Weather report percentages can vex viewers

The percentage, by the way, refers to the percent of days that experience precipitation when the expected weather conditions are in place.

Well hell, if I’d’ve known that, a whole lot of other things would’ve made sense years ago. Like how we can be in 80% chance of snow when it’s snowing on me.

At least I’m not alone.

4 thoughts on “Weather report percentages can vex viewers

  1. Wow, I am right there with you on that one. I just kind of thought of it like Spock predicting odds for things based on sensor readings. I don’t see where people would get the idea that it referred to the amount of area that would get precipitation or the amount of time that would be spent precipitating, though. I wonder what meterologists do if there were conditions no one has ever seen before. Like if the sun exploded, you wouldn’t have any previous data to base a percentage on. On which to base a percentage.

  2. I’m with jzimbert – I thought it was a prediction, like odds on a sports game.

    I wonder how much it would cost to check the distribution of possible outcomes – say, by a Monte Carlo analysis – and weight the probabilities in the forecast accordingly. (Thus, if two equally likely tracks lead to 50%-rain conditions and 10%-rain conditions, report a 30% chance of rain.)

  3. I don’t know if they do that… I get the impression from reading forecast discussions that they generally know which models are currently running the more accurate predictions, and they go with those with some modification for outliers.

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