Jump to content
Thunder?
Local
Radar
Pollen

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


Recommended Posts

Spotted a post you think may be an issue? Please help the team by reporting it.
  • Replies 1.5k
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

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

Posted Images

Posted
  • Location: Longton, Stoke-on-Trent.
  • Location: Longton, Stoke-on-Trent.

    I think the problem is that some people latched onto this and proclaimed it was a guarantee that the winter that year was going to be cold, which is nonsense because nothing is certain in weather and predictions are based on probabilities. The same way the papers latch onto the Met Office contingency planners and misinterpret them to create their headlines of a BBQ summer or freezing winter. It leaves people (perhaps unfairly) sceptical that there is any use to such predictions and parameters.

    Edited by MattStoke
    • Like 2
    Link to post
    Share on other sites
    Posted
  • Location: Woodland Garden, South Yorks
  • Weather Preferences: Warm and Humid weather, Thunderstorms
  • Location: Woodland Garden, South Yorks

    Just another feeble attempt at pattern matching under a glamorous name, designed to sound intellectual and pseudo-scientific. It's already been demonstrated time and time again that pattern matching, under whatever guise, and no matter how intellectual the process is dressed up to sound, has a success rate no better than pure random chance. As such, one might as well use a crystal ball.

    Edited by Thundershine
    • Like 1
    Link to post
    Share on other sites
    1 hour ago, coldwinter said:

    Plenty of papers on the subject as @interitus said in the other thread

    imageproxy.php?img=&key=8d7953939bb9d610
    RMETS.ONLINELIBRARY.WILEY.COM

     

     

    Yes, the Kryjov paper, was going to repost this link. At the time back in 2015, way up this thread, it was paywalled. By using 500mb data at an arbitrary random location on the Taymyr peninsula it was possible to get an October geopotential - winter AO correlation of 0.62 over the 1976-2013 period, not quite the 0.9 touted for the mythical OPI but promising nonetheless. The method used in the paper above was alluded to in a follow up which shows it as calculated slightly differently - area averaged and at different altitude. Importantly their results appeared to be stationary over time which gives some hope that it may retain its utility.

    The main raft of papers commonly refer to Arctic sea ice or northern hemisphere snow cover, either individually or in combination with various other indices eg QBO etc Work such as the Cohen SAI have famously shown strong links to winter AO though have since been questioned as non-stationary - the correlations may be more an artefact of a causative link rather than the cause itself. Also the proposed trop-strat-trop pathways have been difficult to reproduce in modeling studies.

    To single out one author as a starting point, the works of Yannick Peings are a treasure trove -

    His work on Ural blocking for example demonstrates that as well as generating the wave driven strat response, also leads to the Kara sea ice and Siberian snow cover which are suggested as possible causative factors by others.

    Edited by Interitus
    • Like 4
    Link to post
    Share on other sites
    Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.
    53 minutes ago, Thundershine said:

    Just another feeble attempt at pattern matching under a glamorous name, designed to sound intellectual and pseudo-scientific. It's already been demonstrated time and time again that pattern matching, under whatever guise, and no matter how intellectual the process is dressed up to sound, has a success rate no better than pure random chance. As such, one might as well use a crystal ball.

    Indeed, Thundershine.

    And if one were to wait for that absolutely perfect pattern-match to come along (anything-else simply won't do!) one may just as well wait for the wind to reassemble sandcastles...? For each perfect match there will be (from a deterministically chaotic perspective) an almost infinite number of utterly useless nearly-but-not-quite scenarios...

    Link to post
    Share on other sites
    Posted
  • Location: Lincs
  • Location: Lincs
    10 minutes ago, Interitus said:

    Yes, the Kryjov paper, was going to repost this link. At the time back in 2015, way up this thread, it was paywalled. By using 500mb data at an arbitrary random location on the Taymyr peninsula it was possible to get an October geopotential - winter AO correlation of 0.62 over the 1976-2013 period, not quite the 0.9 touted for the mythical OPI but promising nonetheless. The method used in the paper above was alluded to in a follow up which shows it as calculated slightly differently - area averaged and at different altitude. Importantly their results appeared to be stationary over time which gives some hope that it may retain its utility.

    The main raft of papers commonly refer to Arctic sea ice or northern hemisphere snow cover, either individually or in combination with various other indices eg QBO etc Work such as the Cohen SAI have famously shown strong links to winter AO though have since been questioned as non-stationary - the correlations may be more an artefact of a causative link rather than the cause itself. Also the proposed trop-strat-trop pathways have been difficult to reproduce in modeling studies.

    To single out one author as a starting point, the works of Yannick Peings are a treasure trove -

    His work on Ural blocking for example demonstrates that as well as generating the wave driven strat response, also leads to the Kara sea ice and Siberian snow cover which are suggested as possible causative factors by others.

    Not much point reading, as its just pseudo-scientific ?  The Ural blocking in November is definitely interesting to watch, we had an anomaly there last year, which helped disrupt the PV, not quite giving the cold here that a lot of people wanted, but close and then eventually culminating in the  SSW. Everything is linked and the atmosphere gives us clues, it's never as simple as A+B=C which i think people keep getting confused with 

    • Like 3
    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
    • Mixed June continues with a cool northerly for Friday. Still feeling warm in any sunshine

      The June weather is all over the shop. On minute heavy rain and cold then warm sunshine the next. The rollercoaster continues for the next few days although improvements from the north for next week. Read the full update here

      Netweather forecasts
      Netweather forecasts
      Latest weather updates from Netweather

      UK Storm and Severe Convective Forecast

      UK Severe Convective & Storm Forecast - Issued 2021-06-24 08:35:19 Valid: 24/06/2021 0600 - 25/06/2021 0600 THUNDERSTORM WATCH - THURS 24TH JUNE 2021 Click here for the full forecast

      Nick F
      Nick F
      Latest weather updates from Netweather

      EURO 2020 football weather - Home and Away

      As we move towards the Knockout phase of Euro 2020 there is more hot and sunny weather across mainland Europe but rain may trouble Wembley. A bit mixed this weekend for the UK Read more here

      Jo Farrow
      Jo Farrow
      Latest weather updates from Netweather
    • Recently Browsing   0 members

      No registered users viewing this page.

    ×
    ×
    • Create New...