Tropical Wave A disturbance in the tropics without a defined circulation.
Tropical Depression A rotating system of thunderstorms in the tropics with winds less than 39 mph.
Tropical Storm A rotating system in which the maximum sustained surface wind speed is between 39 – 73 mph. Storms are named when they reach this strength.
Hurricane An intense rotating tropical weather system with maximum sustained surface wind speeds of 74 mph or higher.
Storm Surge An abnormal rise in sea level accompanying a hurricane or other intense storm, and whose height is the difference between the observed level of the sea surface and the level that would have occurred in the absence of the cyclone. Storm surge is usually estimated by subtracting the normal or astronomic high tide from the observed storm tide.
Tropical Storm Watch An announcement that sustained winds of 39 to 73 mph is possible within the specified area within 48 hours.
Tropical Storm Warning An announcement that sustained winds of 39 to 73 mph are expected somewhere within the specified area within 36 hours.
Hurricane Watch An announcement that sustained winds of 74 mph or higher is possible within the specified area. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane watch is issued 48 hours in advance of the anticipated onset of tropical storm force winds. Be ready to implement your hurricane preparation plans immediately if a warning is issued.
Hurricane Warning An announcement that sustained winds of 74 mph or higher are expected somewhere within the specified area. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the warning is issued 36 hours in advance. All preparations should be completed immediately. If you are evacuating you should travel outside of the evacuation zone. It is strongly recommended that you stay in a safe building until the storm has passed.
