Stratosphere Temperature Watch

[Evening thunder]

I have followed this thread with great interest since it was started and I think it is probably one of the best on Netweather. I have learnt alot since the start of this thread to add to the basic info I already knew.

I really enjoy the great posts that are made in here and will continue to follow with interest especially with this major SSW currently occuring.

Keep up the great work guys

[chionomaniac]

Morning all.

We have probably gone Major today.

The next weeks forecasts are still looking excellent wrt length and duration of the MMW. The corresponding drop in temperature after the rise is forecast to be 'stuttery' to say the least and the mean zonal winds at the 10 hPa level are forecast to be negative for some time.

The next chart shows the propagation of the zonal negative winds to the surface at T+192. As one can see there is a large area of blue in the troposphere towards the NP. Hopefully this will allow high pressure to build up in this area. Also to note on this chart is the positioning of the bulk of positive zonal winds. The deeper orange colour indicates this and shows that the strongest positive anomaly is positioned at the 200 hPa level around 20-30ºN. Perhaps this is where the jet stream will lie?

So taking this into account there is a good chance of high latitude blocking starting to form in around 8 days time. that will take us into the first few days of February and give it a few more days to strengthen could we be likely to see something around the 5th. I think that is SMs projected date as well.

All in all things still look promising but as ever we need everything to fall into place.

c

[Guest North Sea Snow Convection]

I have followed this thread with great interest since it was started and I think it is probably one of the best on Netweather. I have learnt alot since the start of this thread to add to the basic info I already knew.

I really enjoy the great posts that are made in here and will continue to follow with interest especially with this major SSW currently occuring.

Keep up the great work guys

Thanks StormMad. It would be worth more people from the model thread reading this thread as it might help manage expectations of when cold weather might arrive. A lot of changes are going to impact on the models but lag time must be allowed for this to happen. Too many people are expecting changes next week at the surface when in reality it is not going to happen. I would estimate, at a guess, it might be about 2nd week of Feb before we might see that happen. However the models WILL show some dramatic changes in time IMO and as this event proceeds and feeds into model starting data, then those changes will manifest themselves. Probably during the course of the coming week - although the confused and erratic output has already started! Can't promise a big freeze but there are reasons for optimism if people can be more patient.

Edited January 24, 2009 by North Sea Snow Convection

[chionomaniac]

Thanks StormMad. It would be worth more people from the model thread reading this thread as it might help manage expectations of when cold weather might arrive. A lot of changes are going to impact on the models but lag time must be allowed for this to happen. Too many people are expecting changes next week at the surface when in reality it is not going to happen. I would estimate, at a guess, it might be about 2nd week of Feb before we might see that happen. However the models WILL show some dramatic changes in time IMO and as this event proceeds and feeds into model starting data, then those changes will manifest themselves. Probably during the course of the coming week - although the confused and erratic output has already started! Can't promise a big freeze but there are reasons for optimism if people can be more patient.

Going on from that there has been trends from previous MMWs to almost give us two waves of cold. One early and one later on. If we are to get an early one then it will still probably be around 300 hrs away in forecasting time - well into FI.

[blitzen]

If this 'strat' warming event does turn out to have a positive effect on a cold spell for the uk soon (along with other pieces of the jigsaw) then it will certainly be an area of interest in future seasons along with the models. Well done to all involved as it certainly is a riveting thread!

[Weather-history]

Here is a comment of the warming event on this on this website

http://keeneweather.blogspot.com/

and here as well

http://newxsfc.blogspot.com/2009/01/sudden...ic-warming.html

[Cloud 10]

Here is a comment of the warming event on this on this website

http://keeneweather.blogspot.com/

and here as well

http://newxsfc.blogspot.com/2009/01/sudden...ic-warming.html

Thanks for those links Mr Data,i especially like this paragraph from the second link:

"Pronounced weakenings of the NH wintertime stratospheric polar vortex tend to be followed by episodes of anomalously low surface air temperatures and increased frequency of occurrence of extreme cold events throughout densely populated regions such as eastern North America, northern Europe, and eastern Asia that persist for ~2 months."

[BLAST FROM THE PAST]

Ok southerly jet persisting, with blocking developing but too far north for major cold spell for UK but overall temps close to or a little below average over the month.

BFTP

[chionomaniac]

Good Morning all.

Well, as expected we have a MMW today. The mean zonal winds are now easterly at the 10 hPa level at 60ºN (indicated by the red -2.7m/s).

The best news today is that if anything the recovery of the stratospheric vortex looks delayed. The zonal winds at 30 hPa level look slower to recover.

At the end of each winter the stratospheric normally reduces in strength with temperatures rising for the summer. This is called the Final Warming (FW). There is a strong possibility that the vortex may not recover its strength after this warming event and we may have an extremely early FW. If this is the case then I reckon a cold spring awaits after a cold Feb. We shall see as it may be a bit early to think along these lines. As one can see there has never been a final warming in January before.

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

c

[Glacier Point]

ECM forecasts suggest that the MMW will rip the polar vortex in two and quite literally scatter it to the four (two) winds.

From this....

to this .....

The inference here will be height rises centred towards Greenland and Svalbard.

Latest zonal wind analysis identifies a record strength mean value at the upper levels propagating downwards:

The anomaly is also looking very healthy and we could well be seeing a record strength anomaly developing over the next 10-21 days. My punt for peak impacts from this would be round about the 10-14 February although it is likely in the lead up to this there will be progressive blocking to our north.

It's an interesting discussion about whether the PV would be able to reform given the magnitude of the event, possible duration and timing. The west QBO is not weakening quickly just yet. When it does we are likely to see a slump in zonals over the Tropics and increase over the polar field but that assumes the west QBO behaving like most others. Clearly, this one is very different.

[sandstorm2]

Myself, like other members of the forum knew very little about the Stratosphere before this major event started to take place and I must give my thanks to the experts for posting their thoughts and analyses.

SS2

[Guest North Sea Snow Convection]

Thanks for that GP. I have been looking forward to your thoughts on this for when the event actually arrived. It seems a long time posting on this thread and watching the initial forecast and progress of the MMW over what is now at least 10 days!

It confirms what a massive event it is, and of course the best part of all, is the fact that prospects for a large surface effect are getting more and more promising.

Fo me a review of large MMW 's with a +QBO would be of value, especially as it is accompanied by a solar minimum. It has dispelled some pre conceived ideas and assumptions I have had on this.

[Weather-history]

The impact of the warming can be seen here

The 10mb New Years Day chart

Yesterday's 12z chart and the vortex has split into two

[Guest North Sea Snow Convection]

I believe the change over to the easterly QBO phase will be expected by around April so depending how fast the westerly phase decays the margins will be interesting re the timing of any FW, especially in view of the potential impact on the PV over the remainder of the winter/early Spring as already suggested.

[chionomaniac]

I believe the change over to the easterly QBO phase will be expected by around April so depending how fast the westerly phase decays the margins will be interesting re the timing of any FW, especially in view of the potential impact on the PV over the remainder of the winter/early Spring as already suggested.

As you know Tamara, the change to easterly QBO has already started, but it has to filter down to the middle stratosphere and it is here that it can be delayed with a slight stretching out of the westerly phase. I am sure that that is responsible for the reported stronger pulses in the middle stratosphere in the last month.

If you look at the following data you can see a trend.

http://www.geo.fu-berlin.de/met/ag/strat/p...kte/qbo/qbo.dat

The QBO normally takes a good few months to change from westerly to easterly at the 30 hPa level after the 20 hPa has changed to easterly. The QBO changed to easterly at the 20hPa back in November so it may be a couple of months yet for the middle strat to follow.

c

Edited January 25, 2009 by chionomaniac

[Lettucing Gutted]

The stability though the atmospheric profile will also be concrete from surface to 10Hpa, we might also see a global temperature inversion.

So could this "global temperature inversion" be a very cold polar troposphere and very warm polar stratosphere combination extending well into the mid latitudes?

[Guest North Sea Snow Convection]

As you know Tamara, the change to easterly QBO has already started, but it has to filter down to the middle stratosphere and it is here that it can be delayed with a slight stretching out of the westerly phase. I am sure that that is responsible for the reported stronger pulses in the middle stratosphere in the last month.

If you look at the following data you can see a trend.

http://www.geo.fu-berlin.de/met/ag/strat/p...kte/qbo/qbo.dat

The QBO normally takes a good few months to change from westerly to easterly at the 30 hPa level after the 20 hPa has changed to easterly. The QBO changed to easterly at the 20hPa back in November so it may be a couple of months yet for the middle strat to follow.

c

Yes, in terms of changing over I was referring to the eventual complete change

I didn't know the stats though that you have just provided re the 20hPa level - thanks for that

[tundra]

I mentioned this in the model thread that the warming last year that some are comparing this event to only got down to the 100hpa on the stratosphere zonal temperature series charts and that was the last warming at the end of February.

This is a completely different animal as Chionomaniac and North sea snow convection have already said.

[chionomaniac]

Zonal winds are forecast to stay strongly negative in the middle stratosphere (10-30 hPa)for a good period of time that may well exceed 10 days! Remember the longer these winds are negative in the stratosphere, the longer duration tropospheric impact.

The initial propagation down the troposphere is quick and strong which is probally partly responsible with the topsy turvy modelling at present.

However even after this the mid range impacts of the SSW are indeed looking good.

c

[chionomaniac]

The 10 hPa warming has now peaked ( note the revised scale!) at a record amount.

The warming at 30 hPa level has probably reached its maximum as well - not quite a record there.

The record warmth has displaced the cold air and created record cold anomalies at the tropics and

into the southern hemisphere.

[Guest North Sea Snow Convection]

Implications of the sustained length of the knock on effect of easterly zonal winds through this intense warming event make it more and more likely that a favourable surface effect will be noticed and the present initial downwelling of negative anomalies paves the way for full propagation of the main event. Which is still to come in its full on glory!

Super indications for the remainder of winter and into the Spring too

[sandstorm2]

could you please excuse my ignorance, have been trying to work out what the abbreviations MMW and SSW mean would somebody be good enough to reply, sorry if this is off topic.

SS2

[Guest North Sea Snow Convection]

could you please excuse my ignorance, have been trying to work out what the abbreviations MMW and SSW mean would somebody be good enough to reply, sorry if this is off topic.

SS2

Hi SS2

MMW = Major Midwinter Warming

SSW= Sudden Stratospheric Warming

[sandstorm2]

Hi SS2

MMW = Major Midwinter Warming

SSW= Sudden Stratospheric Warming

Thank you, knew the last word was warming but that was it, lol.

[Guest North Sea Snow Convection]

Thank you, knew the last word was warming but that was it, lol.

Just to define that a bit more for you - an MMW is defined when the zonal mean winds at 60N and at the 10hPa level become easterly during the winter months. The first day that this occurs is defined as the 'central date of the warming'. From reading the thread and a lot of the excellent documentation that chionomaniac has especially supplied, you will see that this particular MMW went 'major' this weekend