Fri Aug 28 2015 06:49 PM
Re: Tropical Storm Watches and Warnings Up for Central Bahamas for Erika


I think the challenge is the NHC is trying to average the model outputs instead of picking one group. Assume it's 12:30 pm but you don't know this. You ask 4 people to estimate what time it is - 2 tell you it's noon, 2 tell you it's midnight, and not knowing who is right, you decide to go with the average and estimate its 6 pm. You will still be way off. Same principle here - one group of models says it's going to dissipate, one group says it's going to intensify possibly to a CAT 1 hurricane and go north. Clearly one group is really on target and one is way off. But instead of choosing a group they are blending the solutions and coming up with an answer that is bound to be wrong, just less wrong than they would be if they chose one group of model outputs.

This is always the case, and while it may be more of a weakness with Erika than usual, in fairness to the NHC, the expert models are also expertly weighted, and when the forecast isn't verifying well with the expertly weighted averages, we still have expert humans at the helm to make other adjustments as needed.

The science is simply not good enough yet to always handle how these weaker, less organized systems interact with the islands. And this season is already a challenging one to forecast in.

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