Stratosphere Temperature Watch

[chionomaniac]

Great post as normal.

I guess the key thing will be for the warming stratosphere not to create blocking too far West as we are seeing at the moment. Do you see any signs that the new wave might create blocking further East (i.e. more focused towards Greenland than the Canadian Arctic) and for the vortex to displace further East - i.e. more towards Scandi? My concern at the moment is that if it's too far West then it will just lock in a mild pattern for W Europe.

Yes,that is the main concern Ben. Because the block over the Pacific is so great it will take some time for any disruption to reach us. There are the first signs on the GFS output today. The sausage shape polar vortex is forecast to release more energy into the Atlantic segment with signs of a split following as the following two forecast charts show.

T+120 at 100 hPa

And at T+240

wrong chart see below at end of post

This could leave to the building of a Siberian High that could retrogress eatwards if the disrupted flow continues. Ironically this would then give the first signs of height rises over Scandinavia that I have been questioning TEITS about. But it is a big if and a long way off presently.

I understand that warming of stratosphere doesn't equate to cold here in the UK (but it seems to be a good sign of that being likely). Maybe this is dealt with elsewhere in the thread (I haven't read it all) but can anyone explain for me please:

1. Why warming of the stratosphere tends to point to cold in the UK (in winter at least) and

2. What causes the stratosphere to warm or cool at this time of year when the sun is very weak.

Much obliged for the assistance and sorry if it involves going over old ground.

Hi WB

If you have read the first post and still require further explanation then I will be more than happy to answer.

c

Edited January 4, 2011 by chionomaniac

[beng]

Yes,that is the main concern Ben. Because the block over the Pacific is so great it will take some time for any disruption to reach us. There are the first signs on the GFS output today. The sausage shape polar vortex is forecast to release more energy into the Atlantic segment with signs of a split following as the following two forecast charts show.

T+120 at 100 hPa

And at T+240

wrong chart see below at end of post

This could leave to the building of a Siberian High that could retrogress eatwards if the disrupted flow continues. Ironically this would then give the first signs of height rises over Scandinavia that I have been questioning TEITS about. But it is a big if and a long way off presently.

Thanks for that - makes sense. I think if we get the core of the vortex towards Baffin this winter, then a big Easterly could be on the cards - Feb 56 (another la nina) springs to mind

[chionomaniac]

Today we are seeing a trend forecast of transfer of the bulk of the polar vortex towards Northern Canada. Both the ECM and GFS are hinting towards this on the lower 100 hPa level.

if the vortex travels a little bit further west towards Alaska then this will open up the door possibly for us from the east. However a large degree of uncertainty regarding this remains.

Further up the stratosphere the polar vortex looks like regaining strength at the 1 hPa level quite quickly and as yet no significant vortex reduction programmed at the 10 hPa level despite the warming. Very much a case of watching over the coming days. I would say that the next 10 days will have more Atlantic than blocking influence.

[karyo]

Further up the stratosphere the polar vortex looks like regaining strength at the 1 hPa level quite quickly and as yet no significant vortex reduction programmed at the 10 hPa level despite the warming. Very much a case of watching over the coming days. I would say that the next 10 days will have more Atlantic than blocking influence.

Thanks for the update.

I think this is in line with what GP posted a few days ago. I.e the warming is unlikely to propogate downwards thanks to the increasing effect of La Nina.

Karyo

[snohobo]

There does seem to be quite a warming occuring at the moment, is this not going to benefit us in any way due to la nina effects or is it very much up in the air?

http://acdb-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/t60_90n_30_2010.pdf.

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_TEMP_ANOM_JFM_NH_2011.gif

[chionomaniac]

There does seem to be quite a warming occuring at the moment, is this not going to benefit us in any way due to la nina effects or is it very much up in the air?

http://acdb-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/t60_90n_30_2010.pdf.

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_TEMP_ANOM_JFM_NH_2011.gif

In terms of warming, as warmings go, I would rate this as moderate and we are not (so far) likely to see a full collapse of the polar vortex as would be seen in a SSW. What we are likely to see is distortion of the polar vortex away from the North Pole and to some extent a weakening of zonal mean winds. These may not weaken as much as expected due to a possible upwelling phase in the stratospheric vortex. Positionally we will have to see if the La Nina influences the same as was seen in Feb 2009. This was a major hindrance in regards to the formation of blocking in favourable areas for us.

Presently the upper vortex is controlling things and the vortex is due to transfer energy from Siberia towards northern Canada, but crossing northern Greenland as it does so. As this occurs we are unlikely to see blocking in this area untilthe vortex transfers away and potential vorticity reduces.

Favourably we are seeing the coldest mid stratospheric temperatures over Alaska forecast for around 10 days time. It is my guess that this will be where the main body of the upper polar vortex will transfer to by the end third of January. All very far off and subject to change.

c

[beng]

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_TEMP_ANOM_JFM_NH_2011.gif

That seems like an amazingly abrupt end to the cold conditions at the 5hPa level and something of a warming as far down as 100hPa already.

For comparison here's the huge event from 2009 - which started several weeks later.

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_TEMP_ANOM_JFM_NH_2009.gif

Edited January 7, 2011 by beng

[Mark Bayley]

The latest forecast doesn't look all that inspiring, with a rapid cooling of the 10hpa and 30hpa! I'm guessing the current warming should at least disrupt the PV for a time, however it seems its being disrupted unfavorably for us, the below chart indicating it setting up over the Baffin Islands.

That would support the strong Canadian storm which has been forecast by the models in the long range, which helps create a Atlantic ridge and build heights over Greenland. Whether it would be transient with low pressure pushing through, i can't say. Some of the more experienced members seem to think so! Long term I'm thinking the rapid cooling over the stratosphere will help reorganize the PV, lower heights over the arctic with the AO returning to positive? That obviously doesn't bond well for sustained cold here. I look forward to the next update from CH

Edited January 8, 2011 by Mark Bayley

[SNOWPLOUGH]

Thanks for the update Mark, can you give me a link to the website for the forecasted warming charts?

Thanks.

Dan

[Mark Bayley]

Thanks for the update Mark, can you give me a link to the website for the forecasted warming charts?

Thanks.

Dan

This is the overall link

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/diag.php

For those specific graphs, see this link. Second chart down, below wind and fluxes

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php

I would await an update from a more experienced member, one who knows a lot more about this subject area than me.

[SNOWPLOUGH]

This is the overall link

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/diag.php

For those specific graphs, see this link. Second chart down, below wind and fluxes

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php

I would await an update from a more experienced member, one who knows a lot more about this subject area than me.

Ok, thanks anyway.

EDIT : would a warning at say Oslo have similar effects to one over the pole?

SP

Edited January 8, 2011 by SNOWPLOUGH

[chionomaniac]

I think Marks assessment is a pretty accurate summation of the longer term outlook.

For the median term after any possible mid Atlantic blocking, we need to keep a close eye on the lower vortex to see how far west it travels and whether this allows any pressure builds to the East. Presently this is not indicated, but it would not take too much shifting west for this to change. In the meantime we don't know how many trains need to pass before the level crossing barrier will be raised again.

Snowplough, any warming seen in the stratosphere tends not to be a stationary affair at first. The warmer air tends to wrap itself around the vortex before getting sucked in. If this fails to occur then we can be left with a pool of warmer uppers around the surf zone of the vortex and an upper ridge builds where the collect. We would much rather see a significant warming enter the vortex completely as this will have the effect of putting a stick into a moving wheel. That is not forecast to occur this time.

[SNOWPLOUGH]

I think Marks assessment is a pretty accurate summation of the longer term outlook.

For the median term after any possible mid Atlantic blocking, we need to keep a close eye on the lower vortex to see how far west it travels and whether this allows any pressure builds to the East. Presently this is not indicated, but it would not take too much shifting west for this to change. In the meantime we don't know how many trains need to pass before the level crossing barrier will be raised again.

Snowplough, any warming seen in the stratosphere tends not to be a stationary affair at first. The warmer air tends to wrap itself around the vortex before getting sucked in. If this fails to occur then we can be left with a pool of warmer uppers around the surf zone of the vortex and an upper ridge builds where the collect. We would much rather see a significant warming enter the vortex completely as this will have the effect of putting a stick into a moving wheel. That is not forecast to occur this time.

Thanks for that Chiono, I understand that now. hopefully we see a warming occur in a favourable location to destroy the PV so.

Dan

[Weather-history]

For the median term after any possible mid Atlantic blocking, we need to keep a close eye on the lower vortex to see how far west it travels and whether this allows any pressure builds to the East. Presently this is not indicated, but it would not take too much shifting west for this to change.

Februarys 1956 and 1991, note the intense polar vortex over the Davis Strait

http://www.wetterzentrale.de/pics/archive/ra/1956/Rrea00119560201.gif

http://www.wetterzentrale.de/pics/archive/ra/1991/Rrea00119910202.gif

[chionomaniac]

Februarys 1956 and 1991, note the intense polar vortex over the Davis Strait

http://www.wetterzentrale.de/pics/archive/ra/1956/Rrea00119560201.gif

http://www.wetterzentrale.de/pics/archive/ra/1991/Rrea00119910202.gif

Interestingly 1956 was a strong La Nina year.

Latest update.

We are in the process of coming to the end of a moderate warming of the upper stratosphere. This has helped lead to a large Pacific based block and very negative AO. It now looks like following this the vortex is set to increase in strength dramatically - up to just below 50 m/s at the 10 hPa level at T+240.

However one beneficial aspect of this is that the residual warming has traversed over to our sector of the hemisphere. I believe that with the vortex towards the Canadian sector this could be beneficial to height rises to the east. My only concern would be will they be north enough to drag down cold air.

The 100 hPa levels show that there are opportunities to the east at T+240 with both the GFS and ECM.

All in all there is still something to keep us interested and I am now on the look out for eastern height rises at the furthest ranges of the outputs

c

[BLAST FROM THE PAST]

Interestingly 1956 was a strong La Nina year.

Latest update.

We are in the process of coming to the end of a moderate warming of the upper stratosphere. This has helped lead to a large Pacific based block and very negative AO. It now looks like following this the vortex is set to increase in strength dramatically - up to just below 50 m/s at the 10 hPa level at T+240.

However one beneficial aspect of this is that the residual warming has traversed over to our sector of the hemisphere. I believe that with the vortex towards the Canadian sector this could be beneficial to height rises to the east. My only concern would be will they be north enough to drag down cold air.

The 100 hPa levels show that there are opportunities to the east at T+240 with both the GFS and ECM.

All in all there is still something to keep us interested and I am now on the look out for eastern height rises at the furthest ranges of the outputs

c

Indeed C with a retrograde signal to start again and with a Feb IMO akin to 1942 and indeed with RJS thinking 1947 as another analogue i think look E or NE...not NW. There is a healthy Siberian HP maybe wanting to play ball.

BFTP

Edited January 9, 2011 by BLAST FROM THE PAST

[jethro]

That's one hell of a ramp!

[chionomaniac]

Quick update.

Firstly, we are still seeing a moderate warming forecast for the next couple of days at the 10 hPa level. However this is not a uniform warming and is centered over North Europe whilst a cold pool and therefore vortex is shifted towards the Canadian sector. If we look at the average temperature at this level between 60-90ºN this doesn't show the whole picture.

Because the warm air doesn't become integrated with the vortex we see an upper area of ridging build.

The displacement of the vortex and upper ridge transmits itself and influences the position of the lower stratospheric vortex and subsequent tropospheric vortex position. This, in term will influence the pattern of ridge building seen in the troposphere.

Therefore we would expect the lower stratospheric vortex charts for the upcoming period to help as a guide to tropospheric ridge placement.

At around 5 days the emphasis on both the ECM and GFS is for a slight build up of heights towards Scandinavia.

However, this is where things become more complex. Firstly when compared to the Greenland High seen last month the stratospheric signal is very weak, and secondly we are forecast the large MJO event entering phase 7 which is bound to counteract this signal. As has been suggested previously the La Nina base conditions will also interact with any large phase 6/7 event and any NH 500Hpa composite anomaly charts should be amended appropriately. The La nIna heavily modifies any northern blocking and will drive high latitude ridges further south.

Looking towards the T+240 charts at 100 hPa I am seeing indications from the GFS that any ridge may be slightly further west (still weak signal), more centered towards the UK, so disparity exists at upper levels and it may well be a few days yet before we see agreement.

[beng]

http://wattsupwiththat.com/2011/01/11/nearly-70-of-the-usa-is-covered-in-snow/

one thing that may have an impact on stratospheric temps over the next week or so - given the southerly latitude of much of the USA - there ought to be an albedo impact which could help warm the stratosphere.

[Alan Robinson]

http://wattsupwithth...overed-in-snow/

one thing that may have an impact on stratospheric temps over the next week or so - given the southerly latitude of much of the USA - there ought to be an albedo impact which could help warm the stratosphere.

I thought the USA was entirely in the northern hemisphere

[beng]

I thought the USA was entirely in the northern hemisphere

I don't think I claimed it wasn't? What I was driving at is that snow cover across so much of the united states will have an increase in the planet's albedo; notably in the southern states, the sun is already becoming stronger so snow cover there leads to greater albedo relative to the average.

Anyway something of a warming underway again

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_TEMP_ANOM_JFM_NH_2011.gif

Edited January 13, 2011 by beng

[chionomaniac]

I don't think I claimed it wasn't? What I was driving at is that snow cover across so much of the united states will have an increase in the planet's albedo; notably in the southern states, the sun is already becoming stronger so snow cover there leads to greater albedo relative to the average.

Anyway something of a warming underway again

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat-trop/gif_files/time_pres_TEMP_ANOM_JFM_NH_2011.gif

Ben, I am of the thought that unless these warmings propagate far further down the stratosphere (which they are not forecast to do) then we will not see any benefit from them.

[beng]

Ben, I am of the thought that unless these warmings propagate far further down the stratosphere (which they are not forecast to do) then we will not see any benefit from them.

Yep - agree with that - still worth keeping our eyes on though. :-)

[Alan Robinson]

I don't think I claimed it wasn't? What I was driving at is that snow cover across so much of the united states will have an increase in the planet's albedo; notably in the southern states, the sun is already becoming stronger so snow cover there leads to greater albedo relative to the average.

Anyway something of a warming underway again

http://www.cpc.ncep....JFM_NH_2011.gif

Perhaps it is me being too literal? Southerly latitudes are all south of the equator, or put another way, a location with southerly latutude is closer to the south pole than the north.

Perhaps your meaning was low latitude?

[beng]

Perhaps it is me being too literal? Southerly latitudes are all south of the equator, or put another way, a location with southerly latutude is closer to the south pole than the north.

Perhaps your meaning was low latitude?

Well I meant southerly latitude within the N Hemisphere. Low latitude would be better