Stu:
Thanks for sharing. I appreciate the explanation and have implemented some rules based on your post. Inserting rules for wind and sun before the cloudbase rules will help to have a more informative and varied set of conditions that just rain and cloudbase.
Michel:
The false condition I get the most often is when the CCC returns "Clear" based on cloudbase alone. I am experimenting with cloudbase and solar radiation. For example, if the rule requires cloudbase > 2500 AND solar radiation > 400 then it will not return "Clear" on a cloudy day. This does NOT work at night, because it will never return "Clear" if it is dark outside. But I don't care so much about cloudbase conditions at night because only Herb is awake in the middle of the night and he can't see the difference between clear and partly cloudy in the dark anyway.
This is not a perfect solution, but it is more accurate during the day than cloudbase alone. Because I have just started to experiment with this, I'm not sure that 400 is the right solar number, but I will watch it over the next several days and see if I can tweak it for accuracy.