an indication that something is going to happen
presage - sign
A ‘presage’ is a sign or even a feeling of what is going to happen in the future. This formal word is, unlike some of its synonyms, used almost exclusively in relation to something bad. It can be used as either a noun or a verb. As a noun it is an indication of something, as a verb, it means to make a prediction or give a warning of what is to come.
Some experts believe that the recent dips in the market could presage a general recession, so we should consider taking appropriate measures.
The patient is showing a number of symptoms that typically presage the onset of a cardiac arrest.
The lawyer felt that the jury’s quick deliberation time was a presage of a guilty verdict.