a feeling that trouble is coming

misgiving, bad omen

a sign of what is to follow; a person who prepares for the coming of another person or thing

messenger, herald

something that (often by mistake) causes something secret to be known

revealing

evidence, clue

evidence, clue

suggesting

exhibitive

(something, a happening, regarded as) a sign of something good or warning of evil fortune

sign of something to come

an omen

indication, forewarning

indicating correctly what will happen

telling of the future

a mark, object, symbol etc used to represent something: 'mathematical sings' such as '+', '-', 'x', '?'; a word or words, design etc on a board or plate to give a warning, or to give direction; to write (one's name) on (a letter, application form etc)

indication, evidence

a strong feeling or reaction

indication, forewarning