Learn Dutch: Ik kom doorweekt aan, behalve als het stopt met plensen. - I will arrive soaked, unless it stops pouring.

Since "behalve als" introduces a subordinate clause, shouldn't the verb go to the very end? Why is it "stopt met plensen" instead of "met plensen stopt"?

Behalve als does send the conjugated verb to the end of the clause, but prepositional phrases like met plensen are an exception. They can naturally be placed after the verb at the very end of the sentence. You could also say behalve als het met plensen stopt, but putting the prepositional phrase last often sounds a bit more relaxed.

Could I use "tenzij" instead of "behalve als" here?

Yes, you absolutely can. Tenzij and behalve als both mean "unless" and are usually interchangeable. Behalve als (literally "except if") is slightly more conversational and common in spoken everyday Dutch, while tenzij can sound just a tiny bit more formal.

The English translation says "I will arrive", but the Dutch sentence uses the present tense "Ik kom aan". Why is there no future tense verb?

In Dutch, the simple present tense is the standard way to talk about the future, as long as the context makes it clear the event hasn't happened yet. Using the future tense with zal (Ik zal doorweekt aankomen) would be grammatically correct but sounds unnecessarily formal or dramatic for this situation.

Why is "aan" placed right before the comma instead of next to "kom"?