Sour Grapes
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PoP (Probability of Precipitation)

Speaking of the weather, I've invested a fair amount of time over the years trying to understand exactly what this means. Based largely on my own sense of who and what are reliable, I've concluded that this definition from the National Weather Service is a good one, despite the obvious bit of awkwardness:
12-hour Probability of Precipitation (PoP12)

Is the likelihood, expressed as a percent, of a measurable precipitation event (1/100th of an inch) at a grid point during the indicated valid period.
It would read so much better if it ended "during the indicated 12 hours." There's a much longer but useful explanation consistent with the definiton at this University of Texas page (attributed to the NWS but unavailable anywhere else, at least that Google knows about anyway).

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