbo was neg though so differences elsewhere to consider.

Have you considered the warming from 01 Jan 1985 to my untrained eye the atmosphere looks to have the same profile as what we have at the moment. Just a thought.

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I have done so - not too great: CET in the 4's both Jan and Feb, qbo was neg though so differences elsewhere to consider.

There was a short wintry spell at the end of February 1971 and more especially during the first part of March. In the far SE, some places never got above freezing during early March.

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Today the main question I find myself, is are we about to see a minor or major stratospheric warming? Well looking at the evidence we are certainly going to have a minor warming but I am unconvinced as of yet that we will be due a major warming. The major warming crireria requires the zonal winds to be reversed in the middle stratosphere (10hPa level) at 60N.

Looking at the forecasts the temperature rises presently are limited to the middle to upper stratosphere. Ideally I would like to see evidence pretty soon that these are going to propagate down to the 30hPa level, which is already showing signs of the warming tailing off before we get above average.

post-4523-1231923844_thumb.png

The mean zonal winds forecast also does not show enough at present to suggest the vortex is about to collapse in on itself, with the 10hPa mean winds still not reducing below 20m/s.

post-4523-1231924209_thumb.png

When I look at both the NCEP and ECMWF vortex forecasts there are similarites with evidence of the stretching of the vortex like an elastic band. But is it too strong to snap? Minor warming IMHO until we see the vortex weaken.

post-4523-1231924437_thumb.png

post-4523-1231924463.gif

post-4523-1231924509.gif

c

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Given that we seem much more prediposed to blocking this year, perhaps a minor warming is all it'll take to disrupt the PV and allow heights to rise over Scandinavia?

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Have you considered the warming from 01 Jan 1985 to my untrained eye the atmosphere looks to have the same profile as what we have at the moment. Just a thought.

Yes. Good spot. My head must have been spinning like those vortices by the time I got to that one the other night!

Given that we seem much more prediposed to blocking this year, perhaps a minor warming is all it'll take to disrupt the PV and allow heights to rise over Scandinavia?

Yes, but we won't know for some time - early to mid Feb. It will depend on how much propagation of temps and wind anomalies filter down from the upper stratosphere. With minor warmings they can oft pass by unnoticed.

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Guest North Sea Snow Convection

I think a little time has to be given regarding the 30mb level. I don't think we can assume it will happen immediately, just like that, necessarily.

I wouldn't be surprised to see an initial slight to moderate warming - evough to weaken the PV. Any warming will weaken the PV after all. Then, further warming which will complete the exercise. But I think we need to let events unfold - this evolution isn't over yet. A faily major warming is still quite possible IMO :)

It would be interesting to know what is happening with the west QBO - again, I would relate what is happening in the stratosphere, and the potential intensity of any warming, with how this phase is waning. As Jim H has said, it could be an 'indicator' warming.

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