The National Weather Service (NWS) is the official U.S. government agency charged with issuing weather watches, warnings, and advisories and is the source used by iAlert.com. Below is the criteria used by NWS forecasters when issuing a tropical storm watch or tropical storm warning for the affected coastline.
TROPICAL STORM WATCH: means tropical storm conditions of 39-73 mph (34-63 kts or 63-118 kph) are possible within 36 hours for affected coastline.
TROPICAL STORM WARNING: means tropical storm conditions of 39-73 mph (34-63 kts or 63-118 kph) are expected for defined coastal area within 24 hours or less.
A tropical storm is less powerful than a hurricane. Criteria for Hurricane Warning