Emergency managers seem to have their own language when talking about hurricanes. Use this glossary of terms to better understand the storm language.
ADVISORY — A message from the National Hurricane Center in Miami giving warning information with details on tropical cyclone location, intensity, movement and precautions that should be taken. The advisory will contain a resume of all warnings in effect
EMERGENCY ALERT SYSTEM (EAS) — A system designed to permit government officials to issue up-to-date and continuous emergency information and instructions to the public in case of a threatened or actual emergency. It is replacing the Emergency Broadcast System.
EMERGENCY PUBLIC SHELTER — Generally a public school or other such structure designated by county or city officials as a place of refuge. A volunteer group such as the American Red Cross or Salvation Army usually manages a shelter.
EMERGENCY OPERATIONS CENTER (EOC) — A State, county or city emergency facility that serves as a central location for the coordination and control of all emergency preparedness and response disaster activities.
EYE — The center of a tropical storm or hurricane characterized by a roughly circular area of light winds and rain-free skies and the lowest pressure. An eye will usually develop when the maximum sustained wind speeds exceed 78 mph. It can range in size from as small as 5 miles to up to 60 miles (20-50 km) but the average size is 20 miles. In general, when the eye begins to shrink in size, the storm is intensifying.
EYE WALL — An organized band of convection surrounding the eye, or center, of a tropical cyclone. It contains cumulonimbus clouds (A cloud type that is dense and vertically developed. It is heavy and dense with a flat base and a high, fluffy outline, and can be tall enough to occupy middle as well as low latitudes.), and the severest thunderstorms, heaviest precipitation and strongest winds.
FEEDER BANDS — In weather forecaster terminology its the lines or bands of thunderstorms that spiral into and around the center of a tropical system. Also known as outer convective bands, a typical hurricane may have three or more of these bands. They occur in advance of the main rain shield and are usually 40 to 80 miles apart. In thunderstorm development, they are the lines or bands of low-level clouds that move or feed into the updraft region of a thunderstorm.
FLOOD WARNING — The expected severity of flooding (minor, moderate or major) as well as where and when the flooding will begin.
HURRICANE: — A tropical cyclone in the Northern Hemisphere with sustained winds of at least 74 mph (64 knots) or greater in the North Atlantic Ocean, Caribbean Sea, Gulf of Mexico or the eastern North Pacific Ocean. These winds blow in a large spiral around a relatively calm center of extremely low pressure known as the eye. Around the rim of the eye, winds may gust to more than 200 miles per hour. Hurricanes draw their energy from the warm surface water of the tropics and latent heat of condensation, which explains why hurricanes dissipate rapidly once they move over cold water or large land masses.
HURRICANE ADVISORY — Notice issued by the National Hurricane Center, numbered consecutively for each storm, describing the present and forecasted position and intensity. Advisories are issued at six-hour intervals at midnight, 6 a.m., noon and 6 p.m., Eastern Daylight Time.
HURRICANE EYE LANDFALL — When the eye, or physical center of the hurricane, reaches the coastline from the hurricane's approach over water.
HURRICANE HUNTERS — The 53rd Weather Reconnaissance Squadron of the U.S. Air Force Reserve, based out of Keesler Air Force Base in Biloxi, Miss. As a part of the 403rd Air Wing, the crew flies Lockheed WC-130 aircraft into tropical storms and hurricanes to gather meteorological data for the National Hurricane Center.
HURRICANE PATH OR TRACK — Line of movement (propagation) of the eye through an area.
HURRICANE SEASON — The portion of the year having a relatively high incidence of hurricanes. The hurricane season in the Atlantic, Caribbean and Gulf of Mexico runs from June 1 to Nov. 30.
HURRICANE WARNING — A warning added to a hurricane advisory that sustained winds of 74 mph (64 knots) or higher associated with a hurricane are expected in a specified coastal area within 24 hours or less. A hurricane warning can remain in effect when dangerously high water or a combination of dangerously high water and exceptionally high waves continue, even though winds may be less than hurricane force. A warning is used to inform the public and marine interests of the storm's location, intensity and movement. The National Hurricane Center chooses a distance of approximately 300 miles.
HURRICANE WATCH — An announcement added to a hurricane advisory that hurricane conditions pose a possible threat to a specified coastal area within 36 hours. A watch is used to inform the public and marine interests of the storm's location, intensity and movement.
LANDFALL — The term used to describe where the hurricane eye actually passes over land, usually used to describe the continental States rather than islands in the Caribbean.
NATIONAL HURRICANE CENTER (NHC) — A Branch of the Tropical Prediction Center under the National Weather Service, it is responsible for tracking and forecasting tropical cyclones over the North Atlantic, Caribbean, Gulf of Mexico, and the Eastern Pacific.
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA) — An Administration of the U.S. Department of Commerce, it is the parent organization of the National Weather Service. It promotes global environmental stewardship, emphasizing atmospheric and marine resources.
NATIONAL WEATHER SERVICE (NWS) — A primary office of the National Oceanic and Atmospheric Administration, it is responsible for all aspects of observing and forecasting atmospheric conditions and their consequences, including severe weather and flood warnings.
NOAA WEATHER RADIO — A 24-hour continuous broadcast of existing and forecasted weather conditions operated and broadcast by the local field offices of the National Weather Service.
NORTH ATLANTIC BASIN (SOMETIMES CALLED THE ATLANTIC BASIN) — The Atlantic Ocean north of the equator, the Caribbean Sea and the Gulf of Mexico.
RADAR (RADIO DETECTION AND RANGING) — An electronic instrument using ultra high-frequency radio waves to detect distant objects and measure their range by how they scatter or reflect radio energy. Precipitation and clouds are detected by measuring the strength of the electromagnetic signal reflected back. Doppler radar and NEXRAD are examples
SAFFIR-SIMPSON DAMAGE-POTENTIAL SCALE — A scale, developed in the early 1970s by Herbert Saffir, a consulting engineer, and Robert Simpson, then Director of the National Hurricane Center, to measure the intensity of a hurricane from 1 to 5.
SHELTER PERIOD — The period in which people are forced to evacuate their homes. This time may vary from several hours to a couple of days depending upon the severity of the hurricane.
STATE OF EMERGENCY — A declaration made by the Chief Elected Official of a state, county or city government which entails a heightened level of activation and mobilization of staff to protect property and lives.
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. Note: waves on top of the storm surge will create an even greater high-water mark.
STORM TIDE — The actual level of seawater resulting from the astronomic tide combined with the storm surge. If the storm comes ashore during astronomical low tide, the surge will be decreased by the amount of the low tide. If the storm makes landfall during astronomical high tide, the surge will be that much higher.
SWATH — The width of the path of the hurricane. Usually this path area is about 125 miles wide with 75 miles to the right of the eye and 50 miles to the left of the eye.
TROPICAL DEPRESSION (TD) — A tropical cyclone in which the maximum sustained surface winds (1 minute average) are 38 miles per hour (33 knots) or less. Characteristically having one or more closed isobars (Lines drawn on a weather map indicating regions of equal pressure. When the lines are close together, this indicates a rapid change in air pressure, accompanied by strong winds.), it may form slowly from a tropical disturbance or an easterly wave, which has continued to organize. At this point, it gets a cyclone number, starting with "TD01" at the beginning of each storm season.
TROPICAL DISTURBANCE — A discrete system of clouds, showers and thunderstorms (organized convection). Generally are 100 to 300 miles in diameter, originate in the tropics or subtropics, and maintain their identity for 24 hours or more. Approximately 100 of these types of events occur annually during hurricane season.
TROPICAL STORM (TS) — A tropical cyclone in which the maximum sustained surface wind speed (1 minute average) is within the range of 39 to 73 mph (34 to 63 knots). At this point, the system is given a name to identify and track it. In the Atlantic/Caribbean/Gulf of Mexico basin, the names start with "A" each season.
TROPICAL STORM WATCH — An announcement issued by the National Hurricane Center for specific areas that a tropical storm or a forecast of tropical storm conditions poses a possible threat to coastal areas generally within 36 hours. A tropical storm watch normally should not be issued if the system is forecast to attain hurricane strength.
TROPICAL STORM WARNING — A warning issued by the National Hurricane Center for tropical storm conditions including possible sustained winds within the range 39 to 73 mph (34 to 63 knots) which are expected in a specified coastal area within 24 hours or less.