In an ominous manner; with sinister foreboding(adverb)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "ominously" in a sentence
"Maya leaves the room causally as if to visit the ladies 'and the cameras keep zooming in ominously on her naked mannequin."
"For example, things begin ominously in Matt Brighton's DVD Authority review of To Catch a Thief."
"And now, as we emerge from the pine-wood, a new Dolomite – a huge, dark, mournful-looking mountain ominously splashed with deep red stains – rises suddenly into towering prominence upon our left, and seems almost to overhang the road."