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chionomaniac

Stratosphere Temperature Watch

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Firstly a Happy and Healthy New Year to all.

Latest Update.

Well, 2008 ended with a marked cool down of the upper stratosphere with an increased and fairly symmetrical strengthening polar vortex becoming established over the North Pole. We have been waiting for this to occur all winter and if you compare the start of last winter to the start of this winter there is a marked difference between the two. The beginning of Dec last year(2007) is similar to the end of Dec just gone. In effect, the stratosphere's cool down below average, is a month later this time.

post-4523-1230895008_thumb.png

post-4523-1230895038_thumb.png

2008 ended with the zonal winds increasing at the top of the stratosphere and this is now propagating lower down in the stratosphere. The net effect will be a strengthening polar stratospheric vortex which will eventually filter down to the troposphere, ( look below 100hPa), in the same way that the negative wind zonal anomaly is doing so now.

post-4523-1230895957_thumb.png

The effects of the positive zonal anomalies will probably be felt in the troposphere around the last third of January and one would imagine that the Atlantic jetstream will be invigorated and we will be back under milder maritime air masses.

The stratospheric wind anomaly forecast suggests further rising of the zonal wind anomalies before a levelling off or reduction.

post-4523-1230896289_thumb.png

This of course has an effect on the stratosphere temperatures which are forecast to remain well below average for the foreseeable future.

post-4523-1230896428_thumb.png

I wouldn't be surprised to see the zonal winds reduce mid January and await with interest to see if we do get a mid Jan warming as suggested as a possibility by Jim Hughes.

One last thing is that the QBO doesn't seem to have reduced last month with even some stronger pulses detected.

post-4523-1230896872_thumb.png

The strong westerly QBO will influence the stratospheric zonal wind anomaly and I fear that until we see this reduce zonal winds may well stay above average for the foreseeable future.

Regards

c

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Those very warm spikes during late January and throughout February 2008 looked interesting.

Did they correspond back then to any major cold outbreaks at the surface?

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Those very warm spikes during late January and throughout February 2008 looked interesting.

Did they correspond back then to any major cold outbreaks at the surface?

Yes the one at the end of February , if you track the anomaly down to the surface gave us the cold outbreak at the start of April. The January warming didn't really make it down to the troposphere.

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tks ch,

I too believe that it may be into late January before anything changes enough in the Stratosphere for a more blocked effect on the weather in the Troposphere to show into February.

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Guest North Sea Snow Convection
Firstly a Happy and Healthy New Year to all.

The strong westerly QBO will influence the stratospheric zonal wind anomaly and I fear that until we see this reduce zonal winds may well stay above average for the foreseeable future.

Regards

c

Happy New Year :nonono:

I have wondered, and admittedly hoped as well, that the recent stronger pulses of the +QBO might be final resistance actions before a fairly quick weakening from herein. We are going to have to wait a long time for Jan's QBO figures to verify this, but any warming wave breaking that occurs to disrupt the vortex again, and most especially reduction in peak of upper zonal winds that do materialise this month will be greatly assisted by any rapid weakening of the QBO, and perhaps more relevantly be a symptom of that weakening occuring - and pavING the way for a better recovery of stratospheric temperatures asap.

That is being especially optimistic, because as things stand they look none too good with the polar vortex strengthening and re-grouping with the stronger QBO and below average temperatures ETC up there.

We do need to see a recovery by the start of February at the very latest in order to provide some late winter interest, otherwise the second half of the winter might risk following the 2001/02 season with a lot of zonality, after the cold December and festive season was over, through January and into February too.

If we are going to get any joy, it will be a case of seeing it first on the ECM stratospheric forecasts IMO. So a case of watching/hoping/waiting for the next week or two

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Guest North Sea Snow Convection

Another factor that hasn't been mentioned is any La Nina recurrence which will not help any wave breaking prospects. The atmosphere needs to put a dampener on these signs somehow!

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The interesting thing here is that the vortex still remains weak this year, unlike in the previous two winters.

Look at the latest CPC cross section of height anomalies – which is indicating that the AO is starting to go in to more negative territory.

post-1798-1230910930_thumb.png

How does this correlate (or does it correlate at all?) with the cold stratospheric temperatures that have prevailed since mid December? Or does it suggest that, in certain cirumstances, a cold NH stratosphere does not automatically equate to a strong polar vortex? Does this in any way explain the models difficulty in coming to terms with the current synoptics?

Sorry, more questions than answers, but this is a bit of a mystery to me.

MM

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Does this in any way explain the models difficulty in coming to terms with the current synoptics?

MM

the answer I got from NOAA was that there was no insertion of anything other than routine observed data at the start of any run. No additional was made at any stage so the models, according to that, have no idea what the Stratosphere, ENSO, AO, NAO are doing or maybe about to do?

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The interesting thing here is that the vortex still remains weak this year, unlike in the previous two winters.

Look at the latest CPC cross section of height anomalies – which is indicating that the AO is starting to go in to more negative territory.

post-1798-1230910930_thumb.png

How does this correlate (or does it correlate at all?) with the cold stratospheric temperatures that have prevailed since mid December? Or does it suggest that, in certain cirumstances, a cold NH stratosphere does not automatically equate to a strong polar vortex? Does this in any way explain the models difficulty in coming to terms with the current synoptics?

Sorry, more questions than answers, but this is a bit of a mystery to me.

MM

The real cooling of the stratosphere has only really started towards the end of December with a corresponding increase in zonal westerly stratospheric winds. It is akin to the hoover has only just been switched on, and it will take some time before a strong stratospheric vortex will influence and cause a strong tropospheric vortex. So the AO may be trending negative presently but I would be surprised if it still trended that way when the full effects of the stratosphere strengthening vortex will be felt in the troposphere probably by the end of Jan.

Sorry, I don't know what influence this has on the current model difficulty.

c

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the answer I got from NOAA was that there was no insertion of anything other than routine observed data at the start of any run. No additional was made at any stage so the models, according to that, have no idea what the Stratosphere, ENSO, AO, NAO are doing or maybe about to do?

John , thanks for clearing that one up for me. You've probably made this clear in the past in one of your many helpful posts.

At first glance though I'm surprised there is no Stratospheric data used by the models. However as the lag effect is three to four weeks and models only go out 16 days maximum then this would probably be low down on their list of enhancements.

Of course if GFS went out to four weeks..................................no, better not go there!

MM

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The real cooling of the stratosphere has only really started towards the end of December with a corresponding increase in zonal westerly stratospheric winds. It is akin to the hoover has only just been switched on, and it will take some time before a strong stratospheric vortex will influence and cause a strong tropospheric vortex. So the AO may be trending negative presently but I would be surprised if it still trended that way when the full effects of the stratosphere strengthening vortex will be felt in the troposphere probably by the end of Jan.

Sorry, I don't know what influence this has on the current model difficulty.

c

the AO shown this morning is already trending up into +ve

or rather is predicted to do so!

see this link to NOAA

http://www.cpc.ncep.noaa.gov/products/prec..._index/ao.shtml

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The real cooling of the stratosphere has only really started towards the end of December with a corresponding increase in zonal westerly stratospheric winds. It is akin to the hoover has only just been switched on, and it will take some time before a strong stratospheric vortex will influence and cause a strong tropospheric vortex. So the AO may be trending negative presently but I would be surprised if it still trended that way when the full effects of the stratosphere strengthening vortex will be felt in the troposphere probably by the end of Jan.

Sorry, I don't know what influence this has on the current model difficulty.

c

C,

Many thanks for your reply - what I'm getting at here is do we know just how strong is the link between a cold stratosphere and strong tropospheric vortex in a year when the "stratospheric cold" has already been disrupted.

In addition, the fact that it has already been disrupted - does that mean that, when the vortex appears, it is less likely to set up camp over Greenland (as in 2007 and 2008) or move to other regions perhaps more conducive to cold for the UK?

MM

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C,

Many thanks for your reply - what I'm getting at here is do we know just how strong is the link between a cold stratosphere and strong tropospheric vortex in a year when the "stratospheric cold" has already been disrupted.

In addition, the fact that it has already been disrupted - does that mean that, when the vortex appears, it is less likely to set up camp over Greenland (as in 2007 and 2008) or move to other regions perhaps more conducive to cold for the UK?

MM

MM

The two points above are the kind of questions I wanted to know the answers to, at the start of winter, which is why I started this thread. The interaction between the stratosphere and troposphere is one that is increasingly coming under scrutiny with the aim to increase the understanding of the processes involved between the two.

I do believe that we will find that the tropospheric vortex will strengthen by the end of the month, and with the positioning of the stratospheric vortex now almost directly over the North Pole, I wouldn't be surprised to see the tropospheric vortex set up camp above Greenland. However one can't be sure as there are other factors such as SSTs, GWO, La nina state, etc that will also have a bearing.

c

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Another factor that hasn't been mentioned is any La Nina recurrence which will not help any wave breaking prospects. The atmosphere needs to put a dampener on these signs somehow!

Tamara (at the risk of sounding stupid) I have to admit that I don't fully understand the mechanisms involved here, so any help would be appreciated!

c

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Tamara (at the risk of sounding stupid) I have to admit that I don't fully understand the mechanisms involved here, so any help would be appreciated!

c

hi guys, do you think theres a possibility that perhaps the stratospheric cooling event wont have a massive impact? i think there is still potential for some good wintry spells to come throughout late january and february. the la nina is obviously an issue, which will probably bias a positive NAO, but i think that a good swathe of january could still be cold. perhaps february could put a dampener on the winter.

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hi guys, do you think theres a possibility that perhaps the stratospheric cooling event wont have a massive impact? i think there is still potential for some good wintry spells to come throughout late january and february. the la nina is obviously an issue, which will probably bias a positive NAO, but i think that a good swathe of january could still be cold. perhaps february could put a dampener on the winter.

Well I guess there is a possibility, but I know where my money would be, and I wouldn't bet against a stronger, more northerly based jet than we have at the moment, come February. You are right though, that we still have a window of opportunity before the end of the month for cold conditions to persist. After that trending mild, but in reality we won't know until nearer the time.

c

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Guest North Sea Snow Convection
Tamara (at the risk of sounding stupid) I have to admit that I don't fully understand the mechanisms involved here, so any help would be appreciated!

c

A strenghtened La nina, especially in conjuntion with the +QBO will add more fuel to the fire of the pacific jetstream, the polar vortex and hence will offset any warming tendencies./chances. The strong nina last winter was extra food and drink to the flat zonal jetstream and the polar vortex which dominated the winter as we know.

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A strenghtened La nina, especially in conjuntion with the +QBO will add more fuel to the fire of the pacific jetstream, the polar vortex and hence will offset any warming tendencies./chances. The strong nina last winter was extra food and drink to the flat zonal jetstream and the polar vortex which dominated the winter as we know.

Thanks, I wondered if there was anything more to it than that. It seems that every time we get something in our favour there is something else that throws a spanner in the works. In this case as the QBO will be set to weaken the la nina will probably strengthen!

c

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Guest North Sea Snow Convection
Thanks, I wondered if there was anything more to it than that. It seems that every time we get something in our favour there is something else that throws a spanner in the works. In this case as the QBO will be set to weaken the la nina will probably strengthen!

c

The jury is still out on the la nina - so I wouldn't worry about that just yet. :)

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Dec QBO has come in at +10.46m/s which is slightly higher than forecast. Jan is forecast to be around +6m/s so I wonder will it come in slightly greater than that. Looking on the bright side, next winter it should be a stonking negative value!

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Well IMO the jet and hemispheric pattern as responded directly with the solar cycle, lunar pahsing and planetary magnetic fields. Ozone in the Stratosphere is created when High Energy UV light from The Sun interacts with Oxygen. Currently the lower levels of UV emissions mean less Ozone is being created. This has a direct affect on the path and wiggles of the Jet Stream induced by Planetary Waves as a result of the Ozone being formed. We haven't needed SSW event to bring widespread cold. I am still hopeful for more very cold outbreaks for this month.

BFTP

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Well IMO the jet and hemispheric pattern as responded directly with the solar cycle, lunar pahsing and planetary magnetic fields. Ozone in the Stratosphere is created when High Energy UV light from The Sun interacts with Oxygen. Currently the lower levels of UV emissions mean less Ozone is being created. This has a direct affect on the path and wiggles of the Jet Stream induced by Planetary Waves as a result of the Ozone being formed. We haven't needed SSW event to bring widespread cold. I am still hopeful for more very cold outbreaks for this month.

BFTP

I too am hopeful for further out breaks of cold this month, Fred. After all it is only the 3rd today and I do not believe that the powering tropospheric vortex will occur until quite near the end of the month. I do believe that once the Atlantic jetstream increases in strength it will be very difficult to reduce again. But not impossible as the stratospheric influence is only one of a number that effect our weather. Your research with Roger is very interesting but I do not know enough about the subject. I am awaiting with interest to see how your forecast and also Roger's for America verifies at the end of winter.

Regards

c

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Latest info:

The zonal wind mean anomalies have increased over the last week with a subsequent cooling of the stratosphere. These increased westerly winds are still likely to take a little time to propagate downwards and increase the tropospheric polar vortex. The concern is that once this occurs that it may be some time before the grip of the vortex loosens.

However, today there may be the first signs of light along the dark, cold, stratospheric tunnel. GP mentioned the other day, that a strong mountain torque event could have some influence further along the line and perhaps the ECM stratosphere forecasts are just picking this up, at the extremity of their forecasts. This fits in with the thoughts from the other side of the Atlantic. It is too early to say whether this forecast is correct, or if it is, how much warming will occur, but at least it is a start!

Zonal winds high but with possible first signs of reducing:

post-4523-1231163584_thumb.png

Possible tentative signs of less cool stratosphere:

post-4523-1231163644_thumb.png

As ever, only time will tell what is going to happen.

c

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That would be a blessing. A stratospheric warming event mid January would considerably increase our chances for northern blocking and cold outbreaks in February (especially the 2nd half).

I have everything crossed!

In the meantime, mid latitude highs will be our best chance for cold.

Karyo

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La nina tends to go together with a low angular momentum state and with a stationary high pressure just north of the equator to the north east of Australia. This usually gives plenty of energy into the western Pacific jet as cold air meets warm. A fixed rossby wave pattern can occur as a result with particular jet stream patterns. It is normally fixed patterns with slow moving high pressure in northern latitudes which cause the stratospheric vortex to wobble (a warming). Positioning of these events due to the strength of la nina is critical so we need to be very carefull about interpretting a link between la nina and the stratospheric vortex movements.

ECM forecasts suggest more high pressure near the UK which would sort of back up GP's idea in the angular momentum thread.

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