Usage patterns
不吉な予感がするto have an ominous feeling
For some reason, I had an ominous feeling that day.
不吉な夢を見るto have an ominous dream
Last night I had an ominous dream.
不吉なことを言うto say something ominous
Please don't say such an ominous thing.
〈事〉の不吉な前兆an ominous sign of〈something〉
The black clouds were an ominous sign of the coming storm.