amazing, astonishing, astounding, blindsiding, dumbfounding(also dumfounding), eye-opening, flabbergasting, jarring, jolting, shocking, startling, stunning, stupefying, surprising

unannounced, unanticipated, unexpected, unforeseenawesome, awful, breathtaking, fabulous, heart-stopping, marvelous(or marvellous), miraculous, portentous, prodigious, staggering, stupendous, sublime, wonderful, wondrousextraordinary, phenomenal, rare, sensational, spectacularbefuddling, bewildering, confounding, confusing, discomfiting, disconcerting, dismaying, flustering, muddling, nonplussing(also nonplusing), perplexing, upsettingincomprehensible, inconceivable, incredible, unbelievable, unimaginable, unlikely, unthinkablesingular, uncommon, unique, unusual, unwontedconspicuous, notable, noticeable, outstanding, remarkableimpressive, striking