forbiddingly
    adv 1: in an unpleasant or menacing manner; "it was forbiddingly
           dark in the corridor"

Forbidding \For*bid"ding\, a.
   Repelling approach; repulsive; raising abhorrence, aversion,
   or dislike; disagreeable; prohibiting or interdicting; as, a
   forbidding aspect; a forbidding formality; a forbidding air.

   Syn: Disagreeable; unpleasant; displeasing; offensive;
        repulsive; odious; abhorrent. -- For*bid"ding*ly, adv.
        -- For*bid"ding*ness, n.
        [1913 Webster]