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Showing most liked content on 22/11/12 in all areas

  1. 13 points
    First I have to say Hello! New to this forum, and found this topic while I was searching for some stratosphere info on the web. Thank you Google. Quite a debate I must say, on a real high level. I wont interfere with your debates, so I am just going to share my thoughts occasionally. My first post post might be a bit sluggish, but I promise I will try to get in the overall flow of this topic. Things seem to be on a roll (no pun intended) against the polar vortex, or at least that's how I see it. Better defined easterlies starting to appear. Not that surprising, given the High building into the polar circle. I find it quite amazing how the ensemble mean is still keeping a 300+ anomaly on a 10-day range. Talk about ensemble consensus. Looking "cool", temperature wise. Now as it was already pointed out, it looks like the P.V. will reform after this split-up that is being almost literally thrown in our faces by the models. I don't want to speculate or anything, especially because its quite far out. But am I the only one glad to see this appearing in the models? And I am sure you have all seen it already. This is a bit awkward post, but I promise I will improve with time. Best Regards.
  2. 5 points
  3. 5 points
    I haven't really had much time to look at the charts earlier but have picked out the best ones tonight. So we are seeing a wavering wave 2 event that is causing the vortex to split at around day 8-9 right into the middle stratosphere. http://wekuw.met.fu-...var=ha2&lng=eng If one follows the charts above, we can see the wave reduce and then increase in intensity. It is the second wave increase that splits the polar vortex - this was suspected all along when the split was first forecast. This split is very much tropospherically induced - mainly as a result of the strong ridging on the Pacific sector. We can see that this has created a situation where a warming is upwelling from the troposphere into the mid levels of the stratosphere by day 10. very strong at 70 hPa: and now reaching 30 hPa: This is the first half of the story and is very much respobsible in the tropospheric northern blocking outputs seen - and we still don't know where or how the vortex will reform. Or do we? Well, the second half of the story can give us a clue. It very much looks like the Pacific high could get replaced by an Aleution low which is a ripe position for possible wave number 1 feedback into the stratosphere. If this occurs then it will be different to the trop up split through the vortex. This is more likely to come in the form of an over the top through the surf zone type of format. And this is likely to be seen in the form of a displaced vortex from the pole ( towards the Atlantic sector initially then probably to Eurasia - in the strat). As the vortex displaces a warming occurs towards the Pacific sector and will hopefully propagate downwards. GP touched on this last night and the evidence of a top up warming/ displacement scenario is clear to see in the extended outlook at the top of the stratosphere. Long term, this could be great news. Not only are we seeing the stratospheric vortex being disrupted from below, preventing the cooling vortex from influencing the troposphere, but it looks like that by the time that this wears off the upper vortex has warmed, hitting the upper cold temperatures and vortex strength. I suspect that if that is the case then any mild winter interlude, following the initial wave 2 split, could be very short indeed.
  4. 1 point
    Hello. This year I decided to make a seasonal "outlook" of my own. I guess its a statistical forecast, because it is based on reanalysis. This is basically just a composite or a blend of the winters in the past. I used certain winters and blended them together. I have chosen the years and months, based on the overall global setup and similarities in the oceanic and atmospheric features. The graphics were made on October 29, when I finished my analysis process and first published on November 1st on a weather forum in my country. So lets say I have 1 month "lead time" before the start of the forecasted period. This is my first attempt of "statistical" forecasting, so I don't really expect much success to be honest, but I need to test it, so i decided to make a "public test", by posting it on different weather forums. Some interpretation is required. This is basically an average picture, like an ensemble mean, so it has its respected deviation and variance. But just the average or "middle" picture will suffice for my first attempt. I posted this on a forum in my country, so the text on the graphic is in my language (Slovenian). But some words, like the names of the months are similar, so I think you will understand what period is represented on the graphic. I am only aiming at the DJF 500mb geopotential height anomaly for the verification in March, when the forecasted period is over. Now the graphics. Keep in mind that this is unaltered in any way. And it was made in the end of October, when none of these features were present in the seasonal models. At least not in this magnitude. Corresponding precipitation anomaly: And temperature anomaly: And I will also add the December 500mb height anomaly, made on the same date with the same system. And this was CFSv2 when I made these graphics. I first posted these images on a weather forum in my country, on November 1st. And all the graphics were made before that. Here is the link to that topic to prove it. Basically so no one can say that I "cheated", by looking at current models (which differ anyway) and intentionally making a similar picture. Best regards.
  5. 1 point
    This is an extract from the conclusion of the Gerber paper. Looking at the CPC charts at the high levels kept seeing random pockets of higher temps and wondered why they appeared almost in isolation and completely randomly? Not sure if this is correct explanation so please correct my thinking if am off on one here. The theoretical work of Charney and Drazin (1961) suggests that a stronger vortex will limit Rossby wave propagation into the stratosphere, thus reducing the amplitude of the Brewer– Dobson circulation. In the lower stratosphere this provides the correct intuition: the net wave forcing of the stratosphere is reduced when the vortex is colder, especially when there is no stationary wave forcing in the lower stratosphere, as explored by Kushner and Polvani (2004). At upper levels, however, wave breaking increases with a colder vortex, as potential vorticity gradients along the edge of the vortex create a wave guide higher into the stratosphere. In effect then has this downward trend to a very cold temperature at 30hpa assisted the creation of activity at 1 hpa ? The strong warming signalled on CPC charts continues
  6. 1 point
    Its my original thoughts using soalr/lunar cyclic effects. I'm not convinced its saying early end to cold now and Dec has been hard to call, just posted original thoughts and see how they pan out. Its looking a very interesting start to winter regards BFTP
  7. 1 point
    Welcome Recretos. We look forward to your input.
  8. 1 point
    Just a post to confirm what has been said on the model thread. Last nights post still stands, regarding any mild interlude. All signals are pointing to the polar vortex reforming and displacing to the east Atlantic/ Eurasion side of the pole. Here is the growing wave 1 signal: http://wekuw.met.fu-...var=ha1&lng=eng And here is it's (forecast) affect right down at 70hPa With such a displacement one could see a North Atlantic ridge at the very least with a west based -ve NAO
  9. 1 point
    Hi P.P.! I'm always aware of the number of 'lurkers' who flit through the threads and I do try and be as clear about my understanding of things as I can . LG makes me feel that this can be a bit of a fail at times! For a number of years now I've been talking about 'when Mother N. takes over the warming' as I've always been mindful of the extent of the potential Carbon cycle (from the size it has operated at over recent geological past) and that any warming will just bring part of that 'hibernating' cycle back into play. This does all depend on the relationship between temperature and GHG's and whether you can accept that either temp or GHG levels can lead the 'dance' in raising their levels in the atmosphere. For me it appears apparent that this relationship holds and the rare occurrences of CO2 rises occurring first have lead to the global temps rising and we all know what occurs when orbital forcing raises global temps. I know the way the cycle expands is not fully understood but if you pull back from the complexities all you are left with is that they will respond. We have raised global temps already (and it would appear that we have not reached the potential temp that GHG's dictate it should rise to?) so we will see some melt back of the ice sheets over time. This will introduce natural carbon from the currently 'hibernating' carbon cycle. The Methane losses from both permafrost and submerged Hydrates are part of this response and , over time, will lead to further hikes in global temp which , in their turn , will release back into the carbon cycle even more GHG's. If we accept that we are on this path then I feel we owe it future generations to think about clawing back the CO2 that we have placed into the atmosphere in the hope that this will slow and stop the process and allow Nature to take care of the global Carbon cycle.?
  10. 1 point
    Thanks to catch up TV I've finally seen this now and I thought it was pretty good actually!
  11. 1 point
    Time to start playing catch up for Scandinavia me thinks still a bit further to go tho http://www.yr.no/pla...sinki/long.html
  12. 1 point
    I would recommend a book that touches on this subject, "The Dance of Air and Sea; How oceans , weather and life link together", by Arnold H Taylor..
  13. 1 point
    The Met Office, regardless of whether there is a cold spell or not, are just covering their a**e. The general public and the more sensationalist media will tear them to shreds if they speak in overly certain terms and the outcome doesn't match. Suffice it to say they'll be informing central government of any potential risks coming up and should dangerous conditions be much closer they'll make these thoughts public. I pity the Met at times because they're damned if they do and damned if they don't. Anyone with a genuine undertanding of meteorology is aware by now that we have a substantial risk of a significant cold weather event on the horizon.
  14. 1 point
    Morning, just a quick summary, but it's looking good!...Few charts that stand out; http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha1_f240.gif - Wave 1 really gets going by D10 from yesterday 12Z ECM. http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha2_f240.gif - Signs of Wave 2 making a come back as well still. The broader pattern towards a split by the end of November into early December remains and the warming event continues to grow as well. http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwf30f240.gif http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwf50f240.gif If you flick through the zonal mean wind charts as well there is definitely a reduction in speeds between say 50N and 80N towards the end of the forecast period; http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=all&var=u&lng=eng#fig11 10hPa and 30hPa zonal wind at 60N signaled to decrease with time by early December; http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/ts.php?plot=fluxes&alert=1&lng=eng There's not much sign of any significant warming yet, but I presume that will take place with time once the above factors get to work, but from what I can see of the 12Z ECM from yesterday's it maintains good consistency with the GFS model and clearly there are plenty of variables there which are likely to really nibble away at the vortex come the turn of the month. All good signs from what I can tell!... Regards to all, M.
  15. 1 point
    Its from exacta ( james madden) so the more unreadable it is, the better !!
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