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Old 04-23-2017, 07:22 PM
Riemann Riemann is online now
Join Date: Nov 2015
Location: Santa Fe, NM, USA
Posts: 4,262
Originally Posted by DSYoungEsq View Post
This is easy to decipher.

For the Atlanta area, there is 100% confidence that roughly 50% of the area will see showers. Broken down into hourly segments, the confidence remains close to 100%, and the coverage is around 50% at any given time. In other words, scattered showers are predicted with almost 100% certainty.
I can see that makes the numbers work, but I'm skeptical that this corresponds to reality. Unstable air and convectional showers are usually rather unpredictable, I find it hard to believe that a forecast would come up with close to 100% certainty for almost exactly half the area continuously for, what, 9 hours.

I still lean toward the view that they are not really calculating probabilities. What I'd really like to see is some kind of clear explanation of what they are doing and what the numbers mean, but as you can see from that other thread, nobody seems to know, and nothing is documented on their website (or any website that shows hourly numbers).

Last edited by Riemann; 04-23-2017 at 07:26 PM.