Tropical terms and how a meteorologist might use them
Tropical wave: a broad, generally disorganized axis of relatively low air pressure over tropical waters. "We will keep a close eye on a tropical wave just west of Africa as it has a chance to organize and strengthen in the coming days."
Tropical depression: a tropical low-pressure system with a full wind circulation of speeds of 38 mph or less. "The tropical wave we've been monitoring has developed into Tropical Depression Number One. We will continue to monitor this organizing system."
Tropical storm: a tropical low-pressure system with a full wind circulation of speeds of between 39 and 73 mph. "The National Hurricane Center indicates that Tropical Depression One has strengthened into a tropical storm named Alex with maximum winds estimated at 50 mph."
Hurricane: a tropical low-pressure system with a full wind circulation of speeds of 74 mph or more. "Tropical Storm Alex has strengthened into a hurricane. Steering winds should guide this ferocious system northwestward, over the open waters of the Atlantic, in the coming days."
Eye, eye wall, and spiral bands: the three main structural components of a hurricane. "Aircraft reports who Hurricane Alex's lowest air pressure is 955mb in its eye. Alex's maximum winds of 110 mph were found in its eye wall - or the tall ring of thunderstorms surrounding the eye. Spiral bands of clouds and rain continue to circulate around Alex - feeding moisture and energy to its central core."
Watch and warning: storm bulletins. A "watch" means conditions are possible within two to three days. A "warning" means conditions are likely within one to two day. "Hurricane Alex's likely path is east of Bermuda, but still close enough that the National Hurricane Centers has hoisted a Hurricane Watch for the island. Hopefully, Alex will stay on-course, but if it happens to make a closer pass to Bermuda, the watch may later be upgraded to a warning. We will continue to closely monitor Alex."