I suggest following translations:
Literal: [It's surprising] what all such a storm is good for!
Correspondingly: Such a storm is good for many things you wouldn't expect!
The composition can be stripped down as follows:
- Wofür so ein Sturm gut ist!: A storm is good for something
- Wofür so ein Sturm alles gut ist!: A storm is good for several things
- Wofür so ein Sturm nicht alles gut ist!: A storm is good for several things you wouldn't expect.
1) Meaning of wofür
Wofür so ein Sturm gut ist!
The interrogative pronoun wofür ("for what") is part of an exclamation here. In exclamations, interrogative pronouns more or less refer to their answers without explicitely naming them, leaving it to the speaker to think about it. For example: Was das kostet! ("What that costs!") means That costs a lot!. Wie schön! ("How beautiful!") means This is very beautiful. Wofür das gut ist! means That is good for something!.
2) Meaning of alles
Wofür so ein Sturm alles gut ist!
Just as the word all in several varieties of English,1 alles can be used after an interrogative pronoun to indicate that the answer comprises more than one entity. This works with wer alles, was alles, womit alles, wofür alles and several more. Wer wohl alles kommt? ("Who all might come?") or Ich frage mich, wer alles kommt ("I'm wondering who all is going to show up") means that the questioner expects more than one person to show up. Wofür das alles gut ist! (somewhat colloquial, "What all that's good for!") means that the questioner expects more than one purpose to be there.
3) Meaning of nicht
Wofür so ein Sturm nicht alles gut ist!
In exclamations of the pattern
interrogative pronoun + "alles", nicht can be used as an emphasis of alles if the answer is considered particularly diverse and/or surprising by the speaker. It doesn't negate anything here. English has a similar idiom: whatnot.
Other examples include: Wer nicht alles zu ihrer Party gekommen ist!, Was es nicht alles gibt! (very idiomatic), Wofür das nicht alles gut ist!.
1 https://ygdp.yale.edu/phenomena/what-all; https://www.merriam-webster.com/dictionary/all (entry 1.8)
PS: from a native speaker point of view, the sentence isn't weird at all ;)