Tropical Cyclone Warnings and Watches - North Atlantic Systems

North Atlantic Systems

The following terminology used by the US National Hurricane Center is the model for countries around the North Atlantic and in the Caribbean basin. This is also used for the Pacific coasts of Mexico, Central America, southern California, and Hawaii. The timing and naming of tropical cyclone advisories, watches, and warnings has changed over time. In 1958, tropical cyclone advisories were issued every six hours starting at 0400 UTC each day. During 1967, hurricane watches were used to designate areas where hurricane conditions were possible in the next 24 hours, while hurricane warnings indicated areas where the hurricane center should cross the coast. Small craft, gale, and storm warnings were issued for hurricanes not expected to make landfall. By 1987, the definition of tropical cyclone watches had changed to areas where gale or hurricane-force winds were possible within 36 hours, with warnings issued when gale or hurricane-force winds were expected within 24 hours. In 1987, gale watches/warnings were renamed tropical storm watches/warnings. In 1991, advisory timing shifted back to every six hours starting at 0330 UTC every day. In 1992, advisory timing changed to every six hours starting at 0300 UTC each day. The length of time used for watches and warnings changed again in 2010, with watches using a 48 hour time frame and warnings using a 36 hour time frame.