That's an impossibility, Tdol. A possibility cannot finish. Opinions can't finish and that's what modal and semi-modals do, offer our opinions on various fact situations. But only the fact can come to be or not come to be.
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Humble: It almost certainly will rain today.
Tdol: It very likely will rain today.
Riverkid: It probably will rain today.
Lenka: It may rain today.
BobK: It might rain today.
Mike: It probably won't rain today.
Rewboss: It almost certainly won't rain today.
Red 5: It may not rain today.
Coffa: It might not rain today.
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Which person's possibility finishes, Tdol?
I think you missed his point. Try the above with "yesterday".
That's an impossibility, Tdol. A possibility cannot finish.
That's plain wrong. Any possibility that is linked to time can end. My possibility of winning the lottery ends if I don't buy a ticket before they close the machines.
That sounds rather unnatural. Nobody would say that -- I've certainly never heard or read anything like that.
The possibility that things may be different yesterday than they actually were is exactly zero. How would you go about, for example, making a cake yesterday? It can't be done. In fact, some scientists believe it would be impossible even if you had a time travel machine. But the day before yesterday, the possibility of making that cake was still pretty strong.
Bill said it might rain yesterday -- but he was wrong.
Re: examples of past tense 'might' 
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