without warning

abrupt breakneck brief frantic gone off half-cocked harum-scarum hasty headlong heedless hurried ill-advised impatient impetuous indiscreet jump the gun madcap off the hip off the top of head plunging precipitant quick rapid rash reckless refractory rushing subitaneous swift unanticipated uncontrolled unexpected unforeseen violent willful

careful cautious slow

amazing astonishing extraordinary remarkable shocking startling stunning sudden unanticipated unforeseen unpredictable wonderful

chance electrifying

accidental fortuitous from left field impulsive out of the blue unpredicted

expected normal ordinary predictable usual

unannounced unanticipated unpredicted

announced celebrated expected glorified predicted recognized

suddenly unawares

aback by surprise forthwith sudden unanticipatedly unaware unexpectedly without delay without hesitation

abruptly all of a sudden quickly swiftly

short

aback all at once asudden forthwith on spur of moment sudden unanticipatedly unaware unawares

expectedly slowly

expeditiously hastily promptly quickly rapidly speedily

fleetly

apace double-quick flat-out full tilt hotfoot hurriedly posthaste quick swift

slowly

sluggishly

apace double-quick expeditiously flat-out fleetly full tilt hastily hurriedly in no time posthaste promptly quick quickly rapidly speedily without losing time

slowly sluggishly