A region of cloudy, relatively disorganized, weather in the tropics These sometimes develop into a tropical storm (and later into a hurricane).
Tropical cyclone that maintains its identity for at least 24 hours and is marked by moving thunderstorms and with slight or no rotary circulation at the water surface. Winds are not strong. It is a common phenomenon in the tropics and is the first discernable stage in the development of a hurricane.
A powerful storm that forms over water in the tropics or subtropics and holds its strength for 24 hours or more. As it gains power, it may become a tropical wave, tropical depression, tropical storm, or hurricane.
Cyclonic winds that develop in the tropics.
an unorganized mass of clouds, showers, and thunderstorms that are generally 100 to 300 miles in diameter and develop in the tropics or subtropics
a cluster of showers and thunderstorms with little or no circulation
a cluster of thunderstorms that is beginning to rotate.
A distinct tropical weather system of apparently organized convection originating in the tropics or subtropics and maintaining its identity for 24 hours or more. It may or may not be associated with a detectable perturbation of the wind field (in other words, a tropical disturbance does not always have a center of lowest air pressure- where the wind spirals towards).
A term used by the U.S. National Weather Service for a cyclonic wind system in the tropics that is in its formative stages.
A moving area of thunderstorms is in the tropics.
Tropical cyclone with wind speeds less than 20 knots.
An area of convection originating in the tropics. Has the potential to develop into a tropical depression.
An organized mass of tropical thunderstorms, with a slight cyclonic circulation, and winds less than 20 knots.
Often the earliest stages of a tropical cyclone. Normally an organized area of thunderstorms that forms in the tropics and persists for more than 24 hours. Low pressure might form at the surface, but winds around remain below 30 mph.
A discrete tropical weather system of apparently organized convection--generally 100 to 300 nmi in diameter---originating in the tropics or subtropics, having a nonfrontal migratory character, and maintaining its identity for 24 hours or more. It may or may not be associated with a detectable perturbation of the wind field.
An area of organized convection, originating in the tropics and occasionally the subtropics, that maintains its identity for 24 hours or more. It is often the first developmental stage of any subsequent tropical depression, tropical storm, or hurricane.
An organized mass of thunderstorms with a slight cyclonic wind circulation of less than 20 knots.
An organized group of thunderstorms often found over a tropical ocean that generates a slight cyclonic flow of less than 37 kilometers per hour. Can develop into a hurricane.
A hurricane goes through many stages as it develops. As the warm, moist air over the ocean rises in the low air pressure area, cold air from above replaces it. This produces strong gusty winds, heavy rain and thunderclouds that is called a tropical disturbance.
A discrete system of clouds, showers, and thunderstorms (organized convection) that originate in the tropics. Generally 100 to 300 miles in diameter and originating in the tropics or subtropics, disturbances have a nonfrontal migratory character, and maintain their identity for 24 hours or more. It may or may not be associated with a detectable perturbation of the wind field. An upper level of low pressure causes this to occur. Approximately 100 of these types of events occur annually during hurricane season.
