Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ōmĭnōsē, adv., v. ominosus fin.
ōmĭnōsus, a, um, adj. [omen], full of foreboding, portentous, ominous (post-Aug.): mons avibus obscenis ominosus, Messala ap. Gell. 13, 14, 6: res, Plin. Ep. 3, 14, 11.
Adv.: ōmĭnōsē, ominously: ominose retentus, Ps.-Quint. Decl. 6, 5.