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OCTOBER PATTERN INDEX (OPI) MONITORING WINTER SEASON 2014-2015


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So I think we can chalk December off as a CET that will end up at least normal and probably around +5 or more. The AO will out turn on average above normal as will the NAO.  Therefore I suggest the OPI has not worked for December. 1-0 to the Met Office long range this time around. An embarrassment for the likes of Piers Corbyn at WeatherAction and James Madden at Exacta snomageddon forecasts.

 

However, the OPI from what I can tell only suggests at least 2/3 super negative AO months in a winter given the near record -ve value this year. So there is still time for it to claim some success. 

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As ever, a great summary of how things stand from Ed and I think for the last 19, or pretty much 20 days now we have all been waiting for this point in the month and beyond. It's been rather 'fun' wat

The discussion of the OPI index trend is understandably causing a lot of interest and (cautious) excitement amongst members after Riccardo's very interesting opening post that started this thread. The

The monitoring page of the “October pattern index†(OPI) is presented. The OPI index  represents a analytic synthesis of the October hemispheric pattern at 500 hPa, and shows from  previous studi

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Posted
  • Location: st albans
  • Location: st albans

    So I think we can chalk December off as a CET that will end up at least normal and probably around +5 or more. The AO will out turn on average above normal as will the NAO.  Therefore I suggest the OPI has not worked for December. 1-0 to the Met Office long range this time around. An embarrassment for the likes of Piers Corbyn at WeatherAction and James Madden at Exacta snomageddon forecasts.

     

    However, the OPI from what I can tell only suggests at least 2/3 super negative AO months in a winter given the near record -ve value this year. So there is still time for it to claim some success.

    PC and JM weren't wrong PB. Just misunderstood! I guess they could point to more respected met figures such as dr Cohen being surprised by the nw Asian trough but if their forecasts were less sensational, their bust wouldn't be so obvious. PC will have an excuse - it was frosty on quite a few nights after all and n Scotland has been quite wintry.

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    Posted
  • Location: Bude
  • Weather Preferences: Extreme weather...heavy snow and heat waves
  • Location: Bude

    So I think we can chalk December off as a CET that will end up at least normal and probably around +5 or more. The AO will out turn on average above normal as will the NAO.  Therefore I suggest the OPI has not worked for December. 1-0 to the Met Office long range this time around. An embarrassment for the likes of Piers Corbyn at WeatherAction and James Madden at Exacta snomageddon forecasts.

     

    However, the OPI from what I can tell only suggests at least 2/3 super negative AO months in a winter given the near record -ve value this year. So there is still time for it to claim some success.

    We are only half way through December, still over two weeks left, so your statement is too early, come back in 16 DAYS!

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    Posted
  • Location: Coatbridge, North Lanarkshire (this lockdown) Freuchie, Fife (normally)
  • Weather Preferences: cold and snowy in winter, a good mix of weather the rest of the time
  • Location: Coatbridge, North Lanarkshire (this lockdown) Freuchie, Fife (normally)

    I'm not sure we should expected the OPI to 'work' as well for December, to be honest - the average CET for -1.5 OPI or lower Decembers is 4.5C, compared to an average January CET of 1.8C and 2.4C for February. The AO value is perhaps a little more disappointing than expected but with a plunge in its value expected by the end of the month we should come out around neutral maybe even slightly negative:

    ao.sprd2.gif

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    Posted
  • Location: Bratislava (240m)
  • Location: Bratislava (240m)

    Exactly, we can't say whether the OPI has worked or not based on December alone. I'll start to worry if January slowly disappears down the snow drain.

    Edited by AderynCoch
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    • 2 weeks later...
    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL

    Looking at the longer range models they show little sign of fitting the OPI predicted Europe height anomalies.

    If the first two weeks of January don't match the forecast then the second half of January would have to be monumentally cold negative to even come close.

    OPI is looking shaky.

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    Posted
  • Location: Manchester
  • Location: Manchester

    Looking at the longer range models they show little sign of fitting the OPI predicted Europe height anomalies.

    If the first two weeks of January don't match the forecast then the second half of January would have to be monumentally cold negative to even come close.

    OPI is looking shaky.

    Agreed! I can't see this pattern flipping so easily. Greenland seems totally unable to get any pressure rise so far this winter.

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    Posted
  • Location: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire

    Agreed! I can't see this pattern flipping so easily. Greenland seems totally unable to get any pressure rise so far this winter.

     

    I think we can forget Greenland heights for the foreseeable. The pattern looks fairly stable to me and no amount of optimism changes the fact we've got HP limpeted to the S of us- which is seemingly perpetual.

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    Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

    Looking at the longer range models they show little sign of fitting the OPI predicted Europe height anomalies.

    If the first two weeks of January don't match the forecast then the second half of January would have to be monumentally cold negative to even come close.

    OPI is looking shaky.

    Doesn't mean that the theory doesn't have some basis it just means they are other factors in play that need to be considered as well. As it is it's not over yet two months to go and lets see what happens.

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    Posted
  • Location: Penrith Cumbria
  • Weather Preferences: Cold, snowy winters and warm sunny summers
  • Location: Penrith Cumbria

    We can not give up on the OPI just yet as the index covers the whole 3 month period.

    Winters 1985/86 1986/87 1990/91 1955/56 to name but a few were all back end loaded and confirmed the OPI signal.

    However, time is running out and we will need a massive change in January similar to 1986 for the OPI to be a true winter indicator.

    Andy

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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL

    We can not give up on the OPI just yet as the index covers the whole 3 month period.

    Winters 1985/86 1986/87 1990/91 1955/56 to name but a few were all back end loaded and confirmed the OPI signal.

    However, time is running out and we will need a massive change in January similar to 1986 for the OPI to be a true winter indicator.

    Andy

    This was my point. The longer this Winter goes on without showing the OPI forecast, the more extreme must the remainder of the Winter become to make it a confirmed theory.

    The models show absolutely zero sign of the forecast pattern out to the 10th January so the theory is on a sticky wicket, and believe me, I want this work.

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    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 I too can't see anything sustained before the final third right now, its probably worth nothing that the final December CET looks to be near enough the OPI average. Also the actual Winter 2013 turned out slightly warmer than the OPI average but delivered in March.

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    Posted
  • Location: Coatbridge, North Lanarkshire (this lockdown) Freuchie, Fife (normally)
  • Weather Preferences: cold and snowy in winter, a good mix of weather the rest of the time
  • Location: Coatbridge, North Lanarkshire (this lockdown) Freuchie, Fife (normally)

    Doesn't the OPI signal get weaker as the days get longer? I remember reading some posts saying that back in October.

    Other way round (somewhat counterintuitively) - January and February show the greatest correlation with it with December the weakest.

    Too early to write it off yet IMO, but you would certainly expect at least one winter month to deliver a stonkingly negative AO and, most likely, a significant cold spell if we are to have much faith in it. Some of the strat charts we've seen suggest we might not be too far off that mid January onwards but certainly we haven't seen that signal materialise just yet.

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Other way round (somewhat counterintuitively) - January and February show the greatest correlation with it with December the weakest.

    Too early to write it off yet IMO, but you would certainly expect at least one winter month to deliver a stonkingly negative AO and, most likely, a significant cold spell if we are to have much faith in it. Some of the strat charts we've seen suggest we might not be too far off that mid January onwards but certainly we haven't seen that signal materialise just yet.

     

    Yes it is too early to write it off and as accurately comment their findings did suggest better correlation with the latter 2 winter months. There was far too much hype by some about what they actually printed. It does still need a peer review in my eyes and I doubt it will in the end be any more of a guide than others already in use. But it will, if the theory can be shown to be statistically correct and sound meteorologically another addition to the growing number of factors amateurs and professional can use to try and predict the winter months. I find this totally absorbing and great to see in meteorology, or is it, climatology? As an ex forecaster the amount of additional data available since I retired is fairly amazing to me.

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    Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

    A reminder of the OPI charts for the winter:

    opi1.jpg

    Two thoughts to date:

    1: If these charts are going to get anywhere near verifying, there will need to be a drastic model turnaround in the next 14 days.

    2: The positive anomaly over Greenland/Canada is similar to some of the charts that appeared in the run-up to Christmas. Patterns do have a habit of repeating in winter, I feel. I wonder therefore if we might see another attempt to build a Canadian/Greenland ridge in the near future.  

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    Posted
  • Location: Rotherhithe, 5.8M ASL
  • Location: Rotherhithe, 5.8M ASL

    It'll be interesting to hear from Riccardo to see why things are not going as envisaged

    Courtesy Ryan Maue

    post-19153-0-70862000-1419954335_thumb.j

    That will take some budging 1060 mb *if* only it could have relocated towards Greenland/NW Canada, currently ushered by extensive -ve anomalies credit to the lobe of pesty vortex, totally devoid of HLB at this juncture.

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    We are only half way through December, still over two weeks left, so your statement is too early, come back in 16 DAYS!

    15 days later and the original statement stands. It wasnt too early to make the statement as there was already strong support for it out to at least 10 days i.e. 26th. Therefore not enough time to change the outcome.

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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL

    Does anyone know whether the Italian team are going to try and investigate where the theory went wrong to try and improve on it for next Winter? Similarly, Cohen;s SAI theory?

    I hope both teams don't give up and continue to search for an answer to winter seasonal forecasting.

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    Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

    Does anyone know whether the Italian team are going to try and investigate where the theory went wrong to try and improve on it for next Winter? Similarly, Cohen;s SAI theory?

    I hope both teams don't give up and continue to search for an answer to winter seasonal forecasting.

     

    As posted a few days ago in the Strat thread, Cohen mentions the Barents/Kara Sea low pressure anomaly interfering with the tropospheric influence of the anomalously high Eurasian snow cover:

     

    https://www.aer.com/science-research/climate-weather/arctic-oscillation

     

    It's unforseen things like these anomalies that can really make it hard to make a reliable winter forecast I guess, no matter what index you base it on or many indices.

    Edited by Nick F
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    Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL

    Well exactly Nick, unforeseen. Why was it unforeseen is what needs to be investigated. Clearly, these unforeseen realities have overridden other signals.

    I think many, including myself partly hung ourselves on the OPI, unfortunately it seems that both December and January will come in with net +AO and +NAO which does not reflect the large -OPI figure.

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    Posted
  • Location: Broadmayne, West Dorset
  • Weather Preferences: Snowfall in particular but most aspects of weather, hate hot and humid.
  • Location: Broadmayne, West Dorset

    If we have a pattern change to negative AO say last week of Jan and lasting through Feb will people be quite so ready to write off the OPI theory.

    I would be more inclined to let the rest of the winter pan first before making any decisions as to it's viability or lack thereof.

     

    I can just imagine if the OPI had been presented back in autumn 1946 and a first half of january 47 being mild after a brief bit of cold around Christmas 1946 and people queuing up to call it a busted flush. they wouldn't have looked so clever come March 47.

     

    Just musing to myself...................................................

    Edited by mcweather
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    Posted
  • Location: Nottingham, UK
  • Weather Preferences: Cold and snowy or warm and sunny
  • Location: Nottingham, UK

    Had the sea ice extent been less than what we have now, then I would imagine the Siberian high would have been allowed to develop and we may well have had a cold pattern set up by now. As many have mentioned, the OPI should be used as a tool in the tool kit, and is not the tool kit itself.

     

    Wasn't there another Index that the team were working on to do with Zonal patterns that contradicted the OPI outcome (I can't remember what it was called)

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    Posted
  • Location: Lee, London. SE12, 41 mts. 134.5 ft asl.
  • Weather Preferences: Snowy, wintry weather
  • Location: Lee, London. SE12, 41 mts. 134.5 ft asl.

    Good points there mcw and as LS states earlier, the negative OPI figure tends to correlate well with more a -AO, in Jan/Feb, rather than Dec.

    But as we know only well, a -AO on its own, does not a cold and wintry UK make, we could also do with some assistance from the Atlantic sector, with hopefully a more neutral/negative NAO, as we head into the 2nd half of winter.

    But nevertheless, still to early to throw the OPI on the scrap heap yet!

    Tom.

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    Posted
  • Location: Ludgershall, Wiltshire
  • Location: Ludgershall, Wiltshire

     

    Wasn't there another Index that the team were working on to do with Zonal patterns that contradicted the OPI outcome (I can't remember what it was called)

    Yes there was now you mention it. It was a potential fly in the ointment. Can't remember what it was called either but it was mentioned in this thread a couple of months ago I think.

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