bad omen

a bad omen and an ill / evil omen (a bad sign which indicates that, when a bad thing happens, something even worse is going to happen; a sign that something bad or evil is going to come) — дурное предзнаменование, дурная, плохая примета; дурной знак

...The union of England and Scotland on May 1, 1707 was preceded by an evil omen when, in the last few days of April, 31 whales were found beached on the sands of Kirkcaldy.

take/see sth as an ill omen — принять что-л. за дурное предзнаменования, за дурной знак

It’s a bad omen that/when... — это не предвещает ничего хорошего, это не сулит ничего хорошего; это не к добру

Example Sentences:

...It’s a bad omen that their daughter was born on Friday the thirteenth.
...They say iit's a bad omen when a black cat crosses your path.
...Should I have taken it as an ill omen when I saw my desk was the closest one to the photocopier? Not a chance. I'm writing this on my seventh ...
...It's always an ill omen when the week starts with me being unable to find my pocket comb.
...It’s a bad omen when a voodoo witch smears the blood of a chicken on your front door.

Opp.:
a good omen — хороший, добрый знак; хорошая, добрая примета

...Over the bay, he could see a falling star coming down through the sky towards him, and he took it as an omen that it would change his luck in the future. (David Holmes)

Related
doom (death or destruction; any terrible event that you cannot avoid)
to meet your doom
...She had a sense of impending doom (= felt that something very bad was going to happen).