Is 2017 Shaping Up To Be A Lean Season?

Discussion in 'Alpine & Snow' started by Old School Mike, Jun 15, 2017.

  1. Rush

    Rush Pool Room

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    Three month forecasts for winter rainfall issued on May 25th 2017
    [​IMG]
    Reality.
    [​IMG]

    Three month forecast for minimum winter temps issues on the same date.
    [​IMG]
    Reality.
    [​IMG]

    Three month forecast for maximum winter temps issues on the same date.
    [​IMG]
    Reality.
    [​IMG]

    So what was wrong with the forecast exactly?
     
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  2. Rush

    Rush Pool Room

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    A quote for David Rodgers, ex-head of the UK Met Office who now works for the World Bank.
    "Regarding the use of ensembles. The ECMWF is moving away from any deterministic forecasting. We have to understand and make decisions with uncertainty. But focusing on the deterministic approach is not helpful which is why we make bad decisions. Getting users/stakeholders to make decisions informed by uncertainty will get us making decisions. Forecasts may not be better, but they will more useful."

    Internal BoM surveys suggested that those that understand probability rate the seasonal forecast. Those that fail probability comprehension questions think the seasonal forecast is a load of junk.
     
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  3. Ralph_Plow

    Ralph_Plow One of Us

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    No hindsight?
     
  4. Rush

    Rush Pool Room

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    Skill maps for three month rainfall forecasts issued in May.
    [​IMG]

    For Max temps
    [​IMG]

    For Min Temps
    [​IMG]
     
  5. teckel

    teckel Pool Room Ski Pass: Gold

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    Well, the temps for a start. (I'm talking the SE of the continent where the mountains are, given that this is a snow forum, and the maps I put above concentrated on that.
    80% chance of min temps higher than average. No, they were average to below average. OK, they fitted in the 20% chance.
    80% chance of max temps higher than average. 80% chance indicates high certainty, and one could probably assume that they expected them to be well above. They were average to slightly above average. But the forecast probabilities can't be compared with how warm/cold/wet it was. Like comparing apples and pears.

    Going on their forecasts, one would have said that the season would be a shocker. Well, the first half was, due to the persistent highs in June and July. But the season has turned out to be a good one.
     
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  6. Red_switch

    Red_switch Old n' Crusty Ski Pass: 30 Day

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    Great post.
     
  7. Red_switch

    Red_switch Old n' Crusty Ski Pass: 30 Day

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    Why would you make that assumption when they make no mention of magnitude?
     
  8. teckel

    teckel Pool Room Ski Pass: Gold

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    What I said 2 sentences later. However, if they're so sure, they should say how much warmer they expect it to be. If they can't do that, their forecast is pretty useless. Why would anyone heed it?
     
  9. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    Um,... an 80% chance of exceeding the median minimum is a prediction that minimum temperatures are likely to be below the median. All because you have literacy issues doesn't mean that the forecast is incorrect.
     
  10. teckel

    teckel Pool Room Ski Pass: Gold

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    Really Einstein? The chance of exceeding a temperature means you are talking about a higher temp.
    Now see this map:
    [​IMG]
    The accompanying text says:
    Those areas that BOM thought would be warmer correspond with the red areas of the map.
     
  11. Telemark Phat

    Telemark Phat Pass the butter Ski Pass: Gold

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    Well I sure got pwned.