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chionomaniac

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Everything posted by chionomaniac

  1. The OPI has yet to be scutinised and vetted independently and submitted to journals - and until it is, it will not be taken on board by the met (rightly too). But luckily we can watch the hypothesis being played out in the meantime. It is one thing building an index to fit retrospective dates, but quite another to get this to work in the future - as last year showed.
  2. Interestingly Steve, that October plot has a significant positive anomaly across the East Siberian/Alaskan arctic. It is here that Cohen hypothesises that we are more likely to see raised pressure due to the reduced amount of sea ice. And in turn, that this induces feedbacks later seen in winter that can lead to negative AO conditions (through changes in the storm tracks, jet stream changes and planetary waves inducing stratospheric change). -see bottom of page 7 here: http://web.mit.edu/jlcohen/www/papers/Cohenetal_NGeo14.pdf The OPI system not only measures the pressure differentials, but also takes into consideration the axis of the NH Rossby cross pole waves and it is these combined together that I believe Riccardo et al have encorporated into their index. Interestingly, totally seperate from the OPI winter composites that you have been posting in this thread, there are other analogues that also suggest later winter Arctic blocking - more of that to come at a later date..... Edited to get link to work!
  3. Possibly something like this set up Carinthian, from Jamstec.
  4. How good is your Italian Steve. Links to last years Italian forum threads http://www.centrometeotoscana.it/forum/index.php?topic=7364.msg http://www.centrometeotoscana.it/forum/index.php?topic=7364.msg I guess google translate comes in handy but not perfect if I remember from last year.
  5. Thank you for posting this Riccardo, and welcome to Netweather. I have been following your work with the October Pattern Index since last year. There does seem an extremely high correlation between October's pressure pattern and the following winter's AO index - but it appears that last year may not have been as accurate as previous years. Is there a reason for this? I am looking forward to seeing this year's index values tested and thank you for linking to your work. c
  6. Regarding the SAI, I have read from those that have lookes at the correlation that this still exists from around week 39 in the year until week 43, so that if the snow starts to advance prior to the 1st October then the correlation will be pretty similar. Regarding the miniscule above average 30hPa temperature during the seasonal autumnal drop off, I suspect it matters very little. November is the first critical month.......
  7. With tomorrow being the first of October, we are getting into the business end of Autumn - an important time for the precursers for the following winter to be determined. So far we know precious little that we can confidently predict the state of going into winter. I would limit the variables of sun activity and the descending negative QBO state as those that we can have a good grasp of at this point. Even the ENSO forecasts are variable with the possibility of a weak El Nino remaining favourite. So that leaves us unable to firmly point towards what winter will bring. However, October is an important month, and many conditions that can possibly determine winter will be set during this month. So we will need to look out for the rate of snowfall over the NH landmasses (the snow advance index - SAI), the southern extent of this snowfall (the snow cover extent index- SCE) and also how this will affect the perturbations of the polar vortex during this month ( the October Pressure Index). Further monitoring of the extent of Arctic Ice Gain and the main Ocean patterns including an updated Enso state and atmospheric response can be gathered by the end of the month, and hopefully by then we will have some clues as to what type of winter these suggest. But all of this can be overridden by the state of the stratosphere which is why the monitoring of this during November will be critical in helping us determine any forecast for winter. I certainly feel a little bit more optomistic than this time last year, but at this point it will be too early to suggest too much. Roll on October!
  8. I would have to look back to check. Early thoughts probably around the end of October.
  9. Re MT,Yes is the answer - but normally later on in the autumn when the stratospheric vortex is stronger and therefore a strong breaking tropospheric wave can have more of an impact.
  10. I know that last year my winter forecast was wrong because I seriously underestimated the cooling and resilience of the stratospheric vortex but the main headline regarding cold ( Not another 1947) was correct. Thank goodness I didn't forecast record breaking cold! Funny enough my gut instinct thought that it would be mild and wet but this wasn't supported by the comparison years analogues which suggested near average. Really I had to go with these analogues. I would love to see GP's forecast for last winter in hindsight!
  11. I guess that it is important to differentiate between those who use the known atmospheric states to help predict the what weather the winter will bring and those who hopecast or do just guess. It is early days yet, but the likes of Cohen et al, are really helping in longer range winter forecasting for the northern hemisphere!
  12. Nope, a guess is what I would do to predict the (random) lottery result. However, the atmosphere can have predictable and more reliable responses to set criteria. Granted that this may not occur every time, however more than often it does, so we are more likely to see set atmospheric conditions lead to these responses which increase probabilities of certain weather types prevailing at certain locations. That is why we look at the MJO for instance - these phases of tropical convection have been scientifically linked to coincide with a corresponding long wave wavelength pattern, which in turn can lead us to help forecast set pressure patterns across the hemispheres. Those who don't recognise this will always be far behind in forecasting abilities to those that do.
  13. Not strictly true. In fact, far from it. It was no surprise that a strongly positive QBO last winter contributed to the stratospheric driving of the troposphere. But this was just one of many factors that assisted the poor winter (snow wise) that the UK endured. It may be too early to assess all of the ingredients in the mix for winter this year, but rest assured that already the ingredients that we do know are likely, are far better for something colder and drier! It is wrong to suggest that teleconnective drivers don't tell us anything.
  14. Technically, that is summer...........and no misrepresentation there!
  15. Certainly agree with that as I mop up the inside of my conservatory!
  16. Got up to 116.4mm/hr at 10.15 this morning. Certainly impressive whilst it was occurring. I also like to see how well the NW radar verifies - and again very impressive (I am in the blob to the south of Burgess Hill)
  17. Really heavy torrential rain with gusty winds in the embedded squall line here. I just saw an amazing CG that struck not too far away. Passing through now.
  18. Oops - I just realised that I have written the wrong pressure in my guess! It should have said 989mb (not 998).
  19. Down here in the SE we'll be lucky to see a day (daytime max) under 20ºC for a considerable part of the month. Even the CET max last month only dipped to 19.4ºC on the 8th with most days above 20ºC. Today was a typical day down here - whilst a lot of the rest of the country had considerable rainfall we avoided this and had warm sunny spells with temps in the low to mid 20's. I suspect August will continue in the same vein.
  20. In East Grinstead today and the monsoon has well and truly hit!
  21. Great news - clear blue sky with small medium level convective cumulus has reached Brighton. Expect the temperatures to soar now!
  22. The sun is desperately tring to pierce the cirrus shield in Brighton. Come on - you can do it!
  23. The detritus is really annoying. And there is a fair amount of it to get through for the bulk of the country before potent home grown storms can develop. There is clear air to the west - and we can see storms developing over the CI's as a result. Also thinning in Lincs area going by this run. A waiting game! http://www.yr.no/satellitt/europa_animasjon.html
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