ぶわっ

adverb taking the 'to' particle

whoosh; fwoosh

Describes something suddenly spreading, billowing, swelling, or gushing outward, such as smoke, steam, or a sudden rush of air.

• 鍋なべのふたを開あけたら、湯ゆ気げがぶわっと立たちのぼった。

  When I opened the lid of the pot, steam whooshed up.

• 風かぜがぶわっと吹ふき込こんできた。

  A gust of wind suddenly blew in.

adverb taking the 'to' particle

burst into tears; suddenly cry

Used when someone suddenly starts crying, often with tears welling up and spilling over.

• 彼かの女じょはその言こと葉ばを聞きいて、ぶわっと泣なき出だした。

  Hearing those words, she burst into tears.