ominous

Ominous didn't always mean "foreshadowing evil." If you look closely, you can see the "omen" in "ominous," which gave it the original meaning of "presaging events to come" - whether good or bad. It is ultimately derived from the Latin word omen, which is both an ancestor and a synonym of our "omen." Today, however, "ominous" tends to suggest a menacing or threatening aspect. Its synonyms "portentous" and "fateful" are used similarly, but "ominous" is the most menacing of the three. It implies an alarming character that foreshadows evil or disaster. "Portentous" suggests being frighteningly big or impressive, but seldom gives a definite forewarning of calamity. "Fateful" implies that something is of momentous or decisive importance.