STORM FACT
Tropical disturbance, tropical wave
A cluster of clouds and thunderstorms in the tropics without a defined circulation.
Tropical depression:
A rotating system of thunderstorms in the tropics with winds of less than 39 mph.
Tropical storm
A rotating system of strong thunderstorms with top sustained winds of 39 to 73 mph. Storms are named when they reach this strength.
Hurricane:
An intense, rotating tropical weather system with sustained winds of 74 mph or higher.
Tropical storm watch:
Tropical storm conditions are possible in the watch area within about 36 hours.
Tropical storm warning:
Tropical storm conditions are expected in the warning area within about 24 hours.
Hurricane watch:
Hurricane conditions are possible in the watch area within about 36 hours. Your hurricane preparations should be underway.
Hurricane warning:
Hurricane conditions are expected in the warning area within 24 hours. All preparations should be complete, and if evacuating, you should be on your way to a safe place.
Storm surge:
A mound of ocean water up to 20 feet high that can come ashore with a hurricane. Evacuation zones are identified by the likelihood of being flooded by this rising water. Most hurricane-related deaths are from storm surge flooding. Storm surge flooding can occur over 100 miles of coastline and may extend inland several miles.
Category 1 (winds 74-95 mph)
Storm surge 4-5 feet above normal. Damage primarily to shrubbery, trees, foliage, and unanchored homes. No real damage to other structures. Some damage to poorly constructed signs. Low-lying coastal roads inundated, minor pier damage, some small craft in exposed anchorage torn from moorings.
Category 2 (winds 96-110 mph)
Storm surge generally 6-8 feet above normal. Considerable damage to shrubbery and tree foliage; some trees blown down. Major damage to exposed mobile homes. Extensive damage to poorly constructed signs. Some damage to roofing materials of buildings; some window and door damage. No major damage to buildings. Coast roads and low-lying escape routes inland cut by rising water 2 to 4 hours before arrival of hurricane center. Considerable damage to piers. Marinas flooded. Small craft in unprotected anchorages torn from moorings. Evacuation of some shoreline residences and low-lying areas required.
Category 3 (winds 111-130 mph)
Storm surge generally 9-12 feet above normal. Foliage torn from trees; large trees blown down. Practically all poorly constructed signs blown down. Some damage to roofing materials of buildings; some wind and door damage. Some structural damage to small buildings. Mobile homes destroyed. Serious flooding at coast and many smaller structures near coast destroyed; larger structures near coast damaged by battering waves and floating debris. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Flat terrain 5 feet of less above sea level flooded inland 8 miles or more. Evacuation of low- lying residences within several blocks of shoreline possibly required.
Category 4 (winds 131-155 mph)
Storm surge generally 13-18 feet above normal. Shrubs and trees blown down; all signs down. Extensive damage to roofing materials, windows and doors. Complete failures of roofs on many small residences. Complete destruction of mobile homes. Flat terrain 10 feet or less above sea level flooded inland as far as 6 miles. Major damage to lower floors of structures near shore due to flooding and battering by waves and floating debris. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Major erosion of beaches. Massive evacuation of all residences within 500 yards of shore possibly required, and of single- story residences within 2 miles of shore.
Category 5 (winds more than 155 mph)
Storm surge generally greater than 18 feet above normal. Shrubs and trees blown down; considerable damage to roofs of buildings; all signs down. Very severe and extensive damage to windows and doors. Complete failure of roofs on many residences and industrial buildings. Extensive shattering of glass in windows and doors. Some complete building failures. Small buildings overturned or blown away. Complete destruction of mobile homes. Major damage to lower floors of all structures less than 15 feet above sea level within 500 yards of shore. Low-lying escape routes inland cut by rising water 3 to 5 hours before hurricane center arrives. Massive evacuation of residential areas on low ground within 5 to 10 miles of shore possibly required.
