noun, noun which may take the genitive case particle 'no'
very stormy weather at sea; heavy storm at sea
Refers to extremely rough sea conditions, typically used in maritime or weather contexts.
大時化のため、今日の漁は中止になった。
Today's fishing was canceled due to the very stormy sea.
大時化の海に出るのは危険だ。
It's dangerous to go out on a very stormy sea.
noun
very poor catch of fish due to stormy seas
Used in fishing contexts to describe a very bad haul caused by rough sea conditions.
先週は大時化で、魚がほとんど獲れなかった。
Last week, because of the very stormy sea, we caught almost no fish.
時化 means 'stormy weather at sea' or 'poor catch' in general, while 大時化 emphasizes an extreme degree.
Compound of 大 (おお, 'big, great') and 時化 (しけ, 'stormy sea weather; poor fishing catch'). The exact historical derivation of 時化 is uncertain.