、。
She got lost, and on top of that, it started raining.
Literal
She [topic-は] road [to-に] got-lost, on-top-of-that rain [subject-が] began-to-fall.
Two structural features stand out. First, the masu-stem conjunction 迷い (rather than 迷って) joins the clauses — this 連用形中止法 is more common in written or narrative Japanese and gives a slightly literary feel. Second, 降り出した uses the compound verb ~出す to mark sudden onset — rain didn't gradually begin, it started all at once. そのうえ ('on top of that') escalates the situation, framing the rain as an additional misfortune piled onto being lost.