Jump to content
Paul

Stratosphere temperature watch - 2016/17

Recommended Posts

I still love watching that video animation.. :)

  • Like 2

Share this post


Link to post
Share on other sites

Thanks Guys for the excellent and very informative introduction 

To the thread,not a topic i am well up on,but the expertise of you 

Guys is second to none,and makes learning alot easier 

Keep up the excellent work,i wil be watching this thread in the

Coming months. 

C.S

Share this post


Link to post
Share on other sites

Interesting indeed Malcolm...

Let's see how back on track the discredited Cohen metaphors can go this year, sorry am not buying any of them.

Yes we have rampant 60N and south Snow advance early in season, sadly the feedback loops - bust by solar max - are poor correlations to winter predictive outlooks.

r( correlation) will sync with SAI within a parameter where Smax or Smin is not in effect - however as an informer of natural winter progression it is not a useful steer.

Pacific Variability including IO

Atl SST

Vortex Strength

Sea Ice

these are the four drivers... Guess which one I know holds the final sway given the thread ;)

  • Like 4

Share this post


Link to post
Share on other sites

Just looking through Dr Butler's tweets following @knocker's post above, and noticed this from 1 day ago. 

And AO still looking to stay negative until at least 1st Nov  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml

So many confusing signals - I guess that's why we all find it so interesting!

 

  • Like 1

Share this post


Link to post
Share on other sites

So it seems development of the polar vortex has been weak so far this autumn.

Can anyone explain what an anomalous and meridional flow is and how that is linked to heat flux and its impact on thermal gradients?

GP mentioned the westerly wind being restricted to the southern hemisphere (I take it he's talking about the QBO?) - I wonder if this is linked to the SH not following its usual pattern of final warming?

Edited by Frozen Britain
  • Like 2

Share this post


Link to post
Share on other sites

Thanks GP, quick question to anyone who can answer really, this bit:

"That is near perfect geoeffective positioning for upward wave (Wave 1) deflection into the vortex leading to a push of the vortex towards the North Atlantic"

Wouldn't that mean a +NAO for us and a stronger jet? Or is this what we'll have to have before further blocking can take hold towards end of Nov?

  • Like 3

Share this post


Link to post
Share on other sites

Having read gp and rubens in depth summary of the stratosphere.  What is the most likely scenario weather wise out of this weak vortex??  Or like most on netweather need to know. Will this provide a cold and snowy outlook in the nxt few months.  Hope so 

Share this post


Link to post
Share on other sites
1 hour ago, Glacier Point said:

I know it sounds counter intuitive tcc, but there are good reasons for a weak vortex and more precisely a weak zonal wind flow during November to substantiate a tropospheric ridge in the mid Atlantic. Other drivers [ENSO state, Maritime Continent forcing] are aligned nicely to deliver this.

Thanks GP, be interesting to see what happens!

Share this post


Link to post
Share on other sites

It's getting hard to hide excitement with the 06z ramping things up even further. I do not recall seeing charts like this so early in the season, 2010 was more modest, wasn't it?

GFSOPNH06_384_41.png

  • Like 6

Share this post


Link to post
Share on other sites

Ruben stop it now lol. Everything seems a bit odd weather wise this autumn.  Maybe were on to something totally new to the world weather.  A big change on the way maybe??  Who knows.  All I want is some cold ❄ ❄ 

  • Like 2

Share this post


Link to post
Share on other sites
2 hours ago, Glacier Point said:

Well this is getting interesting and a possible game changer. Why chop down a tree when you can squash a seedling ?

Following the lead of the models of late last week, we have begun to tick down on a warming signal and significant weakening of zonal wind speeds in the middle and lower stratosphere. Both GEFS, GFS and EPS remain solid on developing this.

The operational GFS getting close to a reversal..

u_65N_10hpa.jpg

And right down the middle of the GEFS mean, some members dropping into reversal..

u_65N_10hpa_gefs.jpg

The EC EPS is similar and would give a sizeable clustering around +5 to +8 m/s. That is one weak vortex. Already. Even if we were to assume worst case scenario, those two GFS members going up would still translate to a sizeable negative zonal wind anomaly.

The mid tropospheric modelling continues to develop a deep upper lower dominating the North Pacific in the week 2 time frame.

gfs-ens_z500a_nhem_52.jpg

That is near perfect geoeffective positioning for upward wave (Wave 1) deflection into the vortex leading to a push of the vortex towards the North Atlantic. We are yet to see these being manifested in the strat modelling as they are a little way off, so a weak vortex looks set to become event weaker.

IMG_2901.JPGBeen waiting for effect of MT event in early October to evolve. 

 

IMG_2900.JPGIMG_2899.JPGSOI showing a neutral balance from slightly positive to negative. Delicate balancing. 

Last years Kara Sea High still resinates, an indicator of transition to Solar min. 

I believe the OPI prediction will work this year as there is no El Niño and a less energy from the Sun. 

 

 

  • Like 4

Share this post


Link to post
Share on other sites

Saved these early this morning from the 00z gefs run

these are ens mean charts remember

gives a flavour of the environment that the strat vortex will be attempting to develop in 

 

 

IMG_4484.PNG

IMG_4485.PNG

IMG_4486.PNG

  • Like 2

Share this post


Link to post
Share on other sites
2 hours ago, Ruben Amsterdam said:

It's getting hard to hide excitement with the 06z ramping things up even further. I do not recall seeing charts like this so early in the season, 2010 was more modest, wasn't it?

GFSOPNH06_384_41.png

Interesting chart, but it's for 5th November (T+384). How reliable are these charts at such ranges?

  • Like 1

Share this post


Link to post
Share on other sites
24 minutes ago, Paul_1978 said:

Interesting chart, but it's for 5th November (T+384). How reliable are these charts at such ranges?

I have observed them to be approximately 85% to 90% accurate in terms of the actual event but as to how much energy the wave contains that will have to be verified when ECMWF on Berlin  Uni site reaches the 25th October. 

For the professionals they have GLOSEA5,ECMWF and GFS to compare in the here and now but cannot disclose. 

  • Like 3

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.

  • Similar Content

    • By Paul
      Here we go then, already plenty of interest in the strat this year, and with a La Nina likely, perhaps a less hardcore strat than last year can be expected?
      @chionomaniac will be along soon to fill in his thoughts on where things may be headed this year, but in the meantime, I've copied his excellent strat guide from 2015 below. 
      For more info you can also read his full tutorial here:
      https://www.netweather.tv/charts-and-data/stratosphere/tutorial
      Ed's opener from 2015/16
      As ever, the first post will become both a reference thread and basic learning thread for those wanting to understand how the stratosphere may affect the winter tropospheric pattern, so forgive me for some repeat from previous years, but it is important that those new to the stratosphere have a place that they can be directed to in order to achieve a basic grasp of the subject.
      The stratosphere is the layer of the atmosphere situated between 10km and 50km above the earth. It is situated directly above the troposphere, the first layer of the atmosphere and the layer that is directly responsible for the weather that we receive at the surface. The boundary between the stratosphere and the troposphere is known as the tropopause. The air pressure ranges from around 100hPa at the lower levels of the stratosphere to below 1hPa at the upper levels. The middle stratosphere is often considered to be around the 10-30hPa level.

      Every winter the stratosphere cools down dramatically as less solar UV radiation is absorbed by the ozone content in the stratosphere. The increasing difference in the temperature between the North Pole and the latitudes further south creates a strong vortex – the wintertime stratospheric polar vortex. The colder the polar stratosphere in relation to that at mid latitudes, the stronger this vortex becomes. The stratospheric vortex has a strong relationship with the tropospheric vortex below. A strong stratospheric vortex will lead to a strong tropospheric vortex. This relationship is interdependent; conditions in the stratosphere will influence the troposphere whilst tropospheric atmospheric and wave conditions will influence the stratospheric state.
      At the surface the strength and position of the tropospheric vortex influences the type of weather that we are likely to experience. A strong polar vortex is more likely to herald a positive AO with the resultant jet stream track bringing warmer and wet southwesterly winds. A weaker polar vortex can contribute to a negative AO with the resultant mild wet weather tracking further south and a more blocked pattern the result. A negative AO will lead to a greater chance of colder air spreading to latitudes further south such as the UK.
       AO chart

      The stratosphere is a far more stable environment then the troposphere below it.
      However, the state of the stratosphere can be influenced by numerous factors – the current solar state, the Quasi Biennial Oscillation (QBO), the ozone content and distribution and transport mechanism, the snow cover and extent indices and the ENSO state to name the most significant. These factors can influence whether large tropospheric waves that can be deflected into the stratosphere can disrupt the stratospheric polar vortex to such an extent that it feeds back into the troposphere.
      Ozone Content in the stratosphere
       Ozone is important because it absorbs UV radiation in a process that warms the stratosphere. The Ozone is formed in the tropical stratosphere and transported to the polar stratosphere by a system known as the Brewer-Dobson-Circulation (the BDC). The strength of this circulation varies from year to year and can in turn be dictated by other influences. The ozone content in the polar stratosphere has been shown to be destroyed by CFC's permeating to the stratosphere from the troposphere. The overall ozone content in the polar stratosphere will help determine the underlying polar stratospheric temperature, with higher contents of ozone leading to a warmer polar stratosphere. The ozone levels can be monitored here: 
      http://www.cpc.ncep.noaa.gov/products/stratosphere/sbuv2to/index.shtml
      One of the main influences on the stratospheric state is the QBO. This is a tropical stratospheric wind that descends in an easterly then westerly direction over a period of around 28 months. This can have a direct influence on the strength of the polar vortex in itself. The easterly (negative) phase is thought to contribute to a weakening of the stratospheric polar vortex, whilst a westerly (positive) phase is thought to increase the strength of the stratospheric vortex. However, in reality the exact timing and positioning of the QBO is not precise and the timing of the descending wave can be critical throughout the winter.
      Diagram of the descending phases of the QBO: (with thanks from http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/qbo/index.html )

      The QBO has been shown to influence the strength of the BDC, depending upon what phase it is in. The tropical upward momentum of ozone is stronger in the eQBO , whereas in the wQBO ozone transport is stronger into the lower mid latitudes, so less ozone will enter the upper tropical stratosphere to be transported to the polar stratosphere as can be seen in the following diagram.

      http://www.atmos-chem-phys.net/13/4563/2013/acp-13-4563-2013.pdf
      However, the direction of the QBO when combined with the level of solar flux has also been shown to influence the BDC. When the QBO is in a west phase during solar maximum there are more warming events in the stratosphere, as there is also during an easterly phase QBO during solar minimum, so the strength of the BDC is also affected by this – also known as the Holton Tan effect .
      http://strat-www.met.fu-berlin.de/labitzke/moreqbo/MZ-Labitzke-et-al-2006.pdf
      http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50424/abstract  
      http://onlinelibrary.wiley.com/doi/10.1002/2013JD021352/abstract
      The QBO is measured at 30 hPa and has entered a westerly phase for this winter. As mentioned warming events are more likely during solar maximum when in this westerly phase – with the solar flux below 110 units. Currently, we have just experienced a weak solar maximum and the solar flux heading into winter is still around this mark. This doesn’t rule out warming events, but they will not be as likely – perhaps if the solar flux surges then the chance will increase.
      Latest solar flux F10.7cm:

      http://www.swpc.noaa.gov/products/solar-cycle-progression
      Sudden Stratospheric Warmings:
      One warming event that can occur in the stratospheric winter is a Sudden Stratospheric Warming (SSW) or also known as a Major Midwinter Warming (MMW). This, as the name suggests is a rather dramatic event. Normally the polar night jet at the boundary of the polar vortex demarcates the boundary between warmer mid latitude and colder polar stratospheric air (and ozone levels) and this is very difficult to penetrate. SSWs can be caused by large-scale planetary tropospheric (Rossby) waves being deflected up into the stratosphere and towards the North Pole, often after a strong mountain torque event. These waves can introduce warmer temperatures into the polar stratosphere which can seriously disrupt the stratospheric vortex, leading to a slowing or even reversal of the vortex.
      Any SSW will be triggered by the preceding tropospheric pattern - in fact the preceding troposheric pattern is important in disturbing the stratospheric vortex even without creating a SSW.  Consider a tropospheric pattern where the flow is very zonal - rather like the positive AO phase in the diagram above. There has to be a mechanism to achieve a more negative AO or meridional pattern from this scenario and there is but it is not straightforward.  It just doesn't occur without some type of driving mechanism. Yes, we need to look at the stratosphere - but if the stratosphere is already cold and a strong polar vortex established, then we need to look back into the troposphere. In some years the stratosphere will be more receptive to tropospheric interactions than others but we will still need a kickstart from the troposphere to feedback into the stratosphere. This kickstart will often come from the tropics in the form of pulses and patterns of convection. These can help determine the position and amplitude of the long wave undulations Rossby waves - that are formed at the barrier between the tropospheric polar and Ferrel cells. The exact positioning of the Rossby waves will be influenced by (amongst other things) the pulses of tropical convection, such as the phase of the Madden Jullian Oscillation and the background ENSO state and that is why we monitor that so closely. These waves will interact with land masses and mountain ranges which can absorb or deflect the Rossby waves disrupting the wave pattern further - and this interaction and feedback between the tropical and polar systems is the basis of how the Global Wind Oscillation influences the global patterns.
      If the deflection of the Rossby Wave then a wave breaking event occurs – similar to a wave breaking on a beach – except this time the break is of atmospheric air masses. Rossby wave breaks that are directed poleward can have a greater influence on the stratosphere. The Rossby wave breaks in the troposphere can be demonstrated by this diagram below –
      RWB diagram:

      https://www.jstage.jst.go.jp/article/jmsj/86/5/86_5_613/_pdf
       This occurs a number of times during a typical winter and is more pronounced in the Northern Hemisphere due to the greater land mass area. Most wave deflections into the stratosphere do change the stratospheric vortex flow pattern - this will be greater if the stratosphere is more receptive to these wave breaks (and if they are substantial enough, then a SSW can occur). The change in the stratospheric flow pattern can then start to feedback into the troposphere - changing the zonal flow pattern into something with more undulations and perhaps ultimately to a very meridional flow pattern especially if a SSW occurs - but not always. If the wave breaking occurs in one place then we see a wave 1 type displacement of the stratospheric vortex, and if the wave breaking occurs in two places at once then we will see a wave 2 type disturbance of the vortex which could ultimately squeeze the vortex on half and split it – and if these are strong enough then we would see a displacement SSW and split SSW respectively. The SSW is defined by a reversal of mean zonal mean winds from westerly to easterly at 60ºN and 10hPa. This definition is under review as there have been suggestions that other warmings of the stratosphere that cause severe disruption to the vortex could and should be included. http://birner.atmos.colostate.edu/papers/Butleretal_BAMS2014_submit.pdf
      A demonstration of the late January 2009 SSW that was witnessed in the first strat thread has been brilliantly formulated by Andrej (recretos) and can be seen below:
       
      The effects of a SSW can be transmitted into the troposphere as the downward propagation of the SSW occurs and this can have a number of consequences. There is a higher incidence of northern blocking after SSW’s but we are all aware that not every SSW leads to northern blocking. Any northern blocking can lead to cold air from the tropospheric Arctic flooding south and colder conditions to latitudes further south can ensue. There is often thought to be a time lag between a SSW and northern blocking from any downward propagation of negative mean zonal winds from the stratosphere. This has been quoted as up to 6 weeks though it can be a lot quicker if the polar vortex is ripped in two following a split SSW. A recent paper has shown how the modelling of SSW and strong vortex conditions have been modelled over a 4 week period. This has shown that there is an increase in accuracy following weak or strong vortex events – though the one area that the ECM overestimates blocking events following an SSW at week 4 is over Northwestern Eurasia.
      http://iopscience.iop.org/article/10.1088/1748-9326/10/10/104007
      One noticeable aspect of the recent previous winters is how the stratosphere has been susceptible to wave breaking from the troposphere through the lower reaches of the polar stratosphere - not over the top as seen in the SSWs. This has led to periods of sustained tropospheric high latitude blocking and repeated lower disruption of the stratospheric polar vortex. This has coincided with a warmer stratosphere where the mean zonal winds have been reduced and has led to some of the most potent winter spells witnessed in recent years.
      We have also seen in recent years following Cohen's work the importance of the rate of Eurasian snow gain and coverage during October at latitudes below 60ºN. If this is above average then there is enhanced feedback from the troposphere into the stratosphere through the Rossby wave breaking pattern described above and diagrammatically below.
      Six stage Cohen Process:

      The effect of warming of the Arctic ocean leading to colder continents with anomalous wave activity penetrating the stratosphere has also been postulated
      http://www.tos.org/oceanography/archive/26-4_cohen.pdf
      As ever, I will supply links to various stratospheric websites were forecasts and data can be retrieved and hope for another fascinating year of monitoring the stratosphere.
      GFS: http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/
      ECM/Berlin Site: http://www.geo.fu-berlin.de/en/met/ag/strat/produkte/winterdiagnostics/index.html  
      Netweather: https://www.netweather.tv/charts-and-data/stratosphere
      Instant weather maps: http://www.instantweathermaps.com/GFS-php/strat.php
       NASA Merra site: http://acdb-ext.gsfc.nasa.gov/Data_services/met/ann_data.html
      Previous stratosphere monitoring threads:
      2016/17 https://www.netweather.tv/forum/topic/86485-stratosphere-temperature-watch-201617/
      2015/16 https://www.netweather.tv/forum/topic/84231-stratosphere-temperature-watch-20152016/
      2014/2015 https://forum.netweather.tv/topic/81567-stratosphere-temperature-watch-20142015/
      2013/2014 https://forum.netweather.tv/topic/78161-stratosphere-temperature-watch-20132014/
      2012/2013 https://forum.netweather.tv/topic/74587-stratosphere-temperature-watch-20122013/
      2011/2012 https://forum.netweather.tv/topic/71340-stratosphere-temperature-watch-20112012/
      2010/2012 https://forum.netweather.tv/topic/64621-stratosphere-temperature-watch/?hl=%20stratosphere%20%20temperature%20%20watch
      2009/2010 https://forum.netweather.tv/topic/57364-stratosphere-temperature-watch/
      2008/2009 https://forum.netweather.tv/topic/50299-stratosphere-temperature-watch/
    • By Paul
      A new thread, for posting and discussing tweets about the forecast models currently. Please only post tweets in this thread, not the main model or banter threads. 
      The reason for this change is that a tweets are, by their nature brief, which in turn can leave them open to multiple interpretations, which in the fast-moving model thread can mean a lot of reaction to misinterpretations which pulls the whole thing off on a tangent.
    • By Paul
      To cater for those who prefer a slower pace, more in depth discussion around the models, we've decided to setup this new thread. So if the drama and excitement of the main model thread isn't quite your thing, then please feel free to post into this thread. 
      You're also welcome to cross-post - so if you've made a longer post in the model thread, you can copy it into here, and vice-versa. 
    • By Paul
      A fresh new model thread as we start a cold spell. 
      We've made a change this morning, and that is to start a new model tweet thread. The reason for this change is that a tweets are, by their nature brief, which in turn can leave them open to multiple interpretations, which in the fast-moving model thread can mean a lot of reaction to misinterpretations which pulls the whole thing off on a tangent. So please don't post tweets into this thread - keep them to the new thread. 
      We've also started another new thread this week, and that's the In depth (chilled out) model thread, for those who want a slower paced look at the models. Cross-posting to this and the new thread is fine, the best route to doing this is to use the multiquote button (the + sign bottom left of the post), then when you go to post your new post, you'll see a button bottom right allowing you to quote the post & copy it over. 
      If you're unsure where to find the models, head over to the Netweather Charts and Data homepage, where you'll have access to all the main ones - including our in house NetWx models, the SR hires version is particularly handy when it comes to forecasting snow showers at shorter range. 
      As ever, please keep this thread to model discussion only - and that does mean actually discussing the output, not just moaning about it. If you want to moan, ramp, or even moan about ramps, please head over to the model banter thread:
       
  • Recently Browsing   0 members

    No registered users viewing this page.

×