まもなく雨が降り出した。

まもなく雨が降り出した。

Soon after, it began to rain.

まもなく雨(あめ)が降(ふ)り出(だ)した。

Mamonaku ame ga furidashita.

間もなく (まもなく)

soon; before long; in a short time; lacking time to ...; without time to ...

雨 (あめ)

rain

が (が)

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

降り出す (ふりだす)

to begin to rain; to begin to snow

Readings: ウ、あめ、あま-、 -さめ

Meaning: rain

Readings: コウ、ゴ、お.りる、お.ろす、ふ.る、ふ.り、くだ.る、くだ.す

Meanings: descend, precipitate, fall, surrender

Readings: シュツ、スイ、で.る、 -で、だ.す、 -だ.す、い.でる、い.だす

Meanings: exit, leave, go out, come out, put out, protrude