ominously

adv

1. In an ominous manner; with sinister foreboding.

   “From first to last he was ominously polite, and ominously silent.”

   “His nostrils flared ominously and his fists opened and closed at his sides.”

   “However, the next day dawned ominously with an overcast sky and we postponed our start till 8 o'clock.”

   “Just as the Census Bureau forecasts growing racial diversity under any future level of immigration, it likewise projects ominously slow growth in America’s working-age population without more immigration.”