Jump to content
Cold?
Local
Radar
Snow?

Stratosphere Temperature Watch 2015/2016


Recommended Posts

Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Welcome to the latest stratospheric temperature watch thread.

     

    A bit later this year with a new thread – but better late than never! It is now the 7th winter stratospheric temperature watch thread on netweather, and how much have we learnt in the past years!

     

    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.

     

    post-4523-0-18608100-1445108495_thumb.jp

     

    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

     

    post-4523-0-98399500-1445108530_thumb.jp

     

    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 )

     

    post-4523-0-81160900-1445109156_thumb.jp

     

     

    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.

     

    post-4523-0-84025300-1445109455_thumb.pn

     

    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:

     

    post-4523-0-07912200-1445109707_thumb.gi

     

    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:

     

    post-4523-0-89616500-1445109931_thumb.pn

     

    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:

     

    post-4523-0-05125800-1445110713_thumb.pn

     

     

    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

     

     

    Last year we saw a large snow gain but unfortunately tropospheric atmospheric patterns prevented the full potential of these being unleashed on the stratosphere – hence no SSW, but this winter could be different, but we will have to wait until the end of October.

     

     

     ENSO Influences

     

    One of the main influences in the global atmospheric state this winter will be the upcoming El Nino, and that is forecast to be the strongest since 1997. Studies have shown that SSW’s are more likely during strong ENSO events ( http://www.columbia.edu/~lmp/paps/butler+polvani-GRL-2011.pdf) 

     but also that there is a particular pattern of upward propagating waves. During El Nino events wave formation is suppressed over the Indian Ocean Basin whilst it is enhanced over the Pacific Ocean

     

    http://link.springer.com/article/10.1007%2Fs00382-015-2797-5

     

    The ENSO pathway taken may be all critical this year as can be demonstrated by this paper  http://www.columbia.edu/~lmp/paps/butler+polvani+deser-ERL-2014.pdf

     

    This can lead us to suggest that a rather distinctive wave 1 pattern is likely this winter with the trigger zone likely to be over the north Pacific in the form of a quasi stationary enhanced wave 1 – a traditional Aleutian low SSW trigger pattern is suggested by Garfinkel et al ( http://www.columbia.edu/~lmp/paps/garfinkel+etal-JGR-2012.pdf ) and this should be expected at some point this winter.

     

     post-4523-0-09272000-1445111934_thumb.pn

     

    post-4523-0-79972200-1445111955_thumb.pn

     

     

     

    The reported incidence of SSW in EL Nino years is roughly around 60%  - which is more than ENSO neutral years.  A big question remains however, whether the ENSO wave 1 pattern will override the negative HT effect that the wQBO with the reducing solar ouput link brings. And even if it does, and we do achieve a displacement SSW, the next question is how will this affect the Atlantic sector of the Northern Hemisphere? My suspicion is that even if we do achieve a SSW this winter it will be in the second half, and also any subsequent blocking may not be quite right for the UK and, that if we were to achieve a –ve NAO, any block will be nearer Canada than Iceland, leaving the Atlantic door ajar.  It is still too early this winter to be making any definitive forecasts – the next 6 weeks are very important stratospherically, determining in what vein winter will start. Already we are seeing a forecast of weak wave activity disrupting the growing vortex and it will be interesting to see if this is repeated during November.

     

    And it will be especially interesting to see what occurs in November and what is forecast for December before winter starts because typical strong El nino wQBO stratospheric composite analogues tell an opposite story. They suggest that the stratospheric vortex will be disrupted and weaker early in the winter before gaining in strength by February.

     

    December:

     

    post-4523-0-29048900-1445114859_thumb.pn

     

    January

     

    post-4523-0-49007100-1445114945_thumb.pn

     

    February

     

    post-4523-0-51753800-1445114952_thumb.pn

     

    The mean zonal winds are already forecast to be below average so perhaps an early disrupted vortex is more likely this year!

     

    post-4523-0-19666800-1445115247_thumb.pn

     

    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.

     

     

     

    GFShttp://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: http://www.netweather.tv/index.cgi?action=stratosphere;sess=75784a98eafe97c5977e66aa65ae7d28

     

    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:

     

    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/

    Link to post
    Share on other sites
    Spotted a post you think may be an issue? Please help the team by reporting it.
    • Replies 1.2k
    • Created
    • Last Reply
    Posted
  • Location: Lincolnshire - 15m asl
  • Weather Preferences: Frost and snow. A quiet autumn day is also good.
  • Location: Lincolnshire - 15m asl

    You sound cautiously pessimistic this year Chio - but I'll draw some crumbs of comfort from the suggestion of a weak vortex early on and then a potential SSW later in the season that MIGHT bring more blocking. Enough to make sure that this is the best thread once again of the winter months... and maybe the atlantic cold pool can affect the jet enough to aid in the disruption of the atlantic weathertrain...

    Link to post
    Share on other sites
    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    You sound cautiously pessimistic this year Chio - but I'll draw some crumbs of comfort from the suggestion of a weak vortex early on and then a potential SSW later in the season that MIGHT bring more blocking. Enough to make sure that this is the best thread once again of the winter months... and maybe the atlantic cold pool can affect the jet enough to aid in the disruption of the atlantic weathertrain...

    I think cautiously pessimistic at this point is a fair assessment. But I am not ruling out any surprises - especially early winter before the vortex cranks up. There are slightly conflicting signals which means that a straightforward El Nino winter forecast is anything but that!

    Link to post
    Share on other sites
    Posted
  • Location: @scotlandwx
  • Weather Preferences: Crystal Clear High Pressure & Blue Skies
  • Location: @scotlandwx

    I think cautiously pessimistic at this point is a fair assessment. But I am not ruling out any surprises - especially early winter before the vortex cranks up. There are slightly conflicting signals which means that a straightforward El Nino winter forecast is anything but that!

     Not providing odds of any nature

     

    This is an superb dissection of an atmospheric mode that was within last 7 years non existent. Vortex wins.

     

    Any forecasts you see excluding the wintertime variations of the vortex you know will be wrong ( that includes Nino analogs and SSTs). Hint

     

    :)

    Link to post
    Share on other sites
    Posted
  • Location: Netherlands
  • Location: Netherlands

    Hi Chio, first of all many thanks for this wonderfull summary! I will give it some attention to the weather geeks in the Low Countries.

     

    Two small things. In the first selection of years (december chart) I noticed 1962. I think you mean 1982?

     

    And in Januar 1998 in stead of 1996?

    Link to post
    Share on other sites
    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    http://www.terradaily.com/reports/Forecasters_look_higher_for_clues_to_winter_weather_999.html

     

    According to this publication, stratospheric forecasting can double the accuracy of forecasts for 2-4 weeks ahead.

     

     

    Fantastic summary there as usual Chiono. I've looked at 500 mb height composites for February under W QBO and a strong El Nino and found a signal for anomalously high pressure west of the UK with a trough over Scandinavia... but no signal for the high latitudes either way, despite that vicious looking 10 mb composite. Delays working down to the troposphere perhaps?.

     

    The high heights west of the UK appear to be in large part a consequence of the Pacific jet barreling into the Atlantic from around Florida to The Azores Isles.

     

     

    Having said that, there's an interesting progression when looking at 10 mb, 30 mb and 100 mb levels for February. I've used 1958 instead of 2003 (i.e. only strong El Nino + W QBO winters) but the theme is broadly similar:

     

    FebStrat_10_30_100mb_GPH.PNG

     

    Increasing signs of a ridge over Greenland, but more west-based in terms of the -ve NAO... which is in line with your concerns but could be adding to the strength of positive height anomalies west of the UK at the 500 mb level (which are around +10 dam).

    Link to post
    Share on other sites
    Posted
  • Location: Netherlands
  • Location: Netherlands

    http://onlinelibrary.wiley.com/doi/10.1002/2013JD021343/abstract

    -> we are in a declining phase of the solar cycle.

    Using 13 solar cycles (1869–2009), we study winter surface temperatures and North Atlantic oscillation (NAO) during four different phases of the sunspot cycle: minimum, ascending, maximum, and declining phase. We find significant differences in the temperature patterns between the four cycle phases, which indicates a solar cycle modulation of winter surface temperatures. However, the clearest pattern of the temperature anomalies is not found during sunspot maximum or minimum, but during the declining phase, when the temperature pattern closely resembles the pattern found during positive NAO. Moreover, we find the same pattern during the low sunspot activity cycles of 100 years ago, suggesting that the pattern is largely independent of the overall level of solar activity.

     

    So the pattern described by Chio could be the right one.

    Link to post
    Share on other sites
    Posted
  • Location: Northwich south cheshire SACRA MEMBER 16/122
  • Weather Preferences: snowy winters,warm summers and Storms
  • Location: Northwich south cheshire SACRA MEMBER 16/122

    Thanks Chio for such a superb opening Post, started to follow

    And try to understand this thread last year, and with such

    Excellent posts from the knowledgeable posters in this thread

    I am starting to understand (although still a long way to go) and

    Learn this subject of the weather, thanks again and keep up

    The good work.

    C.S

    Link to post
    Share on other sites
    Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset

    Ah.. The first proper sign of winter approaching, not the geese flying overhead, leaves falling from trees but Chiono opening the Strat thread! The second sign naturally is the Berlin strat charts fully opening for business on the 1st of November :-)

    Fantastic summary, as always, Chiono, probably cementing most people's thoughts, which is much less (on occasion, wild!) optimism aka 14/15's E-QBO / high snow cover pre-winter frenzy and a more tempered W-QBO / declining solar cycle / dice generally less loaded on paper viewpoint. But as always a strong EL Nino will be the wild card here, plenty up for grabs. Sustained Wave1 activity looks a likely outcome and as we know displacement can be good for us but more often than not a thorn in our side as cold plunges down through Eastern Europe or away to our west down through the Mid Atlantic, possibly the form horse this time around. But better have wave activity than not, especially early winter as the vortex will be winding itself up and being fuelled from the W-QBO as well no doubt.

    Less proper sustained blocking but with a bit of luck thrown in, I can see a couple of real cold snowy spells coming about in the way 1981 produced. Now that sounds like wild optimism! :-)

    Link to post
    Share on other sites
    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Hi Chio, first of all many thanks for this wonderfull summary! I will give it some attention to the weather geeks in the Low Countries.

     

    Two small things. In the first selection of years (december chart) I noticed 1962. I think you mean 1982?

     

    And in Januar 1998 in stead of 1996?

    The reanalysis data isn't that clear. I used yr's 82/83, 87/88, 97/98, 02/03 - perhaps I should have included 57/58 as well and if I had have done then DEC and Jan would have been the same, but Feb would have had a completely different look to it because of the Feb 58 SSW.

     

    post-4523-0-13764900-1445171212_thumb.pn

    Link to post
    Share on other sites
    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    While not Nino's, those strat charts do remind one a little of winters 09 and 11. They were both +QBO winters.

    Link to post
    Share on other sites
    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    http://www.terradaily.com/reports/Forecasters_look_higher_for_clues_to_winter_weather_999.html

     

    According to this publication, stratospheric forecasting can double the accuracy of forecasts for 2-4 weeks ahead.

     

     

    Fantastic summary there as usual Chiono. I've looked at 500 mb height composites for February under W QBO and a strong El Nino and found a signal for anomalously high pressure west of the UK with a trough over Scandinavia... but no signal for the high latitudes either way, despite that vicious looking 10 mb composite. Delays working down to the troposphere perhaps?.

     

    The high heights west of the UK appear to be in large part a consequence of the Pacific jet barreling into the Atlantic from around Florida to The Azores Isles.

     

     

    Having said that, there's an interesting progression when looking at 10 mb, 30 mb and 100 mb levels for February. I've used 1958 instead of 2003 (i.e. only strong El Nino + W QBO winters) but the theme is broadly similar:

     

    FebStrat_10_30_100mb_GPH.PNG

     

    Increasing signs of a ridge over Greenland, but more west-based in terms of the -ve NAO... which is in line with your concerns but could be adding to the strength of positive height anomalies west of the UK at the 500 mb level (which are around +10 dam).

    Hi thanks singularity. The publication that you quote is based from the paper linked to by Tripathia and Charlton et al in the first post (http://iopscience.iop.org/article/10.1088/1748-9326/10/10/104007 ) and also in the last thread - the forecasting by the ECM improves in both Vortex Intensification periods and SSW's.

     

    We can see in VI strong events that if anything over the UK the increased temperature anomaly observed is slightly underestimated by the model through weeks 1-4 but overall the accuracy if very good

     

    post-4523-0-39699500-1445177063_thumb.pn

     

    Whereas typically in weak vortex events the observed overall model accuracy is again improved compared to average but week 4 there is an overestimation of negative anomalies over northern Eurasia - but fairly accurate for the UK

     

    post-4523-0-05923800-1445177435_thumb.pn

     

    Your findings regarding anomalies towards the troposphere are accurate and with a 'ridgy' Atlantic there may be periods where this exteneds towards us leaving benign 'warm' high pressure episodes this winter.

    Link to post
    Share on other sites
    Posted
  • Location: Burton-on-Trent
  • Location: Burton-on-Trent

    I thought a strong El Nino typically brings a mild first half of winter and cooler 2nd half. Interesting that the analogues are going for the opposite. So many mixed signals this year.

    Link to post
    Share on other sites
    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    Hi thanks singularity. The publication that you quote is based from the paper linked to by Tripathia and Charlton et al in the first post (http://iopscience.iop.org/article/10.1088/1748-9326/10/10/104007 ) and also in the last thread - the forecasting by the ECM improves in both Vortex Intensification periods and SSW's.

     

    We can see in VI strong events that if anything over the UK the increased temperature anomaly observed is slightly underestimated by the model through weeks 1-4 but overall the accuracy if very good

     

    attachicon.gifScreen Shot 2015-10-18 at 14.56.25.png

     

    Whereas typically in weak vortex events the observed overall model accuracy is again improved compared to average but week 4 there is an overestimation of negative anomalies over northern Eurasia - but fairly accurate for the UK

     

    attachicon.gifScreen Shot 2015-10-18 at 14.56.59.png

     

    Your findings regarding anomalies towards the troposphere are accurate and with a 'ridgy' Atlantic there may be periods where this exteneds towards us leaving benign 'warm' high pressure episodes this winter.

     

    You're very welcome  :hi:

     

    Taking the two very strong El Nino events from the past half-century in isolation (82/83 and 97/98) does produce 500 mb anomalies that feature a band of positive height anomalies extending right across the North Atlantic and just about into the UK. Given how the surface patterns relate to this, I am keen to make sure I have other things to occupy my mind in the face of 'limpet highs' sat in undesirable locations. Let alone combinations of that with high pressure over Europe which seems likely to happen at times given how the extended Pacific jet displaces the Azores High to the east (or so it appears from those analogue years).

    Link to post
    Share on other sites
    Posted
  • Location: Slovenia, Central Europe 1050m ASL
  • Location: Slovenia, Central Europe 1050m ASL

    Congrats on a new season and a great new intro post! :)

     

    I have nothing major to share, just some forecast anomalies, showing the GEFS and GFS going for a bit less organised vortex going into November, as expected.

     

    geopotentialheightisobar.png geopotentialheightisobar.png

     

    temperatureisobaric-in-1.png temperatureisobaricens-i.png temperatureisobaricunwei.png

     

    The zonal wind zonal mean forecast from GFS does show a less organised vorex, also compared to this time last year. Of course its just a forecast. 

     

    u-componentofwindisobari.png u-componentofwindisobari.png

    Link to post
    Share on other sites
    Posted
  • Location: Woodham Walter Essex,between Danbury and Maldon 42 m asl
  • Location: Woodham Walter Essex,between Danbury and Maldon 42 m asl

    Sorry guys, I am looking for the archived first Strat thread or the earliest one available. Can't seem to find it, although I am on a phone - which probably doesn't help- can anyone link it for me please ?

    Link to post
    Share on other sites
    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    All the previous strat threads are linked to in the first post....

    Link to post
    Share on other sites
    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

    Sorry guys, I am looking for the archived first Strat thread or the earliest one available. Can't seem to find it, although I am on a phone - which probably doesn't help- can anyone link it for me please ?

    Is this what you are looking for? :)https://forum.netweather.tv/topic/50299-stratosphere-temperature-watch/

    You should have seen it rooted at the bottom of the post.

    Edit: it is great to see this thread up and running but I'll remain as bystander it is quite a complicated subject.

    Link to post
    Share on other sites
    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.

    Top quality intro, as always. :good:

     

    I had posted the sessions for the international conference on sun -climate relations in the climate thread but there was a lot of interesting new research (particularly on Wednesday)  that relates to the stratosphere.

     

    Conference topics with abstracts.

     

    http://scc.geomar.de/frontend/index.php?page_id=506&v=List&do=0&day=121

    Link to post
    Share on other sites
    Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

    Top quality intro, as always. :good:

     

    I had posted the sessions for the international conference on sun -climate relations in the climate thread but there was a lot of interesting new research (particularly on Wednesday)  that relates to the stratosphere.

     

    Conference topics with abstracts.

     

    http://scc.geomar.de/frontend/index.php?page_id=506&v=List&do=0&day=121

     

     

    Thanks Nouska - looks like some quality topics in there. Do you subscribe to the strat list?

    Link to post
    Share on other sites

    Excellent introduction

     

    It will be interesting to see how the strong Nino matches up with the +QBO. I'd place bets that the strong Nino with wave breaking events in the N. Pacific and perhaps N. Atlantic that will eventually win out but I think it will be rather difficult. As you've stated, the chances of a SSW are heightened with a Nino. Should be a fun battle. 

     

    Cheers from across the pond on another insightful thread. There is much to be learned about the troposphere-stratosphere dynamic. 

    Link to post
    Share on other sites
    Posted
  • Location: Broadmayne, West Dorset
  • Weather Preferences: Snowfall in particular but most aspects of weather, hate hot and humid.
  • Location: Broadmayne, West Dorset

    As ever Chiono a superb summary of the runners and riders in this winters weather stakes.

     

    Have followed the start thread for a few years now since the days of the late lamented Glacier Point.  it is clear that trying to make prognostications for the coming winter

    without taking into account the potential state of the vortex and strat connections is really just p*****g in the wind.

     

    Look forward to your future updates Chiono  and also posts from other knowledgable guys like Lorenzo, Recreteos etc.

     

    Thanks for all your hard work and the time you put in.

    Link to post
    Share on other sites
    Posted
  • Location: Dublin, ireland
  • Weather Preferences: Snow , thunderstorms and wind
  • Location: Dublin, ireland

    As ever Chiono a superb summary of the runners and riders in this winters weather stakes.

     

    Have followed the start thread for a few years now since the days of the late lamented Glacier Point.  it is clear that trying to make prognostications for the coming winter

    without taking into account the potential state of the vortex and strat connections is really just Tut**g in the wind.

     

    Look forward to your future updates Chiono  and also posts from other knowledgable guys like Lorenzo, Recreteos etc.

     

    Thanks for all your hard work and the time you put in.

    The late lamented GP is back with us. Happy days  :)

    Link to post
    Share on other sites

    Archived

    This topic is now archived and is closed to further replies.

    ×
    ×
    • Create New...