Rule reminder
'Prima che' (before) always requires the subjunctive. Other temporal conjunctions like 'dopo che' (after) and 'quando' (when) normally use the indicative, but 'prima che' is unique because the action it refers to has not yet occurred at the time of the main action — making it inherently uncertain.
Leave before the storm arrives. Choose the correct form: 'Parti prima che arrivi il temporale.'