。
She couldn't arrive on time because of the storm.
Literal
Storm [because-of-ため] she [topic-は] on-time [at-に] arrive-could-not.
のため here is the written/formal 'because of,' typically used for objective causes like weather, traffic, or circumstances rather than emotional reasons. 定時 ('fixed time') specifically refers to a scheduled or appointed time — more precise than the broader 時間通り ('on time'). The potential negative できなかった ('could not') is attached to 到着する via suru-verb potential conjugation.