The origin is false. It comes from the adjectival form of "sneg" (snow) which is "snežan" (along the lines of "snowy"). Also it doesn't derive from Croatian as there is a same Macedonian, Serbian and Slovenian name, so it must be labeled as "Slavic". [noted -ed]
I agree with the above comment that the meaning of SNJEŽANA (spelled that way) is incorrect: while the first element is slavic SNEG or SNIJEG as the case may be (snjeg is spelled wrong), the second is actually an adjectival suffix -AN with a feminine ending. Thus the meaning "like snow, snowy".