Jump to content
Cold?
Local
Radar
Snow?

Stratosphere Temperature Watch 2012/2013


Recommended Posts

Posted
  • Location: falkirk, scotland, 16.505m, 54.151ft above sea level
  • Weather Preferences: dry sunny average summers and really cold snowy winters
  • Location: falkirk, scotland, 16.505m, 54.151ft above sea level

    post-18233-0-23980700-1360949656_thumb.g

    i am still learning about the strat but i have a small question as i have been hearing all winter that we need to see propagation to see the effects of a SSW in the trop could someone plz tell me what level we need to see the temps rising for us to see trop effects and in the chart i have posted where i have put the arrows do we need to see the temp rise pass that green line before it can be classed as a SSW at that level and is it after this point we see the effects

    Link to post
    Share on other sites
    Spotted a post you think may be an issue? Please help the team by reporting it.
    • Replies 2.5k
    • Created
    • Last Reply

    Top Posters In This Topic

    Top Posters In This Topic

    Popular Posts

    Steve whilst I agree to a certain extent, more especially with regards to the difficulty in forecasting exact placement of tropospheric synoptics (particularly with regard to the UK in the overall sch

    Posted Images

    post-18233-0-23980700-1360949656_thumb.g

    i am still learning about the strat but i have a small question as i have been hearing all winter that we need to see propagation to see the effects of a SSW in the trop could someone plz tell me what level we need to see the temps rising for us to see trop effects and in the chart i have posted where i have put the arrows do we need to see the temp rise pass that green line before it can be classed as a SSW at that level and is it after this point we see the effects

    The first arrow points to the final warming of the stratosphere that winter, when the vortex dissipates for the summer half of the year.

    The second arrow is associated with an SSW last January and yes it is after this time where typically we look for most effects. The green line is just the mean temperature, so crossing this doesn't necessarily mean it is an SSW, the most commonly used indicator is looking for reversed zonal winds at the 10mb level at 60°N.

    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

    Posted Image

    Posted Image

    Link to post
    Share on other sites
    Posted
  • Location: st albans
  • Location: st albans

    getting late in the season now but renewed wave 1 activity coming into the upper strat in a weeks time and a small rise in temps aswell. both ecm and gfs are showing the strat vortex displacing towards ne scandi/nw siberia in week 2 which sits well alongside the trop output.

    Link to post
    Share on other sites

    getting late in the season now but renewed wave 1 activity coming into the upper strat in a weeks time and a small rise in temps aswell. both ecm and gfs are showing the strat vortex displacing towards ne scandi/nw siberia in week 2 which sits well alongside the trop output.

    The 10mb against the trop output maybe, but the higher levels are being shifted to Greenland while below the vortex lingers over central northern Siberia. Ridging over our neck of the woods from 20mb downwards is generally replaced with a trough at the start of March.

    Edited by Interitus
    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

    http://acdb-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra/t90n_10_2012_merra.pdf

    Can anybody explain whether we should expect the stratosphere to fall into line given that we are close to record lows at 10hpa or whether the troposphere will continue to override this signal.

    Link to post
    Share on other sites

    Well, I think that is what we are going to find out, once we put the composites into practical use. Posted Image

    I am already doing the ENSO filtering, and February is now 100% completed, and ready for coding the data files for upload.

    And here is the finished Phase 8 (0.5) for February, in ENSO neutral phase, and with AMP>1

    Posted Image

    P.s.: The MEI dataset goes till December 2012, so that is why I also decided to use the dataset for GWO Jan 1970-Dec 2012. So no 2013 dates included.

    EDIT:

    Just for fun, I did the same thing as yesterday. Taking the Phase 8 (0.5) which is now corrected with Neutral ENSO and AMP>1, and I plotted 10mb anomaly, with a 12-day negative lag applied. So before the onset of the phase. And I added the anomaly of this year for a similar period, around 12 days before the onset of the phase 8. Of course the anomaly of this year is much greater in the reanalysis, because it contains much less days than the GWO phase composite. Now I am not really trying to make a specific point here. Only trying to say that it should be quite interesting to experiment with all this data. Posted Image

    Posted ImagePosted Image

    This is incredible and I'm sure many will thank you for taking the time to do this.

    Keep us updated

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

    Thanks weatherjunkie. :)

    To be honest, I was really short on time recently, so for the past two weeks, I haven't even opened the project files, let alone edit them. Next week I will have some more spare time, and I will try to make as much progress as I can.

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Catchgate, Durham,705ft asl
  • Location: Catchgate, Durham,705ft asl

    http://acdb-ext.gsfc..._2012_merra.pdf

    Can anybody explain whether we should expect the stratosphere to fall into line given that we are close to record lows at 10hpa or whether the troposphere will continue to override this signal.

    Those sorts of temperatures suggest a re-strengthening of the polar vortex as we head into

    early spring which sets the alarm bells ringing with regard to our summer prospects.

    • Like 1
    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.

    Why is that?

    Yes, I don't think it will have too much affect on summer prospects. The FW reversal may just be a little later this year which ironically I think could help Spring prospects with a more favourable positioning of mid latitude highs. Will start monitoring in a bit more detail again to see whether this occurs.
    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

    Hi Chiono,

    What does FW mean please?

    Thanks

    S

    Final warming.

    • Like 1
    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 Chiono,

    What does FW mean please?

    Thanks

    S

    Yes, the final warming occurs every spring when the polar stratosphere has warmed to such an extent, compared to the mid latitude stratosphere, that the temperature gradient can no longer create a polar vortex (stratospherically). At this point the polar westerlies that have dominated during the polar winter, reverse to polar easterlies, which are characteristic of the polar stratospheric summer (One summer long slow stratospheric warming.) We then have to wait until Autumn for the stratosphere to cool again and the vortex rebuilds. The stratosphere conditions are predictable and settled during the summer months and therefore have a more predictable tropospheric impact (can be considered a constant) when compared to the large temperature changes that can occur during stratospheric winter that have larger tropospheric impacts.

    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: UK/ EU resident in Almeirim de Fazendas, Portugal
  • Location: UK/ EU resident in Almeirim de Fazendas, Portugal

    Those sorts of temperatures suggest a re-strengthening of the polar vortex as we head into

    early spring which sets the alarm bells ringing with regard to our summer prospects.

    Seems to be a pattern doesn't it in quite a few recent years. I wonder if some chilly March weather will then change quickly to some warm Spring weather such as we have seen in recent years before the final warming in the stratosphere kicks in and sends the jet stream south once again?

    The differences though with last year are that the QBO is due to switch positive and this will be less conduisive to blocking over the pole come the summer- also the timetable seems to be later than this time last year. We were already heading towards that very mild March by this stage. It could be that we will see any such change this year maybe a month or so later. But time as always will tellPosted Image

    Edited by Tamara Road
    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Ludgershall, Wiltshire
  • Location: Ludgershall, Wiltshire

    I wonder if some chilly March weather will then change quickly to some warm Spring weather such as we have seen in recent years before the final warming in the stratosphere kicks in and sends the jet stream south once again?

    Could it be a case of having a coldish March followed by a warm April, perhaps a bit like 1987? March 1987 had a CET of 4.1 and April 10.3, so an abrupt change took place there! I would imagine it wouldn't be as extreme as that this year though if we were to get a similar pattern. I'd be interested to know peoples thoughts on this?

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Catchgate, Durham,705ft asl
  • Location: Catchgate, Durham,705ft asl

    Seems to be a pattern doesn't it in quite a few recent years. I wonder if some chilly March weather will then change quickly to some warm Spring weather such as we have seen in recent years before the final warming in the stratosphere kicks in and sends the jet stream south once again?

    The differences though with last year are that the QBO is due to switch positive and this will be less conduisive to blocking over the pole come the summer- also the timetable seems to be later than this time last year. We were already heading towards that very mild March by this stage. It could be that we will see any such change this year maybe a month or so later. But time as always will tellPosted Image

    That sums it up perfectly!

    The similarities between the 10 hpa temperatures for this winter and last winter are quite striking

    with both having strong warming's in January followed by a plunge to much below average in early

    spring which seems to create a "late vortex".

    Shown here on the graph which summer blizzard posted.

    acdb-ext.gsfc.nasa.gov/Data_services/met/metdata/annual/merra/t90n_10_2012_merra.pdf

    Obviously very early days looking at summer prospects,so hopefully things

    can fall into place differently to last year!

    • Like 1
    Link to post
    Share on other sites
    Posted
  • Location: Barnet/south Herts border 130m asl
  • Weather Preferences: snow, thunderstorms & all extreme weather
  • Location: Barnet/south Herts border 130m asl

    a big thanks to all those who have contributed to this thread this season - the usual suspects and the newcomers too, gets better every year :)

    Link to post
    Share on other sites
    Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

    Yes, I don't think it will have too much affect on summer prospects. The FW reversal may just be a little later this year which ironically I think could help Spring prospects with a more favourable positioning of mid latitude highs. Will start monitoring in a bit more detail again to see whether this occurs.

    Interestingly our current 30 hPa zonal profile (again very similar to 1969) suggests a continuation of the anomalously cold upper stratosphere well into the spring and summer with a cold banding of below average stratospheric temperatures across the tropics, which should allow for enhanced convection in the central equatorial Pacific this summer - MJO phase 8. The really eyecatching piece of analysis is for a strongly positive Antartic Oscillation at times this Austral Winter (therefore average stratospheric conditions over the Equator, therefore better chnaces of maintaining colder stratosphere over the Arctic therefore less blocking this summer).

    Edited by Glacier Point
    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: Ludgershall, Wiltshire
  • Location: Ludgershall, Wiltshire

    The really eyecatching piece of analysis is for a strongly positive Antartic Oscillation at times this Austral Winter (therefore average stratospheric conditions over the Equator, therefore better chnaces of maintaining colder stratosphere over the Arctic therefore less blocking this summer).

    So better prospects for Summer 2013 then with mid latitude blocking more likely, or have I got the wrong end of the stick?!

    Edited by Don
    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

    Interestingly our current 30 hPa zonal profile (again very similar to 1969) suggests a continuation of the anomalously cold upper stratosphere well into the spring and summer with a cold banding of below average stratospheric temperatures across the tropics, which should allow for enhanced convection in the central equatorial Pacific this summer - MJO phase 8. The really eyecatching piece of analysis is for a strongly positive Antartic Oscillation at times this Austral Winter (therefore average stratospheric conditions over the Equator, therefore better chnaces of maintaining colder stratosphere over the Arctic therefore less blocking this summer).

    When do you expect blocking to subside GP? Should we be expecting another warm April.

    • Like 1
    Link to post
    Share on other sites

    Interestingly our current 30 hPa zonal profile (again very similar to 1969) suggests a continuation of the anomalously cold upper stratosphere well into the spring and summer with a cold banding of below average stratospheric temperatures across the tropics, which should allow for enhanced convection in the central equatorial Pacific this summer

    Do you have any links regarding this, how does it enhance tropospheric convection?

    Even a cooler than average upper stratosphere has a still far higher potential temperature than the lower strat and top of the tropical troposphere. Cooling above the tropopause has been shown as a response to strengthened convection and overshooting, not a cause, there is a negative correlation between warmer SSTs and cooler lower stratosphere.

    Though stratospheric circulation and upwelling (such as SSW response) may possibly encourage overshooting into the stratosphere, likewise a possible but unclear link between QBO and hurricanes - the actual amount of overshooting is very limited from examination of potential and cloud temperatures

    The distribution of convective events into the tropopause region falls off rapidly above the average level of neutral buoyancy, which can be derived from the surface equivalent potential temperature and is approximately the 345 K potential temperature level (Folkins et al. 2000). A very small fraction of this convection reaches tropopause levels, as expected from a small proportion of locations with surface equivalent potential temperatures of 370-390 K. Very few individual locations see clouds colder than the tropopause even 3-4% of the time (Figure 3). Even in regions of the most active convection, clouds are colder than the tropopause less than 0.5% of the time (Figure 2).

    http://www.atmosp.ph..._Gettelman.html

    Link to post
    Share on other sites
    Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

    I suspect the mechanism at play here is a modification of the Walker Circulation allowing for increased (decreased) wind shear allowing for taller and more extensive thunderstorm clouds (increased divergent flow) to develop.

    Here are the analogues for 30 hPa zonal winds with a high degree of similarity for this year and rolled forward to June-July-August

    post-2478-0-66192500-1362001931_thumb.jp

    And the OLR anomalies that go with them depicting a very clear suggestion of increased TC east of the Dateline and Africa and decreased convection in the east Pacific / Central Americas.

    post-2478-0-63143500-1362001954_thumb.jp

    So better prospects for Summer 2013 then with mid latitude blocking more likely, or have I got the wrong end of the stick?!

    at this stage, probably better than 2010-2012.

    Edited by Glacier Point
    • Like 5
    Link to post
    Share on other sites
    Posted
  • Location: Chelmsford
  • Weather Preferences: Hot and dry summers with big thunderstorms.
  • Location: Chelmsford

    I suspect the mechanism at play here is a modification of the Walker Circulation allowing for increased (decreased) wind shear allowing for taller and more extensive thunderstorm clouds (increased divergent flow) to develop.

    Here are the analogues for 30 hPa zonal winds with a high degree of similarity for this year and rolled forward to June-July-August

    post-2478-0-66192500-1362001931_thumb.jp

    And the OLR anomalies that go with them depicting a very clear suggestion of increased TC east of the Dateline and Africa and decreased convection in the east Pacific / Central Americas.

    post-2478-0-63143500-1362001954_thumb.jp

    at this stage, probably better than 2010-2012.

    PDO is at last looking like it may edge towards neutral/positive - first summer for a good while! A positive QBO is also good for summer weather, not sure what a -MEI would bring though.

    Analogues show some decent years there GP, 2006 is probably the outstanding one however some poorer ones there!

    Surely a more positive PDO would be a big step up GP? What are your thoughts for Spring - a more el nino spring would be wetter? Whilst a perfect spring would be one with low angular momentum and a weak MJO however for a decent summer, June would need to see a more active MJO and stronger angular momentum?

    Edited by Alex
    • Like 1
    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.

    Evening all and time for a Spring update.

    To recap- this winter we have seen a dramatic cooling of the polar stratosphere during autumn leading into winter. This was then followed by a SSW in early January that led to the tropospheric staged downwellings and cold spells during January and February. The stratospheric vortex has since regained strength whilst the upper stratosphere cooled.

    The temperature profile is now demonstrated quite nicely by the full atmospheric temperature anomaly profile for the first two months of the year:

    post-4523-0-00935900-1362171729_thumb.gi

    The three main downwelling phases can be seen below and correlate pretty well with the colder NH episodes to mid latitudes (even the UK)

    post-4523-0-75767600-1362172057_thumb.gi

    All in all this correlates pretty well with what was suggested prior to winter stratosphere wise and correlates well with a downwelling SSW event.

    I would tend to say that the SSW was an early winter event compared to recent years and this allows the reformed vortex to be subject to late winter wave activity. And this seems to be what has occurred. There is evidence that the polar vortex has been subject to strong wave 1 activity the last few days:

    post-4523-0-27383700-1362172364_thumb.gi

    This has again led to another warming of the mid to upper stratosphere (not another SSW) which in turn will lead to a tropospheric impact. How strong this impact will be remains to be seen, however, it is no surprise to see the west based -ve NAO from the displaced vortex and the mid March super cold ensemble runs that have therefore resulted.

    My initial thoughts that we could see mid latitudes highs predominate will be compromised somewhat by this increase in wave 1 activity.

    So looking at the 100 hPa forecasts we see the ECM and GFS inconclusive with the actual vortex positioning. The only constant is that energy will be transferred to the Siberian segment with a split vortex a distinct possibility.

    post-4523-0-71245300-1362172964_thumb.pn

    The ECM hints at the same.

    Worth watching - but with the added warning that we could be left in the milder zone whilst eastern europe freezes during early Spring due to the positioning of the split.

    • Like 6
    Link to post
    Share on other sites

    Create an account or sign in to comment

    You need to be a member in order to leave a comment

    Create an account

    Sign up for a new account in our community. It's easy!

    Register a new account

    Sign in

    Already have an account? Sign in here.

    Sign In Now
    ×
    ×
    • Create New...