A Tropical Storm Warning is issued when Tropical Storm conditions including winds of 39-73 mph are EXPECTED in a specified coastal area within 36 hours. A Tropical Storm Warning is issued when sustained winds of 34 to 63 kt 39 to 73 mph or higher associated with a tropical cyclone are. An announcement that sustained winds of 34 to 63 knots 39 to 73 mph or 63 to 118 kmhr are expected somewhere within. A hurricane warning is issued when hurricane-force winds are expected within 24 hours A hurricane warning can remain in effect when. Because hurricane preparedness activities become difficult once winds reach tropical storm force sustained winds of 39 to 73 mph the hurricane..