ทบทวนภาษาอังกฤษแล้วยังงงๆเรื่อง have + past ?

English problem. (have + past)?
I will go to shopping,
1) if it has stopped raining
2) if it stopped raining
3) if it stops raining

Questions:
Are these all correct grammatically?
Is there any difference in meaning?
Which one is more natural?

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