I agree a notice should arrive some days before deletion at least for questions that have been opened for some time (let's say more than 30 days)
In this way if you want to save the asnwer to your question on your local environment you can do it.
I don't think new questions should receive an alert prior deletion, cause too many people posts wrong/duplicate questions.
One of my questions was deleted. It has been opened for 1 year!!! And it was deleted with no notice!!! I wasted 30 minutes to search for it in my own questions, once I couldn't find it I started to suspect it could have been deleted.
I had to come here on meta to discover the sad truth, questions are deleted with NO prior notice, No alert, NOTHING!
This is disrespectful to the community, to the guy who asks a question and even more to the poor guys that took time to write good answers.
I don't argue about the reason it was deleted, probably not useful, but it was very useful to me, I liked the answers I received and I liked to read them again once in a while. Now I can't do this anymore, and I don't even have a copy of it on my local environment since it was deleted without even sending me an alert.