Tropical cyclone warnings and watches
Warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane strength. They are notices to the local population and civil authorities to make appropriate preparation for the cyclone, including evacuation of vulnerable areas where necessary. It is important that interests throughout the area of an alert make preparations to protect life and property, and do not disregard it on the strength of the detailed forecast track. Tropical cyclones are not points, and forecasting their track remains an uncertain science.
A tropical storm watch is issued by the National Hurricane Center when tropical storm effects are a possible threat to an area within 48 hours. Tropical storm effects include winds from 39 to 73 mph (35 to 64 knots, 63 to 117 km/h). Maritime flags indicate this with a single square red flag.
A tropical storm warning is issued when tropical storm effects are expected within 36 hours or less. Maritime flags indicate this with two square red flags.