This still doesn't explain clearly why the word order in this sentence is like this. There are many Norwegian sentences which if translated literally and with the original Norwegian word order would make no sense to the same extent as "what if rains it"
But if you wanted to ask "Is it raining?" you would say "Regner det?" which would literally translate to "Raining it?/Rains it?" So why isn't the subject/verb order switched here like it seems to be for other questions?