I'm sorry, I didn't check well enough for that. It wasn't in my paperback Latin-English dictionary, which is the first source I go to, because it is the easiest. I just now checked on Wiktionary and found it there.
...since there was no procellosus in Latin (and such a construction would have been semantically suspect, at any rate).
Well, I was (until just now) of the thought that the suffix -osus was usually appended to "attribute" or "quality" nouns such as dolor and animus, to indicate an abundance of that quality in the referent. While I was on Wiktionary, I looked over the list of Latin words suffixed with -osus, and I found many, such as arteriosus, in which -osus is appended to a noun describing a "thing", rather than a quality, and so describing a thing "full of (other things)". I think procellosus to be of that category.Why ever?
The suffix still seems better suited for being affixed to quality/attribute nouns, but I have (just now) learned the scope of its application is much broader than that. I have occasionally to "unlearn" my misapprehensions.